Hi, on turning over my 4wd saph the fuel pump
connectors are getting 12 volts but pump not priming. I believe I read somewhere that the cps controls the initial prime but if I've got 12 volts across the connectors then am I safe to assume the cps is working and it must be the pump itself is dead?

Many thanks.

 

If your getting voltage to the pump then yes it’s got to be the pump at fault

 

Thanks Adam

Just to add I have connected a spare car battery directly across the fuel pump terminals and nothing. So I assume that means it is dead unless I am missing something obvious.

 

Make sure the terminals on the pump are spotless and you are getting a good connection

 

Give the pump a tap with a screw driver or small hammer, it maybe just stuck

Would be worth changing anyway

 

Thanks, I'll try that before buying a new one.

 

You are not missing anything, unfortunately it is time for a new fuel pump.

 

Update: Gave the fuel pump terminals a really good clean and rigged it up to the battery again and it's working now. Trouble is still no fuel at the fuel rail. I've run it ten seconds but bone dry. Now I'm thinking fuel filter? Cant see what else it could be.

 

Start from the basics, remove the outlet from the pump and see if your getting anything out it and work your way from there

 

There isn't a chance you reversed the wiring jim

 

Yes, I did! Now running and fuel to the rail! Thanks for everyone's help. Hoping this bad boy will start now after being sat for 9 years.

 

Happy days

I would still fit a new pump , you don't want it running lean

 

Double post

 

Wired it back up but pump not priming off the fuel wiring loom so now thinking this must be CPS related as I know the pump is working. I believe the cps switches the earth for the pump via the ECU.

 

Maybe clean the lugs on the Crank pulley. Pull the 3 plugs on the bulkhead and clean and spray them jim, they always give a bit of trouble

 

Thanks james, I'll try that next. I feel it is something simple. If that doesn't work I'll try a new CPS.

Thanks for all the help.

 

This should help you test the crank sensor

 

Fantastic, thank you very much.

 

The crank sensor won't stop the fuel pump priming, it will not pulse the injectors if the ecu gets no crank sensor signal.

I'd be looking at the inertia switch located in the spare wheel well first, press the white button in. There is also a fuel pump relay (yellow) located near the ecu, listen for a click when you turn the ignition on and another click 3 seconds later when it switches the fuel pump prime off.

 

Thanks Wes, I'll try that.

 

The crank sensor apparently switches the Earth in the ecu for the fuel pump relay

 

Thanks everyone for your assistance. Now fuelling fine on the loom and nearly starting. Its spluttering but not quite starting but I think this may be due to the 6 month old fuel in the tank. I'm going to drain and replace with fresh this week then hopefully it will finally fire up. 🤞

 

Great that OP has it running, but as an aside the Weber won’t run the pump unless it receives input from
the CPS.

Martin

 

Not sure where you guys are getting your information (some bloke down the pub read it on the internet somewhere?), but in reality, it simply isn't true.

I even made a video to prove it, turn up the volume, wouldn't want you to miss the fuel pump coming on:

 

Marty, that's great, thanks for clarifying that. I guess the fact it is fueling doesn't mean the cps is okay then? Could the spluttering be down to the cps then rather than my assumption it is bad fuel?

 

how do you know your car doesn’t have an old Ahmed bayjoo chip and has the relay wired constant? No need for the cheeky cunt replies we’re trying to help the guy

 

Because its a standard car / ecu / wiring. If relay was constant it wouldn't prime now would it.

It was not a cheeky cunt reply, simply trying to help someone having a problem by giving facts, and responding to incorrect information.

 

You obviously had the CPS disconnected? All my advice is from first hand experience through my years of ownership.

Without doubt this is the sensor used to close the relay when the engine is running, but I had always believed they would not prime without it either, sure I remember Mark Shead said it once on here as well. Logically it does not make sense, as the CPS will not supply an input until the engine is running, so I may be wrong.

I know for a fact the prime is temperature related, as I have experimented with it before.

If it's running I don't see how this can be a bad CPS, to me this is more fuel related.

Are you able to describe more about how it runs?

Martin

 

Some disagreement in here!

L8 does not have fuel pump prime temperature compensation. It does have fuel pump prime with key to on (3s iirc), it does not need the crank position sensor connected to the ECU at all for this to happen. It does then need crank position input for the ECU to recognise engine rotation therefore ground fuel pump relay to run pump.

Don't get too stressed gents, COVID 19 is much bigger in this world currently.

If that pump has sat for 9 years, change it, you will also probably find crispy wires on your phase sensor. If the CPS has a white wire, change it. All good practice from experience. Makes sure you do have fresh fuel. 6 months old stuff is garbage.

Enjoy