I have a '92 Volvo 940GL which is spitting and sputtering at ignition. At one time it was on but only shortly when I stepped on the accelerator. What's the problem?

Hi Dr Phil,

It could be due to dirty throttle body. Too much carbon deposit on it could prevent the throttle from closing properly (thus affecting the TPS idle switch) so the ECU is confused whether its idle or acceleration mode.

Regards,
Amarin.

Dear Dr. Phil,

Hope you're well. If this problem has slowly become more severe, I suspect: (a) a failing fuel pump; (b) a failing fuel pump check valve (#1326899, about $40 at a U.S. Volvo dealer).

A failing fuel pump may need extra time to build pressure and may not supply enough fuel to meet the need when strong acceleration is required. Does the engine "stutter" or run "rough" under strong acceleration? If so, this would suggest the fuel pump is "on the way out".

A failing fuel pump check valve allows fuel to drain away from the engine, on shut-down. Thus, on start-up, the engine is briefly starved for fuel, until the pump re-builds pressure. If the car thereafter runs smoothly, even under strong acceleration, then the check valve likely is the culprit, as a failing pump would not be able to supply enough fuel, causing the engine to run "rough".

Hope this helps.

Yours faithfully,

Spook

Thank you for your suggestions on the fuel pump and check value. I've been a Volvo owner for 32 years and have replaced 2 in-tank fuel pumps. It can be a hassle standing in the back of the trunk and bending over.

Dear Dr. Phil,

Hope you're well. As your car has a turbo-equipped engine, it uses the Bosch fuel/engine management system. I believe that in '92 cars, the main fuel pump is mounted on the underbody, approximately below the driver's seat. The fuel pump check valve is screwed into the main fuel pump, on the end with the electrical connectors. A tube - sheathed in black plastic - connects the fuel filter to the fuel pump check valve.

How many miles on the in-service main pump? The Bosch main pumps are quite durable: if the in-service pump has less than 200,000 miles on it, it may not be the culprit.

I've changed in-tank fuel pumps on wagons. Access to the send unit is via an plate in the cargo space floor. That surely is easier than working inside a trunk.

Hope this helps.

Yours faithfully,

Spook

My engine is non turbo.There's approximately 240,000 on the odometer.Can you offer any price help on the in-tank fuel pump? A Bosch in-tank fuel pump is running about $131.58 on-line.

Dear Dr. Phil,

Hope you're well. With 240K miles, the factory-installed pump(s) is/are at - or very close to - the end of its/their service life(s).

Volvo VADIS - a superseded dealer parts/service database - shows that 1992 940 wagons were equipped with a turbocharged engine, while sedans' fuel/engine management was of the Rex/Regina type.

Thus, if your car does not have a turbo, then it has Rex/Regina fuel management: such cars have a single, in-tank fuel pump Volvo Part #3507736). Cars with the Tex/Regina system have a square ignition coil, mounted on the front face of the driver's side strut housing. Cars with the Bosch system have a cylindrical ignition coil, mounted on the passenger-side strut brace.

A Bosch system in-tank fuel pump - a pre-pump (the main pump is mounted on the underbody beneath the driver's seat) - costs about $40, for an after-market unit. A Volvo brand unit will cost about $150.00.

Hope this helps.

Yours faithfully,

Spook

Have you made sure all the vacuum lines are tight??