M42 Full Rebuild now won't start

[bmwman91]

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

[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.

[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.

[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]

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

[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?

[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]

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

[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]

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?

[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]

I just don't understand why they would work before and not now. So weird. I'll see if I can get them to make any noise at all. If not, i'll just get 4 new ones. This is getting out of hand. Well, it has been for quite some time.

[Balleristic31]

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.

[theTBLACK]

OK, well it really does sound like the injectors, or MAYBE the regulator. If the regulator was stuck open, you would still get some amount of fuel pressure in the rail, and then you would at least get a mist out of the injectors. That is what I would think anyway.

So, as suggested by Balleristic, you can try directly connecting them to 12V. Don't have them on too long obviously. Maybe listen or feel for a click or other noise to indicate that the solenoid is firing, or if it is off the rail look for the pintle pin to move.

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?

[bmwman91]

OK, well it really does sound like the injectors, or MAYBE the regulator. If the regulator was stuck open, you would still get some amount of fuel pressure in the rail, and then you would at least get a mist out of the injectors. That is what I would think anyway.

So, as suggested by Balleristic, you can try directly connecting them to 12V. Don't have them on too long obviously. Maybe listen or feel for a click or other noise to indicate that the solenoid is firing, or if it is off the rail look for the pintle pin to move.