No Spark/No Fuel pump prime.. any ideas?

[rich4130]

Hi all,

Have smoothed the bay in my G40, and now have got it to the stage of starting it after the loom has been extendeed, and is dead!

What would be a common link between no spark and the fuel pump not priming?

Does the ECU/hall sender have some control over this?

Fuel side is fine as when relay is bridged its comes into life, any ideas?

How many earths should there be for these functions?

Thanks,

Rich

[rich4130]

Have tested all the usual yellow fuse in engine bay etc!

The red/yell wire to the fuel pumps seems to have continuity with ground tho, surely this isn't correct? Although this does this with my original loom also, could it be relay related?

[Jezza-7]

Possible hall sender. There are 2 that are near to the coil and they can get mixed up. One goes into the coil and the other to a plug that has something to do with the fuel pump. Noticed on my mates car when these were swapped the fuel pump didnt prime at all.

[rich4130]

Checked!

Have actually cut that plug out of the loom and connected the wires together, have also plugged the existing engine loom back (unmod) back in and still nothing.

This doesn't seem correct at all though:

The feed to the 2x fuel pumps (red/yell wire) has continuity with ground somewhere!?)

Basically it seems there is a short to ground connected with the inline pump, as red/yell and metalwork on car make the tester beep!

This goes away when the plug is removed from the inline pump, so there must be a short somewhere inside the pump if that makes any sense at all!!!?

(defo isn't the lift pump as have snipped the wire where they connect at the yellow plug under the dash, also isn't connected to any of the engine loom/relays etc as have disconnected the plug at the fusebox)

Any ideas?!

[Jezza-7]

Shorting inside the pump? Thats weird. You could put a cable in from one end of your car to the pump and see if that works at all?

[rich4130]

Very odd!

The only thing connecting the pump to the car elec wise is the earth and I have observed..

Stripped the insulation off the wires 2" away from the pump (with the red/yell disconnected inside car, but still on the pump)

That the tester beeps on either wire with the other probe earthed on the rear ligh earting point!

Terminals all ok on pump etc, tis weird!

Cars been stood for 18months and fuel pump is approx 4 years old..don't get it.

[rich4130]

tho with pump wires straight to battery seems to work....

[rich4130]

Given up for now!

Have tried another engine harness still nothing!

The fuel pump should prime regardless of the ECU or not?

I suspect my King lead may be damaged, but that also wouldn't affect fuel?

Tested the relays, all click etc when put to 85/86.

Have the earth to the gearbox mount, and also the lambda earth, that should be all to get it to prime as fuel pump earth via interior harness?

Anyone want a g40? haha.

[G40supercharged]

The pump will probably show low resistance to ground as it's a coil of wire inside, so to a tester it looks like a short circuit. The ECU is responsible for priming the pump when the ignition is turned to the on position. There is a relay that powers the ECU itself from the ignition switch. You can check that the ECU is powered by looking for 5V on one of the terminals to the blue temperature sender. This volatge comes from the ECU.

[LightDiodeNEAL]

Sound *pure* daft, but I was foxed by mine for a day or 2... The coil wire is the same plug as another one thats next to it.... If they're wrong way round, then fuel primed but no spark...
Worth an ask
NEAL