Fuel pump running after starter failed to turn motor over
08-05-2024, 01:59 PM
#1
Fuel pump running after starter failed to turn motor over
My early 1985 944 has suspected ECU problems. I disconnected the 2pin plug to the starter motor to simulate an engine stoppage.
Applied "ign" then "start" from key and back to "ign" and expected the fuel pump to run then stop as no signals from the ref/speed
sensors were received. I attached a 21 Watt bulb to simulate the starter relay as well. However the pump continued and would
only stop when the key was turned to "off". Has anybody had this rather risky scenario.
Applied "ign" then "start" from key and back to "ign" and expected the fuel pump to run then stop as no signals from the ref/speed
sensors were received. I attached a 21 Watt bulb to simulate the starter relay as well. However the pump continued and would
only stop when the key was turned to "off". Has anybody had this rather risky scenario.
08-05-2024, 04:01 PM
#2
More likely that someone has changed the relay or wiring to allow the pump to run. The factory wiring does not allow the fuel pump to receive power until engine rotation is proven.
08-06-2024, 12:42 AM
#5
Burning Brakes
The 'never mind' above was me thinking of stuck contacts, but the fuel pump power comes directly from the battery so it wouldn't stop with the ignition off. I'm with Gage on this one, someone has changed the wiring, most likely to save money on a replacement relay.
08-06-2024, 05:32 AM
#6
next steps
Thanks for the replies. I will look at a mysterious relay ( Not DME ) that seems to have a timer purpose. Some genius had forced
the contacts together. The wiring of this car has been savaged, so I will be spending a lot of time inverted you know where. If I
ever figure this out, or not I will close this thread.
the contacts together. The wiring of this car has been savaged, so I will be spending a lot of time inverted you know where. If I
ever figure this out, or not I will close this thread.
08-06-2024, 09:22 AM
#7
Trending Topics
08-08-2024, 07:46 AM
#8
Minor omission in thread
Apologies to all !!!
The ECU Darlington transistor was a bit lethargic so I ( cleverly??) fitted a smaller relay in the circuit to help
hold the DME relay on. However, this appeared to confuse the ECU somewhat. The ECU is happy to see
the back of my "Bodge" and so am I.
The ECU Darlington transistor was a bit lethargic so I ( cleverly??) fitted a smaller relay in the circuit to help
hold the DME relay on. However, this appeared to confuse the ECU somewhat. The ECU is happy to see
the back of my "Bodge" and so am I.
08-20-2024, 06:25 AM
#9
Extra relay OK
I replaced my "Bodge" relay with a more robust one with a little more current draw. This solved the fuel pump always running problem.
The first relay had a high coil resistance may have picked and held with leakage current.
My 944 runs for approximately 30+ minutes idling and then shuts down. Allowed to cool down for a time it will run again. Speed/ref
sensors or ECU ? This will call for another new thread.
The first relay had a high coil resistance may have picked and held with leakage current.
My 944 runs for approximately 30+ minutes idling and then shuts down. Allowed to cool down for a time it will run again. Speed/ref
sensors or ECU ? This will call for another new thread.