Help me confirm lift pump failure...

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philelvey

philelvey

Active Member
Posts
186
Location
Halifax, W. Yorks
Hi to all,
Just a quicky - this morning Harry our disco fired then stopped (never done that before), then wouldn't fire again.

After a few more attempts I tried the lift pump priming lever, and hello, there was no resistance whatsoever when operating it. Cranked the engine a tad to make sure it wasn't resting on the cam, then tried again with the bleed screw open.

There was the SLIGHTEST bit of pressure right at the end of the lever stroke, that was bringing a very small dribble of fuel out of the bleed screw.

After that I cranked it again and HELLO it did fire up, but after stopping it and trying the prime lever again there's still no resistance through the whole stroke.

My thought is "Ok the lift pump is beggered" - but money is tight and I can't afford to go buying replacement parts unnecessarily.

If you esteemed ones can confirm my diagnosis that would be appreciated.

Ie. I'm right in thinking that a healthy lift pump should have a decent amount of resistance when priming (when fully bled and fuel is coming through)??
 
Sounds like a lift pump to me or a clogged filter, have you been running veggie or biodiesel? Think a new lift pump is only a tenner + vat
 
Nope proper diesel. I've read not to buy the cheapies - the better ones are about £25+vat
Filter has been recently changed, along with sedimenter cleaned. I'll go ahead and get the lift pump. Fingers crossed....
 
Yeah Delphi are the choice, but if your on a budget the cheapest ones are better than a broken one. Cracked sedimentor bowl or leaking seal? Diesels only need 3 things to start fuel,air,compression just start by checking the cheap options first. If you definitely have heat from glow plugs and good compression from the starter then it's air and fuel, air filter clean and no pipes blocked then it's just the fuel delivery left. I would bypass the sedimentor and let the filter do it's job, all that's left then is lift pump, fuel filter housing,injection pump, injectors. Check them all for air leaks, then it's either bad fuel or replacing parts cheapest first!
 
Ok update this morning. I went out and turned the crank manually slightly and tried the lift pump lever again - this time I had pressure and was bringing fuel out of the bleed screw. Possibly unfortunate co-incidence of it resting on the cam first two times??

Anyway, I won't replace it straight away (may do still later), but the experience has brought up other interesting possibilities, as I have been chasing "lost" power - a couple of months ago over a period of about a week it felt like it lost about 10% of it's power, and I've been trying to think of the cause ever since.

The pain is that it's not a dramatic loss of power, so it's not really obvious, but it's definitely down. So far I've:
- cleaned the sedimenter bowl (didn't look for cracks - what materials/fittings do you need to bypass this)?
- Service with new oil filter, air filter, fuel filter
- New silicon turbo hoses
- New intercooler

I've spent lots of time searching existing threads and reading others experiences. Those experiences and my instinct makes me think it is fuel-related in some way.

I hadn't considered air in the fuel supply before - Lyndon you mention checking for air leaks - can you expand on the most likely leak points, and how do you check - listening?

The other thing you've mentioned which has got me thinking is compression - question - how difficult should it be to crank the engine around with a standard sized 1/2" ratchet handle? Thing is mine is EASY - I did it for the first time on the weekend, and expected it to be really hard (Haynes suggests taking out the glow plugs), but a 10 year old could turn mine without breaking a sweat.

Finally, the other thing I've noticed as I've been poking around the engine bay, is fuel around the No 1 injector, so this must be leaking a bit? What the most likely leak points in that part of the head? Could that be related to any of the above issues?

Cheers!
 
Try and put a live from the battery to fuel stop solenoid and then try and start it.

Had similar a few weeks ago. Put a new £40 lift pump on as it had no residents to find I had no power to fuel stop solenoid due to immobiliser.

I now have a switch in the cab to turn on/off
 
Lift pump on a 300 tdi is run off the cam so if nothing on lift pump try cranking a little and pump again but try wire to battery that is a common fault
 
Oh sorry for the confusion - it is running again - has been since I had a 2nd go on Sunday. It's just the lack of power that I'm investigating now.

I think it's still possible the lift pump is dodgy - I've read that it'll still run even with a dodgy pump - In terms of tracking down the lost power - I'd like to try the cheaper things first.

What fittings do you need to bypass the sedimenter?
 
philelvey said:
Ok update this morning. I went out and turned the crank manually slightly and tried the lift pump lever again - this time I had pressure and was bringing fuel out of the bleed screw. Possibly unfortunate co-incidence of it resting on the cam first two times??

Anyway, I won't replace it straight away (may do still later), but the experience has brought up other interesting possibilities, as I have been chasing "lost" power - a couple of months ago over a period of about a week it felt like it lost about 10% of it's power, and I've been trying to think of the cause ever since.

The pain is that it's not a dramatic loss of power, so it's not really obvious, but it's definitely down. So far I've:
- cleaned the sedimenter bowl (didn't look for cracks - what materials/fittings do you need to bypass this)?
- Service with new oil filter, air filter, fuel filter
- New silicon turbo hoses
- New intercooler

I've spent lots of time searching existing threads and reading others experiences. Those experiences and my instinct makes me think it is fuel-related in some way.

I hadn't considered air in the fuel supply before - Lyndon you mention checking for air leaks - can you expand on the most likely leak points, and how do you check - listening?

The other thing you've mentioned which has got me thinking is compression - question - how difficult should it be to crank the engine around with a standard sized 1/2" ratchet handle? Thing is mine is EASY - I did it for the first time on the weekend, and expected it to be really hard (Haynes suggests taking out the glow plugs), but a 10 year old could turn mine without breaking a sweat.

Finally, the other thing I've noticed as I've been poking around the engine bay, is fuel around the No 1 injector, so this must be leaking a bit? What the most likely leak points in that part of the head? Could that be related to any of the above issues?

Cheers!
Click to expand...


The leak on the injector could be the copper washer, look at bustees guide to see photos

The sedimentor all you need is a bigger fuel pipe to fit over the existing pipe and two hose clips. You can take the feed pipe of the lift pump and put it into a jerry can if it runs ok then your problem is between tank and lift pump, of still bad then your problem is between lift pump and injector. Sorry it short descriptions but have to type on my phone.
 
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