200Tdi Fuel Bleed Question: The saga continues...VICTORY!

[gm13]

Posted this on D-90, thought I'd tap the knowledge bank here too.

While priming with the lift pump I can hear air bubbles in the tank and fuel/air moving through the lines. Should this be the case, should fuel be able flow through the injection pump and back to the tank by manually priming the lift pump without the bleed screw on the filter open?

Also, there isn't enough space to account for all the air in the system, can there be an air leak somewhere without a diesel leak? I can prime the lift pump and continually hear a stream of bubbling in the tank.(navydevildoc on D-90 suggested an air leak in the line before the sedimentor, going to replace that in the am)


The symptoms:
Will idle but stalls under load/up hill, sometimes I can rev it up but typically stalls after. starts again ok if a little rough.

I've just installed a sedimentor, new fuel lines from the sedimentor to the new lift pump and onward to the new fuel filter.
Fuel sprays at idle when I crack the line at the injectors.

This has been driving me bonkers, Thanks in advance for any ideas.

 

[tpond]

I would suggest carefully checking all connections. It does not take much of a leak to couse the symptoms that you note. Does it fire right up when cold, or do you need to crank it a little?

 

[gm13]

I would suggest carefully checking all connections. It does not take much of a leak to couse the symptoms that you note. Does it fire right up when cold, or do you need to crank it a little?

I do need to crank it a bit.

 

[Snagger]

Re-reading your initial post has highlighted one problem and possible cause - the sequence should be tank - sedimenter - lift pump - filter - injection pump. The filters are designed to be pressurised, not under suction, and the lift pump is designed to push, not pull. You are putting excessive strain on the pump diaphragm, which may have split, and have certainly created a system that is desperately trying to suck air in through the filter seals.

The lift pump has two non-return valves inside it - that's how the diaphragm can generate a flow in the right direction. It does sound like you have air leaking into the feed pipe under suction, though. Check the unions at the pump, sedimenter (if fitted) and tank. Check the line for splits or chafing, and if none of that shows anything, fill the fuel tank fully and try bleeding again - if you get air-free fuel, that points to a pin hole leak in the pick-up pipe inside the tank (steel ones corrode and can rust through). Make sure you check your engine oil level for signs of rising and smell the dipstick for diesel - a holed diaphragm in the pump will not only allow air into the fuel system, but also fuel into the sump.

While hand priming, you will only get fuel through the injection pump if the ignition is on (not running, though) - the shut off solenoid operated by the ignition switch isolates the injection pump from the fuel filter line with the switch off.

Make sure the fuel filter is in good order - they should be replaced every 12,000 miles. Make sure it only has one o-ring at the top and bottom (top only on Tdi); having another will cause air leaks and the symptoms you describe, and it's easy for an o-ring to be stuck inside the housing groove. Also check that the return line to the tank is free flowing and on a Tdi that the leak-off pipes across the injectors (small braided hose) aren't leaking - they're prone to splits along the seam which allows air into the system when shut down, allowing fuel to drain back to the tank and making start up more difficult (shouldn't affect running once started, though, so not likely to be the cause of your issues).

 

[gm13]

Re-reading your initial post has highlighted one problem and possible cause - the sequence should be tank - sedimenter - lift pump - filter - injection pump. The filters are designed to be pressurised, not under suction, and the lift pump is designed to push, not pull. You are putting excessive strain on the pump diaphragm, which may have split, and have certainly created a system that is desperately trying to suck air in through the filter seals.

The lift pump has two non-return valves inside it - that's how the diaphragm can generate a flow in the right direction. It does sound like you have air leaking into the feed pipe under suction, though. Check the unions at the pump, sedimenter (if fitted) and tank. Check the line for splits or chafing, and if none of that shows anything, fill the fuel tank fully and try bleeding again - if you get air-free fuel, that points to a pin hole leak in the pick-up pipe inside the tank (steel ones corrode and can rust through). Make sure you check your engine oil level for signs of rising and smell the dipstick for diesel - a holed diaphragm in the pump will not only allow air into the fuel system, but also fuel into the sump.

While hand priming, you will only get fuel through the injection pump if the ignition is on (not running, though) - the shut off solenoid operated by the ignition switch isolates the injection pump from the fuel filter line with the switch off.

Make sure the fuel filter is in good order - they should be replaced every 12,000 miles. Make sure it only has one o-ring at the top and bottom (top only on Tdi); having another will cause air leaks and the symptoms you describe, and it's easy for an o-ring to be stuck inside the housing groove. Also check that the return line to the tank is free flowing and on a Tdi that the leak-off pipes across the injectors (small braided hose) aren't leaking - they're prone to splits along the seam which allows air into the system when shut down, allowing fuel to drain back to the tank and making start up more difficult (shouldn't affect running once started, though, so not likely to be the cause of your issues).

Thanks for the thoughtful reply. In the op my description of fuel component routing is wrong, they are plumbed correctly though: sedimentor>lift pump>filter>Injection pump. (I'll edit that)

The pin hole leak inside the tank is a possibility that I've not considered. I'll fill it up fully and see what happens. I went to replace the last old length of fuel line that runs from the tank to the Airtronic heater T then to sedimentor, but it's fairly well jammed up at the feeder tube on the tank, don't want to risk breaking the metal elbow. Looking into a replacement for that today. I've gone over and re-tightened all hose clamps en route to the LP too, just don't SEE anything that looks problematic.

Next up: connecting the injection pump to a jerry can of diesel and running the line from the filter into a jar, we'll see...

 

[atlcruiser]

Not sure if you checked but I had an issue with the pick up tube being rusted away on a 110 we had in here 2.5TD. It ran great at full to 1/2 full then started the symptoms you describe.

 

[gm13]

Not sure if you checked but I had an issue with the pick up tube being rusted away on a 110 we had in here 2.5TD. It ran great at full to 1/2 full then started the symptoms you describe.

I just now filled the tank with jerrry cans, same issue. Thought I found the problem after getting more light on things this am. 2 of the leak off hoses between injectors had tiny splits(even though they are less than 1yr old), replaced, same as before

I can see air bubbles streaming down inside the clear bowl of the filter when it's idling, just got to find the leak, re re-tightened things....
Wondering if the new sedimentor is faulty.

 

[Red90]

If the lift pump is working, when you crank, you should get tons of flow from the filter bleed screw. If you do not get this, you have a massive intake side leak or a dead lift pump.

The return lines should have nothing to do with anything as those are all after the engine and the filter.

I "assume" you have a proper stock setup with the spill lines going directly to the tank and not to the filter.

 

[gm13]

VICTORY! She's purring now. The OE, Land Rover, made in England, last of it's kind, according to Trevor at Rovah Farm, brand spankin new, old stock lift pump that I installed yesterday was defunct, a bubble pumper. When I ran it off a jerry can to the IP it ran great, the lift pump wasn't moving anything into the jar. Just because it's new doesn't mean it works. Manually it would pump fuel and air though. New one arrived this afternoon, (had ordered 2 on Mon.) popped it on and it purred. Then my wife came down to tell me there wasn't water at any of the faucets in the house...The Camel Trophy of repairs continues. I should have taken a picture of the Hi-Lift being used to pull the well pump from the pitless adapter down in the casing.



Thanks for the input folks.

 

[Red90]

Good to hear. I've been through 4 lift pumps in 5 years. They are very unreliable....

 

[paulnb57]

"they are very unreliable"

Depends on he brand, Britpart are awful, I would go for the genuine part.....
Paul

 

[Red90]

"they are very unreliable"

Depends on he brand, Britpart are awful, I would go for the genuine part.....
Paul

2 were genuine, 2 Britpart. The genuine ones are 10 times the cost.

 

[gm13]

"they are very unreliable"

Depends on he brand, Britpart are awful, I would go for the genuine part.....
Paul

It was the genuine part that had the problem, though I agree, typically best to go that route.