Fuel pump problem
Discussion
Happy Christmas everyone !
had my first breakdown last night - 4 o/c Christmas eve - not ideal! Just lost power and stopped about a mile from home. Fuel pump not priming but immobiliser LED switching off OK with the remote fob. Luckily I was 100 yrds from a local garage forecourt so managed to push it onto there.
Fuel pump fuse was OK so I guess it's the relay. Tried hotwiring the fuel pump just to get home (-ve on the lower small spade, tested for continuity with the chassis, +ve on upper larger spade). Pump then ran constantly but still wouldn't start.... Could there be an air lock or something in the fuel system or have I got it connected reverse polarity? Is it possible to damage the pump by reversing the polarity?
Any thoughts gratefully appreciated! Paul
had my first breakdown last night - 4 o/c Christmas eve - not ideal! Just lost power and stopped about a mile from home. Fuel pump not priming but immobiliser LED switching off OK with the remote fob. Luckily I was 100 yrds from a local garage forecourt so managed to push it onto there.
Fuel pump fuse was OK so I guess it's the relay. Tried hotwiring the fuel pump just to get home (-ve on the lower small spade, tested for continuity with the chassis, +ve on upper larger spade). Pump then ran constantly but still wouldn't start.... Could there be an air lock or something in the fuel system or have I got it connected reverse polarity? Is it possible to damage the pump by reversing the polarity?
Any thoughts gratefully appreciated! Paul
just got her home by linking a live +ve feed directly to pin 87 of the 'main' relay, everything worked fine then!
This pin looks like the +ve feed from the ECU to the 'contact' of the 'main' relay and also the injectors.
used spend's wiring diagram here: http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Can't really work out what the main relay is doing here. It just seems to be providing a +ve contact feed for the fuel pump / purge valve relay. Why are two series relay contact required?
Anyway, I'll investigate further tomorrow but it looks like a bad ECU is a possibility.
This pin looks like the +ve feed from the ECU to the 'contact' of the 'main' relay and also the injectors.
used spend's wiring diagram here: http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Can't really work out what the main relay is doing here. It just seems to be providing a +ve contact feed for the fuel pump / purge valve relay. Why are two series relay contact required?
Anyway, I'll investigate further tomorrow but it looks like a bad ECU is a possibility.
There are a few various RV8efi versions of what the main/fuel relays power on. Basically the ecu powers them up, but can't switch the power reqd so the relays are used.
That diagram doesn't show the fuse that is always live and supplies the main power to the two relays (brown wire).
Dave
That diagram doesn't show the fuse that is always live and supplies the main power to the two relays (brown wire).
Dave
yes thanks, noticed the second page of the PDF shows this +ve supply to the relays. This makes more sense and seems to reflect what I have ('98 450). Anyway I've isolated the problem to the 'main' relay and have a couple of the Bosch parts on order from my local Lucas. Many thanks again for your help. Paul
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