Maybe the fuel pump?

[crazeetxn]

Truck died on me a few months back. It had been having a hard time for a while and finally quit.

Randomly, if I'm at a light or whatever, it would idle way down and act like it wanted to die. It would only do it briefly and then straighten back up. I'm thinking if it were internal, it would do it more frequently, but it just seems to do it when it wants to. Thought it was bad gas so I ran some treatment through it.

When it finally died, I realized there wasn't any fuel in the filter and changed the pump. Fired right up and ran good...now it's doing the same thing again. The parts store had a Carter pump (thought they were supposed to be pretty good?) and that's what I put on it about a year ago and that's what I put on it a few months ago.

Is there anything that could make the pumps go bad or just my luck on a pump?

[LBJ]

May not be your problem, but I just had a similar problem. Your gas cap may not be venting. This creates a vacuum in the tank that the fuel pump will finally not be able to overcome. Runs fine for a while, then starts to malfunction. Shut off the engine and let it sit for a while and the tank slowly releases the vacuum. Drive again, then the vacuum starts to build again. Same thing over and over. The more gas in your tank, the quicker the problem shows itself.

Remove your cap, put some duct tape over the fill port to keep it sloshing out, punch a small hole in it with an awl, and go test drive. If it keeps running, then fix the gas cap vent or buy a new cap.

Or possibly, your fuel filter is clogged. Change that out also. Most carbs have a small filter at the carb gas inlet. Sometimes there is another filter along the chassis. Check for those and replace also.

[crazeetxn]

Good idea! Didn't think about the gas caps. Makes sense though, because yes, when it starts acting up, if I kill it or let it sit for a while, no problems.

I'll change those and the filter at the carb too, just to rule them out.

Thanks!

[geezer#99]

Edelbrock carb?
Could be too much fuel pressure.
They don't like more than 5 psi.
You might need a regulator.

[68longhorn]

What year truck? Does it have the original distributor?

When my fuel pump died, it died. No start, nothing.

The factory distributor from on my 86 had 4 wires to a esc module that went bad and caused the truck to idle down, loose power, etc. You can loop 2 wires together or replace with an older distributor

[crazeetxn]

Thanks for the help ya'll. Got side tracked since I posted this.

Changed the fuel caps and filter, ran higher octance gas, and it still gave me the symptoms. Since the fuel pump had a warranty, changed it out again too. Same thing. Tuned the carb, same thing.

Changed the plugs today and we'll see how the trip to work is tomorrow.

longhorn, it's an '86 with a stock 350. If I keep having problems, I'll look at the module. When I put my motor back together (Oct '14) I went with all new plugs, wires, cap, rotor, fuel pump, carb...ran great until a few months ago. Now it's just bugging me.

Not that it matters, but I used to drive about 30 mins one way to work. Now I only drive about 10. Just putting that out there if that helps any.

[Dead Parrot]

Check the suction line from the tank to the metal line. Out of sight and with no pressure, often forgotten. Mine was crumbling away when it started allowing air to be sucked into the intake side of the fuel pump. For a while, it had symptoms similar to yours. Went through many of the same steps you have before I thought to check that piece of hose.

[Blessed66]

Originally Posted by crazeetxn

Not that it matters, but I used to drive about 30 mins one way to work. Now I only drive about 10.

It might make all the difference, actually.

How long has the driving situation been like this? No problems when you had the long commute? What plugs are you running? Have you pulled atleast one bank to read them (color of electrode)?

I would urge you to try out everything simple first, and that includes checking fuel lines like Dead Parrot mentioned, but also to not assume anything you've done 2 years ago is still like new.