Massillon Preacher

Okay, bought a 1971 F100 with a 390 and a Holley 4160 4 barrel carb on it. The first couple days this thing ran like a charm, probably best I have seen for age before and I've had a couple of these. Then one day heading to church as I stopped at first stop sign just a few hundred yards from home and started to give gas it just sputtered, did this whole way there which was just a couple more stop signs and back home and every day I start it up it starts right up but then after few odd seconds 20 to 40, it starts sputtering and shuts off. I changed fuel filter and have checked for vacuum leaks and then I noticed this, after it sputters off the main body has gas continue to be sent in from the front bowl, a considerable amount even though the truck is off. It also seems that right as it shutting off from the sputtering it is not getting any gas in the main body from the bowl. I know easy answer, carb rebuild which I am going to do but also would like to know the exact issue, one so I can help another and two because yes I am that ****. LOL What are your thoughts as to why it would continue to pour gas through jets even though truck is not even running. I will also say that the fuel filter I changed out was on for a long time it seems and it was putrid red rust color what came out of the filter when I shook it out after getting it off. The new filter I put on is a clear one and it too has a small amount of red sediment already in it after only a couple starts over the last few days, I know tank needs cleaned or replaced but wanted you to know this as well as you comment.

Braggs

Sorry, I'm not a carburetor guru but that whole thing where gas keeps being squirted in even after shutdown doesn't sound good. My understanding is that gas is supposed to be sucked in by the vacuum created from the engine running. If it's squirting in when not running, that's gonna create a flooded scenario on startup.

Too high of fuel pressure could be an issue where the excessive pressure pushed past a rubber o-ring or something. If the mechanical fuel pump has been replaced with an electric one, make sure you have a low pressure fuel pump (made for carbs) not a high pressure fuel pump (made for fuel-injected vehicles). Voltage check would be good here too as higher voltage will run the motor faster (higher pressure).

In addition to the inline fuel filter, there's also a fuel filter built into the fuel inlet on the carburetor. If the other filter was catching stuff, this one might need cleaning too.

The reason for dying (lack of gas) could be a bad mechanical fuel pump (if you have one), especially if you've been using ethanol gas. The ethanol deteriorates the leather diaphragm in the pump causing holes and less gas pumping. Of course it sounds like you have a rusty fuel tank too. Ethanol gas will also attract more moisture into the gas tank and cause rusting too. IMHO, it'll be quicker and easier to simply replace the tank than trying to clean it out.

techrep

iTrader: (1)

Needle valve is gunked up and stuck open.. they control your float level or your float is cracked and full of fuel.

Massillon Preacher

[QUOTE=techrep;4863063]Needle valve is gunked up and stuck open.. they control your float level or your float is cracked and full of fuel.[/QUOTE


This is what I was thinking myself, gonna take her apart tonight or tomorrow and see whats up.

Thanks.

techrep

iTrader: (1)

Yep...let us know what you find..

Massillon Preacher

Rebuilt holley 4160 carb, put back on and it started first time for just a second or two, nothing after. Looked and no spray of gas when hitting pedal at all, filter gets gas and then just runs back empty after I quit trying to start it, what are thoughts, it was spraying before rebuild.

GhostriderI

Double check the float adjustment, just as to low (needle valve stays open and floods engine), set to high can keep the valve closed not letting fuel in (starving for fuel/no fuel). As to the fuel line draining back as soon as you shut it off I would suspect check valve spring is getting weak (it is going to drain back to release pressure, but, that should take a few minutes to an hour to happen)

Hope this helps

Half ton

Have you replaced your EGR valve?. THe EGR valve can cause the engine to die.?.