Help Please - ECU problem?

[simon67]

Griff 4.3 wouldn't start today. Turns over but no fuel pump priming. hard wired fuel pump to battery & starts (but with pump whiring constantly). Pump relay clicks when ignition on.

Had to be recovered on a truck - very embarrasing as everyone in the village points at the prat with his flash motor on the back of a recovery vehicle!

My ECU casing is severely corroded so I suspect it could be an ECU fault.

Any ideas before I go and buy a new? ECU ? Would the ECU let everything else work but the pump?

Thanks

Simon

[spend]

There is fuse for the fuel & the relay as part of the ECU loom , you may also have tripped the inertia switch. If those dont fix your problem it may well be the immobilizer that is interupting the supply. These are all quite quick and easy to check with a multimeter.

Dave

The immob for the fuel is capable of failing whilst the rest of the immob functions OK.

Edited by spend on Sunday 20th May 21:00

[simon67]

Thanks Dave - do you know where the fuse is located ? - Don't think it's the immobiliser as the ignition works

Cheers

Simon

[GreenV8S]

simon67 said:

Griff 4.3 wouldn't start today. Turns over but no fuel pump priming. hard wired fuel pump to battery & starts (but with pump whiring constantly). Pump relay clicks when ignition on.

Had to be recovered on a truck

Why did you have to recover it? If it runs with the pump wired direct to the battery then you know you've got a fairly straight forward electrical problem to solve. You also know that the car is a runner with the direct wire in place, so you can get it home, to the garage or whatever.

[Jay Ayegees]

First thing I would do is to check the two Bosch fuel relays in the loom in the passenger footwell - try swapping them over.

Sounds like the ECU is okay if it ran okay when you direct wired the pump.

Edited by Jay Ayegees on Sunday 20th May 21:01

[simon67]

Had to get it home from the driveway of a guy that I had been visiting to look at an e-bay car for sale. When home I could use the tool box, find enough wire etc. It's always much better fixing things in your own driveway. So fuel pump OK, Relay OK, Inertia switch OK (I think). Look slike ECU but an expensive thing to replace

Cheers
Simon

[spend]

Huh... The ECU switches on the fuel relay - if the relay is OK then the ECU is


Batt +ve -- Fuse
..............|
ECU-------- Relay ---- Fuse box --- Batt +ve
..............|
........... Immob
..............|
........... Inertia switch
..............|
........... Pump
..............|
........... Ground


Dave

[griffter]

simon67 said:

Pump relay clicks when ignition on.

You sure the pump relay clicks AS WELL as the 'main' relay?
The pump relay should click on for 2-3 secs then click off again when you turn the ignition (and/or disable the immobiliser). Then it should click on again when you turn the engine over (though obviously you won't hear it, but a multimeter would tell you). If it's clicking as above, then the ECU sounds OK, and the problem is likely to be wiring between the loose relays and the fuel pump. Check the connections to the inertia switch and work towards the fuel pump.

If the relay clicks on for 2-3 secs to prime the pump but does NOT click on when you turn the engine over, the likely candidate is the engine speed signal to the ECU from the ignition amplifier. The ECU only powers the pump (other than to prime it) when this pulsed signal is present - telling the ECU the engine is turning over.

It's pretty unlikely the ECU's suddenly started to misbehave like this IMHO. More likely a loose connection in the fusebox, 'loose relays' loom, immobiliser connections or ECU multi-pin connector. I'd bypass the immobiliser to eradicate that, then clean the ECU connector, then start hunting with a multimeter. The alternative is to try a substitute ECU of course, if you can find one. For the purposes of diagnosis a period 14CUX for a Range Rover might do the job - just don't run it for any length of time as it'll under-fuel.

[SIMON67]

Thanks Griffter



I'll work through logically this weekend - I'm working in Jersey at the mo. Fingers crossed that it's the relay. I must admit that I assumed that the rekay was OK as I heard it click when the ignition was on.



Apart from this glitch she is running superbly. Seeing all of the exotics over here in the glorious sunshine is making me jealous that I'm in the repmobile & not the Griff



Cheers



Simon

[SIMON67]

Update - she's fixed. Thanks to a mate who suggested chucking the fuel pump relay on the floor & then trying it again. Will try to find a new one today.

Thanks for the sugestions

Cheers

Simon