I've about had it!

[VA72C10]

good info here guys. Hope you find the issue. It's either fuel, air, or spark

[rogergodding]

Originally Posted by VA72C10

good info here guys. Hope you find the issue. It's either fuel, air, or spark

You narrowed it down for me!

[Classic Heartbeat]

How many volts do you have going into your HEI? How is it wired in? If you have it wired through your stock harness with a resister wire, then you won't be getting enough voltage to the coil. Not enough voltage is almost as bad as too much. Check the voltage going in. WES

[CaptRMW]

Originally Posted by rogergodding

Sorry if I am jumping around with the symptoms, but I had the thing running and it would run as long as I wanted it to sitting in the driveway.... I replaced the fuel pump which did nothing as far as air in the line, then I replaced all of the rubber hoses involved in the fuel line and cleared the junk from the bottom of the sending unit line (inside the tank). The "sock" was completely wasted in the tank and the line was full of crap. I was sure it was fixed at this point!!

When you cleared the junk from the fuel pickup in the tank I think you were most likely very close to the problem. Clean the tank thoroughly which means removing it if you didn't do so already (clean like you were going to eat out of it) once it is free of debris and water you will need new filters and clean out the bowl of the carburetor. Two drops of water in strategic locations in most carburetors will render them inoperable. Good luck, Roger

[rogergodding]

uummm..... I checked the inlet filter and it was dirty but was passing fuel since I could hear fuel squirt into the carb, I changed the plugs, why not? ..... same problem. Truck would start and then die, would almost keep running if I pumped the gas pedal alot..... I go in the house for some more hops and barley........ a few minutes go by and my son calls me and tells me to come outside...... he started the truck and it was running/idling..... we drove up the street and back..... it starts up now and seems fine.....

[kevmic28]

I have that similiar problem. For the most part it runs fine then sometimes it struggles to get gas. With the Quadrajet I had on it it would stall and die. I put a Edlebrock carb on it and it runs so much better but still have fuel issues. I have a glass filter on it and some days I can see air bubbles going through it and some days its full. No rhyme or reason and I cannot figure it out.

[mr48chev]

Originally Posted by too much stuff

Check the gas cap?

My first thought when you can't get fuel up to the carb on one of these is that it has the wrong gas cap that isn't venting and allowing air in to replace the fuel that is being drawn out of the tank.

Second is the fuel pickup in the tank. If it has the filter sock on it the sock may be plugged. Or it may have trash in the tank that is plugging the fuel pickup either all the time or part of the time.

Then you have to check the full length of the fuel line from where it exits the tank to where it enters the carb. Kinks, smashed spots or other things that would restrict fuel flow.
What does the steel line going into the carb look like if you still have it? is twisted or kinked right behind the nut or at the bend?

And dirt or crud that was in the line before you swapped carbs could still be in the line and plugging up the replacement carb.

If you fill the float bowl through the vent tube will the truck run for a minute or so? sometimes you have to have them run for several seconds before the fuel pump will draw the fuel from the tank.

Can you take the fuel line loose from the carb and put a bottle over the end and crank the engine and pump gas into the bottle? that is the first thing I would check and then go from there.

My bet is that you have a line kinked or plugged.

[rogergodding]

Well, we can finally drive around town with not too many worries in it now. I dumped some seafoam in the tank last week and ran several gallons through it, then it died and wouldn't run again...... fuel filter clogged with black junk, cleaned it out and no problems.... To sum it up, I think we started with a questionable carb and a really clogged fuel line, both in the tank and under the truck....

[swamp rat]

Originally Posted by rogergodding

Well, we can finally drive around town with not too many worries in it now. I dumped some seafoam in the tank last week and ran several gallons through it, then it died and wouldn't run again...... fuel filter clogged with black junk, cleaned it out and no problems.... To sum it up, I think we started with a questionable carb and a really clogged fuel line, both in the tank and under the truck....

Sounds like your tank may need some cleaning, there is a good thread here about how to do it.

More searching may yeld more threads.

http://67-72chevytrucks.com/vboard/s...lean+tank+acid

[rogergodding]

Yeah, the tank had been "cleaned" by the po, gonna keep an eye on the glass filter and tools in the truck to pull it and the one on the carb at all times for now. We plan on doing the Camaro tank conversion later on......

[stsalvage]

I got one more for ya and No one hit on it yet.Even I bet longhorn man has never seen one or touched one in his life.Now I've heard of it But never seen it my self until it happened to me 2 years ago and had to run a electric fuel pump.I wore down the the lobe on the Cam for the fuel pump lever any time under a load it go lean in a heart Beat it turned both of my exhaust manifolds White.Do you have a fuel pressure gauge your fuel pump should be pumping at least 6 pounds.My one question way are you running the GM carb way not a edalbroke 600 there so much more easyer to work on .Or are you a smog state that require you to have factory parts on the truck I just went throw hell with mine.I hope you checked the timing and remember you need to take out the voltage drop when your using the HEI How many miles do you have on this engine

I have over 600,000 on mine with a 16 year old motor never blown a head gasket and i Live out is the desert in Riverside next to the old RIVERSIDE RACE WAY NASCAR

My truck has been in are family sence 1969 we have had 4 motors in it 283 327 307 and the 350 i now have in it now and we put it in in 1995

I've used this truck to haul scrap iron for all 15 years and i haul 3 big trailer with it

the trucks been updated with all new 1972 hardware for safety disc brakes power steering on frame power brakes But it still has the 2 speed power glide and the 4:10 rear gear

and i replace all the factory wire harness 10 year ago with factory repop M&H factory harness

[rogergodding]

Flat cam lobe had crossed my mind, but luckily that's not it. The reason for the Q-jet is that's what it came with and we just got this one in October.....