1999 Chevy Suburban Hesitation

Tal’s question:

My 99 Chevy Suburban acts up when it’s really cold outside, hesitating and stumbling when I try to accelerate. One guy thought it was the coolant temperature sensor telling the computer it was hot when it really was cold. So he changed it out, but it made no difference at all. Help!


Well, it was a good guess, but it obviously didn’t fix things. I assume you have no stored trouble codes, because the other mechanic would have told you that. If you don’t have any trouble codes, first have the fuel pump pressure checked when it is really cold outside. I’ve seen the pumps on those Suburbans cut out when they get too cold, and cause stumbling without setting any codes. There is no fuel pressure sensor on that engine, so the computer has no idea what the real fuel pressure is. So if the pressure is low, the computer often can’t set a trouble code because it doesn’t know the pressure is low. I fixed one like that last year and a new fuel pump solved the whole problem.

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