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Fuel pump or transmission?

Hey everyone,
I have a '93 Volvo 850GLT, and recently it’s started acting up on me. It starts fine, but once we get rolling it feels like when I press the gas pedal, the engine doesn’t get any gas. If I try and idle it, the engine RPMs die down and the engine dies, but if I press too much on the gas it refuses to accelerate unless I coax it. I can keep it in first gear with just the right amount of constant pressure on the gas, and I found that even though when I press down on the gas pedal to accelerate nothing happens, when I release the pedal, as it returns to its regular position the engine gets a kick. If I rhythmically work the pedal a little, I can get it to accelerate and eventually shift up. If I apply too much pressure, though, like I said, she stalls and that’s that.

Because it doesn’t want to shift, my mechanic says it’s probably a transmission issue, but my car is an automatic and A: I don’t wanna spend that kinda money on a transmission right now and B: A few of my more car-minded family members say that when an automatic transmission dies, there’s normally muck or metal in the transmission fluid, and my fluid is fine. Could it be something to do with the fuel pump or gas lines?

Weak fuel pressure is a very likely cause for your problem.

My first suspect would be a partially-clogged fuel filter.
If the filter hasn’t been changed w/in the past couple of years, or if you can’t recall when it was last changed, then change it. With any luck, that will resolve the problem.
(Please note: Some Volvos have two filters–one in the tank, and one under the hood. I don’t know if this applies to your car, but I would focus on the one under the hood.)

Then, if the symptoms continue, I would suggest two things:

Get a new mechanic, as anyone listening to the symptoms you describe should not be attributing them to a bad transmission.
Have your new mechanic check the fuel pump’s output pressure.

Definitely check fuel pressure before going all out on the transmission. You can get a loaner fuel pressure gage at most chain parts stores and do this diagnostic yourself. See where your fuel pressure stands and go from there. Yes, if you can’t remember changing the filter, then it is time to do so…

Engine running issues can cause what feels like an issue with the transmission. The transmission may be set to shift at a certain RPM/throttle position and will continue to do so even if the engine doesn’t have enough power to be in the normally appropriate gear. I saw a truck with a failing ignition coil pack that had a several stored codes relating to various misfire conditions and a check engine light. It was shifting really rough too but was smooth as silk after I replaced the coil pack.

If the fuel system doesn’t solve this, check for stored codes and possibly look into the ignition system.