DRHurst
New Member
Hello
Hoping this forum will help throw some light on a frustrating issue I have with a ‘barn find’ W123 M102 which is refusing to pump fuel. The car incidentally has been sitting for a few years, however it does crank with compression and every indication would suggest it should run with a little tlc.
I have used this forum and maintenance manual to complete the following steps in an attempt to fix this issue without luck and so now have come to the point which every bloke dreads which it to ask for help!
Here is a précis of the issue:
1. Pump makes a brief sound (like it’s about to run) when ignition is switched on but does not run/energise.
Diagnostics Performed:
1. DVM across the pump connectors shows a very brief 12v (a second and no more) then nothing.
2. Cleaned tank and applied fresh fuel.
3. Connected a separate 12v supply to the pump and it runs fine.
4. Pump Relay tested and even replaced; click heard when ignition is turned, followed by a further click.
5 Removed relay and bridged pins 7 & 8 with same results as ‘1’ above; Pump makes a brief sound when ignition is switched on but does not run/energise.
6 Removed, cleaned and refitted fuel sender unit.
7 Removed, cleaned and refitted all fuses.
8 Searched high and low for the OVP Relay but can’t find one??!
I have to assume the relay is shutting the pump down due to further circuit logic or indeed failure, however I have exhausted my expertise and now throw this to the mercy of the experts and enlightened out there.
Any help that can offered would be very gratefully received.
Thanks
Dave
Hoping this forum will help throw some light on a frustrating issue I have with a ‘barn find’ W123 M102 which is refusing to pump fuel. The car incidentally has been sitting for a few years, however it does crank with compression and every indication would suggest it should run with a little tlc.
I have used this forum and maintenance manual to complete the following steps in an attempt to fix this issue without luck and so now have come to the point which every bloke dreads which it to ask for help!
Here is a précis of the issue:
1. Pump makes a brief sound (like it’s about to run) when ignition is switched on but does not run/energise.
Diagnostics Performed:
1. DVM across the pump connectors shows a very brief 12v (a second and no more) then nothing.
2. Cleaned tank and applied fresh fuel.
3. Connected a separate 12v supply to the pump and it runs fine.
4. Pump Relay tested and even replaced; click heard when ignition is turned, followed by a further click.
5 Removed relay and bridged pins 7 & 8 with same results as ‘1’ above; Pump makes a brief sound when ignition is switched on but does not run/energise.
6 Removed, cleaned and refitted fuel sender unit.
7 Removed, cleaned and refitted all fuses.
8 Searched high and low for the OVP Relay but can’t find one??!
I have to assume the relay is shutting the pump down due to further circuit logic or indeed failure, however I have exhausted my expertise and now throw this to the mercy of the experts and enlightened out there.
Any help that can offered would be very gratefully received.
Thanks
Dave