Help me diagnose problem

[muckyp]

Ok I have finally got to the point of starting my truck after it has sat for many years. I have had the truck about a year and a half and the PO said he and his son had been working on it for several years. It has a 454 with HEI. I have gotten it all rewired. It started up with out too much problem bit it won't stay running. After it runs for a couple of minutes it starts popping and then will backfire and die. It seems to prefer being choked a little. If i attempt to accelerate at all it will die. Any suggestions as to the problem?
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[stich626]

blown powervalve.

[muckyp]

Do Edelbrock carbs have power valves? But on that note I had a Holley on there first and then switched it out for an Edelbrock, with the same or at least very similar problems.
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[1968SWBBigBlock]

HEI module gone bad would be my 1st guess
When the start to heat up the short out and die
Let it cool off and it will run again

[muckyp]

Thanks for the replies. It will start right back up if I choke it again. Does that still sound like HEI module?

[463]

i think i would start with a base timing check, check the vac advance with a vac pump for a leak down test , check the advance weights in the dis. the backfire is a timing thing in my books. how old is the fuel? are all the plug wires wired up correct? and never take any thing for granted when there has been others with there fingers on it.

[pat 70/71]

Might be running lean/low fuel pressure is my guess. change out the carb to a known good carb and see what happens. Plus check all electrical connections at the dizzy. Does it get real hot for the time it is running? Pretty sure Edelbrock afb type carbs don't have power valves. hope this helps. cheers, Pat

[muckyp]

Thanks guys, I will take a second look at the wires and I am getting another carb tomorrow and hope for the best. Pat 70/71, I would say that it does get pretty warm pretty quick. I have not been able to run for very long, but it seems to warm up fairly quick.

[RustyParts]

Might want to check the fuel filter also.

[C20-67_N_MO]

Originally Posted by muckyp

Thanks for the replies. It will start right back up if I choke it again. Does that still sound like HEI module?

*** Yes. Remember this is an electrical module. they do go out from time to time.

Originally Posted by 463

i think i would start with a base timing check, check the vac advance with a vac pump for a leak down test , check the advance weights in the dis. the backfire is a timing thing in my books. how old is the fuel? are all the plug wires wired up correct? and never take any thing for granted when there has been others with there fingers on it.

*** Another good advise given.

Originally Posted by muckyp

Thanks guys, I will take a second look at the wires and I am getting another carb tomorrow and hope for the best. Pat 70/71, I would say that it does get pretty warm pretty quick. I have not been able to run for very long, but it seems to warm up fairly quick.

**** Best advise I can give you is this. And take it as you like; try only one thing at a time. PERIOD!

Originally Posted by RustyParts

Might want to check the fuel filter also.

*** More good suggestions. But just take it easy and troubleshoot ONE item at a time. ***

Good luck.

[dadsworktruck]

I would be interested to know how old the fuel is, are the fuel lines in good order and is the pump in good condition...

[Zeke's Garage]

All the above mentioned items are well worth looking at, but it does sound a bit like a fuel delivery problem. Do you have a way to test fuel pressure from the pump?
Also double check your static timing. Set #1 cylinder to TDC, and verify that the harmonic balancer lines up with the marker, and that the rotor is pointing to #1 terminal... then check the firing order.

Good Luck!

Shawn

[ChevLoRay]

My first impression is a small vacuum leak. You mentioned that it started right up wihen you choke it. If the engine is warm, then that means it is getting air from somewhere besides the air horn. When it is running again, and the choke is off....put your hand over the air horn and limit the amount of air that the carb gets. If you can keep it running by keeping your hand over the carb....you have a vacuum leak somewhere. If it dies when you cover the air horn, you don't have a vacuum leak.

Since it has been some time since it ran, it wouldn't hurt to know that it doesn't have an intake leak. If you want to find out, spray some starter fluid (ether) along the intake to head gasket and see if the engine speeds up. If so, you know you have an intake gasket problem.

[muckyp]

Just wanted to let you guys know the solution to my problem. I had the timing way off. Once I got the timing set it ran fine. Thanks for all the help. I should have it move under it's own power by next weekend.