fuel pump problems Ljet conversion

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fast3.0csi

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I have had over the years problems with the fuel pump not working. I did the lJet from djet conversion about 4 years ago and the car runs great but for some reason the pump will come. I have replaced the pump and starts for a while and it starts again. I had the car towed several times due to this problem. When I think I got it fixed it happens again..

Have anyone here had this problem before? Thanks

72 3.0csi
 
Help us help you....

What does this mean?

"but for some reason the pump will come. "
 
fuel pump problems

I'm sorry. I was so frustrated. The pump will not come on. I have changed it twice. The big relay twice. I have checked the AFM, fuses and wiring. I'm missing someting???? Thanks
 
the engine is cranking??

So do I change the ignition switch? The fuse pump relay is part of combo relay?
 
I think what we are saying is that every wire, connection and component involved in the circuit from the ignition switch to the fuel pump has to be considered. Assuming you have the correct wiring diagram for your model and year, start with the cheap stuff and check that the wires and connections are solid and clean from the ignition switch to the relay to the pump etc. Check the status of any grounds involved.

Then start looking at the components themselves and test for operation.

Good luck, let us know what you find.

Doug
 
Firstfives.org has a faq on combo relays repair with wiring diagram, principles of operation, and some testing. Since you've changed both the pump and relay, it sounds like signal or wiring. There's a fair amount of current at start that can wear down pins and connections so amp the main power signals/ fuse terminals, clean them, make sure they're tight with full contact AND getting full amps without high resistance.( heat if you have an infrared gun) The cars are getting old and that means wiring too which usually is just a good cleaning of the offending connection.

The relay recieves signal( s) from several sources ( coil ( -), ecu(+), etc.) so you need to induce the signal from the afm when the door is temp propped open, coil grounds to signal the ecu to run, ecu to combo relay, etc. So that should narrow it down.

It may help to know which combo relay you have also- 530i or 528; one has an extra pin, so check the wiring plug to make sure that's not it.
 
Fuel Pump

I ran a dedicated 14 gauge ground wire from the battery to the pump ground wire point at the rear of the car, (under the left rear seat next to the ECU) and have had no problems of this nature since. Go figure but it worked for me. (D-jet) Not sure of the mods to go to L-jet...if the pump is in the same place and you use this existing wiring, EZ to run a ground back and see. I would try this first.
 
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Hi,

I just did the L-jet conversion this year and had a similar problem. I had brand new bosch fuel pump that failed. The car ran the first couple times I started it but stopped working within days. I could hear the intank pre-pump running but not the main pump. There was power at the pump so I took it out and bench tested it and it seemed to be jammed. It wanted to pump but didn't. I replaced it with the 30 year old pump from my e12 parts car and it's been working fine since July. I bought the pump from Lajolla Independent and theywere good about sending a new one. I do plan to install it before I take a long trip.

Do you have an in tank pre-pump? I wired my pre-pump and main pump together from position 8 (grn/violet wire) from the e12 engine plug. The l-jet system only sends power to the pumps when the ignition switch is in the start position. Then when the engine fires and you release the key/switch the door in the Air Flow Meter opens and triggers a switch that sends power to the pumps. This is for saftey, if you're in an accident and/or the engine stalls that pumps stop sending fuel. With your ignition in the on postion and the engine not running remove the hose from the AFM use a long screwdriver to prop open the door/flap and you should hear the switch and your pumps should run.

There used to be a good write up by Jim Ockner, regarding the l-jet conversion on the old CS Register website, that's what I followed in doing my conversion. Most of that CS Register technical was transfered to e9coupe tech info but that article did'nt make it. I have it in a word file and would be glad to send it to you if you think it would help.

Good Luck,

John M
 
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Thanks John

I did my conversion with the same instructions and it started up the first time. That was 4 years ago. I don't have a pre-pump but am interested in more information on how to wire on in and what type? Pictures if not asking to much?

I haven't tried all the tests yet but have in the passed. I changed the two or three times but not with a new one. I used one from a running car. But, out of the blue it stopped. I have had the car towed three times I know..I have also made several hundred miles trips without a problem. Tonight, I will go thru the testing again. Any information I really appreicate it. My e-mail address is: [email protected] Thanks
 
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