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91 740 turbo starting problems /electrical gremlins

I recently purchased a 1991 740 turbo and am having some problems with starting the car and the electrical system.

From time to time, all the electronics in the car will cut out while I

am driving. This means the headlights, turn signals, a/c fan, and radio far, power locks and mirrors, and windows will all stop working. The ABS and SRS lights are lit up on the dash. I know when this is

*not* happening since when the lights are on, the bulb failure light is always on (even though all the bulbs are working). When I turn off the car and restart it, everything works fine again.

This happened the other day, so I shut off the car and when I tried to re-start it, nothing happened. The engine did not crank or anything. I was able to push start the car (it's a manual transmission) and drive home. I took it to the mechanic the next morning (needed a push start again) and he replaced the starter motor. Now when I turn the key, the engine will crank, but it will not always turn over. Sometimes it will turn over for a second and then stall. If I try to start it too many times the starter motor will stop running (I'm guessing the battery is out of juice) and the only thing that will get it going is a jump start or a push start.

the mechanic is suggesting replacing the fuel pumps (he claims there are two) at a cost of about $500, or at the very least replacing the battery which he claims would give me a few more shots at getting the starter motor to turn the engine over.

I don't really have a lot of money right now, so am thinking I may just spring for the battery in the hopes that it'll give me enough juice to get the engine started.

I'm wondering what the cause of the electrical and starting problems may be, and why the old starter would have just crapped out like that. going over the repair records for the car, the ignition was replaced about a year ago so is relatively new.

Thanks!

Reply to
theo.chan
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If by "ignition was replaced" you mean the ignition switch, that takes my main suspect off the list.

If the battery connections haven't been given a good cleaning lately, now's the time. My 85 765T has a pair of wires that attach to the positive terminal via a ring connector, and when that makes bad contact the electrical system cuts out. Also give each wire at the battery a little tug; I had one wire corrode in two under the insulation (and have known a couple other 740/760 owners with the same problem).

Mike

Reply to
Michael Pardee

I forgot to mention - the fuel pump idea is out in left field, but the battery may not be. I've had several batteries fail intermittently. If the brushes in the alternator are worn enough, you could lose all electrical power occasionally.

Mike

Reply to
Michael Pardee

Well the problem is definitely *not* the fuel pumps. I would check all the battery cables, and the lugs where they attach to the engine block, starter, and alternator. Don't forget to check the grounds as well, make sure nothing is loose , corroded, or broken under the insulation.

Reply to
James Sweet

Thank you everyone for your replies. I replaced the fuel pump relay today (the one that was previously installed was original from '91!) and the starting problems seem to have disappeared.

The electrical problem still seems to manifest itself from time to time, such as the power mirrors do not work, but they used to a few days ago and simply quit. If the radio is on and I press one of the mirror buttons, I can hear the mirror motor engage for a split second and then the radio turns completely off and the mirror does not move.

Thoughts?

Reply to
theo.chan

You've got some bad connections somewhere, did the fuse panel get wet? Try pulling the radio fuse and reinserting it a few times. Also check the ground strap from the engine to firewall.

Reply to
James Sweet

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