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300TDI Lift Pump or Injector Pump problems...

Posted: Wed May 29, 2019 3:41 pm
by withabix
Came back from a few days away in San Francisco to find that my Defender wouldn't start. It was fine immediately before the trip, but 5 days later...won't start.

Turns over fine and the fuel cut-off solenoid clicks when I turn the ignition, so I assume that must be OK. But she won't start.

Oil and water both look fine.

Fuel filter was full of fuel and looks clean.

Lift Pump priming lever moves up and down with no noticeable resistance - so I assume this is the problem (diaphragm gone?). The priming lever doesn't push any diesel out of the bleed screw in the fuel filter housing.

...or have I got an air leak in the main fuel line somewhere???

I haven't checked to see if I've got 12 volts at the injector pump yet, so I guess that's next.

Other than fitting a new lift pump before any more troubleshooting, what else can I try???

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Wed May 29, 2019 4:22 pm
by red90
The priming lever won’t work if the engine is in the wrong spot. Just crank the engine and see if fuel comes out the bleeder. The system is self bleeding.

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Wed May 29, 2019 7:51 pm
by withabix
Thanks - fuel system usually primes itself fine - eg after a fuel filter change, but it isn't doing (can't get diesel to come out of the bleed screw and the engine won't start), so something must have failed.

I've done two whole batteries' worth of cranking today and I can't get fuel through.

I've found who's got my voltmeter so tomorrow I will check the voltage at the injector pump. I guess if there's 12 volts there and replacing the lift pump doesn't solve the problem, then I've either got an air leak in the pipe from the tank to the lift pump or my injector pump is goosed? Any other possibilities to look at?

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Wed May 29, 2019 11:27 pm
by obalme
I hate to ask a stupid question but is there diesel in the fuel tank?

Also, you should stop cranking and start just using the priming pump until you get some diesel coming through, you are going to wear out your starter.

Some fuel tanks have a plastic filter on the suction in the tank, these have caused me problems in the past. I just remove them, they are not needed as you have a water filter and a fuel filter before you get to the injection pump.

Good Luck

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Thu May 30, 2019 12:46 pm
by withabix
Ha! Yes, my first thought was that some junkie had siphoned my tank, but it’s still half full.

No filter in my tank - I put a new tank and suction pipe on myself a couple of years ago.

Waiting for my voltmeter to come back...

I can’t get the lift pump to prime at all, no matter what I do.

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Fri May 31, 2019 9:58 pm
by obalme
Ok, no success yet?

1) If you have an air hose try blowing the fuel line backwards, and then try priming it.
2) Try a trick my son learnt from a heavy duty mechanic. Pressurize the fuel tank "not to much" while cranking the engine over, this will push the fuel down the fuel line.
3) All else fails, replace the fuel line to the tank, usually by this time you have solved the problem but it dose make you feel better that you've done something with you time and money .

If the injection pump has been working in the past, it will pull fuel out of the fuel tank even if the lift pump is only partially working.A lift pump is cheap and easy to replace and you can always keep the old one for a spare if it is not the problem.

Cheers, Oliver

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Sat Jun 01, 2019 12:16 pm
by withabix
Waiting for a Delphi lift pump to arrive, to eliminate that from the equation.

Replaced the fuel stop solenoid anyway yesterday as I had a new Bearmach one already. That was fun - my Defender has DDS so some breakout with hammer, screwdriver and Dremil was required - they aren’t made for removing as that’s an anti theft measure...

Jerry-rigged 12 volts to it and it clicks, so just waiting for my voltmeter to determine which of the 3 wires feeding the DDS is the ignition live. At least if it needs replacing again, I’ve done the hard work removing the anti-theft measures! From reading the internet, I can throw the DDS module away as it doesn’t feed back to the 10AS - it’s a one-way device.

I’m hoping it’s the lift pump - I can’t get it to prime at all.

After that I guess I’m dropping the fuel tank to check the pipe work. The in-tank pipe is only 4 years old, from when I replaced the tank.

Re: 300TDI Lift Pump or Injector Pump problems...

Posted: Sat Jun 01, 2019 2:40 pm
by withabix
It’s alive!

Looks like the problem was the fuel stop solenoid being stuck. Having a DDS made it a bugger to replace, rather than the 10 minute job it could be.

It was obviously the original 22-year old one.

At least the DDS is no longer in the way, it isn’t required and it’s the white wire that’s the live 👍

The priming issue was probably the cam being in the wrong position, preventing hand priming after I took off and reinstalled the fuel filter.

DDS removal skill level: Expert 😂
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