Poor power. Bad injectors, bad fuel pump, or spark plugs

[breaksr]

I'm working on another '91 Q45 in the near future and I think I may need some advice. I took her out for a test drive this afternoon and the car had a very strong hesitation from low speeds. Almost bucking a certain points. Owner had just bought the car from an auction for very cheap so I'm guessing very little maintenance had been done. 120K on the odometer and the usual hornets nest in the trunk and oil leaking from the drivers side valve cover tells me this could be a major over haul. Owner only wants me to do the spark plugs to start with but I'm thinking some of the fuel injectors maybe bad. Would an old and loud fuel pump give the car erratic acceleration? I already warned him that changing the plugs might not fix the rough acceleration. Oddly enough there is very little shaking when the car is in drive at a stop.

[elwesso]

Demand that the pump be replaced FIRST. Spark plugs wont clear up that. Goofy things happen when the car doesnt get enough fuel. You MUST do that first, or nothing else will work out.

Ive seen SO many people REJECT FUEL PUMPS as the cause of that because they figure that it either works or it doesnt. This is NOT the case, as it can quasi work (May work on the other 2 speeds but not on low speed). They start replacing everything under the sun until they finaly decide that the fuel pump caused everything.

[cccpman]

I agree, had similar problems with a failing pump. Big sign to confirm would be a buzzing sound coming from the right rear of the car. Turn the car on and listen for it (head in the trunk, or from the right rear passenger seat), even if its not the pump the car probably will be needing a new one shortly so its definitely a good thing to replace. Be real careful if you do go to replace the pump, its too easy to bend the floaters arm and that will really throw off your tank readings

As for the plugs, its a real inexpensive fix (and its not such a pain in the *** after a couple replacements).

Oh well, see if you can hear the pump buzzing away

[96Qowner]

... see if you can hear the pump buzzing away

Yeah, if it's noisy, it's gotta go - either now or after he's burned up the FPCU. Few Q45 pumps make it past 120K. First pull the FPCU and take a good look at it for burned spots on the connector or the circuit board.

Replacing the plugs should come much later. They aren't the problem.

[breaksr]

Well that is good information. I've changed two fuel pumps on other Q's (my '91 and a '95) so I'm well educated on how to do it. I figured it might be the fuel pump given the amount of noise inside the car and the poor pickup from a stop. If I could find a used one like I did last time then it is actually not that bad a service charge for this customer.