My little brother and I are fixing up a 1979 D100 for his first truck and have a problem. The truck has the stock 318 with the 2bbl carter and it won't stay running for long and backfires out of the exhaust almost constantly. It has a fuel cell mounted in the bed with the lines run through the bulkhead between the cab and bed linked to the stock fuel lines. It also has open headers right now since it won't run long enough to get it to a muffler shop. It had headers on it when I bought it and ran fine, but the kid who sold it to me cut the entire collector off the driver's side (because it hit the starter!). It started doing the backfiring thing when we replaced that side with a complete header.
I'm wondering if it may be starving for fuel or if the open headers are causing it?

 

I would start by checking the timing. Changing the back pressure is one thing that changes the ability of the engine to breath. A change in the ability of the engine to breath usually necessitates a change in timing.

 

It had headers on it when I bought it (or at least most of them ) and it ran fine. The problem started when we got a complete set on it. I'll try to retime it and see what happens. We also pulled the carb and the fuel bowl looked like someone dumped jello in it! We cleaned it out and replaced the float and gaskets, so maybe that will help too?

 

Jello in the carb is definitely not a good thing and will cause problems. LOL

 

It was pretty ugly lol. I also wondered if the fuel cell may be causing it to starve out. It's a 25 gallon racing cell with the pickup at the right rear corner. We have the lines run straight through the bulkhead and linked to the originals. When I tried to drive it, it made it about 4 blocks and died. It wouldn't restart and the next time we tried we had to prime it by dumping gas down the carb.

 

from the sounds of it there may be bad gas in the fuel cell if the float bowl had jello in it. you may want to take the fuel cell out and rinse it out. may also want to change the fuel filter after you get it going again.when i changed the fuel tanks in my 91 the fuel that came out of the fuel tank i installed in my 91 was nasty and looked like it had been sitting for a long time.

 

We drained the cell when we got it and put 10 gallons of fresh gas in it when we mounted it. How would we rinse it out if needed? I know water can do just as much damage on some engines so that probly wouldn't be a good idea, would it?

 

water would not kill it but since you emptied it and then filled it with fresh gas it should be ok but your fuel filter might be clogged.

 

I'll change the filter tomorrow as well as put another one just before the carb. I have to patch in the line anyway since my brother twisted the steel line removing the carb . I was thinking of putting a clear glass filter on so we can keep an eye on the fuel flow.
Anything else I should watch out for?
One more thing if it matters- the headers are two different brands (Hooker and Headman). They are the same length, but could that be part of it? I didn't think it would be an issue since when we got it the driver's side was just 4 tubes with no collector and it ran fine. We do have the other Hooker if that may be the problem.

 

you could try sticking or adding some rubber fuel line and sticking it in a 5 gallon plastic gas can....then you would know if it is an issue with your fuel cell...i dont think it would be a header problem as ive run cars with open headers before for thousands of miles with no probs...cept the police...lol