Fuel pump voltage
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
Fuel pump voltage
I did a data log of my 89 6 spd and sent to a chip tuner. He said the Fuel Pump voltage is 7.7 and not 12. Have any of you seen this? The FP pressure is 43 PSI car running. Thank you
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
In a word - NO !!!
The only way a C4 fuel pump could be running at 7.4 Volts is if there was a bad connection and there are about 1/2 ohm of resistance somewhere in the wiring to the pump. And even if that was happening - I don't see how the tuner could read that.
The only way a C4 fuel pump could be running at 7.4 Volts is if there was a bad connection and there are about 1/2 ohm of resistance somewhere in the wiring to the pump. And even if that was happening - I don't see how the tuner could read that.
Melting Slicks
Joined: Jul 2005
Posts: 2,649
Likes: 863
No version of the C4 has an ability to feed the fuel pump a pulse width modulated voltage. The wiring to the fuel pump is pretty basic - it supplies either "battery voltage" or no voltage - there is no middle ground available..
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
When I put the pump in. The voltage to the pump is 12 volt. Why is the ECU saying it is 7.7. my chip guy said he looked at a data log of another 89. It's fo voltage was 12 volts.
so is there something wrong with my ECU or is there a bad ground wire? Thank you
so is there something wrong with my ECU or is there a bad ground wire? Thank you
Team Owner
Joined: Sep 2003
Posts: 25,393
Likes: 2,741
^^^^
The diagnostic tree for DTC 54 FSM 6E3-59 and for 'intermittent' 6E3-B-2
**** This car best I recall has some after-market relays wired into the system and likely in the past had 'Cranks But Doesn't Run' issues?
The diagnostic tree for DTC 54 FSM 6E3-59 and for 'intermittent' 6E3-B-2
**** This car best I recall has some after-market relays wired into the system and likely in the past had 'Cranks But Doesn't Run' issues?
Last edited by WVZR-1; Apr 12, 2023 at 07:51 AM.
