M42 Full Rebuild now won't start

[Balleristic31]

Sometimes when injectors sit around they seize up. It happens especially if they are all gunked up with bad fuel or fuel with water/ethanol in it.

[theTBLACK]

For the avoidance of doubt, I just bought 4 rebuilt injectors. I'll throw those on when they arrive.

What about fuel pressure - should I check the pressure where it comes up and out of the feed line or what?

What steps should I take next?

[bmwman91]

Yeah, if you can check the fuel pressure than by all means do that. IIRC you should see 40-45PSI with the pump relay jumped and the engine off.

[theTBLACK]

Should I just plug in the gauge where the Fuel comes out of the feedline?

[bmwman91]

I don't know, to be honest. I have never had to measure my fuel pressure! I just know that the spec in our cars is 3BAR / 45PSI.

My guess would be that the gauge goes inline with the feed hose to the rail so that it measures the pressure you get in the system as it flows through the regulator.

[theTBLACK]

I don't know, to be honest. I have never had to measure my fuel pressure! I just know that the spec in our cars is 3BAR / 45PSI.

My guess would be that the gauge goes inline with the feed hose to the rail so that it measures the pressure you get in the system as it flows through the regulator.

Got it. I'll check the manual. However, it isn't likely that all of the injectors aren't firing. Any other culprits or next steps? Could the regulator be bad?

[jpod999]

Are you sure there aren't any blocks or kinks in the fuel lines?

[theTBLACK]

Are you sure there aren't any blocks or kinks in the fuel lines?

Yes. There is a steady stream coming up from the feed line. Pump is new as is the filter. I haven't measured PSI yet.

[jpod999]

Yes. There is a steady stream coming up from the feed line. Pump is new as is the filter. I haven't measured PSI yet.

This is befuddling. Sorry I can't help much more. Sub'd to see how the injectors help.

[MVincken]

There should be a very audible "click" when the injectors are connected to 12v and Fire. If you don't hear/feel anything they may be toast. But I have unstuck a few injectors by giving them a CAREFUL but firm whack on a hard surface.

Hit them over and over with the 12v pulse and not a constant stream of 12v because that can burn out the solenoid as stated above.

try this indeed, no need to order a ton of parts before you really know what the problem is right?

It will be best to let somebody pulsate the 12v to the injector and yourself gently tap the injector with something hard (small wrench or something)

it can take a while but you definitely will feel it when the injector is working properly, it will make a feelable click every time you apply the 12v to it.

*btw: is your fuelpump running when you´re starting? i can´t remember reading it.

[bmwman91]

Yes, the fuel pump seems to be working properly in his car.

[jpod999]

Yes, the fuel pump seems to be working properly in his car.

From one of the OPs post on the previous page though it sounds like the fuel pump doesn't kick on when turning the key. In my car, when you would turn the key to Ignition I always heard the pump kick on before turning all the way to Start.

This post:

Okay. I'll try that next.

Can you speak at all to the issue of the fuel pump not coming on when I turn the key to the run position?

[theTBLACK]

I'll give that try.

If any of you guys read this this morning, the fuel pump is not kicking on as it should when you turn the car on.

I'm almost 99% sure that when you turn it right before cranking, the fuel pump primes. Mine isn't doing that and I don't know why.

I'll try hooking up the injectors and seeing if I feel anything - because at this point, I'm not sure what else to do in order to get them to fire.

If you have any other suggestions for today, let me know as I'll be at it all day today.

I'm going to check the fuel pressure at the feed line where it comes up from under the car and make sure I have good pressure there.

[Dj Buttchug]

remember that motronic will not always prime the fuel pump when you key on...

[theTBLACK]

remember that motronic will not always prime the fuel pump when you key on...

Yeah mine never does. I replaced the relay with a new one for good measure and I'm installing the remanufactured injectors.

Tuesday I'm taking it to a professional - I've given up.