direction needed to complete this project

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kb0nai
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Joined: Sat Jul 16, 2016 5:32 am
Location: reno, nv

direction needed to complete this project

Post by kb0nai »

Here from the e9 forum.
I have been completing maintenance issues, long forgotten. This e24 is too be my DD, and i love the car. But to be a DD it HAS to be reliable. Bought last year.

I have an issue that I, non mechanic, can't figure out and need the help of the forum members.

When starting the car first in the am, it starts strong and runs great. I go to the gym and when leaving 1 hour later the fuel pump doesn't run. I jumper the fuel relay to get pump running and go home. One touch and release, is all that it takes. If left to sit for 1 more hour, and no intervention, it fires up and runs just fine.

To me that sounds like a relay problem. I have replaced main and fuel relays. Problem remains.
Have replaced temp coolant sensor, no go.

My e24 lives outside, since the e9 owns the garage. It is currently raining/snowing so quick analysis is problematic.

Where to start and what to check.

thanks steve
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tschultz
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Re: direction needed to complete this project

Post by tschultz »

Is your filter clogged? How old is the fuel pump?
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kb0nai
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Re: direction needed to complete this project

Post by kb0nai »

pump age ?
new fuel filter
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Da_Hose
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Re: direction needed to complete this project

Post by Da_Hose »

Don't have the ETM handy, so I can't give exact pins, but I would try the following.

Attach extra leads to the pump so you can directly power it. Tape the ends up and leave them somewhere you can easily get power to them.
Start and drive the car, then stop back at home.
Confirm the fuel pump doesn't run.
Pull the relay, and apply power to the leads connected to the pump.

If it still won't run with direct power, then the pump seems to be the issue. My guess would be that it has a fault when hot, but when cool it will start (worn commutator?)

If it runs with direct power, put the relay back and try again. If giving it a "kickstart" gets it working with the relay right away, then I wonder if there is a corrosion issue on the wiring. Corrosion causes heat, and things can act weird when they get really hot.

Good luck figuring it out.

Jose
1987 M6 - My dream car
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Brucey
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Re: direction needed to complete this project

Post by Brucey »

from memory (do check the ETM for your car) there is wiring through the OBC/immobiliser relay that disables the fuel pump. I would check that.

If you want to know if the fuel pump is seeing power or not, you can run a set of wires with a 12V LED on from the pump wiring.

However the symptoms you describe do sound like a lack of fuel, but that doesn't mean that the fuel pump isn't running at the right time.

Remember that the fuel pump normally only runs during cranking. There are two other hypotheses that are worth exploring here;

1) that (probably due to a bad connection somewhere) there is a voltage drop to the fuel pump, and that it doesn't always run during cranking (when there are reduced volts available). Priming the system by jumping the relay may allow the engine to start, at which point instead of ~10V (as on cranking) you suddenly have ~14V so the pump then runs OK.
[BTW The car may start from cold with no fuel pressure because the CSI can spit a certain amount of fuel into the inlet via gravity alone. When the engine is hotter, the CSI won't open....]

2) that there is a leak (probably in the flexible part of the fuel line in the engine bay) and the check valves in the fuel line are not perfect. This may allow the fuel line to mostly drain down within a few minutes of the engine stopping. The engine won't restart when warm because it may take a while for the fuel system to re-prime itself (pump only runs on cranking). On a cold start again the CSI may dribble enough fuel in via gravity alone to let the engine fire up. If you have this exact fault there ought to be a terrible smell of fuel in the engine bay.

a bad main relay can cause the same kind of trouble (which you have covered) but a bad contact onto the main relay (eg in the socket) can do exactly the same thing.

hth

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kb0nai
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Location: reno, nv

Re: direction needed to complete this project

Post by kb0nai »

Thank you to all.

More diagnostic info.

The thermostat is now replaced. The car wouldn't heat up to normal temp. I installed a 71c. Now needle to just under 1/2 way. Does it truly need the 80c.(i have one)
I live in the desert and try to run a little low.
had no effect on starting issue.

If I understand, the pump doesn't run except in the start mode. Using a siphon for flow in drive?
Cold start (csi)can start, but does not function when warmed up, even if not to full temp

When car at normal run temp, it starts.

I will clean the contacts, relay and plug at fuel and main tomorrow. And will take power reading of those circuits at relay/plug.

No snow tomorrow, yeah!! will try to get more correct info.

Thanks again for every ones response
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raykoke
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Re: direction needed to complete this project

Post by raykoke »

Someone named Brucey expounded in this thread:

viewtopic.php?t=20585

;-)

Cheers,

Ray
'85 ///M635
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slofut
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Re: direction needed to complete this project

Post by slofut »

Ray,
Did you get this problem solved? Would it run every time with the relay socket jumped?
Bill
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raykoke
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Re: direction needed to complete this project

Post by raykoke »

slofut wrote:Ray,
Did you get this problem solved? Would it run every time with the relay socket jumped?
Bill
I weren't the OP there.

You could PM him and ask, but it appears he's been absent since 2013 :)

memberlist.php?mode=viewprofile&u=16406

Cheers,

Ray
'85 ///M635
kb0nai
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Re: direction needed to complete this project

Post by kb0nai »

I haven't been absent since 2013. but have finally gotten the issue fixed.
I went to the links that Brucey listed and did a complete diagnostic.
Same problem
got a friend that is a BMW mechanic to do same and came away with same results.
Sent the ECU to Programma, they came back with no issues to chip boards. But with the TEST they also FLUX ? the board if no repairs are indicated.

I assume that they skim coat the boards with a conductive fluid to fill hairline cracks in the boards surface.
This is my understanding after speaking to the contact at Programma.
As a plumber I understand the use of flux.
I am NOT a mechanic.

NOW WORKS LIKE NEW.

I was in way over my head. but I didn't drown.
Installed new ignition wire set/w cap and rotor. Best it has run since purchase. New injectors tomorrow.

thanks for the inspiration and info to all that posted.

steve
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Brucey
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Re: direction needed to complete this project

Post by Brucey »

it sounds like you had a dry joint in the part of the ECU that signals the fuel pump, and they (programa) fixed it, yay!

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kb0nai
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Joined: Sat Jul 16, 2016 5:32 am
Location: reno, nv

Re: direction needed to complete this project

Post by kb0nai »

Installed reman injectors today. Runs like a new car. smooooooth.
Thanks again Brucey and all others.
Even my wife is impressed with the outcome. Since it is Mother's day, a win/win.

My e9 is getting this same basic engine installed with a Schrick cam.
My learning curve will be invaluable.

Forums rock!
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