Is My Fuel Pump Finally Dying?

[rednucleus]

Anyone know of a business that repairs ecu's?

[BOSSMAN]

Update - the gremlin lives on. Still getting an intermittent pump - but I have found the problem is with the computer control unit. When  I wiggle either of the two connectors, I get intermittent loss of power to the ecu. Have unplugged the connectors and checked them with the meter and they do not cut out no matter how many ways they are pushed/pulled/bent etc.  So I assume I have a bad solder joint from the connector to the board? When it works, all is well, but when wiggled wrong, instant stop.

Might be a chassis grounding issue.  Think about it, at first if you kick the gas tank and you can get the pump to work how does this relates to a problem ECU.  When my pump stop working, I too checked the power and it was good but the problem was the ground.  I would clean the battery terminals first and hard wire a ground wire to the gas tank to make sure you have a proper ground. 

[rednucleus]

No, it's definitely one of the plugs going to the ecu. Just a coincidence that the gas tank sloshing got it working.  I can hold the ecu in my hand, wiggle the plugs, and the ecu lights go on & off  & the pump cycles off and on. It's more than just the pump not running, the entire ecu blinks off.  I think it's the 15 terminal plug. Circuit board looks fine but may try to re-solder all connections associated with the plugs. Or find somewhere to send it for repair.  Also checked codes - no fuel pump code, but does tell me to check my temperature sensor. All else is ok.

[rednucleus]

Hopefully last update.  Cleaned plugs/connectors with deoxit. Did not change problem. Started wiggling individual board components and found touching anything in the corner by the 20 pin connector caused the fault. Soldered all capacitors in that corner, no change. Then soldered the 3 transistors that are screwed to the metal frame and problem appears to be gone. Can wiggle the plugs now and wiggle components in that corner and flex the circuit board with no cut out. Drove for 15 minutes w/o any problem. So, time to try the daily drive routine again and wait and see ... BTW looks like lots of reman S12 ECU's are available on Ebay (A Cardone) but a little bit of a challenge to cross reference the various numbers. Hopefully I will not need one.  For what it's worth, for years I have had intermittent very short "cut outs" - feels just like you turn the key off for only a second. May not happen for weeks, then may happen several times during a drive. Will be interesting to see if those are gone too.
I'll call you if it quits and I need a ride!

[weitrhino]

Intermittent electronic problems can be a nightmare to track down. As you've discovered sometimes you just have to wait for a complete failure in order to find the culprit. Good sleuthing.  I hope this finally nails it for you.

[mc]

good job...i also had issues with the 3 ecu multiple connector, specifically the one closest to the firewall....i had to jiggle it to get it to run correctly ...those wires are at a terrible bend, especially after all these years.

[Wonderingraven]

Wiring all in great shape under cover. New pump ordered. Got to believe the old one is just getting intermittent and dying.

if you don't mind me asking where did you order the whole fuel pump unit from?

[rednucleus]

All I got was the pump motor and then installed it in the original housing - it was a bosche  - I think from Rockauto, possibly Ebay - saw several at both sites. I have not seen a complete pump/housinig/sender assembly anywhere except nissan oem parts sites and no idea on avalability

[Cajun1guy]

Wow Dave, great work! I hope it will behave for you now, those issues with sudden cut-out are real thrill killers. Hard to enjoy the ride when you are anticipating the next shutdown.  Reminds me of a Jeep Grand Cherokee my wife used to have...