Was hunting an electrical gremlin for the longest no-start i've ever had. Previous no-starts that were eventually hunted down were huge vacuum leaks and flooded plugs. This latest no-start lasted 5 days before i managed to track it down.
It begins with me jacking up the car to apply fresh paint, seam sealer and underseal. I also fiddled with the ECU harness. After assembling everything back, it wouldn't start. It would start for a split second before stalling.
(Later, I realised that it was because of the cold start injector)
I (thought I) had fuel at the cold start injector, but didn't check the rest of the injectors.
Frantically troubleshooted everything from Throttle Body to TPS to Ignition Coil to Distributor to Rotor to MAF to Plug cables and finally plugs but everything seemed alright. Car had spark but simply wouldn't start. I took the opportunity to drill a hole in the TPS to reduce oil build up.
Ran to the hardware store to pick up a voltmeter for $4 and began measuring resistance checks across all components. All were well within specifications.
Figured it might be the Fuel Pump/Main Relay so I went to a couple of junkyards but couldn't find said relay. Pursued other possibilities as I waited for Monday(today) to check with the dealers.
Did some googling on the said p/n: 0280230001, and turns out some alfa's and ferrari's running on L-Jet's used it. And the price was an astounding $170 on ebay.
More tests with the Voltmeter revealed that when the relay was triggered i was getting 12v power on pin 87b which powers the pump, but only 0.33v at pin 87 which powers the injector. Weird... both pins are supposed to be energised when the circuit is live.
Fast forward Monday, several dealers had it in stock but not the original Bosch but a KAE variant. Online reviews urged to stay away from the KAE's citing poor QC and it not functioning like the Bosch. Made a call to several notable BMW enthusiasts and received a quote ranging from $25 to $65.
But I wanted to double confirm it was my relay that was at fault. So after getting back from work, I connect a wire from pin 87 to 87b and start the engine... And lo-behold IT'S ALIVE!!
I decide to try to pry open the relay to see if it was salvageable. Certain parties reported success by resoldering similar relays and I simply wanted to try my luck before splashing my moolah. Anyway, on to the pics.
I use a saw to saw along the groove of the relay, repeating on all 4 sides.
I pay attention not to saw into the PCB, and after all 4 sides are done, I gently pry it open and the PCB slides out.
Upon further examination of the solder joints, I spot 1 particular joint that had oxidised and traced it back to pin 87. Bingo.
I break out the soldering iron and take no prisoners as I resolder all main joints.
And am left with not the best work but at least fresh solder. I test continuity to ensure that no solders overlap. I don't want to cause a mini fire.
I proceed to hook it up to the connector and fire up the car. It roars to life.
I then mix up some epoxy and reseal the relay back into its housing.
While i'm at it, I replace the brittle and aging connector with a fresher that doesn't disintegrate upon contact.
And I'm glad to report that my car is running again, better than before thanks to my troubleshooting that cleaned up the distributor contacts, rotor and found a loose spark plug.
Comment