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1999 Volkswagen Passat Fuel Pump Inop?

Tiny
ESCAPEMAX
  • MEMBER
  • 1999 VOLKSWAGEN PASSAT
Electrical problem
1999 Volkswagen Passat 6 cyl Automatic

Hi, I am helping a friend with his 99 Passat. Cranks but wont start. I checked Spark. OK. Checked Fuel Pressure and nothing. Checked the wiring at the pump. No Voltage. Checked the Fuse #28. No Voltage on either terminal. But when I remove the Fuse and check the "Hot" side I get 4.2V. Reinstall the Fuse and check, 0V. Checked the 40 A Fuse next to ECM. OK. Relay appears to be good. Not having a spare on hand, I didnt swap it.
The engine is 2.8 SOHC. Automatic.
Thanks.
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Sunday, August 24th, 2008 AT 10:02 PM

6 Replies

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Swap the relay and see what happens. Same story -apply direct battery voltage to the other side of the fuse-Did the pump come on?


https://www.2carpros.com/forum/automotive_pictures/12900_volks_fuel_pump_1.jpg

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Sunday, August 24th, 2008 AT 10:53 PM
Tiny
ESCAPEMAX
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Thanks. This may sound dumb. The Relay is the one located next to the ECM?
I did think about bypassing the fuse. Working at his place, I had limited tools with me.
Is there a safety/security feature that disables the pump?
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Monday, August 25th, 2008 AT 5:53 AM
Tiny
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Test for power at the injectors harness green and yellow wire with key on run position -do you have it?

The computer fuel pump relay control could be the problem
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Monday, August 25th, 2008 AT 10:41 AM
Tiny
ESCAPEMAX
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Heres the Whole story.
He took the T-Belt off to replace it. Steamed the engine. He asked me for help once it was apart. I got the cams lined up. Put enough parts back on to "Test". Been trying to get it to start. No power at the pump. No power at the fuse. Could be either the ECM or the Relay. Unless theres a Safety switch that I cant find in the Diagrams.
I am not sure if he told me the entire story. But it seems to me that hes been working on it for awhile.
I checked one of the Injectors for power. Had about 5v.
Thanks
Escapemax
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Monday, August 25th, 2008 AT 11:45 AM
Tiny
RASMATAZ
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Direct battery voltage to the fuel pump and see what happens-
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Monday, August 25th, 2008 AT 1:52 PM
Tiny
ESCAPEMAX
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Heres as it stands.
12+ to Pump. Runs

Unpluged one of the Injectors. Had 5.3V on Both terminals.? As I understand it, One is a Ground Lead controlled by the ECM.

Key On, Pump is Inop. Had 12+ to Red wire in ECM. 12+ on Red/Blue wire to Relay. Black wire to Switch shows 0V.

Thanks for the Assist.
Escapemax
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Monday, August 25th, 2008 AT 9:51 PM

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