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Jerry Newton
Jerry Newton, Chevy Technician
Category: Chevy
Satisfied Customers: 4758
Experience:  ASE Master Technician, L1, Master GM Technician. Over 20 years of bumper to bumper GM experience.
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1990 2500 4wd pu truck.started to shudder really bad. I

Customer Question

1990 2500 4wd pu truck.started to shudder really bad. I relate it to the key being turned off quick and then back on again. It will run low on power until the accelerator is floored then it seems to almost smooth out and pull itself. Like water in fuel? Hole in the rotor? It is intermitant. Seems ok till the engine warms up completely
Submitted: 1 year ago.
Category: Chevy
Expert:  Jerry Newton replied 1 year ago.

I would be looking at some scan data on this, if you have an old scan tool, because it might be as simple as a faulty coolant temp sensor, which will show right up on the scan tool. Water in fuel and a hole in the rotor would be present when the engine is cold, too, so I don't think those are right. We had problems with distributor pole pieces on these engines, a distributor will act up when hot but not when cold. There are also issues with the fuel injector wiring where it passes through the air cleaner and up the injectors, the wiring will short in that area and cause all sorts of issues like this.

Those are just a few common ideas to get you going, a good visual inspection of the wiring at the fuel injectors may just turn up the issue. If you can't find another cause, I'd be inclined to put a distributor in it and set the timing according to the instructions on the underhood label.

Customer: replied 1 year ago.
I will start looking and let you know what I see
Expert:  Jerry Newton replied 1 year ago.

Excellent, if you need anything else, just let me know.