fuel pump / ecu wiring diagram needed!!

[4 X MORE]

Hope someone can help. I have starting problems, as in engine spins but takes a long time to fire. I have found that the fuel pump is not running when ignition is switched on and when cranking the fuel pump relay can be heard clicking. I have fitted another relay with same results. Has any one got a wiring diagram (1993 turbo) for fuel pump and ecu so I can check wiring? Cheers!

[Stupink]

does the pump spin momentarily as you put the ignition on, and again when you release the key? that's kinda normal if i recall.. so problem probably lies elsewhere.
After you've tried to start it, and it won't.. press the fuel rail pressure valve in(looks like a tyre valve, possibly has cap on it) if it squirts out a bit then you have fuel presure there so know problem lies elsewhere.. IE injectors not firing or no spark.

[ice man]

I had similar symptons - happened suddenly too.

Follow stu's suggestion and if fuel comes out of the valve all good.

If a lot of air comes out then it may be the fuel tank to fuel pump hose perished and sucking air in. Note this does not cause a fuel leak or obvious smell either.

[4 X MORE]

Thanks for replies. I have checked for fuel pressure at the valve and fuel just dribbles out and pump definately not running when ignition is switched on. Managed to track down a wiring diagram and have sussed that the fuel pump relay is not getting its switched earth from the ECU when the ignition is switched on. Reckon I could have an ECU fault so trying to track down one to borrow. Unless anyone has any other ideas?

[MJ]

put a manual switched earth in to confirm your thoughts before spending out?

I did this on my BMW as a temporary measure ..... over a year ago lol

[4 X MORE]

Why didn't I think of that! Will try at weekend. Strange though that the relay gets an earth when cranking and then suddenly all is up and running ok.

[ice man]

I permanently bypassed my fuel relay by taking out the relay and used a paperclip between two terminals... cant remeber which had to experiment (with a tube adaptor in the fuel rail to attach a hose to at the time - shrader valve depressed would suffice). it was a small terminal on the right and one of the two larger terminals which are close together.

the pump was then running continuosly and i was able to transfer all the petrol out into the wife's car prior to dropping the tank. I even left the paperclip in and pushed the relay back in and drove it for a bit. (to eliminate the fuel pump relay from my investigation)

You need to pressurise the fuel rail properly then test for air bubbles / build up. - if the pump is producing less than the 3 bar required to flow though the FPR then air will accumulate in the fuel rail - especially if it is picking air up from the tank / fuel pump feed pipe.

The fuel pump only spins for less than a second when ignition is switched on... it then goes again once the oil pressure is ok afaik.

[4 X MORE]

Have tried the seperate earth to the relay and engine now fires up instantly. Reckon I will rig up a temporary switched earth until I can track down an ECU. Cheers for help.

[MJ]

no worries, glad I could help [img]/smile.gif[/img]