92 K1500 stumble/hesitation while driving

[Ron88]

Bad Grounds as Mentioned
Cracked Vacuum Line ? sounds like its leaning out at 2000 rpm

 

[Luke Stratton]

My 98 Tahoe had a similar issue no codes but would stumble under acceleration, Took it to the shop it was out of time once the timing was fixed it popped a misfire code on 2 cylinders, replaced all the plugs and also had them clean the fuel system top end, it runs great now and I know eventually I'll need to replace the old popett injectors but hopefully a little further down the line. Just my .02

 

[Schurkey]

My 98 Tahoe had a similar issue no codes but would stumble under acceleration, Took it to the shop it was out of time once the timing was fixed it popped a misfire code on 2 cylinders,

Ignition "timing" is not adjustable on a '98 (Vortec engine).

They may have set the distributor offset--correcting the crank sensor/cam sensor synchronization, but that doesn't change the timing.

It does allow the computer to determine which cylinders are misfiring.

The original poster doesn't have a Vortec engine, there is no crank sensor, so cam sensor/crank sensor synch can't be a problem.

His ignition timing is adjustable, and verifying that has already been suggested.

 

[PlayingWithTBI]

Did you do the paper clip trick to see if you have any stored codes. These OBDI ECMs will turn on the SES light for a while then it'll go out but, the ECM will store the code for 30-40 key cycles or when you disconnect the battery.
https://www.freeautomechanic.com/diagnostictroblecodes5.html

If I were a gambling man I'd say your coil and/or ICM are bad but, if you have a code, it may point you in the right direction. As mentioned above, it's always best if you have a good scanner.

 

[Luke Stratton]

Ignition "timing" is not adjustable on a '98 (Vortec engine).

They may have set the distributor offset--correcting the crank sensor/cam sensor synchronization, but that doesn't change the timing.

It does allow the computer to determine which cylinders are misfiring.

The original poster doesn't have a Vortec engine, there is no crank sensor, so cam sensor/crank sensor synch can't be a problem.

His ignition timing is adjustable, and verifying that has already been suggested.

I understand he doesn't have a Vortec engine, was only statiing that not having it pop a code don't mean much. It is possible for the Vortec to be out of time per say, GM says to get it as close to 0 degrees as possible but if one re installs the distributor one tooth off it will run but not at 0 degrees or top dead center. No its not the same as putting a timing light on it and adjusting the distributor but essentially its adjusting the timing via the computer. potato patato, With all your awesome knowledge nobody else needs to post, yet it still isn't fixed.

 

[Luke Stratton]

My 98 Tahoe had a similar issue no codes but would stumble under acceleration, Took it to the shop it was out of time once the timing was fixed it popped a misfire code on 2 cylinders, replaced all the plugs and also had them clean the fuel system top end, it runs great now and I know eventually I'll need to replace the old popett injectors but hopefully a little further down the line. Just my .02

Forgot to mention that the misfire was due to two plugs being bad and I had replaced them less than a month before so checking the parts you replaced is not out of question.

 

[FastGilla]

Forgot to post what the fix was. It ended up being the fuel pump was not giving enough pressure under load. It had enough pressure to start the truck and idle it all day long, but as soon as there was load, it would stumble and fall on its face. I did replace the fuel pressure regulator before the pump, just because it was cheap and easier than doing a pump, but it had no effect. Thanks for the all the help.

-Brandon