1985 dodge b150. Gas tank clunking with or without gas cap on. This occurs when the engine is off, parked.

Also, engine is missing and sputtering upon acceleration. I have ruled out accelerator pump and improper timing. Any ideas? Thank you!!!

Is your tank return plugged?. Sure sounds like it, does it take a long time put fuel in the tank?

Maybe. Wouldn't loosening the gas cap cause knocking to cease? Tank fills quickly.

It's a new remanufactured holley 2280. Since I'm in Denver I'm wondering if I need to considers jets. Hm.

Are your tank straps loose? Loose fuel sending unit inside the tank?

Higher altitude..yes should go up 2 sizes from stock, that should eliminate stumble.

If you have access to a vacuum gauge, it will help you tune it.

OK, any ideas where I can get jets for a 2280?

What do your plugs look like? Before I buy anything, I’d check those. You can tell a lot from them and might be able to get away with adjusting you air/fuel mixture screw first. Maybe post a picture of what they look like.

I've had my timing set from everywhere between 15 and 35. Advancing the timing does help this problem but doesn't resolve it. I've set the mixture screws to highest vacuum.

I’d still check your plugs first. Does your engine burn oil ? You can really tell what’s going on in your motor starting there. For example, I have an oil burner 360 and was having some stumbling issues and the plugs were wayyyy worse than I thought, no matter the tune, that wouldn’t fix it. I can’t do much about that oil part so I have to keep an eye on plugs every so often.

How’s the condition of your cap/rotor and wires? All vital parts as well

That’s also a huge swing in timing settings. Since you have easy access to hills, you can make pretty easy adjustments to timing under full load. You want it as advanced as possible before you get any knocking or pinging. That should be closer to the 30-35 degrees at full advance.

OK, thanks Deathvictory. I'll work with this.

I'll check the plugs again. She doesn't burn any oil. Cap, rotor, wires etc are all new. I just installed the HEI conversion. New distributor, carb, plugs etc.

But this clunking from the tank is getting to me. It keeps clunking after I I loosen the gas cap. And it clunks even after I'm driving around with the cap loose.

An example of how it bogs on acceleration is... let's say you press the gas pedal down to bring up the RPMs from 800 to 2,000. So you're sitting at 2000 but the engine revs and then bogs and revs and bogs and revs and bogs.

Where is the gas tank in relation to the drive shaft … you sure its not a u-joint coming apart ?

Is the rev problem is a clogged filter or kinked fuel line ? How old is the fuel pump ?

Clunking is with engine off, parked.

No kinked lines, new filter.

Fuel pump is probably very old. But could the the pump really be a culprit?

Does it only happen when you rock the van back and forth, like when you enter or exit? Could be the in tank fuel level sending unit for a gauge maybe.

No, laying under the van engine off in park. Clunk... Clunk... Clunk clunk.... Clunk

Could the sending unit have come unattached and is just floating around in the tank ?

Is the key on or off ?… On the fuel pump might be tryin pressure the line before the starting, and the pump is making the noise and is scrap. Which would explain the surgin in the RPMS

It’s probably a mechanical fuel pump. My guess is also something inside the tank is loose and sloshing gas is moving around. If you’re in an out of the van even in park, gas moves around a lot. Does the sound happen when you walk out to it for the first time of the day before you touch anything?

It sounds like you have a good handle on the tuning and aren’t too far off, even for elevation. FWIW, I drove my 318 with 2bbl through plenty of hills +2-4K feet elevation and never had an issue. So my guess is fuel delivery and whatever is happening in your tank is related, like Frscke1 is saying.

Sounds like you may need to drive around a bit, use your some gas, then drop your tank and start there. Since there are so few parts associated to your tank, I’d guess that the problem will reveal itself pretty quickly. Might be a good time for a new fuel pump too.

Is the fuel pump in the tank on this year, how many miles on the van? Like Death said, dropping the tank would be the easiest solution to finding out what is going on in there. I worked at a garage years ago and it was comical some of the things we would find in gas tanks when replacing the fuel pump. Small plastic balls, marbles, rags, clothes pins, keys, plastic baggies, plus other stuff that had been in the tank so long, it had broken down from being exposed to gas and was floating around in pieces. The plastic bags would be a problem, they would suck up against the pump and restrict the pump from pulling in gas.

Thanks guys. But you're all off. It's probably my fault for explain it poorly.

The van is not moving, the gas is not moving. This sound occurs after the vehicle has been driven and the vehicle is in park with the engine off. Without the key in the ignition. It's almost certainly the sound of pressure building or releasing. But that perplexes me because I have driven the vehicle with the gas cap off and it still happens. There's no pressure release when I relieve the gas cap.

That being said I'm wondering if the fuel pump could be an issue. I'm also wondering if the charcoal canister could be an issue.