Truck won't stay running after new gas tank installed

[1979 GMC Sierra]

Hey guys, i got a new gas tank put in the other day cause my old one was leaking. After it was instealled, i drove the truck home from the shop (15 min drive). The truck then sat for 2 days. Then, when i went to start it, she started and ran for about 30 seconds and then shut off abruptly...like it was out of gas. But there's gas in the tank. I kept starting it, with the same thing...shutting off after 30 seconds. We figured the new gas and vent hoses put on the tank might be a bit too long and were kinked...so we lowered the tank and cut the hoses to make them shorter and stop any kinks. Brought the gas tank back up and started the truck...but the same thing still happens...runs for 30 seconds and shuts off. I can't figure out what is wrong...do you guys have any ideas ? The truck ran fine before i got the new tank put in...so this is weird and frusterating.

Travis

[PRattenbury]

Might be a stupid suggestion, but make sure all the hoses are hooked up to the right thing? One's a vent to the charcoal filter, one's feed to the pump, one's return from the pump, if applicable...

[1425956]

And the three hoses are three different sizes. Don't ask me how I know that...

[1979 GMC Sierra]

Thanks for the info guys. The 3 hoses are hooked up correctly to the right things. Any other ideas ? Has anyone had a similar problem ? I'm starting to think that maybe the sending unit is defective...

[PRattenbury]

Actually I did have a similar problem when I first got my truck. I got it to run the way I dragged it home by putting a set of jumper cables on it and tweaking a thing or two here or there. It'd run for a minute or two and then die. But then I ripped it completely apart and rebuilt most of it, so I have no clue what it might have been that I did right to fix it. I suspected the ignition coil. But I really don't know.

[Gumby]

Could just be chance that you had done the tank, could be something else that was ready to fail. only thing Id say is check the sock on the pickup if you know the lines are ok.



[only problem I have had on a new tank swap was being able to fill it up, acted like it was full only half way, nothing helped. totaly different car then mine but a tip from a guy fixed that. Said to point the nozel towards the right front tire on fill up and sure enough it will fill up now.]

[old Rusty C10]

assuming its the 79 in your signature... could the gas filter be clogged? when it dies does it start right back up? I would also make sure you have steady flow from the fuel pump...

[1979 GMC Sierra]

PRattenbury - the ignition coil, that would be a good guess...however the truck was running good up until the new tank was put in. It would be surreal if a new/unrelated problem happend at the exact time of the gas tank switch. But i can't rule it out.

Gumby - i'll have to try that.

old Rusty C10 - yes, it's the 79 in my signature and picture. Good idea, checking the gas filter is what we'll do next. We lowered the tank yesterday twice (laying on the ground as we don't have access to a hoist, and using the jack to keep it from falling) and checked all the hoses...but we never checked the sending unit or gas filter cause we didn't remove the tank completely. But thats what needs to be done now.

[bharrison1]

check your tank selector valve my 75 was doing this i bypassed the valve and it ran fine