View Full Version : Fuel pump not priming on bmw z3
notjasonthered
Feb 12, 2010, 06:28 PM
Turn the key on , no prime. Pump only runs while cranking. While cranking it pumps some fuel but no prime when you first turn on the key. This is a new fuel pump. All fuses have been tested on a multi meter. I took the line off the pump and replaced with a clear hose to a gas can. Fuel only comes out when turning the engine over.
TxGreaseMonkey
Feb 12, 2010, 06:51 PM
. Check all under dash and under hood fuses with a multimeter and the ignition switch turned to ON. This will test for "power through the fuse." Clean any fuse that's good and refuses to pass voltage.
. Check for a programmed fuel injector main relay (main relay). Main Relays often contain two individual relays. One relay is energized whenever the ignition is on, which supplies battery voltage to the ECM, power to the fuel injectors, and power for the second relay. The second relay is energized for 2 seconds when the ignition is switched on, and when the engine is running which supplies power to the fuel pump.
. Check ignition switch for wear, pitting, or melting.
. Clean main ECM ground.
You may need to intensively study your BMW's fuel system--they can be very involved. I had to do that for Hondas. The link below may serve as a guide:
https://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-7.html#post1245523
notjasonthered
Feb 13, 2010, 12:25 AM
I haven't looked at the ignition switch yet. That's a good idea. Car has set up a while the customer says. The old fuel pump was locked up . I tested it once it was out of the car. Done checked all the fuses and relays. I'll look at the switch tomorrow night when I get a chance. It's snowing it's here in birmingham , al for the first time in forever. I think Texas got the same snow earlier this week. I'm going to bed now.
notjasonthered
Feb 18, 2010, 07:08 AM
Bmw has another fuel relay beneath the drivers seat. This was the problem. Car runs fine now.
TxGreaseMonkey
Feb 18, 2010, 07:10 AM
It sounds like BMWs, instead of having a main relay, like on Hondas, have two separate relays. It's the second relay that supplies power to the fuel pump.
notjasonthered
Feb 18, 2010, 07:17 AM
If you're here this morning I'll run another one by you. I got a 95 dodge avenger with no spark. Had a bad ecu so I replaced it. Now I can pull engine codes but they were no help. Customer says cel is always on. Codes were for a bad intake temp sensor and for radiator fan switch circuit open. I replaced crank position sensor and distributor thinking it was the cam sensor inside the dist. still no spark.