Truck randomly cuts out

[Minuit]

My 91 has been having a strange issue recently. Yesterday, I drove it approximately 5 miles during which time it stalled three times. There isn't any noises or drama when it cuts out, the engine just stops running. When I try to start it again, it starts fine and runs as normal. I'm thinking it's probably an issue with a grounding somewhere. Would I be correct in this assumption?

 

The truck recently got a new crank position sensor which seems to test fine, but could it be involved?

 

Thanks.

[ontin000]

Did it stall at speed or when you came to a stop?

Was your gas tank more than a quarter full?

When was the last time you replaced your fuel filter?

 

Just trying to get more info. It helps w/ the troubleshooting process. :thumbsup:

[Pete M]

does it stop if you jiggle the key?

[Minuit]

Did it stall at speed or when you came to a stop?

Was your gas tank more than a quarter full?

When was the last time you replaced your fuel filter?

 

Just trying to get more info. It helps w/ the troubleshooting process. :thumbsup:

 

1. Stalled the first time at 45 mph, second time in a parking lot, third time at home. So both at speed and not moving, I would say.

 

2. Gas tank was about 3/8 full at the time.

 

3. Mid April. The truck's been driven about 125 miles since then.

 

@Pete: I have yet to try that.

 

New problem: Since replacing the ignition coil (spare one I have), I'm feeling what seems like a hard miss (sort of a bucking or hesitation) at about 35 MPH or so. It feels like the transmission is going back and forth between gears. These seem like symptoms of a throttle position sensor. Would I be correct in this assumption?

 

Thanks for the quick responses! :thumbsup:

[mule13]

i would check the CPS especially the wire that leads to it mine was rubbing the manifold and wore the coating off and shorting out and i had same issues. i found that taped it up with electrical tape and it was good until i bought a new cps worth a try :)

[Minuit]

i would check the CPS especially the wire that leads to it mine was rubbing the manifold and wore the coating off and shorting out and i had same issues. i found that taped it up with electrical tape and it was good until i bought a new cps worth a try :)

 

Checked the CPS wires and they weren't rubbing against the manifold. I believe I have all my recent problems pinned down to my throttle position sensor. Is the proper way to test it simply moving the throttle linkage and reading the voltage with a meter?

 

Thanks! :cheers:

[ontin000]

Yes, you can test the voltages, or you can pull it out and test the resistance. Should be a smooth, linear output.

 

I have had my battles with the 2.5l renix TPS for an automatic, which you can't even find anymore. I had to buy one for the 4.0 and reverse the wiring (why they aren't consistent, I have no idea.)

[Akula69]

Hmmm...ideas:

 

(1) I recently was lurking the other forums and read a thread about a guy who had the same stalling problems who had bought an after-market (believe he said from NAPA) CPS and it was doing the same as you described - seemly after the truck warmed up. He was advised that some after-market CPS units would get squirrely when they got hot, so he took his out of the truck and ohmed it out when it was cold, then warmed it in a toaster oven. Sure enough, when it was cold he was getting about 200-275, but when warmed up he got 0.

 

He went to the Stealership and got one - problem solved.

 

(2) Ignition switch (down low on column) can sometimes be damaged by blower motor pulling too much current through wires. Check for melting where blue plug cannot be removed, or (in extreme cases) wires are singed looking. Ususally involves replacing switch (tilt and straight column switches are different - ask me how I know :doh: )

[Minuit]

Hmmm...ideas:

 

(1) I recently was lurking the other forums and read a thread about a guy who had the same stalling problems who had bought an after-market (believe he said from NAPA) CPS and it was doing the same as you described - seemly after the truck warmed up. He was advised that some after-market CPS units would get squirrely when they got hot, so he took his out of the truck and ohmed it out when it was cold, then warmed it in a toaster oven. Sure enough, when it was cold he was getting about 200-275, but when warmed up he got 0.

 

He went to the Stealership and got one - problem solved.

 

(2) Ignition switch (down low on column) can sometimes be damaged by blower motor pulling too much current through wires. Check for melting where blue plug cannot be removed, or (in extreme cases) wires are singed looking. Ususally involves replacing switch (tilt and straight column switches are different - ask me how I know :doh: )

 

1: Isn't the CPS supposed to show open resistance (at the pigtail harness near the intake manifold, anyway) when ohmed out? If my brain is working today ( :dunno: ) that would indicate it's a bad unit to begin with. Mine tests open cold and warm.

 

2: I'll have a look real quick. Thanks! :thumbsup:

 

Cheers.

 

P.S. My problem with random stalling (at least until after I write this post :doh: ) seems to have mysteriously ceased. Since I started this thread I've put about 15 miles on the jeep and while the hopping and bumping which I believe is the TPS persists, it hasn't stalled. The day I started this thread it stalled 3 times in only a few miles. Just because I had one on hand, I replaced my ignition coil. What's the probability that I accidentally fixed my stalling problem?

[jimoshel]

[quote=

 

What's the probability that I accidentally fixed my stalling problem?

Pretty good?