Okay, I'm a noob and looking at buying a 91 Ranger with 185K miles. I need a little help.

The only issue is that the truck has trouble keeping running. Starts fine. Will run for a few minutes then start to shudder like it is not getting enough gas. The owner says that the plugs, starter, fuel pump and fuel filter have been repalced trying to solve the problem.

He's disgusted and says that he wants to get rid of it because he's heard that a problem with these trucks is that it may have jumped timing. I'm not buying that for the symptoms he's describing.

What else could the problem be? He changed everything that was my initial throughts. What's this "inertial circuit" that I've been reading about? Could that be it? Fuel pump voltage maybe?

Any help is appreciated.

Scott

 

What engine? 2.3, 3.0.....and any CEL?

First things to check would be of course timing, IAC (Idle Air Control) motor, fuel pressure/volume, and EGR.. These will greatly affect a stable idle and running condition/s.. Especially on a high mileage truck.. Being that it starts fine/fast idles fine cold, leads me to believe it's not timing, but should be checked to be sure.. IAC are know to stick, or gum up causing a slow/irratic idle as would a bad TPS or hung open/leaking EGR.. Throttle plate can build up debris causing slow stumbling idle as well, and easily checked/cleaned.. Could be a vauum leak as well.. Thing to do would be to start eliminating the possibilities....

 

Your suggestions make sense. I'll give the truck a once over tomorrow. thanks

 

The inertia switch would not be the problem here. Sounds more like a vacum problem??? Could also be a Igntion Control Module? Unlikely that vehicle has jumped timing if it has good power when you apply acceleration at start up. Listen for vacum leaks and mabey spray around intake area wtih some carb cleaner to see if yo get idle changes.

 

I went ahead and bought the truck. Its the 2.3 L 4 cyclinder engine. Starts great. Idles smooth. No noise or banging at all. No smoke out the exhaust. We drive it a few laps around the parking lot and after a couple of minutes it starts to hesitate. A CEL will come on and then go off. If we keep driving it, it'll die but start right back up.

We parked it and started it back up. We removed the connector to the MAF and the idle did not change. We even gave it a little throttle without the MAF connected and no change to the engine sound or going up in RPMs (no hesitation).

Is Autozone or Pepboys a good place to get a MAF and other parts as I troubel shoot? I know that sometimes OEM parts are best. I will take it to Autozome to read the CEL.

 

You mean..

It'll die at idle (warmed) or it'll die under normal cruise/accel throtlle? Stall...

 

Its hesitates and then dies when cruising at low throttle. We had it idling okay as I recall.

 

If you try and accel. 'harder' will it pull through the stumble, or does it fall on its face and completely stall?

It would or might be helpful to get the DTC.. IAC, TPS, EGR issues, and vacuum leaks usually won't stall an engine under moderate/hard throtlle.. Does it completely die, like shutting off the key, or does it seem to starve for fuel?

 

If I try to accel through the stumble, it does not pull through. It keeps stumbling and stumbles more.

Sorry, I am not sure what the "DTC" is. Is that the CEL code?

The car will completely stall and die like it is starved for fuel. The fuel filter, fuel pump, spark plugs and wires have been changed.

When I drove it home (1.5 miles), it would occasionally start to stumble as I accelerated. I would reduce the throttle and it would generally stabilize and keep going. If I let off the gas completely, it would stall and die. It died 4 times during the trip, but I coasted and restarted it without a problem to keep going.

 

I've been sick as a dog these last few days and haven't been able to work on the truck. I still couldn't help myself from going out and taking a close look at it. Found something that surprised me. Its got 8 sparkplugs for the 4 cylindars.

The previous owner changed the plugs and plug wires onthe passenger side but not the drivers side. They are kind of hidden under the plenum and such (right next to the fuel injectors).

My question now is . . . would the new plugs/wires on on the pax side make it idle fine but the old ones on the drivers side cause the bad throttle condition and intermittent CEL?