Mi16 Fuelling Issue

[24seven 104]

Typically the day I get my 205 fully road legal, it decides it doesn't want to work . Suddenly the fuel pump isn't getting any power, though I've tested the pump itself which is in full working order. I've traced one of the wires to the fuesbox under the glove box, with no broken fuses (Haynes mentiones an in-line fuse on some GTi's at the back of the tray, which I can't find). I've also traced it to a relay box in the engine bay which is part of the engine loom. Cable 76 goes from the pump, to the fusebox and to this relay, at which point 2 brown cables activate it. Am I right in thinking these 2 cables get their signal from the ECU only to prime the fuel pump once the engine is cranking over? I've got a spare ECU I can try, but if that doesn't cure it, what else am I loking at?

 

Cheers,

Guy

[Anthony 1,003]

Have you tried replacing the fuel pump relay, or atleast bridging it with a piece of wire? If you've got spark (ie so the crank sensor and ECU is OK) then it's usually the relay at fault in my experience.

[24seven 104]

Forgot to mention I've tried a couple of different relays in its place, so I don't think its that. Its definitely got spark, quite a god one too. having tested the pump and primed the system, it started very briefly and spluttered to a stop as the pressure dropped, so it's definitely something to do with the wiring/relays/sensors.

 

Are there any other fuses that could have blown? I found the switched live cable from the ignition had split and partialy severed, leaving some exposed strands that chould have shorted against something and blown a fuse, but none of the fuses I've checked are gone.

 

This is so frustrating! It's been fine the whole 3 years I've owned the thing SORN, then literally the day I try to take it out after registering the new engine & taxing it, something goes wrong .

[Anthony 1,003]

On atleast some 405 Mi looms that I've seen, there's another fuel pump fuse next to the relay - have you checked that? Usually seems to be a 10A fuse in there, compared to the 15A fuse in the 205 fusebox, so it's usually the engine bay one that goes pop first.

 

Otherwise, time to dig out the multimeter and see what's what.

[24seven 104]

yup, checked that. there's a pair of 10a fuses on mine, both are ok. Looks like a few hours with the multimeter again as you said. I hate wiring .

[trialster 0]

tried bridging the two thicker wires which go to that relay like ant said? worth a pop!

[24seven 104]

cheers folk, all sorted now. turns out it was a poor earth from the fuel pump to the chassis (or wherever it goes). it was good enough to give a continuity reading, but not enough to run the pump.