fuel pump?
Thread Starter
Instructor
Joined: Jun 2005
Posts: 193
Likes: 0
From: woodinville washington
fuel pump?
question
1991 A4
i turn the key to run without starting the engine, and i do not hear the fuel pump prime. should i hear the fuel pump humm for a few seconds or not?
then i go to start the car and it will not start unless i give it gas, it will simply crank and crank. once started the car runs fine other than a slight idle stumble when comming to a stop.
does it sound like its time for a new fuel pump?
thanks
yellow
1991 A4
i turn the key to run without starting the engine, and i do not hear the fuel pump prime. should i hear the fuel pump humm for a few seconds or not?
then i go to start the car and it will not start unless i give it gas, it will simply crank and crank. once started the car runs fine other than a slight idle stumble when comming to a stop.
does it sound like its time for a new fuel pump?
thanks
yellow
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
You should hear the pump humm for about 2 seconds after the key is turned "on". Do you have a fuel pressure guage? This would be the best way to tell if the pump is working.
If not, after the key is turned "on" go to the schrader valve and take the cap off. Have a rag handy and press the valve with a screwdriver. If fuel comes out under pressure then the pump is working. How much??? need a guage to see.
Try this: Find the fuel pump relay. Should be by the windshield wiper motor (I got a pic if needed). Disconnect the relay. Use a jumper wire to test for a bad relay. Stick one end of the wire in the first terminal of the fuel pump relay connector and the other end of the wire in the last terminal of the connector. Turn the key "on" and listen for the humm and check for pressure. This is a way to troubleshoot the fuel pump relay.
To test the overall health of the fuel pump. You need to drive around with a fuel pressure guage taped to the windshield at all throttle positions. Any significant drops in pressure tell you the pump is dying. Most noticable at WOT.
If not, after the key is turned "on" go to the schrader valve and take the cap off. Have a rag handy and press the valve with a screwdriver. If fuel comes out under pressure then the pump is working. How much??? need a guage to see.
Try this: Find the fuel pump relay. Should be by the windshield wiper motor (I got a pic if needed). Disconnect the relay. Use a jumper wire to test for a bad relay. Stick one end of the wire in the first terminal of the fuel pump relay connector and the other end of the wire in the last terminal of the connector. Turn the key "on" and listen for the humm and check for pressure. This is a way to troubleshoot the fuel pump relay.
To test the overall health of the fuel pump. You need to drive around with a fuel pressure guage taped to the windshield at all throttle positions. Any significant drops in pressure tell you the pump is dying. Most noticable at WOT.
