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Old 12-01-2016, 05:35 AM   #1
g.ruff561
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Loss of acceleration at speed

Here's the deal. On the road at about 70 mph. No idle problems, no electrical problems. Nothing suspect. Accelerator drops to the floor. No gas , no rev, nothing. Everything has electric power. Car coasts to a stop. I popped the hood to check for broken belts. Any smells nothing.

10 minutes later, turned the key. Vroom. All the way home no problems. WTF! When I got home I checked under the hood again. I checked under body. No fuel leaks . Alternator at 13.3. ?????

Any help would be appreciated. Thanks team........G.
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Old 12-01-2016, 06:42 AM   #2
mike.bmw
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I'd suspect a loose battery connection or a loose ground.
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Old 12-01-2016, 07:01 AM   #3
g.ruff561
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I'm thinking maybe pump relays. Keep in mind all electronics worked. Pre set radio stations and 6 button OBC never missed a beat. This is a car I just got one year ago this month so I have done suspension, brakes, belts, ac, oem maf, alternator bushings, Optima yellow top, Alpine HU, steering wheel swap, z3 antenna, all under intake hoses, Ryan G splitter. Car runs like a top. Now this!!
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Old 12-01-2016, 09:07 AM   #4
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I'd agree with the comment about relays, fit new Motronic and fuel pump relays. I once temporarily fixed a dead E30 just by thumping it's fuel pump relay with my Leatherman.
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Old 12-01-2016, 10:58 AM   #5
mike.bmw
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Quote:
Originally Posted by g.ruff561 View Post
I'm thinking maybe pump relays. Keep in mind all electronics worked. Pre set radio stations and 6 button OBC never missed a beat. This is a car I just got one year ago this month so I have done suspension, brakes, belts, ac, oem maf, alternator bushings, Optima yellow top, Alpine HU, steering wheel swap, z3 antenna, all under intake hoses, Ryan G splitter. Car runs like a top. Now this!!
Ahhh, I missed the part about everything electronic working. Disregard what I said earlier about grounds/battery connections.
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Old 12-01-2016, 01:52 PM   #6
g.ruff561
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No worries Mike. Anybody have a pic of the pump / ECU relay location. This is my first M42. The engine bay set up is different. I will check real oem for relay part # and cost. Thanks for the feedback. G.
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Old 12-02-2016, 06:30 PM   #7
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I'll take pic tomorrow for ya I have to check mine tomorrow


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Old 12-03-2016, 09:49 AM   #8
g.ruff561
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@ stretchkid, good looking out. I'll be checking. It's funny, I checked YouTube and there is not much there for E30 M42 general maintenance. Lots of turbo stuff.
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Old 12-03-2016, 10:40 AM   #9
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You have to remove the harness cover.


They are on the driver side. Same part #'s as an m20 (Replacement relay is part Part # 61368373700), usually orange, four prong. The white/silver five prong is your main relay for the ECU...

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Old 12-03-2016, 11:17 AM   #10
g.ruff561
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I might as well replace all 3 since I'm right there. Thanks for the feed back...... G.
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Old 12-03-2016, 11:27 AM   #11
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Main relay is part # 61361729004

Other 2 are the same (one is fuel pump, other is oxygen sensor).
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Old 12-04-2016, 09:19 AM   #12
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After that, which you should do first,
the other things would be fuel pickup screen, filter
and pump, especially if there's crap in the tank.

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