Engine Cuts Out

[Sloan66]

Lots of questions, just got truck running. Truck is 71 w/ 307 and 2bbl trauck sat for 15 yrs before I got it, prior to start up I replaced all fluids, rebuilt carb, new timing chain, all new hoses and gaskets, installed HEI with new wires. Fuel lines and tank flushed, inline filter placed bewteen tank and pump.

Truck start and runs fine, drives good, but randomly in third gear the engine cuts out, any ideas on cause?

Plugs are gapped .045 and timing is a 8 BTC and I did remove the resistor wire to distributor and replaced it with 12 ga. so it plugs into to factory location where the resistor wire did.

[Sloan66]

Come on guys, any ideas? Someone must have a thought? Help

[Mr Chevorlet]

Make sure you are not sucking in air between the gasket on the intake and carb. If you pulled it off to rebuild a wrong gasket could of been used. I had this problem for a couple of years until i decided to track it down, And some one had used a gasket that was close but did not seal correctly. replaced it and never cut out again. This might not be your issue. but you got to start somewhere.

[Longhorn 70]

How does it cut out? Just shut off suddenly? Does it die down? Is this under load? Is it like you turned the key off or does it sound like it ran out of gas?

[domeier]

You could run a temp wire from your HEI 12v source to a multimeter in the cab and at least know you are or are not getting steady power when it craps out? I don't know, man... seems like you went through everything pretty thoroughly. If it's a fuel flow issue, you'd think it would give trouble in 4th gear, not third.

[Longhorn 70]

in 3rd gear he may be hitting a point where there is either not enough fuel or not enough spark. If fuel, it would be a diferent feeling than spark. No spark, tack dies, and the engine just shuts off....No fuel, it usually dies slower and sounds like it is starving.

[68c10airstream]

Hi, typically if fuel goes into a hot exhaust unburned it will backfire loudly. I would assume that your having a lack of fuel. Inline fuel filter in the 2bbl or a plugging sock in the tank on the end of the pickup tube at the bottom of the sender. Easy to check the sock and check on fuel for debris by looking into tank with out sender. Slide your seat all the way forward, release the sender lock ring, disconnect lines and remove it. Now you can look inside tank. Remember no incandesent trouble lights around fuel, hot bulb cold fuel, broken bulb and then a garage fire. I know of many but not me. Every dealership i worked at i was the only mechanis initially with flourescent trouble lights. Good luck, Brian F

[Rufton]

I like filter between tank and pump like you have.
Is your inline filter a larger low pressure drop design?
Not too difficult to measure fuel flow rate w/ stop watch and known volume container; please do it safely w/o any explosions.

[68c10airstream]

Oh, i remember an almost guaranteed forgotten item. If this is an hei that has a control module inside the cap like gm hei, your distributor ground comes through the hold down bolt. Every thing needs to be shiny, bolt, hold down, neck of distributor, block where holddown touches it. I was a gm mechanic up through the ninety's and fixed many trouble code 42 (est bypass) after engine swaps and tune ups involving moving distributors around. Heres what happens, during distributor removal or timing adjustment, the body moves into a new corroded area lacking ground. I used to do a voltage drop test between the neck area that i shined up and the negative battery terminal with the truck running. If volt meter read any value (say 300 milivolt) (that's a third of a volt) i would pull the distributor, clean the base, clean hold down and the block, problem gone, I live in the salty north so it happens often. I went to gm drivability classes, set1, set2 (specialized electronic training) and loved every minute of it. Long time ago so this is memory recall. Good luck, Brian F.

[Daubs]

Check fuel filter. Replaced the gas tank in my 71 with a junkyard version...and it would cut out @ highway speeds. Turns out the gas tank had a little rust in it...and that clogged the fuel filter. Changed filter every month until it came out clean of rust deposits. Problem solved.

[Sloan66]

I'm going to revive this thread as I have checked some things. I have a good ground at distributor, I removed the filter between the tank and pump and I still have the following issue.

Idles smooth, engine runs fine under hard acceleration in first and second gear, when I shift into third initial acceleration is fine, then it just stops accelerating. The engine does not die, it seems like it is starving for fuel. If I let off it comes back and accelerates, but under hard acceleration it drops off. The truck will initially buck then there is no power until I let off gas. If I drive a sustained speed it is fine.

An ideas?

[FLDBRED]

It may sound too simple, but check to see if there is kink in your fuel line where the line bends from frame to connect to the fuel pump.

[Sloan66]

No kinks in fuel line

[69chevy lwb]

There's tons of things that can cause this either electrical, fuel or vacuum start by spraying starting fluid around all vacuum ports and gaskets if it revs up fix it as for fuel and electrical start at one end and go through all of it fix and replace anything that could use it until you find your problem it might cost a little but you eliminate future problems doing this I had the same problem and it turned out my pcv valve was sucking oil Into cylinders 3 and 4 and ruined 2 plugs I wouldn't get a cut out until 2k plus and under a load it would rev fine that was a hard one to find
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[Sandemonium]

Not sure if I know what I am talking about , but here goes.

Is this a 4-speed manual? Would the TCS (it may be TSC) have any impact on this?

Since he can accelerate in first and second with no issues, but as soon as you shift into 3rd and accelerate it dies, it doesn't sound like a fuel delivery issue to me. I had removed that emission component from my Jimmy, but I seem to remember it had some effect that if you shifted into 3rd before it was warmed up it would prevent the truck from increasing the RPMs.

Like I said I may know just enough to be dangerous.

Good luck on your quest for a solution,
Bob
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[Sloan66]

Bob,

The truck has that solenoid on the carb, but the electrical connection that is spoose to go the a sensor on trans is not hooked up. I think the 3 speed has been replaced at some point. what your saying makes since the engine acts like it hits a rev limiter if anyone has experinced that, it just cuts off, I let up and it picks up again. Any idea how I could bypass that system?

[jhwkns]

Do a compression test. It could be a worn out flat camshaft.

[Sloan66]

Well wanted to close this out. Compression was good on all cylinders. Good current to HEI.

Here was the problem, I checked all the fuel lines except the connection to the sending unit! IT WAS LOOSE and was sucking air. Tighten the connect, no more problem! Thanks for all the help.