2.0TD Sudden Power Loss

[Martingo]

Hi All

I experience big problem over the weekend with my Series 2 Land Rover with 2.0TD conversion.

I've been searching on here and it's almost identical problem to this old post below. One minute running fine and the next almost total loss of power, popping and knocking like hell and smoke pouring out the back.

Diesel Fuel lift pump problem? - Maestro & Montego Owners Club

So my first thought was the lift pump had gone but today I checked the strainer, that was clear and if I pump it manually it will delivers fuel to the vent plug on the filter. There is a new filter fitted and that's been in for about a year.

Is it possible that the problem is still the lift pump but it will just manage to manually pump fuel as far as the filter. Not sure what the pressure is supposed to be after the lift pump?

Also are replacement lift pumps available anywhere?

Of course any other ideas of what it might be are welcome. I've read lots of very similar posts on the forum.

There's no EGR by the way.

Cheers
Martin

[robert1]

you might need to spin the top of the pump to make the pipe line up. Is the header tank fitted?
https://www.ebay.co.uk/itm/285369627...AaAsiiEALw_wcB

[Martingo]

No header tank, the lift pump piped directly into the filter.

So is it possible that the pump diaphragm has gone but manually under no pressure it does still deliver fuel to the filter but under running conditions and pressure it will fail? I can imagine this could be the case.

[robert1]

no, a hole in diaphragm would leak from the weep hole, the valves might be bad. If you strip it you might find some of the parts in this kit fit. https://www.ebay.co.uk/itm/203641974663
how much fuel is in the tank? with no header tank you can't run it so low.

[Martingo]

Thanks for the info, I’ll probably strip it down later in the week so that kit might be useful

the tank is prob third full but bear in mind this is series Land Rover so the tank is under the driver seat and relatively high up, plus I’ve been running the engine for about three years now without any issues like this

cheers

[Martingo]

Also I read on another post about similar problem that they were going to add a tee block after the lift pump to allow the pressure between pump and filter to be measured - what level of pressure is after the lift pump?

read quite a bit about the problem of pulling air in on the pipes and pump between tank and lift pump so that might be my next plan of attack. However would air in the fuel supply have as drastic a result as this or would it just run lumpy and small drop in power? As mine is the power has probably dropped 80%!!!!!

[robert1]

In a montego the pump only needs to keep the header tank full, as the header tank overflow returns to the tank there is not much pressure. When the header tank is empty the injector pump should shut off to stop air getting into the hi pressure side but this might not be the case if you are pushing the air in . The injector pump can suck strait from the tank but priming might be hard.

[Doctordiesel77]

If you don't have the vapour separator fitted, it might be worth adding a CAV type filter with an air return to the tank (like the series Land Rover diesel) between the lift pump & the bosch filter? I've done this before, it gets rid of any air related problems, prolongs the life of the main filter & adds an extra water trap.

[Martingo]

I had a look at the CAV filter and they seem mainly to talk about water removal rather than air removal. It seemed like this filter should replace the existing one but you say it’s in addition to existing. By the way the existing filter is a Mann filter and has a manual drain on the bottom. The other thing worth mentioning is that before the conversion the LR had a petrol engine.

I’m assuming that the car type header tank is not used on LR because of the off-road side of things. But without the tank what protects the injector pump against no fuel in the pipe, if for example the lift pump did pack in

still not stripped the lift pump yet

[robert1]

you would need a header tank more off road as the fuel would be sloshing about. this might work, but do strip the lift pump as it seems to have be working for years till now.
https://www.ebay.co.uk/itm/354935971...Cclp%3A2047675

[Doctordiesel77]

The CAV filter head has a banjo bolt in the top, there is a very small hole in it which allows air and a small amount of fuel to return to the tank, the return from the injector pump / leak off from injectors is connected here. The bosch filter head only has two connections so if the vapour separator is not fitted any air that gets in ends up in the injector pump. In theory no air should be able to get into the system, so it shouldn't matter, but i have unblocked a lot of those tiny holes on CAV systems in order to cure mysterious air problems. If you stop the engine when it misbehaves, then bleed to the filter, do you get air coming out?

[Doctordiesel77]

If you are testing the lift pump, the static outlet pressure should be 6 to 10 psi

[Martingo]

I ended up ordering a new lift pump, I guess I was hoping this was the problem but of course it wasn’t. The existing pump was in good condition, no deterioration of the diaphragm. Anyway I fitted the new one just to eliminate future problem. I fitted a length on clear pipe to the filter vent and manually pumped through a pint or more of diesel and there was no sign of any air. So all seems well up to the filter. I also loosened one of the injector couplings and diesel was pumping through clear.

After all this the engine runs no different, it one just about runs and certainly won’t rev at all. It starts and just about ticks over, after a short time the ‘knocking’ get much louder and smoke pouring out.

I think the addition on the air separator might be a good move in future but it’s not going to fix the current problem

[Martingo]

Also no air at the vent after the engine has been running.

[robert1]

"One minute running fine and the next almost total loss of power" is this still the case?
When is is running badly loosen the injector pipes one at a time, if one give no change swap the injectors over and see if the trouble moves cylinder too. that would be a bad injector.