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| | | HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | OK..I need some help. I have a 77 B100 with a 318. Lat weekend I installed a new fuel tank and sending unit (along with everything else from the carb back (lines, filters, fuel pump). The van runs great but the gauge isn't working. There is not a lot of gas in the tank (3-4 gallons) but that should be enough to read on the gauge. I checked the ground wire on the sending unit and it is good and getting a good ground. I also know the other wire (from the sending unit to the gauge) is good because when I ground that out the gauge will rise. I am inclined to put another 5 gallons in to see if that will register but I really don't want to have to pump it all back out if I have to drop the tank again. It could be that the new sending unit is bad but I wouldn't suspect that but is there a way to check it when it is in the tank. One other issue: I pulled the instrument panel to get to the back of the fuel gauge to see if I was getting a connection and when I check it with a test light I don't get a steady light but a pulsing circuit almost as if a blinker would work. What causes that? Any advice or help I can get would be GREATLY appreciated....I really don't want to have to drop the tank again!!! Thank you! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2005 Posts: 21,211 Likes: 25 Supreme Master | Supreme Master Joined: Aug 2005 Posts: 21,211 Likes: 25 | When you first turn the key to 'ON' does the needle move at all? My theory is that these aftermarket sending units are not of the same quality as OEM, so there may be some ohm range variances. Worst case is put your old sending unit back in, if it worked.
Does the pulsing occur with the engine running? If so, that could be an alternator/voltage regulator issue. The lights on my 72 would pulse at idle. I ended up replacing the alternator and regulator (I ran a dedicated ground to the regulator as well). That fixed the issue.
Nate Breece | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2001 Posts: 12,107 Likes: 37 Maniac | Maniac Joined: Aug 2001 Posts: 12,107 Likes: 37 | Like Nate recommends, I would put the old sending unit back in. However, while you have both sending units out, I would use an ohm meter to check that each sending unit (a) has the same resistance value and (b) the value changes smoothly as the float lever arm is moved. You could have a faulty instrument cluster voltage regulator. There are new replacements that re a vast improvement over the old stock regulator. Get the new and improved instrument cluster voltage regulators HERE and HERE or you can build your own as described HERE.
Last edited by Reed; January 25th 2012 3:28 pm.
Windows- they're what make a van worth owning! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | Unfortunately, I don't have the old sending unit anymore. When I dropped the tank to check out the inside of the tank and the sending unit I found them to be way worse than expected. The tank had a hole in it where it had rusted through and the tank was rusted very badly inside and had about 3/4 inch of rust and "gunk" in the bottom of the tank. The sending unit was in bad shape, the wire had corroded through and wasn't attached, the entire sending unit was caked in about 1/2 of rust and gunk and it was so rusted that the float lever wouldn't even move. I am slowly narrowing down the problem (I think). I know the gauge will work because if I ground out the connection at the sending unit it goes to showing full. I know the ground is good because I even ran a ground right from the battery to check it. I know the wire from the sending unit is good because the gauge will move if I ground it out at the sending unit. So....that leaves either a bad sending unit (even though it is brand new) or a bad gauge cluster voltage limiter. It is my understanding that if I put an ohm meter to the sending unit it will give me a reading of 90-95 if the tank is empty or 5-10 on an full tank. I have about 4 gallons in it so I expected the ohm meter to go to 70-80. When I put an ohm meter to it, it read 76 ohms which is about what I would expect so it appears that the sending unit is ok. The gauge just stays on empty. So I am guessing (hoping) it is the gauge cluster voltage limiter. I ordered one today and can pick it up tomorrow. I hope that's it....I REALLY don't want to have to empty and drop the tank again!!!
Last edited by Lee7673; January 25th 2012 11:53 pm.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Nov 2003 Posts: 3,124 pooh-bah | pooh-bah Joined: Nov 2003 Posts: 3,124 | It'll take more gas than that to make the float "float". Think about the surface area of the bottom of the tank and how thick the diameter of the float is. Most vehicles have a "reserve" when the gauge shows empty because there has to be at least a couple inches of gas to get that float off the bottom.
In the event that you ever need to drain the tank again, simply jack up the rear axle just to the driver's side of the pumpkin a bit, and disconnect the line at the fuel pump. Gravity will drain it dry.
Last edited by Boot; January 26th 2012 2:04 am.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2001 Posts: 12,107 Likes: 37 Maniac | Maniac Joined: Aug 2001 Posts: 12,107 Likes: 37 | It'll take more gas than that to make the float "float". Think about the surface area of the bottom of the tank and how thick the diameter of the float is. Most vehicles have a "reserve" when the gauge shows empty because there has to be at least a couple inches of gas to get that float off the bottom. This is true. My 83 Dodge has the plastic 36 gallon tank. When the gauge says empty I actually have about ten gallons of gas left. So that means I can drive about 100 miles on "E."
Windows- they're what make a van worth owning! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2001 Posts: 28,125 Madman! | Madman! Joined: Oct 2001 Posts: 28,125 | What Boot said. With all of what you checked, it has to need more fuel to get the unit to move from just above the reserve fuel. | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2005 Posts: 21,211 Likes: 25 Supreme Master | Supreme Master Joined: Aug 2005 Posts: 21,211 Likes: 25 | Yes..what Scotty, Dr. McCoy, and Mr. Spock said. LOL!
Nate Breece | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2001 Posts: 12,107 Likes: 37 Maniac | Maniac Joined: Aug 2001 Posts: 12,107 Likes: 37 |
Windows- they're what make a van worth owning! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2005 Posts: 21,211 Likes: 25 Supreme Master | Supreme Master Joined: Aug 2005 Posts: 21,211 Likes: 25 | How appropriate considering the war of words lately between Shatner and Fisher. Stop the madness, they are both great franchises!
Nate Breece | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | Well.....since my last name is Hatfield, I don't trust anyone named McCoy!!!! But I will take advice from the other two! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2005 Posts: 21,211 Likes: 25 Supreme Master | Supreme Master Joined: Aug 2005 Posts: 21,211 Likes: 25 | Ahahahahahahahahah! I hear the banjos playing now!
Nate Breece | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2001 Posts: 28,125 Madman! | Madman! Joined: Oct 2001 Posts: 28,125 | It sometimes amazes me how threads topics get turned every which way | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | OK...back on topic. Need more help. I put more gas in the tank and the gas gauge didn't move (but the other three gauges seem to be working). I put the new instrument cluster voltage limiter in and the fuel gauge and amp gauge seem to be working but the temp gauge and oil pressure gauge just spike all the way up. Any suggestions??? Help!!! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Nov 2003 Posts: 3,124 pooh-bah | pooh-bah Joined: Nov 2003 Posts: 3,124 | Are these factory gauges?
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | Are these factory gauges?
Yes. This is the strangest issue. With the old limiter everything is working except fuel gauge and with the new limiter the fuel and amp gauge is fine but the oil and temp spike all the way up right away. | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2001 Posts: 12,107 Likes: 37 Maniac | Maniac Joined: Aug 2001 Posts: 12,107 Likes: 37 | Is this a "new" as in new from a parts store "new" voltage limiter or "new" in the sense that it came from another parts van?
I would look for a grounding issue at the circuit board and the associated wiring. Have you verified that the oil and temp sending units are correct and working right?
Windows- they're what make a van worth owning! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | It's new from NAPA. The other gauges work with the old limiter. I will say this....the new limiter (that NAPA looked up and said was correct) is the same size, has the three prongs (tabs) all in the exact same position but the new limiter has a tab off of the back of it that looks like it would be a grounding tab but the old limiter didn't have one and the new one didn't say anything about grounding the limiter. | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Nov 2003 Posts: 3,124 pooh-bah | pooh-bah Joined: Nov 2003 Posts: 3,124 | Try putting the original limiter in, turn on the key, and give the fuel gauge a couple minutes to register.If that doesnt work, then I'd say you have a problem in the circuit board itself. The simplest fix is to go back to the original limiter, so the other 3 gauges work and if need be, run a new positive wire to the fuel gauge. Do you have a factory wiring diagram? If not there's one here: http://moparbvans.proboards.com/index.cgi?board=factdiags&action=display&thread=241The circuit boards are a common problem in these vans.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | Try putting the original limiter in, turn on the key, and give the fuel gauge a couple minutes to register.If that doesnt work, then I'd say you have a problem in the circuit board itself. The simplest fix is to go back to the original limiter, so the other 3 gauges work and if need be, run a new positive wire to the fuel gauge. Do you have a factory wiring diagram? If not there's one here: http://moparbvans.proboards.com/index.cgi?board=factdiags&action=display&thread=241The circuit boards are a common problem in these vans. Thanks Boot. This is awesome. I did try cleaning the circuit board tonight and I did trace the ground down and cleaned it real good...but no success. I think my next step is to isolate the fuel gauge and run a new positive wire to it. | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Mar 2007 Posts: 4,463 Likes: 12 pooh-bah | pooh-bah Joined: Mar 2007 Posts: 4,463 Likes: 12 | Your amp gauge reading is unrelated to the erroneous readings of the other gauges; it's not powered by the voltage limiter.
You said the fuel gauge appears to be working with the new voltage limiter... what does it actually read that indicates this? I'm suspicious of the readings being inaccurate, as the other gauges haven't changed, and both are acting up. I'm 102% with Boot on using your original regulator, at least until you obtain realistic readings from your fuel gauge.
When the oil and temperature gauges peg, that usually indicates faulty grounding of the instrument cluster, just like Reed said. The "E" terminal on the round multi-pin instrument cluster connector should go to a white/black wire terminating in a terminal which connects somewhere on the dash/chassis metal frame to provide the instrument cluster ground. You said you traced a ground, but have you actually tried checking with an ohm meter between the (-) connection where the voltage limiter plugs in, to the chassis to see if there really is continuity? You could always run a temporary wire directly from the voltage limiter to the battery to be sure.
Typically what actually fails on these fuel gauge systems that throws everyone for a loop while they replace all the other parts right up to the bitter end, is the ground wire that runs between the sending unit on the fuel tank and the frame. It can fail (frequently due to corrosion) internally within it's plastic insulation, or it can have a bad connection on either end, either at the terminals or the contact surfaces. The simplest thing to do is replace it outright, and clean up both the surfaces it connects to. I'd put some dielectric grease on the cleaned up connections to help keep Oxygen and moisture out.
I have to wonder if the tab off the back of the NAPA regulator is actually the flange of a three-terminal solid state regulator like Reed referred you to? They do have a small screw-hole for mounting to a heatsink. If the NAPA limiter is in fact a solid state regulator, (not so easy to tell without measuring it) that tab may need to be grounded since a ground reference is needed for the solid state device to regulate, and that ground reference can't readily be derived from only the input and output terminals.
BTW, if you make up your own solid state regulator, please try to locate a "low dropout" version of a three-terminal voltage regulator; something like an LM2940. They are much less common, but are what was really designed for use in automotive applications. They will regulate over a much wider range of voltage before losing regulation. This is especially important if you may run your battery down. As further benefits, they are typically far more resistant to voltage reversals and nasty voltage spikes than a generic LM7805 regulator, and will disconnect themselves and the load as a protection mechanism in case of a drastic overvoltage condition.
-It's been such a LONG TIME... BlueShift>> 1981 Dodge Ram B250 Custom Sportsman Maxi Van It's what you learn after you know it all, that counts... Are you living to work, or working to live? Learning from my own mistakes is good, learning from yours would be much better! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | Let me see if I can answer. "You said the fuel gauge appears to be working with the new voltage limiter... what does it actually read that indicates this?" With the new limiter the fuel gauge rises to about 3/8 of a tank which is close as I have about 8.5 gallons of gas in it and its a 22 gallon tank (being that I just installed the tank I have kept track of the amount of gas I put in). With the old limiter the fuel gauge doesn't move at all (it is just below "E".) "The "E" terminal on the round multi-pin instrument cluster connector should go to a white/black wire terminating in a terminal which connects somewhere on the dash/chassis metal frame to provide the instrument cluster ground. You said you traced a ground, but have you actually tried checking with an ohm meter between the (-) connection where the voltage limiter plugs in, to the chassis to see if there really is continuity? You could always run a temporary wire directly from the voltage limiter to the battery to be sure." I found the ground wire (white with black tracer) and traced it to a spot on the dash next to the steering column. I took it of and cleaned it real good and sanded down the dash as well to get a good ground. ( I didn't check it with an ohm meter - I will try that today). I did take a ground wire off of the back tab of the voltage limiter (that's the ground tab - its just an extension of the front grounding tab) and ran it to a bolt on the motor but that didn't change anything. 'Typically what actually fails on these fuel gauge systems that throws everyone for a loop while they replace all the other parts right up to the bitter end, is the ground wire that runs between the sending unit on the fuel tank and the frame." I did check this. I decided to use the old wire vs the new one that came with the sending unis as it had a better connection and fit on the sending unit better. I did check it with a meter and I cleaned it (and the frame) real good to make sure I had a good ground. "I have to wonder if the tab off the back of the NAPA regulator is actually the flange of a three-terminal solid state regulator like Reed referred you to? They do have a small screw-hole for mounting to a heatsink. If the NAPA limiter is in fact a solid state regulator, (not so easy to tell without measuring it) that tab may need to be grounded since a ground reference is needed for the solid state device to regulate, and that ground reference can't readily be derived from only the input and output terminals." It is definitely a ground. It is just an extension of the same tab on the front that is the grounding tab (it is all one piece). I held a ground wire to it to the frame but it wasn't screwed or fitted on for a real good connection - was going to try to ground it today with a fitting) I don't know how to tell if it is a "solid state device". "BTW, if you make up your own solid state regulator"... That is WAY beyond my knowledge I am going to try to get a better ground on ther limiter today and see what happens or try to run another hot wire from the limiter to the fuel gauge and see what happens......it's driving me crazy!!!
Last edited by Lee7673; January 29th 2012 9:32 am.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2009 Posts: 3,772 pooh-bah | pooh-bah Joined: Oct 2009 Posts: 3,772 | Hope this isn't your problem but I had a wire come off inside the tank before.
The only Stephentown on earth. I don't mind Coming to work, but that 8hr wait to go home is a bitch. No matter how little I do, I always feel I could do less. "The only thing wrong with a perfect drive to work is that you end up at work." NOVA VANS 1990 Dodge B150
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | I can get all of the gauges working if I run both voltage limiters!!! I am beginning to think that there is something wrong with the old voltage limiter and the new one. As I mentioned before with the old one in, all of the gauges work except the fuel gauge. With the new one in, the only gauge that works is the fuel gauge!!!! If I put the old voltage limiter in and take the hot feed off of the fuel gauge and then hook up the new voltage regulator and run it just to the fuel gauge all of the gauges work.
Is there an issue with hooking it up this way (using two voltage limiters)? If I do this I understand that the hot feed to the 2nd limiter will have to be one that works off of the key.
I am thinking about buying another voltage limiter (because I do think the 1st one is defective) but it is getting expensive since they won't take any electrical parts back.
What do you think????
PS THANKS for all of the help so far!!!!
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2001 Posts: 12,107 Likes: 37 Maniac | Maniac Joined: Aug 2001 Posts: 12,107 Likes: 37 | Uh, if I were you I would pick up a spare instrument cluster and try swapping the whole mess out. You are getting some funky results that sound like a combination of bad wiring and bad components.
Windows- they're what make a van worth owning! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Nov 2003 Posts: 3,124 pooh-bah | pooh-bah Joined: Nov 2003 Posts: 3,124 | If it works, and you can secure the second limiter, I'd say run it. But, if it were me, I'd run an inline fuse (10a max) on the J8-18BK/W line that runs into the "H" terminal on the circuit board plug in. This wire feeds the power to the gauges only, but comes in live from the key switch.
If you follow the diagram back from that plug in, you'll see that that particular wire runs off the key switch terminal 11, which also feeds a bunch of other things as well, on the J10-16R line. So I'd say better safe than sorry.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Feb 2009 Posts: 247 enthusiast | enthusiast Joined: Feb 2009 Posts: 247 | Here is an easy method (listed in the '77 Factory Service Manual) of testing your voltage limiter:
Connect one lead of a voltmeter to the temperature sending unit and the other lead to a good ground.
leave the sending unit lead wire (pink w/black tracer line) attached to the sending unit.
Turn the inition switch to the "ON" position.
A fluctuating voltmeter indicates the voltage limiter is operating.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | AGHHHHH......after replacing (and checking) everything else, I believe the new sending unit I just installed is defective and is the culprit. Looks like I will dropping the tank again this weekend!!!! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Nov 2003 Posts: 3,124 pooh-bah | pooh-bah Joined: Nov 2003 Posts: 3,124 | bummer man. Sorry to hear that, but glad you're persistant!
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | OK....here is the update and it is driving me nuts!!!! Hopefully someone will have some input or an idea. I ran every test and scenario that I could think of and it all kept leading me back to a bad sending unit (even though the sending unit and tank were brand new). So....I got another sending unit and dropped the tank (again) to replace it. When I pulled out the new sending unit it worked (I hooked it up to the gauge) but wouldn't work in the tank. I installed the new sending unit (I did check to make sure it was working before I installed it) and my fuel gauge only comes up to "E" (I have 15 gallons of fuel in it). I have tried to isolate everything to find the issue. I ran a new hot lead direct from the battery to a limiter, a new ground wire direct from the battery to the sending unit (trying to eliminate a bad wire), a new wire from the sending unit to the gauge and it still will only go up to "E". So....it appears that both of the new sending units work but NOT when installed in the tank). Why??? Also...one other thing...if I wire the gauge up without the voltage limiter the gauge reads correctly. I did this the first time when I had 3/8 of a tank and it would read empty when hooked up through the circuit board but would read 3/8 when hooked up to 12 volts (which is what it should have read with the amount of gas I had). I tried it again today and now it reads empty when hooked up correctly but will read about 5/8 of a tank when hooked up to 12 volts (which would be correct with the amount of fuel I have in it now). Why would the gauge read correctly when hooked up direct? I know it is supposed to run at 5 volts coming out of the limiter. My friend and I have probably spent 12 hours (or more) trying to figure this out....including dropping the tank twice, replacing the sending unit twice, changing out voltage limiters, and even trying 3 different gauges and I always get the same results. What am I missing? I REALLY need some help.....its driving me NUTS!!!! Thanks.... | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2009 Posts: 3,772 pooh-bah | pooh-bah Joined: Oct 2009 Posts: 3,772 | I'm trying to picture what your doing to test it before you put it into the tank. Are you hooking it up to the wires that are in the tank for testing or are you just hooking it up someplace after tank but before the gauge?
If it's working hooked up to the tank wiring before you put it in the tank but not after, you have a break in the wire that's making momentary connection or a bad plug in line just before tank.
The only Stephentown on earth. I don't mind Coming to work, but that 8hr wait to go home is a bitch. No matter how little I do, I always feel I could do less. "The only thing wrong with a perfect drive to work is that you end up at work." NOVA VANS 1990 Dodge B150
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2001 Posts: 28,125 Madman! | Madman! Joined: Oct 2001 Posts: 28,125 | This is the reason most people hate automotive wiring.
I'm just grasping at straws here, but what about grounds? Is it possible that with the sending unit installed in the tank and the tank in place, you are loosing a ground or creating one where there shouldn't be one?
I remember my 73 Cuda had a braided wire with 2 clamps on it that clipped to the fuel sender line and to the line running to the carb. An old timer told me once it was to balance the voltage for the sending unit to work properly. Don't know if he was right or not though.
| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2005 Posts: 21,211 Likes: 25 Supreme Master | Supreme Master Joined: Aug 2005 Posts: 21,211 Likes: 25 | Mopar sending units are grounded via the fuel line running up to the engine. That jumper strap must be in place for it to work.
Nate Breece | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | Mopar sending units are grounded via the fuel line running up to the engine. That jumper strap must be in place for it to work. Nate, This is after market tank and sending unit. Its a Spectra sending unit (its the only after market brand I could find and I couldn't find a NOS one). The sending unit has three things coming out of it: a fuel line, a connection for the wire going to the gauge cluster and a tab with a wire coming off of it with a ring at the end for grounding (which I have grounded to the chassis). Do I still need the jumper strap? Thank you in advance...I appreciate all of your input. | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Sep 2008 Posts: 3,473 Likes: 1 pooh-bah | pooh-bah Joined: Sep 2008 Posts: 3,473 Likes: 1 | I have rebuilt my own sending unit in my 75 , same sending unit, anyway it is easy as bending a few tabs and opening up the little box and see if the rheostat is making contact with the finger that is supposed to be doing just that or do like Nate says and put the old one in, best bet if there are no new ones from your dealer. I know there are about three left for the Phoenix vintage FOS from Dodge at stock price. I got one for my tank Change. IF push comes to shove I have another brand new '86 tank and you can get a stock sending unit for it and just bring your wires around to the side of the tank and hook it up. Dodges are all the same set up even my 86 tank is dimpled for the right rear dump of the older models. They were pretty good about making easy changes. Good luck, Just an after mkt glitch I am sure
Cheers! Been There, done that, Member of those.... Built for comfort not for speed ....Well speed too !... I am a vanner, Promise me the world, give me nothing, I'll be back ... next year ! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | I spoke with a mechanic tonight and he thinks the tank might be positively charged (due to all of the excess wiring in the van....a wire might have been hit with a screw...he had 4 batteries in the van....its a mess). He said if it was it would only take a couple of millivolts to cause the gauge not to work. Thoughts? | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Aug 2005 Posts: 21,211 Likes: 25 Supreme Master | Supreme Master Joined: Aug 2005 Posts: 21,211 Likes: 25 | Mopar sending units are grounded via the fuel line running up to the engine. That jumper strap must be in place for it to work. Nate, This is after market tank and sending unit. Its a Spectra sending unit (its the only after market brand I could find and I couldn't find a NOS one). The sending unit has three things coming out of it: a fuel line, a connection for the wire going to the gauge cluster and a tab with a wire coming off of it with a ring at the end for grounding (which I have grounded to the chassis). Do I still need the jumper strap? Thank you in advance...I appreciate all of your input. Ah so. Okay..I didn't know the new sending unit had a dedicated wire for ground. Are you positive the chassis is getting a good ground up the the battery? Mopar wiring in those years is a nightmare I admit...all the lights and stuff are grounded via the chassis as well.
Nate Breece | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2001 Posts: 28,125 Madman! | Madman! Joined: Oct 2001 Posts: 28,125 | Yeah, that's the strap | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Oct 2001 Posts: 28,125 Madman! | Madman! Joined: Oct 2001 Posts: 28,125 | I spoke with a mechanic tonight and he thinks the tank might be positively charged (due to all of the excess wiring in the van....a wire might have been hit with a screw...he had 4 batteries in the van....its a mess). He said if it was it would only take a couple of millivolts to cause the gauge not to work. Thoughts? That's kinda where I was going with the strap deal I was talking about. I wouldn't think the tank being charged would make a difference though because of the rubber seal between the tank and the sending unit. I guess anything is possible though. I you have a voltmeter, test the tank if it will read that low. | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Jul 2009 Posts: 6,256 Likes: 164 Master Metal Sculptor | OP Master Metal Sculptor Joined: Jul 2009 Posts: 6,256 Likes: 164 | YEA!!!! Problem resolved!!...great news. I have the fuel gauge issue resolved! I had two issues going on simultaneously. The float wasn't set right and there is a loose connection in the plug in the rear of the instrument cluster. Since the sender would always work out of the tank but never in the tank, I dropped the tank again (3rd time) and I took the rollover gasket off of the top of the tank so I could see inside and be able to manually move the sender float. I also hooked the sender up to a battery on my bench that was hooked up to a voltage limiter and a fuel gauge. I then put 5 gallons of fuel in the tank while it was out of the van and on my workbench....and nothing happened. I then put another 5 gallons in and the fuel was just beginning to touch the float!!! So I re-adjusted the float rod (bent it) until I was getting it to float and register correctly on the gauge. I then drained the tank again and re-installed it (getting good at this) and the fuel gauge in the van worked but then stopped. I realized that if I wiggled the plug at the back of the instrument cluster, it would work again. I have a very poor connection at the plug and will be changing out the cluster. It feels great to finally get this resolved. NOW......I can start replacing all of the brakes!!!!em resolved!!! | | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Sep 2009 Posts: 868 Likes: 2 old hand | old hand Joined: Sep 2009 Posts: 868 Likes: 2 | Glad to hear it! Always feels great to fix a problem so you can move ahead!
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| | | Re: HELP PLEASE with fuel gauge/sending unit | Joined: Feb 2012 Posts: 271 enthusiast | enthusiast Joined: Feb 2012 Posts: 271 | Yay! Glad ya got it fixed! Maybe when you recover you can help me fix mine since you're a pro now? | | |
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