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Fuel cutting out while cruising

Posted: Fri May 28, 2010 2:05 pm
by grover
I've been running MS successfully for almost two years and just recently started having what I think are fuel delivery issues. Specifically, on two recent trips after driving for about 1 1/2 hours at freeway speeds, the car begins to stumble as though it is running out of fuel (plenty of gas in the tank.) Additionally, I can hear one of the relays quickly flicking repeatedly. One time I got off at an exit and the car just died. When I tried to start up again I could hear that the fuel pump relay wasn't triggering at all. It seems to get a little better after things have cooled down, but this could just be coincidence.

I've gone through and checked connections, grounds, etc.. and everything seems solid. Of course I can't get this to happen on cue so I can't get a datalog to see what is going on. Has something similar to this happened with anyone? Any direction you can provide? It *seems* electrical and not mechanical but I just can't put my finger on it. Thanks in advance folks.

1973 BMW 2002 with MSII V3, EDIS.

Re: Fuel cutting out while cruising

Posted: Sun May 30, 2010 7:44 pm
by drmiller100
is the computer resetting somehow? I have read about this in the manual where if your wiring is weird, the computer could reset if certain things happen.

Maybe triple check your grounds, do some reading in the megamanual about looking at the timer which shows how long the computer has been on.

Re: Fuel cutting out while cruising

Posted: Mon May 31, 2010 11:50 am
by grover
Thanks for the reply. I've been trying to replicate the issue with a laptop attached, and now of course can't. Today I recorded the attached datalog which I'm hoping an experienced user may be able to see some clues in, but I'm just drawing a blank. The only things that are catching my eye are:
1. On line 3039 the voltage drops suddenly to 11.3. Not sure if this is unusually low. Possibly a voltage regulator problem?
2. At idle, the AFR seems to be jumping around way too much (lines 1600-1800 for example.) Not sure what is going on there or whether it may be connected in some way in terms of inconsistent fuel flow perhaps?

Would love to hear some folks thoughts, I'm still a rank amateur at this. Thanks in advance.

Re: Fuel cutting out while cruising

Posted: Sat Jun 05, 2010 1:00 pm
by rumplestilskinfish
sounds like a bad relay.