No pumping for me !

[gifdy]

I need some help from the S series massiv.

Was planning to take the car to work today but it wouldn't start. On investigation this evening it looks like the fuel pump isn't working. Measured the voltage direct on the terminals and nothing. I had to drain the tank recently to replace the fuel sender so I thought there had been a blockage & something had blown. Checked the relay that's ok. The fuse is OK and there is 12V on the fuse.

The diagrams are a bit confusing but it looks to me like the fuse is the last thing before the pump itself. However the wire on the fuse is red and on the pump terminal it's yellow/black. There must be a connection somewhere but I can't locate it. Anyone know where it is or whether there is another fuse somewhere ? Any other other ideas ?

This is the first weekend free I've had in ages so really want to get it running for a hoon. Think it's in a huff

[spivvy]

is the pump priming ?
if not try running a direct feed from the battery see if it works if it does you know definately it is in the wiring

also there is a fuel pump relay that could have shorted out

[gifdy]

No it's not priming. I swappped the relay although I'm not entirely sure I got the right one as the wiring colours don't tie in with any of the diagrams in the bible. I assumed it was one of the free hanging ones on the ECU loom so swapped them both.

Also checked the inertia switch & that seems fine.

Connecting directly is a good idea - I'll try that next. Thanks !

[Colin RedGriff]

Do you have 12v at the pump?

Not sure where the immobiliser sits in the circuit but that cuts the fuel pump off as well.

Check that the earth for the feul pump is good too.

Colin

[gifdy]

Aaaaaarrgghhhhhh !!!! Still not getting anywhere

The pump is OK. I traced the voltage all the way through, the return on the relay coil is not being grounded and so the relay is not switching. The return goes to the ECU (I think ) so it seems the ECU is not switching on the pump for some reason. I forced a ground and the pump ran but the car still didn't start.

There is a spark and the fuel line seems to be clear. It points to the immobiliser but when that is activated the car won't turn over. It's turning over OK when the immobiliser is disabled with the key.

Any other ideas ? Is there a diagnostic thingymajig that can plug into the ECU ? I'm at the point where I just want to hand it over to an indie and get it sorted but I can't get it there !

Cheers

[GreenV8S]

I assume the problem is with the V8S shown on your profile.

If the ECU isn't trying to switch the pump on, and the engine won't run even with the pump hotwired, then you have an ECU problem not just a pump supply problem.

First thing to check are the wire that brings the engine running signal from the dizzy to the ECU, this includes a dropping resister just before it passes through the bulkhead which can fail. Also double check that you are getting 12v switched ignition feed to the coil, if anything is disrupting this then you won't get power to the ignition module, hence no signal to the ECU. Also double check that all connections to the ignition module and coil are secure and no damaged wiring apparent.

Also check that you are getting power to the ECU, this is supplied via the second of the metal cased Bosch relays on flying leads close to the ECU.

[gifdy]

Yes it's a V8S, sorry should have said. Thanks for the inspiration, this gives me something else to try tonight.

[z_chromozone]

Are you sure it is not the relay. If you are going to swop and test, make sure you buy a proper replacement. The cheapo pin / number match ones are no good.

Z

[MWBS3]

Hi

On my S3 - which might not be the same - When I removed the entire hood I found a couple of connector blocks which are located inside the door post on the passenger side ( need to pull the carpet back and look inside ). One is the interior light the other has a bunch of cables and is just in front of the fuel pump, if this is the case it could be where the cable changes colour.

Might be worth checking if all other avenues fail.

Good luck

Mark

[gifdy]

z_chromozone said:

Are you sure it is not the relay. If you are going to swop and test, make sure you buy a proper replacement. The cheapo pin / number match ones are no good.

Z

Mmmm, interesting . I thought a 30A switching relay was a 30A switching relay so bought the replacement in Halfrauds. Like I say, it does switch when you force the ground. Will the ECU's ability to pull down the ground depend on the quality of the relay ? Internal resistance or something ? Something else to try I guess ...

Thanks for the response so far chaps. Forecast is sun on Wednesday !

[GreenV8S]

gifdy said:

Mmmm, interesting . I thought a 30A switching relay was a 30A switching relay so bought the replacement in Halfrauds.

There are lots of different pinout configurations, and you can get twin pole make/break relays or changeover relays that look virtually identical but do significantly different jobs. The Bosch relays that power the ECU, fuel pump and lambda sensors are twin pole.

[gifdy]

GreenV8S said:

gifdy said:

Mmmm, interesting . I thought a 30A switching relay was a 30A switching relay so bought the replacement in Halfrauds.

There are lots of different pinout configurations, and you can get twin pole make/break relays or changeover relays that look virtually identical but do significantly different jobs. The Bosch relays that power the ECU, fuel pump and lambda sensors are twin pole.

The sseries website part number is Lucas FDB502 - do Bosch have an equivalent part? Do you know the part number to make sure I get the right part this time ?

Thanks again

[gifdy]

By the way I found a pdf of a Range Rover/14CUX ECU service manual which has a pretty good fault finding guide. If anyone wants a copy, let me know

[gifdy]

Sorted ! Dodgy connection on the ECU connector - had to remove the shroud to see it !

Thanks everyone for your help

- kenny