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View Full Version : Need Help/ Troubleshooting 95 D90 V8 fuelpump/relays



NevinBC
12-04-2017, 10:14 AM
Took the 1995 V8 D90 for a spin, its been awhile.. I revved the engine driving on a straightaway and all of my electrical/lights surged then went out, along with the engine. my lights/electrical came back online after the momentary outage but the engine had quit. the 7.5A fuse had blown and the fuel pump was not priming when I turn the key.
Currently I have replaced the 7.5 fuse, both under seat relays, hotwired fuel pump and it runs 4.0, checked fuses under bonnet and pushed inertial switch.
-I am not getting power to the 7.5 amp fuse, the "Blue base" fuel pump relay is getting power to the 30, in an attempt to get the pump to prime I connected 30 to 87/87 on the relay and nothing happens.. saw that in a troubleshooting forum elsewhere.
I know I need to start checking pins on the ECU but am looking for some general guidance on how to trace this electrical problem.
thank you for the help.
-Brent

jp-
12-15-2017, 08:34 PM
Main thing for electrical problems: is everything that's supposed to be getting power, getting power? (Don't forget this includes bad grounds which are often forgotten.)

All lights coming on, then going out makes me think ignition switch. Will the motor start (or turn over) with the fuel pump bypassed? If yes to either, probably not an ECU issue. In 23 years of wrenching, I've only had one bad ECU (Mitsubishi). The symptom was no spark, but everything else was working. And only three bad relays in all that time (two Mitsu's and one VW). Have seen dozens of fuel pump and ignition switch failures.

A few posts on this topic on the internet as well:
http://www.defendersource.com/forum/f6/diagnosing-fuel-pump-issues-19999.html

Ignition switch issues are also plentiful:
http://www.defendersource.com/forum/f6/ignition-switch-34421.html