Mitch C

iTrader: (1)

I have an intermittent fault with my fuel pump.

There is a 12v feed to the multiplug at the pump, which lasts a couple of seconds when the ignition is switched on, then drops. The earth has continuity to the chassis.

When plugged on, the pump doesn't work. Reasonable to assume it's the pump.

HOWEVER, when I put a 12v feed direct from a battery pack to the pump, it works.

I cleaned the terminals up, then removed the cables from the multiplug and attached them direct to the pump. No joy.

Any ideas? Maybe not enough current? What readings should I be getting? Any help resolving this would be great.

Thanks in advance.

MBScooby

I'm not an expert on this but I believe that the fuel pump will run/only get power for a couple of seconds with just the ingnition on. It will run constantly when the engine is running. A fuel pressure sensor will stop the pump if no fuel is being used ie when the engine is off.

Hope this helps.
Someone else may provide a better / more technical explanation.

Martin

Mitch C

iTrader: (1)

Cheers mate, that's what I figured, which is why I'm confused as to why the pump isn't pumping if there's power to it from the multiplug, yet it works when power is applied from an external source???

Simon C

It works cos your bypassing the fuel pump relay. Don't ask me where it is, I'm trying to find it myself.

Mitch C

iTrader: (1)

But there is power at the plug...

Simon C

The pump primes then turns off, only restarting when the engine fires up. There is an explination on here somewhere. I'll see if I can find it tomorrow.

Mitch C

iTrader: (1)

Okay, I'll stay up all night trying to figure it out

Bob Rawle

The pump is switched to ground, there will always be a power feed, its the return thats switched. the ecu runs for a couple secs on switch on then stops, when you crank and she fires the ecu starts it up again.

bob

Mitch C

iTrader: (1)

There doesn't appear to be a power feed all the time, just when the ign is switched on, and gives 12V for a few seconds. Is that normal?

Mitch C

iTrader: (1)

And do you know what the fault is?

Typical for it to go now, just as it has been put up for sale. It knows, you know

Mitch C

iTrader: (1)

Still need a hand if anyone can shed some light

They don't sell too well when immobile

Thanks!

David MY99

just take the 12v from your rear license plate lightning.
Fuelpump starts with ign on and goes out when turned of.

Only ****ty part is that you have to keep your lights always on

Simon C

I'm now in the same boat, as you now mitch. I've just changed my pump and now I'm only getting 1.3v to it.

Mitch C

iTrader: (1)

Well, I could just run an ignition feed to it if that wouldn't hurt, but would rather find the fault and fix it properly. Would be another anti theft device though, cos lights would have to be on before starting