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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

I bought a set of NEW original BOSCH injectors ( 0 437 502 015 as i remember )
I've carefully mounted them onto my 924.....and.....

fuel pump wont pump trough new injectors !

i swiched the ignition on and used the A/F meter to make the pressure go up at the injectors....but no fuel comes out....i'm sure the fuel gets to the injectors...since i've unmounted one of them and there was fuel and pressure there. When i lift the A/F i can hear a slight wistle...but no fuel.

It seems that the old injectors were so bad that the bad fuel pump could go trough them..

this or the new injectors are jamed.
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Min · Posted: Sat Jul 29, 2006 3:17 am Post subject:

Shouldn't you be jumpering the fuel pump relay to test your injectors?

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Switching the ignition to on and lifting the fuel metering plate never gets any gas to come out of my injectors either, I always have to jumper the fuel pump relay.
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1987 951 - M193 Version for Japan

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

i forgot to mention that my fuel pump relay is probably bypassed....as soon as i turn the ignition on my fuel pump starts and never stops.

So with the old injectors if i switch the ignition on(fuel pump running forever) and lift the A/F plate the injectors spray.

Its logical that this should happen with the new injectors too. too bad it does not.

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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

so.....this is it? my pump is not strong enough for the new injectors ?

nobody knows anything about this? nobody got this problem until now?
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Ozzie · Posted: Sat Jul 29, 2006 8:34 pm Post subject:

First check you have the right injectors.
Without a fuel pressure guage its a bit hard to tell whats wrong.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

i'm sure that the injectors are the right ones...i will try to get a pressure testing unit and test the fuel pump.
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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

ok i just tested my fuel pump. how ?

i gave it a gas source and on its output i put a BAR-o-meter. i powered the pump at 12V and it almost instantly showed 8 BAR. I did not let it like this for a long time because its a closed circuit.

The pump goes 8 bar...the CIS distributor is fine, the fuel lines are fine...the fuel filter is NEW.....

I told all this to the shop where i bought the injectors from...and they said that it must be smth wrong with the CIS...and that they wont change my injectors unless i fire a complain...and to do this...i must present a paper form a authorised mechanic(the one who changed my injectors) and a written paper from that mechanic that the injectors are bad. But i changed the injectors....so...basicaly i got ripped. for 200 EUR. #### !

I'm gonna try and pump 10-15 bar trough those injectors and see wtf happens....maby they just got stuck.

later edit:
I decided to put back the old injectors and fuel pump and see if the car runs....so i mounted them on and the car started and now runs fine. The only problem is that the old injectors dont spray corectly and the performance and milage is crappy. I'm going to the shop tomorow...they also have a auto-service shop where they mount the parts that they sell and repair cars.....i'm going to tell them that the car runs now and i expect the car to be running after the injector replacement.

Does anyone have the specs on the 924 CIS Fuel Injector? i mean at what pressure should it open and at what pressure should it be at maximum flow.?
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morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

right now i have these parts mounted:

1. new fuel filter
2. cleaned spark plugs
3. working 8 BAR fuel pump
4. new K&N air filter
5. Old crappy injectors that dont realy spray anymore

i took the car for a drive.

until 4000 RPM i have normal...or even more than the usual power...but above 4000 RPM...no power...the engine is hardly reaching 5000 RPM under load and above 4k it wont pull anymore.

I blaim the old injectors wich i removed and left to dry for a few days...i think they dont flow enough anymore...

later edit: i feel like i'm talking to myself here....

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Lizard · Posted: Tue Aug 01, 2006 7:24 am Post subject:

using a piece of high pressure fuel hose and probably 4 hose clamps attach the new injectors directly to the fuel pump if you can with the pressure guage and see if they open under direct pressure,

*warning*
if the injector does not open and you hit 8 Bar of pressure and you dont have the hose clamps REALLY freaking tight then you could have a projectile but if it doesnt try to get a picture of the injector hooked up to the fuel pump with 8 bar of pressure behind it showing that they arent opening and take that picture to the people.

I think that they may have put a protective coating on the injectors that could be sealing them closed, or the other possibility is that your WUR is shot
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Ozzie · Posted: Tue Aug 01, 2006 8:31 am Post subject:

CIS 76-79
System Pressure 4.5 to 5.2 bar
Warm control pressure 3.6 + or - .2 bar
Cold control pressure 1.5 +- .2 bar
Injection valve opening pressure 2.5 to 3.6 bar

Lambda
System 5.4 to 6 bar
Warm 3.65 +- .2 bar
Cold 2.2 +- .2 bar
Injectors 2.7 to 3.8 bar
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

The lambda is the late CIS ?
i have the euro 83 CIS with no lambda sensor.

THX A LOT !
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Ozzie · Posted: Tue Aug 01, 2006 5:32 pm Post subject:

I think all UK and Euro cars had CIS, remember reading in a supplement somewhere.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

morghen · Joined: 21 Jan 2005 Posts: 9102 Location: Romania

ok so i went back to the shop and they told me that they wont change the injectors for me unless i have a written proof from a BOSHC service that they are shot. However they have a point when they say that it cant be that all 4 injectors are jamed. I called the closest BOSCH service ~60 Km away and the guy doing the CIS stuff is in vacantion until 14 Aug

What a bullshit...now i'm stuck with the old injectors that make the car run like crap in high rpms and a bunch of 200 EUR nogood new injectors for two weeks

I'm going to try and pump some pressure trough those new injectors today....i know a guy who has a special bench for testing and cleaning injectors. So...they should open at ~2.5 BAR ...right?
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Ozzie · Posted: Tue Aug 01, 2006 8:44 pm Post subject:

so the book says.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance