Fuel Injectors

[decoupe]

I want to send the injectors out for cleaning and service from the FI system donor - an 81 528i. This has a hose connection to the fuel rail which I believe has a barbed end.

Removal is to heat the hose to soften (boiling water/heat gun) and twist while pulling?

Thanks

 

[bert35csi]

The factory blue book manual method is to use a soldering iron to melt the rubber hose. The method I used is using a sharp razor blade, carefully score and cut the hose length wise just above the barbed nipples and twist out. Use extreme care as you don't want to cut into the soft metal nipple areas and damage the sealing barbed areas.

For re-installing the 8mm fuel injection hoses (Bmw only) into the barbed injectors and fuel rail, do not use any worm clamps. The use of these clamps will guarantee leaks from the hoses as these type of clamps do not form an exact circular seal due to their design. Although, worm clamps can be used for the regular single bulbed nipples. Use the original metal cup method in securing the hoses to the injectors and the fuel rail as illustrated below.

These cups are not crimped on, bascically, it's a compressed fit. Start by cutting all 6 FI hoses to their correct lengths (measure the originals). Insert a cup into an injector and dip the hose into some gasoline for lubrication and push and twist into position (until it bottoms out). Do this for all 6 injectors. Without the lubrication process, there will be too much friction thereby the hose will never go in regardless how much pressure is exerted. Repeat this whole process for the fuel rail end.

Replace all the rubber seals (large and small) seals on all the injectors. A circlip plier is needed for the removal of the big rubber seal. Also replace all the ceramic insulators as pictured above. All these parts are still available through the dealer and are still pretty cheap. http://www.bmwmobiletradition-onlin...el=5233&mospid=47204&btnr=13_0209&hg=13&fg=15

I went through this whole process with the fuel injectors and fuel rail conversion on my coupe about 5 years ago. Here is a couple of pics.

Bert
72 3.5 CSi
88 M6

 

[BarryG]

Bert what FPR are you using?

 

[bert35csi]

Bert what FPR are you using?

Barry, I'm using the stock fuel pressure regulator for the L-jet system.
I actually bought an adjustable rising rate regulator but never installed it.
Bert

 

[decoupe]

Bert:

Any other pictures you have of the FI installation would be greatly appreciated.

Doug

 

[bert35csi]

Bert:

Any other pictures you have of the FI installation would be greatly appreciated.

Doug

Doug,

The previous owner (my former mechanic) actually did the L-jet conversion using the original multi-piece D-jet fuel rail system from the 3.0 CSi or the early L-jet of the 1977 630 CSi so I don't have any pics of the actual conversion process. I just did the tubular fuel rail conversion using brand new injectors and pressure regulator. Just too many fuel rails, hoses and clamps thereby causing too many possible avenues for fuel leaks. The tubular rail also holds better fuel pressure near the injectors.

Bert

 

[decoupe]

Fuel Injector Servicing

For re-installing the 8mm fuel injection hoses (Bmw only) into the barbed injectors and fuel rail, do not use any worm clamps. The use of these clamps will guarantee leaks from the hoses as these type of clamps do not form an exact circular seal due to their design. Although, worm clamps can be used for the regular single bulbed nipples. Use the original metal cup method in securing the hoses to the injectors and the fuel rail as illustrated below.

These cups are not crimped on, bascically, it's a compressed fit. Start by cutting all 6 FI hoses to their correct lengths (measure the originals). Insert a cup into an injector and dip the hose into some gasoline for lubrication and push and twist into position (until it bottoms out). Do this for all 6 injectors. Without the lubrication process, there will be too much friction thereby the hose will never go in regardless how much pressure is exerted. Repeat this whole process for the fuel rail end.


Bert
72 3.5 CSi
88 M6

Bert:

Did you use the metal cups on the fuel rail end of the injector hose or just on the injector end (ie. two cups per injector)?

Doug

 

[bert35csi]

Doug,

Yes, 2 cups are needed per injector. Will you be using the cold start valve on your fuel injection modifications? If yes, an additional cup will also be needed for the fuel rail end.

 

[decoupe]

Bert:

Thanks for the info. No cold start valve needed so that port on the TB gets plugged (somehow) along with a couple of extraneous vacuum ports. Cold starting is handled be the air and coolant temp sensors and the ECU.

Doug

 

[AndyM]

Hey Doug -

I put the IAT sensor in the spot for the cold start valve, then used the extra barb on the fuel rail to feed a small fuel pressure gauge mounted on the dipstick mounting tube.

 

[decoupe]

What is the IAT?? Does that replace the cold start valve? You have the loop style fuel rail?

Just about finished the fuel supply system.

Doug

 

[AndyM]

Sorry. IAT = Intake Air Temperature sensor. I assume your system runs one, but maybe not. I do still have the loop rail on there, but not for long. I'll be replacing it with an L-jet rail and some new injectors shortly. I'm also upgrading the fuel pump, lines and regulator.

 

[decoupe]

Yeah, there is an intake air temp sensor but I'll put it upstream of the TB (details to be resolved) so it reads as close to "outdoor" air temp as opposed to TB/engine compartment. I've blanked off the port with an aluminium plate. I know that you wanted as close to correct as possible with respect to appearance whereas I want as little obscuring the block and intake/TB as possible so any hoses I can eliminate is fine with me.

Are you increasing the size of injectors and the pressure/flow rate of the fuel system? Do your engine mods support/require this? Turbo in your future?

I based everything I've done on what's in the 1980 - '81 535i as far as the new pump, new pressure regulator and serviced OEM injectors all of which are common from the 528i to the 735i in that vintage. My engine has a 282 cam and 9:1 compression (at the most).

May ask for some info on your mapping if you are willing to share but that's a couple of months away.

Doug

 

[AndyM]

It's not gonna matter too much where you put the IAT. I've done it both ways on different conversions.

Your injector set-up will provide plenty of fuel for that motor. I've been running 19# injectors with the stock D-Jet regulator. Even with the regulator turned all the way up, it was barely putting out 2.5 bar instead of the 3 bar it really needs (which you'll have). I made it work by tweaking the fuel parameters, but it really needs the extra pressure. The regulator gave out on me the other week, and the pressure has been fluctuating unregulated between 3-3.5 bar which knocks everything out of whack. That's the primary reason for the change.

The changes to my injectors are more an update than a performance upgrade. I'm swapping over to the Lucas-style disc injectors since the lower body profile fits better into the D-Jet manifold. I'm also hoping the disc spray pattern gives me a better idle. I am going to 22# injectors, but I will change the curve in the ECU to compensate for the larger injectors and higher fuel pressure. I can also turn the fuel pressure down if I need to. I'm still toying around with the idea of a supercharger at some point. I got so far as designing and sourcing a custom crank pulley and buying a boost-sensitive fuel pressure regulator a while back, but put that project on the back burner. Nonetheless, since I have the regulator, I'm going to go ahead and use it now.

By all means feel free to shoot me a PM when you get around to tuning. I know my tables won't be plug-and-play, but they should at least provide a starting point to get the motor running.

 

[decoupe]

http://www.rotrex.com/index1.htm

Hmmm?

 

[AndyM]

Exactly!