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3-Series (E21, E30) Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.

 
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#1 (permalink) Old 01-25-2005, 09:33 AM
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Ok guys and gals....

I am working on a 1987 BMW 325is for a very dear friend...

I located and replaced the correct "main relay" and now I have spark going to the spark plugs... one thing down...

but... my problem is that the fuel pumps are still not getting the switched ground from the computer to turn the relay "on" and turn the fuel pumps on.... this is in priming, and it won't start either....


I get a full 12.5 volts at the chassis power slot on the relay socket, and a switched 12.5 volts when the key is on for the switched relay circuit, but it never gets the ground from the computer to tell it to run or to prime up....

also, I get 12.5 volts to the coil (+) when it is probed... also, it now fires a spark to the plugs (which it wasn't doing before I replaced the main relay)


The big question I have is this... I tested the plug off of the number one injector and it showed voltage to both terminals with the key on, and it would flash to one of the terminals on and off when we tried to start the car....

I can't find this in the book, but this is what I assume...

Does it give power to both terminals and then ground one when the test light goes out, or do I have a short somewhere???

I thought that only one terminal was supposed to have power going to the injector and the other terminal would be an open ground that gets grounded by the injector driver in the computer.... Am I wrong here???

Please help....

Fuel pumps will work when the terminal is grounded on the pinout coming from the computer harness inside the glove box....

so is my computer bad or not sending the proper ground to the fuel pump relay??

and... is it shorted out internally and giving a wrong voltage to the injectors?

I am pretty stumped here people...

used to working on turbododge fwd cars, and Buick Grand Nationals, not BMW's.... used

How can I check the diagnostic codes on this car?

I am going to do the oil change/service interval reset trick as posted below on another thread....


Thanks so much for all the help!!
Ryno
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#2 (permalink) Old 01-25-2005, 05:59 PM
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Quote:
Originally posted by TURBOFREAK@Jan 25 2005, 09:33 AM
Ok guys and gals....

I am working on a 1987 BMW 325is for a very dear friend...

I located and replaced the correct "main relay" and now I have spark going to the spark plugs... one thing down...

but... my problem is that the fuel pumps are still not getting the switched ground from the computer to turn the relay "on" and turn the fuel pumps on.... this is in priming, and it won't start either....


I get a full 12.5 volts at the chassis power slot on the relay socket, and a switched 12.5 volts when the key is on for the switched relay circuit, but it never gets the ground from the computer to tell it to run or to prime up....

also, I get 12.5 volts to the coil (+) when it is probed... also, it now fires a spark to the plugs (which it wasn't doing before I replaced the main relay)


The big question I have is this... I tested the plug off of the number one injector and it showed voltage to both terminals with the key on, and it would flash to one of the terminals on and off when we tried to start the car....

I can't find this in the book, but this is what I assume...

Does it give power to both terminals and then ground one when the test light goes out, or do I have a short somewhere???

I thought that only one terminal was supposed to have power going to the injector and the other terminal would be an open ground that gets grounded by the injector driver in the computer.... Am I wrong here???

Please help....

Fuel pumps will work when the terminal is grounded on the pinout coming from the computer harness inside the glove box....

so is my computer bad or not sending the proper ground to the fuel pump relay??

and... is it shorted out internally and giving a wrong voltage to the injectors?

I am pretty stumped here people...

used to working on turbododge fwd cars, and Buick Grand Nationals, not BMW's.... used

How can I check the diagnostic codes on this car?

I am going to do the oil change/service interval reset trick as posted below on another thread....


Thanks so much for all the help!!
Ryno
[snapback]278771[/snapback]

CAN ANYONE HELP, PLEASE??





BUMP BUMP...
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#3 (permalink) Old 01-25-2005, 06:07 PM
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hey
did your buddy put in an aftermarket chip? cause the chip could be faulty, or a prong bent... take the cover off and have look. also i doubt anythings shorted inside the box unless some how water got inside, maybe there is a short at the fuel pump? i duno if i was reading what you wrote correctly but it sounds like those could be the problem.

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#4 (permalink) Old 01-26-2005, 08:56 AM
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Originally posted by Kowalski@Jan 25 2005, 06:07 PM
hey
did your buddy put in an aftermarket chip? cause the chip could be faulty, or a prong bent... take the cover off and have look. also i doubt anythings shorted inside the box unless some how water got inside, maybe there is a short at the fuel pump? i duno if i was reading what you wrote correctly but it sounds like those could be the problem.
[snapback]279120[/snapback]

Thanks for the response Kowalski!!!!

Nope, this car is bone stock...

I can't see any evidence of a water leak and there was no corrosion on the computer wiring harness where it plugs into the computer box..

>>>Also, the fuel pumps run when you connect that wire on the harness plug to a ground source with the key on.. or jumper the hot wire to the fuel pump with a toggle switch and wire as per the manual's instructions.. so the fuel pumps' wiring seems to be correct and ok, but the relay is not getting the ground sourced from the computer when you turn the key on to prime the pumps or to make them run when it starts (I assume, because I can't get it to start)...

Is it possible that the service/diagnostic port could be coroded (doesn't look like it though) and not getting the proper ground signal for the computer?

The terminals look clean and all, but I don't know if this could keep the car from running and the fuel pumps from coming on properly....

Also, I still have the question about the power going to the fuel injectors when the key is on.... Both terminals have power and then one terminal flashes the test light or pulses when you turn the engine over... I have not checked to see if it is grounding when it flashes or just losing power and going to an open circuit... which wouldn't fire the injector...

I am definetely getting fuel to the rail, but I am not hearing the injectors fire, so I am wondering if I have a ground problem at the computer or something like that....

Is there an external ground that goes to the computer only that I need to check to make sure it is very clean and good??

maybe that is why it is not grounding the pumps and maybe sending power out wrong to the injectors???

ALSO, this car has been jump started in the past and I wonder if it was done wrong as per the instruction manual, if that could have fried the computer???


That is about to be my last option before I give up on it and have to take it to a dealer for service...

Anybody know of a cheap source for a 1987 BMW 325is automatic motronic control unit??? Used in good shape and tested or new and tested???

Is there a way to test the computer alone to see if it is bad?

Thanks all and especially Kowalski!!!

Ryno
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#5 (permalink) Old 01-26-2005, 03:53 PM
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well ebay they're everywhere for like 20 bucks you can pick one up, i duno if they have one for your car tho... but also jumpstarting it wrong would'nt do it cause it would just fry fuses... but try replacing the other relays, there is 3 of them? i think give or take, change those, and then there is a few in the fuse box, look it up in your manual if one of those is for the fuel pump or injectors replace that one. and if its just 2 injectors not failing bring htem into a deisle shop to get tested. they might have crapped out over the years. and i believe that the ECU grounds itself with the mounting bracket, i could be wrong tho.. and also check the injector plugs with a volt meter to see if the voltage is indeed dying.

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#6 (permalink) Old 01-27-2005, 02:52 PM
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Quote:
Originally posted by Kowalski@Jan 26 2005, 03:53 PM
well ebay they're everywhere for like 20 bucks you can pick one up, i duno if they have one for your car tho... but also jumpstarting it wrong would'nt do it cause it would just fry fuses... but try replacing the other relays, there is 3 of them? i think give or take, change those, and then there is a few in the fuse box, look it up in your manual if one of those is for the fuel pump or injectors replace that one. and if its just 2 injectors not failing bring htem into a deisle shop to get tested. they might have crapped out over the years. and i believe that the ECU grounds itself with the mounting bracket, i could be wrong tho.. and also check the injector plugs with a volt meter to see if the voltage is indeed dying.
[snapback]279797[/snapback]

I have met a friend here in town that has a computer that "should" possibly work for me...

I am gonna swap it on tonight and see if it works.....

wish me luck....

Thanks,
RYNO
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#7 (permalink) Old 01-27-2005, 04:14 PM
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well good luck to ya, lemme know if it works!

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