Does this sound like vaporlocking or ????

Harvester of Sorrow · Jul 25, 2011

It is a 1983 1 ton 2wd Chevy quad cab long bed. 454 with a 4spd manual.

The truck has run flawlessly until last fall. It started running shitty and I assumed that it was due to dirty/wet/bad fuel since the rig sits frequently. So I put some HEET and octane booster in it and it started running better/great/ and I towed the scout over to Naches with it. Fast forward to this last tank of gas and it is progressively running poopier.

1. When "cold" it seems to be running "ok". Then, once I get up to 140'ish+ engine temp it will start flat dying under loading. If I stay in it, it of course bucks and spurts everywhere and still will die. Acting way worse than just wet gas. Full engine kind of dead, not just a backfire and miss.

2. Takes a good bit of starting to get the thing fired back up. On average about 10 minutes of sitting...then flooring throttle with some decent short term cranking.

3. Runs at very low idle speed while crawling and then might still die.

I have never had a vehicle vapor lock...so I am clueless if this is what it is?

Should I just put an in-line electric pump in place after my tank selector?

TreeClimber · Jul 25, 2011

Does not sound like vapor lock. Vapor lock occurs when it's soooo damn hot in the engine area, that the incoming fuel line is no longer able to send liquid fuel thru the fuel lines. The surrounding heat causes the fuel to vaporize inside the lines, hence, vapor lock.

You gotta be pullin' some serious heat. Such as a full throttle ascent up a mountain pass. Them exhaust manifolds will be glowing red.

Start with the basics, good clean fuel and filter.

CHOP SHOP · Jul 25, 2011

sounds like water in the carb.

Also pop off the HEI cap and look for a busted rotor or anything out of place. Check the little carbon nipple on the bottom of the coil too.

Is you steering column tilt very loose?

mark · Jul 25, 2011

Might also check for cracked or old fuel lines. My travelette did that at one time (not exact same situation but simular), ended up being cracked rubber line before the pump, and would suck air in the right set of situations.. basicaly was starving the carb.

CHOP SHOP · Jul 25, 2011

mark said:
Might also check for cracked or old fuel lines. My travelette did that at one time (not exact same situation but simular), ended up being cracked rubber line before the pump, and would suck air in the right set of situations.. basicaly was starving the carb.

this too^^^ very common that the short curved hose from the frame to the pump is OEM and bad.

zukkev · Jul 25, 2011

Could just be a bad fuel pump too...check fuel pressure at the carb...also, run a hose into a can, and have someone start the rig-should be a good flow of fuel without airbubbles....ALSO, replace your fuel filter first! I have been bitten before years ago thinking "I just replaced the filter so it can't be that! Changed the pump-still starved for fuel....replaced filter=ran great!:redneck:

wheelinjp · Jul 25, 2011

alot of good info here. try all this, especially the FILTER haha. if none of this fixes it, try switching tanks. sometimes the transfer valve gets messed up and starts sucking air too. Sounds to me like water in the tank and carb, or cracked fuel line. my cj 5 had a bad fuel line at the tank. idled great, and as soon as a load above idle it would act like it was out of fuel. Just a small crack on a rubber line.

Harvester of Sorrow · Oct 5, 2011

Just an update...

It was a combo.

Fuel filter was caked with **** + moldy chaffed soft lines from the hard line to pump connection.

Truck runs sweeeeeet again.