Vannin' Home Forums Dodge How To (Dodge) 77 B300 van won't start

Hi all been around the site for a while but this is my 1st post and I'm hoping maybe someone can give me an idea with my van. this is going to be a little lengthy just for a warning .
I bought my 77 sportsman 300 about 10 years ago if it matters this is a class c camper van . it had been sitting for a while before i got it and the previous owner had it running at one point before he discovered the roof leaking badly and decided to park it in his barn . By the time i got it the fuel system looked like yellow mud inside tank to carb so bad that i took a putty knife to what i could get at in the tank and scraped out about a half inch thick layer of varnish . after getting the tank completely clean to bare metal inside and using a sealer/protective coating for the inside of it , i replaced the fuel line tank to carb and fuel filter i put about 3 gal of gas in it and fired it up . It ran pretty good so i tackled the leaky roof .
After checking things over and determining the rest of the van as far as brakes steering tires and suspension goes was good and road worthy i filled her up with gas and set off on a 2 hour road trip for a weekend of camping .
About 60 miles into the trip it started running terrible stalling out no power so we turned around and took it back home .
the fuel pump had went bad no biggie $20 and 30 mins later the next morning it was fixed but not running as good as it should , the carb was still pretty bad which really showed after the new fuel pump so back to the parts store got the rebuild kit and float for the carb cleaned it out good made the proper adjustments and it was running better than ever so took it out for a 30 mile trip to a closer campground for the weekend no problems .
The problems started after we got back . I was going to drive it a couple weeks later and it wouldn't start being short on time i did a few quick checks spark and fuel and checked the oil . oil was way overfilled and thinned out stunk like gas , ok need another new fuel pump .got a new one under warranty put it on .
still no start this is where I'm stuck at :
It has had a full tune up plugs wires cap and rotor,
entire fuel system has been gone through ,
new timing chain and gear set not a cheapie this was a comp cams double roller set .
ignition timing was verified correct
same with the cam timing after the chain replacement
has great spark fuel getting to the carb
compression was 138-142 on all cylinders .
verified all valves are opening and closing by pulling both valve covers off .
no visible vacuum leaks anywhere not around the carb or intake and all cracked vacuum lines were replaced .
the part I'm stumped at is that it will not run at all even on starting fluid or gas being dumped down the carb . with the amount of gas i dumped down the carb it should have flooded it and the plugs should have been wet they were bone dry like it never made it out of the intake .
I even checked the oil afterwards thinking the intake had cracked and let the gas run into the engine. nope oil still clean no smell of gas . Im lost ,anyone ever ran into this before ? would love to hear the old thing come to life again but I'm not sure it will at this point at least unless i hire a witch doctor to remove the curse on it i think btw the engine is a 360 with a carter bbd and i also replaced the ballast resistor as the old one was broke in half the ignition module is also good as i tried anoth known good one along with the coil on it and no difference
hopefully the van gods of the mopar world will help me figure this out

ok. The varnish in the tank being cleaned out and sealed with some protective coating makes me a little nervous. Are you sure that fuel wont eat this coating (fuel eats about everything)? I like that the fuel line and filter was replaced. I always like to disconnect the line at the carb and let some fuel run into a bucket to ensure that there are no particles getting into the carb. The oil being overfull could be a bad fuel pump, which you have replaced. I think that after all the work performed we should start at the basics. Are we sure we have good spark? There should be a white ceramic resistor somewhere under the hood. The purpose of this is to allow the full battery voltage (around 13.8V) to go to the distributor and coil during starting (resistor bypassed with key in crank position) and then when the key is in the run position the voltage to the distributor/coil is reduced by about 2V to let components last longer. Use an insulated jumper wire with alligator clips to bypass resistor (for testing only) if there is any question about this circuit. Then we need to verify good spark. Next, pull all plugs, one at a time, check gap and spray a second of ether into cylinder. Put all plugs/wires back on and try it. Hopefully, the engine will at least cough. Other things to check, are the plug wires installed correctly? Why was the timing chain/gears replaced? Was this done correctly? I believe that this needs to be indexed correctly. Was the carburetor rebuilt correctly? Is there an internal filter in the carb? Good luck.

If you have fuel and spark, I'd bet its something in the ignition circuit. Check all your fusible links, neutral safety switch and ignition switch. You can check fusible links with an ohm meter, you can bypass the neutral safety switch with a paper clip, but unfortunately, the ignition switch has too many wires. You can probably test it with a meter as well, but might be easier to just replace it if the other 2 things test out OK.

May have washed all the oil off the cylinder walls, and have no compression, on that old beast. Try putting a squirt of oil in each of the cylinders, and then try it. If you have a gauge available check compression.
Aule

This seems to have not had much response, so I'll toss out a few ideas.

Out of curiosity, did you check the color of the spark when it first began running crappy? Sagging voltage can really screw these up. What Superbeast said about the fusible links could come into play here. I've been bitten by them several times. I'd note that an ohm meter can really trick you on a fusible link, as they can corrode internally, and even one remaining strand of wire out of the original bundle of strands will still read OK on your meter. You need to check fusible links for voltage drop end to end while the circuits they power, such as things like the lights, climate control, stereo, etc., are actually turned on.

If you have spark but no starting up, the first thing I have to wonder in light of all the things you checked is if somehow your distributor (or the outer surface of your harmonic damper...) rotated a little throwing the timing way off, or if the magnetic pickup may be positioned incorrectly, which would negatively affect the spark, like if the dwell were way off on points. You could get a decent looking spark in the open air, but it simply wouldn't be adequate to jump electrodes in the increased pressure in a cylinder under compression.

Did you try filing the tips of your spark plug electrodes a little so they have nice sharp edges? High voltage likes to jump from sharp points.

I've had somewhat similar no-start symptoms when the mounting bolts on my ECU ignition module became corroded. Since the ECU obtains its electrical ground from its case, it won't necessarily work correctly with an incorrect ground reference. Try removing those bolts, cleaning off the flanges on the ECU, maybe put some silicon dielectric grease on the bolts, then remount it.

I also ran into a totally nonsensical loss of ground on one of the captive weldnuts on the firewall. It was inserted fully and appeared to be swaged in place properly, but there was absolutely no electrical contact between it and the firewall metal! I had to run a ground wire elsewhere to pick up a good ground for that circuit. Such is life with vintage Dodge vans...

If your entire fuel system was full of varnish, I wonder if more came loose from someplace you couldn't reach inside the carb and plugged the emulsion tubes. This wouldn't account for your engine's refusal to start with fuel poured down the carb, but it could definitely cause a delayed case of poor running like you experienced, and would be very difficult to see during an inspection of the carb.

If you got gas in your oil, you may have chewed up the hydraulic lifters. Loss of oil pressure by killing the oil pump or wallowed out bearings could have a similar effect. You'd still build compression, and the valves might even move up and down, the valves just wouldn't open properly after certain rpms, etc.

Several of the observations you made reminded me that I've heard that some of the intake manifold castings had an insane "feature" where due to the way they were cast a small rubber plug had to be inserted into the floor of the main intake gallery to plug a casting hole. The rubber hardens over the years and eventually the plug falls out, leading to all manner of nasty issues, as vacuum and fuel delivery, crankcase ventilation and lubrication are all compromised when the plug falls out. I've never seen one of these manifolds in person, but I've heard that if the carburetor is removed you can see the plug (or hole...) by looking around the floor of the manifold with a flashlight.

Those ignition resistors are fairly crappy quality anymore too. If the original was broken in two like you said, did someone bypass it to make it run? This would allow it to run but would seriously stress the spark coil.

When you do get it to start again, try the test of spraying some carb cleaner around the base of the carb to be sure you don't have a leak there.

Hopefully a few other Dodge folks will join in here; I'm sure there are more good ideas around. Most of us have been bitten by something like this somewhere along the line.

The van is a 77 correct. I belive they were still using a mechanical fuel pump.If that is the case it is most likely you sustained the fuel dilution on the ride back. The carb would have leaked by.The fuel tank is mounted lower than the carb. The fuel would need to get past the float to get into the motor by over flowing the bowl. I had a 318 with a cracked carb body that caused the same issue. You can unhook fuel line and plug it then atempt to start engine with foot placed firimly on the floor to clear if flooded. Also check fuel tank vent if its plugged it will pressurise your tank. causing all sorts of problems.

ohiocowboy Welcome to the site....