Motronic 4.1 Fuel Pump Pulsing Problem

[roote 0]

hi all,

ive just put everything back together running motronic 4.1 261 200 125 ecu, it was running fine when the eng came out but since its all been back together when you switch the ign on the fuel pump relay pulses constant, ive checked all the usual conections but seams thet the ecu is pulsing on ecu pin 20 but only when the fuel pump relay is fitted, and now ive ran out ideas so any help or if anyones come across this befor it would be great.

[jackherer 543]

It's not something I've seen before but I'd try a different relay if you haven't already.

[roote 0]

ecu pin 20 also is common to injectors and idle control valve, to which is also pulsing and even with fuel relay out, so pin 20 is pulsing but why ?

ive just spent 2 days stripping down and replacing the full loom with a spare i had as old was not so good a state, ive checked all connections and still the same on the new loom.

[Ryan 99]

Check the flywheel sensor and wiring. The 4.1 ECU needs a clean signal from the sensor before it will turn the fuel pump on. It's a safety feature to turn off the pump if the engine stops.