1980 528i Possible Fuel Pump failure, but which one?

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Peter Florance
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Post by Peter Florance »

brotherhay wrote:I wish bavauto had a way I could get a listing online of the items Ive purchased for this car. But, just by looking quick at the price tag of that sensor, Id be willing to bet I bought all of them but that one when I changed out the thermostat housing.

Ill test that thing out tomorrow, but, I also looked into this.

I tested the positive lead on the CS valve, and with the key on, its at about .06v. Turn the car over and it jumps to about 8v, although my battery is really fading.
It's actually a 3 lead device. One lead is the heating element and one provides the ground for the cold start valve when the switch is cold. The case of it is ground (through the tstat housing) Check the Ljetronic FAQ for a wiring diagram that shows the internals of the thermo time switch.
Peter Florance
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1981 E-Street Prepared Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
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Lenny D.
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Post by Lenny D. »

Peter Florance wrote:
brotherhay wrote:I wish bavauto had a way I could get a listing online of the items Ive purchased for this car. But, just by looking quick at the price tag of that sensor, Id be willing to bet I bought all of them but that one when I changed out the thermostat housing.

Ill test that thing out tomorrow, but, I also looked into this.

I tested the positive lead on the CS valve, and with the key on, its at about .06v. Turn the car over and it jumps to about 8v, although my battery is really fading.
It's actually a 3 lead device. One lead is the heating element and one provides the ground for the cold start valve when the switch is cold. The case of it is ground (through the tstat housing) Check the Ljetronic FAQ for a wiring diagram that shows the internals of the thermo time switch.
And which is why a good engine ground and body ground (braided strap ) is imperative to getting negative electrons back to the battery.
HTH

'80 528i
brotherhay
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Post by brotherhay »

Ok, well check this out, add it to the list of causes of crappy starting, then point fingers and laugh!

I looked through the schematics Peter talked about and somewheres either in there, or somewhere else I read that the bosch connectors going to the sensors located on the thermostat housing need to be color matched.

I looked at the thermo-time sensor, it had a brown female end, but the connector was orange. I looked on the brown connector, that was on a beige female end on the ECU temp sensor. I flipped them around and hoped for the best.

So, fired it up, it idled lower, turned the idle up and took it for a spin. Seemed to have more power, more responsive. I knew the true test was to let it sit overnight and see what it does in the morning.

Its 10 am in WI, about 50F outside. Got in the car, turned the key, fired over in about 1 second. Im thinking its case closed, but will test after its sat for a week or so later on down the road

Thanks for all the help fellas, Im thinking this is case closed
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