No start M635csi

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jpr210
Posts: 69
Joined: Tue Jun 25, 2013 2:27 am
Location: Miami, Fla.

No start M635csi

Post by jpr210 »

Help. was running fine but now it cranks but no start. No changes have been made. changed, CTS, FP relay, Main Relay, cleaned AFM. Only clue is main relay was worm/hot even on the unswitched position. even with no key in the ignition, if you present the main relay to the socket, it goes click. battery runs down.

TIA

Jpr
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Brucey
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Re: No start M635csi

Post by Brucey »

by any chance have you swapped the fuel pump relay for the main relay by accident? Or perhaps the wrong relay type has been fitted into the main relay socket? I have heard of this sort of thing happening.....

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
jpr210
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Joined: Tue Jun 25, 2013 2:27 am
Location: Miami, Fla.

Re: No start M635csi

Post by jpr210 »

The original relays (which had been working fine for 3 years) that I used on both the main and fuel were plugged in and behaved the same as the new ones and the used and new main both got hot. part numbers are as per the parts catalog.

Jpr
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Brucey
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Re: No start M635csi

Post by Brucey »

in which case I would assume that there is a fault in the wiring that allows the coil connection to the relay to ne made when it shouldn't.

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Boggie
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Re: No start M635csi

Post by Boggie »

Not sure if THIS will help, considering your main relay comments but it will at least help identify if the Motronic ECU is getting power and the correct inputs...
1985 M635CSI
Classic Car and Bike Collector & Restorer.
jpr210
Posts: 69
Joined: Tue Jun 25, 2013 2:27 am
Location: Miami, Fla.

Re: No start M635csi

Post by jpr210 »

UPDATE

It started!. the reason for the no start condition was simple but not obvious. My ecu has the miller performance war chip. I took the ecu out to make a small global adjustment to the timing curve at my tuner. The tuner, after making the change by mistake, had changed the rev limiter to 0 rpm. Instant theft immobilizer!. Rev limit restored, engine started at the first try. That is resolved. However, my main relay still clicks on just by plugging it in, with the key off and no ecu!. Any ideas why?

TIA

Jpr
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Boggie
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Re: No start M635csi

Post by Boggie »

Doh!
Glad you found that my what a schoolboy error!
:)
1985 M635CSI
Classic Car and Bike Collector & Restorer.
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