'84 BMW 733i starting problems


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Old 09-12-07, 06:42 AM
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'84 BMW 733i starting problems

Wifes car , daily driver .

turn the key nothing , dash lights come on I can put a meter on the cables leaving the battery we have 12.5 volts but no start , not even a click battery voltage remains constant

tried it a dozen or so times yesterday nothing

went out this morning started right up

started 8-9 times in a row then nothing

I thought of the clutch lockout switch so I pulled the harness from the back of the switch and bridged the two wires

nothing

tried a few more times then it started (with the harness back on the switch ) I kept the clutch pedal depressed and tried . it started 4-5 more times then went back to nothing

so I think I can rule out the clutch switch

its getting to hot out there now so the plan is to attack it this evening and clean and tighten all the cable connections under the hood

any other suggestions before I have to pay somebody who knows what he's doing ?
 
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Old 09-12-07, 07:18 AM
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First place I would look is unfortunately the solenoid.
Under the car. Ya, under the car.
Put the voltmeter positive on the black and yellow wire and read the voltage where you can see it well when someone works the ignition.
Should be zero volts and then when you try to start the car, it sould read some value that is quite low. I would guess at 2 volts DC or lower.
Try it until it fails and see what the voltmeter says.
When it fails if the voltmeter says zero volts then the problem is upstream of the wire. If the voltmeter says 12 volts or there about then the problem is the solenoid.
CAUTION
Support car well and block wheels well when being under the vehicle
Let the starter cool when attempting starts (Amperage draw is high when RPM is low)
When bypassing stater switches, make sure car is in Park.

Let us know if you get volt readings or any other info.
Stay cool
 
 

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