200tdi - intermittent power loss - the saga continues

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instantsquid

instantsquid

New Member
Posts
1,362
Location
Tadley, Hants
I know this has been done to death, but I'm rapidly running out of ideas.

The background: 1988 Ninety into which I put a 200tdi a couple of months back. The engine starts without smoke, and most of the time runs sweet as anything - bags of power, etc.

However, on almost every trip now, at some point it will suddenly lose all power. At this point, it'll tick over quite happily, but simply will not rev properly - in neutral with my foot on the floor the revs start to rise then drop, rise then drop - in gear it simply will not rev at all, and I'm lucky if I can get up to 20mph.

If I stop the engine and start it straight away, chances are it'll still misbehave. If I wait 5-10 minutes and then start it, all is well with the world and you'd never know there'd been a problem.

Things I've done: Flushed intercooler, replaced lift pump, replaced fuel filter, lubricated and freed pin under boost diaphragm. The intercooler pipes were brand new when I fitted the engine (aluminium tubes with silicon joints).

The fact that it's intermittent, and the engine doesn't display any symptoms when it's running properly means I'm at a loss as to what to look at next. I've tried to be systematic - only changing one thing at a time, and then driving the car until it misbehaves again.

Any ideas what to look at next? What could cause the engine to behave like this?

Thanks in advance,
Ian.
 
Id say a bit of rust in the tank getting sucked onto the pick up pipe .
Whip your seat off and remove your tank cover and tank sender then take a peek in the tank
 
I had a similar problem. I used a suction pump and pulled loads of fuel and greasey gunk out through the entire fuel pipe from the tank.
Has run fine for a few months since.
 
Quick update - this is still happening :(

It appears to be totally random as to when it occurs. But when it does happen, I have to turn the engine off for 5 or 10 minutes - then it'll be happy as Larry again.

I've had a look in the tank - it's clean as a whistle in there. I've replaced the hose from the tank to the lift pump, and also the return pipe. It was suggested that air might be getting sucked in, but I've checked and double-checked all the pipe connections and am as confident as I can be that's not the problem.

It's not the fuel cap as I have removed the cap when the problem occurs and it doesn't fix it.

Any more ideas? It's so frustrating, as the engine goes so well 99% of the time - it's really got some oomph! But then, without warning I'll lose all power and have to crawl into a layby at 20mph. It doesn't matter how long I leave it ticking over, it doesn't sort itself out. But switching the engine off for 5 minutes or so seems to "reset" whatever the problem is.

It's driving me nuts! :mad:

Ian.
 
Next time it looses all power, immediately pull over and turn the engine off as quickly as possible. Unscrew the fuel filter from the fuel filter housing and then look down the very central channel in the fuel filter. The channel should be full to the brim with diesel; is it? This channel is where nice clean, filtered diesel is stored (all be it a short time when the engine is running) before it is drawn into your injection pump. If the channel is only half full or if it's nearly empty, it's telling you one (or two) of two things:

1) You have a clog before the fuel filter
2) You have a weak (or faulty) lift pump

You say that you have replaced the fuel line between the fuel tank and the lift pump, but have you inspected the pickup pipe? They are notorious for clogging up at the 90 degree elbow (if they don't have the mesh gauze brazed onto the bottom), or developing pin size holes in the elbow which allows air to be drawn in very slowly - enough to have an eventual effect on your power once enough air has been drawn into the pipeline. Remove it from the tank and take a good look at it. A new one will cost you about £25 mind, because only Land Rover seem to supply them.

Another sensible thing to try would be a replacement lift pump if you haven't already. I've had a faulty lift pump straight from the box so it is possibe that you've bought a dud. You want a decent brand like Delphi, not a Britpart component which will give up the ghost after about four weeks. It could well be possible that the diaphragm has failed (possible even intermittently) which will prevent diesel from being pumped up from the fuel tank and it will also act as a barrier in the fuel line for any 'sucking' that the injection pump is doing too.

Once you've ruled these problems out it might be worth having your injection pump checked over, although it sounds very much like a problem before the injection pump to me.

-Pos
 
How about:

Faulty fuel cut off solenoid
Blocked or split/leaking pipe from turbo to fuel pump
Head gasket fault? (Compression test it)
Blocked exhaust (more comon on cat's)
Turbo fault (when it occurs take pipe of to intercooler and see if rotating)
Loose cam belt or pulley (broken woodruff key?)

And then:

Faulty fuel injection pump
 
Cheers guys - a few things to try there. I forgot to add that I've already replaced the lift pump with a Delphi.

I did check the pick-up pipe very carefully - it certainly wasn't clogged, but I suppose it is possible there's a pinhole in it. I'll have another look.

I'm rapidly getting close to thinking that the IP could have a fault - still got a few things to check out before then though.

Ian.
 
pos said:
Next time it looses all power, immediately pull over and turn the engine off as quickly as possible. Unscrew the fuel filter from the fuel filter housing and then look down the very central channel in the fuel filter. The channel should be full to the brim with diesel; is it? This channel is where nice clean, filtered diesel is stored (all be it a short time when the engine is running) before it is drawn into your injection pump. If the channel is only half full or if it's nearly empty, it's telling you one (or two) of two things:

1) You have a clog before the fuel filter
2) You have a weak (or faulty) lift pump

You say that you have replaced the fuel line between the fuel tank and the lift pump, but have you inspected the pickup pipe? They are notorious for clogging up at the 90 degree elbow (if they don't have the mesh gauze brazed onto the bottom), or developing pin size holes in the elbow which allows air to be drawn in very slowly - enough to have an eventual effect on your power once enough air has been drawn into the pipeline. Remove it from the tank and take a good look at it. A new one will cost you about £25 mind, because only Land Rover seem to supply them.

Another sensible thing to try would be a replacement lift pump if you haven't already. I've had a faulty lift pump straight from the box so it is possibe that you've bought a dud. You want a decent brand like Delphi, not a Britpart component which will give up the ghost after about four weeks. It could well be possible that the diaphragm has failed (possible even intermittently) which will prevent diesel from being pumped up from the fuel tank and it will also act as a barrier in the fuel line for any 'sucking' that the injection pump is doing too.

Once you've ruled these problems out it might be worth having your injection pump checked over, although it sounds very much like a problem before the injection pump to me.

-Pos
Click to expand...
Well, the saga continues - but the car hadn't misbehaved for a while so I couldn't move on with the diagnosis. Anyway, it finally did it today so I was able to whip off the fuel filter - as Pos predicted it was almost empty. I've already replaced the lift pump with a Delphi, so I will look elsewhere before replacing that again. Top suspects must be the fuel pick-up pipe, or possibly one of the places where I've used flexible fuel hose to extend the TDI fuel hose. This discovery narrows things down considerably - so, cheers Pos!

Ian.
 
i had exactly the same problem on mine. Turned out to be an inch long piece of insulation tape in the tank that kept getting sucked into the end of the pick up pipe.
turning of the engine and leaving for 5 - 10 mins allowed the vaccum to cease and the tape to fall off untill next time. Hope this helps
 
instantsquid said:
Well, the saga continues - but the car hadn't misbehaved for a while so I couldn't move on with the diagnosis. Anyway, it finally did it today so I was able to whip off the fuel filter - as Pos predicted it was almost empty. I've already replaced the lift pump with a Delphi, so I will look elsewhere before replacing that again. Top suspects must be the fuel pick-up pipe, or possibly one of the places where I've used flexible fuel hose to extend the TDI fuel hose. This discovery narrows things down considerably - so, cheers Pos!

Ian.
Click to expand...

No problem :) Next few things to think about are:

1) Lift pump - double check that your new one is working well, it's not uncommon to have been sold a dud or 'weak' unit. There are quite a few things that can go wrong with them.

2) Fuel pipe between lift pump and pickup pipe - if it's rubber hose, is it re-inforced? It's quite possible that the vacuum created by the lift pump is sucking the pipe shut if it's only single ply rubber pipe. Then again, if it's laminated pipe, the internal laminate could have broken away from the outer laminate, again being sucked shut.

3) Fuel pickup pipe - I'd replace this pipe just as a matter of ruling it out (£20). Unfortunately you can never really tell if they've got small pin hole punctures in the bend or on the length of pipe that sits in the tank (which will obviously draw air in when the fuel is drained low enough). The older style pickup pipes had a metal gauze soldered onto the bottom. It's quite possible that this has become blocked / clogged up, preventing fuel flow if you have one fitted.

4) Fuel tank - drain, steam clean (better) or pressure wash your fuel tank internals clean. There are a couple of places where foreign objects can become lodged or hidden from view and it might just be sods law that something you can't see is moving around the tank (whilst driving) only to find its self being sucked to the bottom of your pickup pipe. You could also rig up a temporary fuel supply from a jerry can or some other form of fuel container, take it for a spin and see what difference it makes.

From what you have said however, it sounds like the problem is more than likely something that you've missed in the fuel tank. An intermittent problem usually has an intermittent cause and something floating around in the tank kind of marries up to that theory quite well.

Good luck with it!
-Pos
 
I'm over the moon! But also, slightly embarrassed.

I was driving the Landy into work this morning when the power loss occurred. I pulled off the road but didn't stop the engine. I slowly lifted the fuel pickup pipe out of the tank to find a big lump of that plastic/cardboard stuff stuck to the bottom of the pipe! The fuel tank does appear to be very clean - apart from this one foreign object that's been floating about in there.

So I'm a very happy chappy now - and I can start tinkering with setting up the injector pump for optimum performance.

(And to all those people who said "check for crap in the tank" right at the beginning - apologies for doubting you!)

Ian.
 
PaulWilde said:
Excellent news Ian, any idea how it got in there ;)
Click to expand...
Nope! I'm assuming it's been in there since before I got the car, but for whatever reason it wasn't getting sucked onto the pick-up pipe when the old (TD) engine was in. Running the tank down low and filling it right up at some point may have washed the culprit into a position where it could be lifted up relatively frequently. I've peered into the tank a couple of times with a torch, and the bottom of the tank was extremely clean, which was why I had discounted "crud" in the tank. This was a single foreign object that I guess had been dropped in through the fuel filler at some point in the past.

Ian.
 
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