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Old 08-03-2020, 11:53 AM   #1
vanaltena
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Default Engine cranks, but doesn’t start. Things I’ve tried..

Hi! Long time reader, first time poster

Full story:

A few weeks ago, whilst driving, the alternator died and my 1981 244GL USA (B21F) ground to a halt. The alternator got replaced, but as the mechanics didn’t have a 50 Amps replacement at hand, they “upgraded” it to an 80 Amps alternator.

This got the car running again, but I noticed some erratical behavior / light vibrations and loss of power by the engine when getting up to speed. However, nothing major and the car runs and starts without issues. Until last week, where it suddenly died whilst idling and waiting in traffic for about 15 min. I got it starting again, but only for a few seconds until it died again. This continued for about 5 minutes until I got it running but with severe loss of power and sometimes shocking pulses of power. I made it limping the car back home. Since then it hasn’t started again.

Things I’ve checked and tried:
- Fuses: all clean and intact
- Fuel pump relay: clicks when turning the key to the On-position, not sure if I can feel it click again when cranking the engine
- Fuel pump relay: replaced it anyway, but still does not start
- I’ve jumped Fuse #5 and #7 to check the fuel pumps. These seem to be working and when cranking the engine it starts without issue and continues to run until I remove the jump wire from the fuses.
- Visually inspected the wires as much as possible without pulling them, they seem fine.
- ECU: cleaned all the connector pins to rule out corrosion issues.

I’m suspecting that it has something to do with the ECU (pink label Bosch 0 280 0800 033) as I’ve read that it can easily get damaged by a voltage spike due to a bad alternator. As I started noticed the vibration and power issues, this seems plausible right?

But before I order a new (used) one, I’m curious to hear what you think. Have I missed something? Could there be another cause to this problem?

Thanks in advance!
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1981 244GL (USA), B21F, non-modified.
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Old 08-03-2020, 12:37 PM   #2
ZVOLV
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Disable the fuel system and see if it runs on starting fluid.
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Old 08-03-2020, 01:09 PM   #3
vanaltena
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Hi ZVOLV, thanks for the tip! How would I go about and do that? And if it does run on starter, what does that mean? I’m a pretty novice mechanic
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Old 08-03-2020, 01:28 PM   #4
ZVOLV
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Disable fuel: unplug fuel pump, unplug injectors (EFI)

Blast two long sprays of brake cleaner past the throttle, crank, run? If run- pulse sprays into the closed throttle plate and keep it running.


If it runs, it's a fuel system issue; not spark or mechanical.








We get 6 litre trucks with dead fuel pumps into the bay with one man under the hood riding on the radiator support this way.

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