truck dies at low speeds and stops.

[BlakeOfDoom]

ok, first things first. my 91 navajo has been having a hell of a time lately. After the truck has warmed up (this is when it seems most apparent) it has a tendency to die when in gear at low speeds, no stumble, no weird hesitation. It just dies.

The rpm's drop down to 1000 and then jump back up to where it was. I was pulling into a parking space today with my foot off the gas and it died before I made it all the way into the space.

This obviously poses some danger, so I'm wondering where I should be looking. The fuel filter has been replaced, that made no difference. I also just put in a new alternator, but i do not think that has to do with this problem. Should i be looking for anything else?

I'm going to go check the fuel pressure regulator and the fuel pump relay, could these be possible issues?

btw, no check engine light or anything.

 

[jrowe6]

check your idle air control valve

 

[BlakeOfDoom]

I've cleaned the IAC recently, but that doesn't necessarily mean it's not the problem. I understand that the IAC can cause vehicles to die at idle, but would this affect it on the road while driving? would the IAC cause the RPM to drop while moving at speed?

 

[jrowe6]

maybe i missunderstood your original post.

does this only happen when you are not on the gas?


if it only happens when the throttle is completely closed then yes i would start by checking the iac. reguardless of speed the iac keeps the engine running the correct rpms when you let off the gas, so if you are running 45mph you let off the gas and the engine just about dies thats pointing to the iac if you ask me. especially if you also have a serious idle problem and CAN keep the engine going by giving it some gas. in other words, if manually controlling the throttle will for sure keep the engine alive in these situations i think the iac is dead.

if the engine is dieing randomly while crusing at a constant speed and you did not let off the gas i dont really know what could be doing that.

so yea....does this only happen when you are 100% off the throttle?

 

[BlakeOfDoom]

The truck only dies when I'm off the throttle at low speeds, it doesnt seem to do it on the freeway when I let the gas off. but that doesnt explain the bouncy tach needle. I'll pull the IAC and give it a good cleaning, hopefully that will help.

 

[jrowe6]

figure anything out?