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914World.com _ 914World Garage _ Electric Gremlins

Posted by: Carlitos Way Oct 25 2004, 10:55 AM

I've got a strange problem that I'm trying to trace. When I start the engine, it runs fine. However, if I try to start it with the headlights on (which I know is not a good idea, but it happened once while testing electrical stuff) then the engine won't start. Then, if I turn on the blinkers the car ends up surging and missing with the "beat" of the blinkers.

Any thoughts/suggestions?

I HATE electrical problems!!!!

Posted by: dlo914 Oct 25 2004, 02:31 PM

electrical problems get the BIRDIE!!!

Posted by: sanman Oct 25 2004, 02:57 PM

alternator, battery or voltage reg. check the charging system. that is where I would Start

Posted by: mudfoot76 Oct 25 2004, 03:10 PM

My car had similar problems. For these problems, a new alternator was the solution. But it wasn't the only problem <_<

Posted by: F4i Oct 25 2004, 03:13 PM

I have a thought on this. I have not tried it yet. I set the fuel px. with the car at idle with no lights on 14v. I have noticed that at idle with lights on the voltage is lower 12v. It goes back up to 14 with some revs. My guess is that the fuel px. is ok at 14v but goes lower when down to 12v. If one sets the fuel px with the lights on it may help. Just theory at this point though. good luck

Posted by: lapuwali Oct 25 2004, 03:34 PM

If the system voltage drops to 12v with the lights on at any engine speed above a "too low" idle (like 500rpm), then the alternator or (more likely) the regulator are suspect. It may just be the ground connections (as in the alternator isn't well bolted to the engine). The function of the regulator is to keep system voltage at 13-14v all the time, regardless of alternator output. It's also possible it's just the connections between the alternator and the regulator. Clean all of the connections, and if the problem doesn't go away, replace the regulator.

What's a "fuel px", btw?

99% of electrical problems are just problems with bad connections, and 99% of those are bad ground connections, which are typically not protected with rubber shields or insulation like +12 connections usually are. As a result, these connections corrode (often invisibly), and stop working, or only work intermittently. The other 99% of electrical problems are caused by previous owners bodging things together. The last 99% are charging system problems (battery/alternator/regulator).

Posted by: F4i Oct 27 2004, 09:16 PM

Sorry, my shorthand, fuel px = fuel pressure

Posted by: bperry Oct 27 2004, 10:24 PM

Years ago, I had a funky problem kind of like this. I think mine
was much worse. In my case the car went into horible idle and
bucking as soon as the headlights were turned on.
After a few on/off cycles of turning the lights on/off and seeing
the problem come and go, I got smoke coming from under the dash.
Nothing like an electrical fire to get your heart going.....
The next morning after I traced everything down, the problem
was actually quite simple.
A light in the Tach had popped out of its socket and the
center post connection (which goes hot when the lights are turned on)
was touching the case of the gauge and shorting to ground.
Amazing that something so freaky and simple caused such a
wierd problem and ended up buring up a few wires.
Still not sure why fuses didn't blow but they didn't.

Just something else to look/check for.

--- bill

Posted by: Carl Oct 27 2004, 10:38 PM

I had a similar problem in my 6. Idle was ok as long as no other electrical load was applied then the engine stumbled badly when even the brake pedal was pressed causing the tail lights to be lit. This was identified when the tach went wild with the engine at idle and the brake pedal pressed but settled when the brake pedal was released.

Tracing the signal line for the tach led to the cd ignition module. Replacing it solved the problem. It seems that at idle the voltage drop from the brake lights being lit caused the cd module to be unstable.

Good luck,
Carl