I've got at 1997 Chevy Suburban. Recently we had the fuel pump changed, because we hit a bump and it gave up the ghost.

In the last month there have been at least three times when we we've stopped, and then started, but instead of shifting into the next gear it basically shifted out of gear - the RPMs went up, but the speed went down.

After letting off the gas, then things re-engage and we can drive off. But it seems to have happened when we're trying for a quick acceleration, say because a semi-truck is coming up behind us.

I know that at least two of the times have been turning from a near or full stop. Last time I changed the oil they also mentioned that our differential fluid needs changing - it was pretty burnt up. Could that be related?

  • This sounds like a transmission problem to me, have you checked the fluid? When was the last time it was changed? – GdD Sep 29 '17 at 14:58
  • @GdD we've never changed the fluid, it was checked when we last changed our oil (in the last month or two). – Wayne Werner Oct 2 '17 at 16:47
  • If it hasn't been changed then you should get it to a reputable transmission shop to get it flushed. Fluids break down and can stop doing their jobs even if the level is okay. – GdD Oct 2 '17 at 16:58

You don't state the mileage, if we assume ~10k/year then 200,000 miles. Chevy recommends changing the transmission fluid and filter every 50,000 miles (for severe duty, i.e. frequent towing, hilly/mountain terrain, use in traffic in hot climate, etc.). I would say try that first.

  • it's at least 200k - the title stated at least 20k more miles than was on the odometer. Of course at its age it's exempt, so I'm not sure what was up there. – Wayne Werner Oct 2 '17 at 16:10

Do you have 4wd? Is your transfer case slipping into neutral? You mention the differential fluid being "burnt up" - are there any metal shavings in it?

I would have a mechanic take a look at the transfer case linkage, the differentials, and then the transmission.

  • it's 4wd, but the 4wd doesn't turn on anymore - which was another question I was going to ask soon – Wayne Werner Oct 2 '17 at 16:10
  • With that information, I would narrow down that it is likely linked to your transfer case or differential. – IdahoFish Oct 9 '17 at 15:29

As it turns out the problem was the fuel pump (or possibly sending unit, as we recently replaced the fuel pump). Even though the fuel pump would turn on (at least, when you turned the key in the ignition you'd hear a "whiiirrrr") it was having trouble starting. After they replaced the fuel pump stepping on the gas pedal gives it all the fuel it needs and we can get up and go.

I'm not sure why it exhibited this way, the only thing I can think of is that everything else in the system acted like it was getting ready to shift, but since it didn't get the proper amount of fuel it never did engage the transmission.

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