2.5L bogs after a few minutes

[atfsux]

I just acquired an 86' Comanche Custom longbed, 4x4 with a 2.5L 5-speed manual. I knew I was buying a fixer-upper, but for just $700 w/AC,...I couldn't resist.

 

Most of the issues have been identified and I can deal with them, but this one has me confused.

 

While driving, and with almost no warning, pressure to the accelerator pedal of anything more than the lightest of touches seems to cause loss of power. Even in 1st gear, attempting to accelerate is pointless. HOWEVER,...if I turn the engine off, then immediately restart it,...everything is fine again,...until another few minutes and/or miles go by,...and it happens again!

 

As it is, I can drive it,...sort of. I just occasionally, before it bogs down, take it out of gear, turn it off, turn the key back, let out the clutch, and let it restart itself. I drove all over town today like this, gathering assorted parts at junkyards.

 

What can cause this condition? What avenue of investigation should I take to track down the fault?

[JeepcoMJ]

sounds like a bad Throttle position sensor, or MAP sensor

[Geonovast]

Exactly what my 91 2.5 did when the fuel pump was on its way out.

[atfsux]

Exactly what my 91 2.5 did when the fuel pump was on its way out.

 

Fascinating! Sounds like something I'll have to investigate. This is the sort of first-hand experienced observation I was hoping for. Thanks!! :bowdown:

 

When I restart the motor, it usually revs higher for a few seconds, too.

[JeepcoMJ]

remember that geonovast has multi-port fuel injection, so his situations would be a little different than yours.

[mvusse]

It sounded a lot like what my fuel pump going out on my 4.0 acted like, until you said a restart fixed the problem. I would actually need to let the truck sit long enough for the pump to cool off before it was okay again (for a while).

[jteckmann]

I've got the exact same set-up ('86, 2.5 TBI) and experienced the same symptoms.

 

If the fuel pump & TPS check out fine, might try checking between your coil and Ignition Control Module. It's a 2-piece unit. Two torx-screws hold the coil in. I checked mine, and was amazed at the junk that had built up in there - the connections to the ICM were corroded pretty bad, and pretty loose around the coil. I cleaned things up as best I could, and that seemed to halt the problem long enough for me to get home. I'm 99% sure that was the root cause of the problem in my case.

 

Mine was due for a tune-up anyways, so I just went ahead and ordered a new ICM, coil, cap & rotor, plugs & wires and changed everything at once, and the issue went away.