E30 M42 Fuel Rail/Injector Removal

[MouseRat]

I want to take my E30 M42 injectors out to clean them. I found a post with some instructions, but these are from an E36 M42 which I know is different.

Is everything here looking in the right order?

1. Remove the fuel pump fuse from the fuse box.
2. Start the engine, and wait for it to stall. Switch off the ignition.
3. Remove the fuel filler cap (the system is now depressurized).
4. Disconnect the battery negative cable before working on any part of the fuel system.

6. Install the fuel pump fuse, then switch on the ignition and wait for a few seconds for the fuel pump to run, building up fuel pressure. Switch off the ignition unless the engine is to be started.

(This is confusing to me, why would I prime the fuel system after de-pressurising it? - Unless the order of where I'm quoting this from is messed up).

3. Remove the upper section of the intake manifold.
4. Pull up the wiring ducting to release the wiring plugs from the fuel injectors.
5. Loosen the hose clamps and disconnect the fuel feed and return hoses from the fuel rail. Be prepared for fuel spillage and take adequate fire precautions. Plug the open ends of the pipes and hoses to prevent dirt entry and further fuel spillage.
6. Disconnect the vacuum hose from the fuel pressure regulator.
7. Unscrew the two bolts securing the fuel rail to the intake manifold.
8. Carefully pull the fuel rail upwards to release the fuel injectors from the cylinder head, then withdraw the complete fuel rail/fuel injector assembly.
9. To remove a fuel injector from the fuel rail, proceed as follows.
A)Pry off the metal securing clip, using a screwdriver. B)Pull the fuel injector from the fuel rail.

Installation should be ok, put it back together like you found it and pressurise the system using step six.

Thanks lads

[E30DarkSide]

You can skip 1-6 (other than disconnecting the battery), the amount of fuel that comes out is minimal. 4-6 doesn't make sense as you have removed the battery cable so it wouldn't run the pump anyways. It would definitely make for no fuel to spill out if you do clear out the system with 1-3 but not a huge deal. Other than that you're good to go, it's all straight forward. Simply take everything out and take pictures or make labels if you need to as to make sure you don't forget where something goes.

[MouseRat]

I've managed to take the throttle body off the intake and the upper manifold off the lower manifold.

I basically can't seem to pull the injectors out the head. I think I can just leave all the wiring attached, pull out the injectors and undo the wiring clips on the underside after?

The guide I found says 'carefully' pull them out (doesn't elaborate), but there's nothing careful about the amount of force needed

Pic of where I'm at:

[Balleristic31]

Remove both fuel feed and return lines. Then just snap the wiring cover off the injectors (no need to pull those tiny metal clips on them they are ment to just break away). Then pull the two 10mm nuts attaching the rail to the lower manifold.

The injectors often are stuck in the lower manifold and usually need some careful convincing (prying) with a tool against the valve cover to pop up and out.

[MouseRat]

The injectors often are stuck in the lower manifold and usually need some careful convincing (prying) with a tool against the valve cover to pop up and out.

Ahh this seems to be my problem.

So then the plastic wiring holder just comes up with the rail, and I take the injectors out the rail?

[Balleristic31]

Ahh this seems to be my problem.

So then the plastic wiring holder just comes up with the rail, and I take the injectors out the rail?

Like I said in the previous post, just pull the plastic wiring holder off the injectors. With a light to moderate amount of force it should just pop off all 4 injectors.

That will give you plenty of room to pry up against the valve cover without prying against the plastic wiring holder.

[MouseRat]

Like I said in the previous post, just pull the plastic wiring holder off the injectors. With a light to moderate amount of force it should just pop off all 4 injectors.

That will give you plenty of room to pry up against the valve cover without prying against the plastic wiring holder.

Oh I see what you mean now, the plastic wiring holder separates BEFORE you pull the rail & injector assembly out.

Thanks for the help man. Really appreciate it.

[MouseRat]

All Sorted. Thanks Gents :up::up:



(I plugged the intake ports right after this)

[varg]

Might want to attempt the "under intake mess removal" while you're in there! That is, if it won't make you fail your MOT!

[MouseRat]

Might want to attempt the "under intake mess removal" while you're in there! That is, if it won't make you fail your MOT!

I Passed my MOT a week ago ;D

All that stuff is coming out! The previous owner has basically done it for me.

He did all the new vacuum lines and coolant lines, he just couldn't be bothered to take the manifolds off to get the unused clump of rubber out

I don't think removing this should effect anything in the eyes of the law...I'll find out when my next MOT is due!

[mike.bmw]

Looks like you already got this sorted, but when I recently replaced my "mess under the intake", I just pulled the entire lower intake manifold assembly (rails, injectors, hard fuel lines, wiring harness, etc) and then separated/reassembled it on the work bench. Much easier to deal with that assembly off the car.

Here it is with new injectors, fuel hoses, and clamps:

[hamann318is]

Definitely easier to get the injectors off when the lower manifold is off the car. Mine took some careful encouragement with a screw driver, but after replacing the o-rings, reassembly was a breeze!

[mike.bmw]

Definitely easier to get the injectors off when the lower manifold is off the car. Mine took some careful encouragement with a screw driver, but after replacing the o-rings, reassembly was a breeze!

Yeah, same here. I used a small pry bar between the fuel rail mounting tab and the fuel rail mounting surface on the intake manifold. At first, I wasn't even sure they were going to separate. I let some penetrating oil soak in for a bit and eventually the injectors came out of the intake manifold.

[MouseRat]

Definitely easier to get the injectors off when the lower manifold is off the car. Mine took some careful encouragement with a screw driver, but after replacing the o-rings, reassembly was a breeze!

Yeah, same here. I used a small pry bar between the fuel rail mounting tab and the fuel rail mounting surface on the intake manifold. At first, I wasn't even sure they were going to separate. I let some penetrating oil soak in for a bit and eventually the injectors came out of the intake manifold.

They were a right pain! They took some persuasion from a big big screwdriver. The lower o-rings were really hard and nearly cracked.


I haven't actually put it back together yet because I'm still waiting for my injectors to get shipped back from their service.
Reassembling outside the car definitely looks way easier.
Thanks for the tips lads

[unixnerd]

When you guys had the manifold off how much crud build up was there inside it and on the backs of the valves. Planning this job over the winter, car has 130k miles.