2.9 missing and stutering under load

[ride-red]

Starts up great and runs fairly decent till about 1800rpms till 2800-3000 then runs awesome.. New parts include fuel pump, filter, fuel pressure regulator, plugs and wires,new neg batt cable and just rebuilt the alternator. Hooked it up to the scanner and and no codes came up on it. dont know how many more parts i should throw at this thing with out just giving up any ideas would be helpful THANKS

 

[mk42gunner]

I'll be watching this thread, mine does pretty much the same thing. I have had to replace the fuel pump relay three times in the last few months; but I have no idea what is causong the relay to go bad.

Robert

 

[1989LongbedGT]

Throwing parts at a vehicle is no way to fix it!

Even tho you replaced the Pump it wouldnt hurt to check fuel pressure.

You mentioned new plugs and wires. how about the Cap and Rotor button? Check for wear at the terminals and look for cracking in the cap.

A plugged cat can cause power loss under load but during normal cruise and operation you may not notice anything. Plugged cat can reveal alot of movement in the exhaust system from pressure building up. Plus it will have a wierd "choking" sound. Kind of like a lawn mower at WOT when you kill ignition or fuel. that boggy sound. lol wierd way to put it but makes sense.

How does it return to idle when off the throtle? Worn injectors, clogged fuel rail or kinked line. It sounds like its being starved of fuel or timing is possibly off.

Remember these engines are very basic and early in there electronic controls of the engine. You still need to make sure all your basics are working properly before getting to deep in engine electronics.

Under d.Gator.d thread try the TPM as well. Unplug it and see how it runs, remember this will set a check engine light. The sensor may still be working within its parameters but not out of limits which will inturn not set a Diagnostic Trouble Code. DTC.

mk42gunner - check for corrosion at the terminals where the Relay slides in. Sounds like you have too much resistance in the circuit or a possible short somewhere.

If it keeps popping fuses or relays the pump it self may be bad creating too much internal resistance, requiring more amperage to turn the pump motor which can overload the circuit and pop a fuse or relay.

Best of luck to you both. Post up what you tried and what has worked and ill see if I can help you from there.

Matt

 

[ride-red]

The cat on mine is removed. i have the timing set properly fuel presure is running about 40-42 psi and the cap and rotor are new. it idles just fine. These are near new parts not just throwing them at it to fix it but within a month or two new...

 

[mk42gunner]

I'll check for corrosion in the plug tomorrow. The wiring looks okay at a glance, but may have a short.

My fuel pump and filter are new (July), and my fuel pressure is 39psi when I check it with the engine off.

I do need to check the cat, that whole sounding like a lawnmower thing is eerily familiar....

All in all, the truck is running decently now, it just occassionally stutters. I have to get the F150 that is in pieces together before I really start tearing into this one. I hope it doesn't rain too much this week.

Robert

 

[1989LongbedGT]

Ok. Could possibly be ignition coil. Can break down underload and not supply enough spark. You would have to check the resistance of the coil and compare to spec

 

[mk42gunner]

Today I took about 15 minutes to clean the female connectors in the fuel pump relay plug. I didn't see any real corrosion, but the 24 year old dielectric grease was pretty nasty.

I used a brass toothbrush to clean what I could get to once the connectors were removed from the plug.

The truck seems to run better than it has in the three months I have owned it; thanks for the idea.

Robert

 

[PGHFord]

Look at the vacuum lines and MAP sensor, just some ideas, I have had MAP sensor go bad and didnt through engine code.