Miss under load at less than 3000 RPM's

[mk42gunner]

My 88 2.9 5sp 4x4 has a noticable miss under load in all gears, until the engine gets above 3,000 RPM's, then all cylinders start to fire and it is like hitting the go fast button on a nitrous system.

The problem is getting worse, sometimes it acts like it doesn't want to pull itslef when taking off from a stop.

I have a new TFI module and coil from unrelated problems. New fuel filters when I replaced the intank pump in July. When I hook up the scanner, there aren't any codes.

I put a can of Seafoam in the tank when I filled up a couple of days ago, thinking it might be clogged injectors.

Does this sound like a clogged cat?

Thanks for the advice,

Robert

 

[jhammel85]

How about the ignition besides the coil and tfi? Check the plugs and wires. Cap and rotor too.

 

[mk42gunner]

How about the ignition besides the coil and tfi? Check the plugs and wires. Cap and rotor too.

Good idea, The Previous owner had just put new plugs in, the wires look good, no idea what the rotor looks like; I do need to check all that.

This morning when I got in it to take my daughter to work the fuel pump relay was buzzing like a rattlesnake. I pulled the codes when I got home -- 87 Primary fuel pump circuit failure.

After looking at the schematics in the Haynes manual, and checking the fusible links; there where only two possibilities, either the fuel pump relay (again) or the computer itself.

The truck runs, albeit poorly; that pretty much ruled out the computer. So I put the third Fuel pump relay on it in three months. Sure am glad that O'reilly's warranteed that part.

Truck runs fine now with no codes.

Thanks for the idea.

Robert

 

[jhammel85]

ugh, What's with that? I've heard stories about the fuel pumps in these trucks never lasting when you get them from advance/o'reillys/autozone.

Well, I'm glad I could help. Hopefully you find something. If not, it's stuff that should be done regularly anyway. Might even be worth pulling a plug and checking it out. They can tell you a lot.

 

[mk42gunner]

It was the little relay on the fender, between the starter relay and the fan motor that I have replaced three times. I would be seriously pissed if I had to drop the tank that often.

Right now I am getting over having arthoscopic surgery done on my knee, after it gets better I will feel like doing some of the "nice to do, but not absolutely necessary mechanical maintenance."

Robert