Strange behaviour - 1990 RR VM TD

OK..it goes like this...the fuel level get s below half and it runs like a pig but only on deceleration at junctions and trafficlights etc.
It's worse pointing down hill and struddles to make 500rpm, indeed it just stalled as I turned into our street giving me a rapid reintroduction to non powered poaer steering and no servo'd servo brakes right when I didn't need it. No Harm done but it's clearly a dangerous issue now.
So whats the thoughts? I was thinking poor fuel...so I ran the last tank into the red and filled up fresh and were back to square one. If I fill it up above 1/2 a tank full it seems fine.
I tried to drain the water seperator but alas the drain screw snapped off so I've not been able to complete that little mission yet. Any one got any other suggestions.
Only other thing I can think of is that maybe the pickup pipe in the tank is perforated lower down. As it seems worse going down back this would tend to suggest the pickup is fitted further to the back of the tank...any one know if this is the case?
Lee D -- Project Percy - Jaguar 4.2 and Auto in to Series IIa 88 see it @ www.lrproject.com 101Ambi '76 / IIa - Percy '64 / Rangie TD '90
alt.fan.landrover hall of fame - http://lobster.dynip.com/afl/index.htm
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Hi!
I had this exact problem on a lorry years ago. It would go for half a day, perfectly, but half way through the day the engine would cease to run on tickover, and if it stalled it would not start until the engine had cooled down. It was one of those irritating problems one just couldn't reproduce in front of the mechanics in the yard!
It was traced to an unfortunate combination of two faults. A blocked fuel tank breather allowed a vacuum to build up in the tank as the fuel level dropped, and this vacuum was strong enough to inhibit the flow of fuel.
Incidentally the other fault was that the wrong camshaft was fitted. The engine was a Cummins V8 which had a low-pressure fuel injection system with unit injectors - i.e. there is no injector pump, but each injector is worked individually by a third camshaft lobe for each cylinder. The lorry was a Ford D 1614, and the engine had been rebuilt using a camshaft from a spare Cummins V8 out of a Dodge K series!! (but.... you didn't want to know that, did you!)
I don't know about VM's, whether they have injector pumps or unit injection. But if your RR has a faulty fuel lift pump and a blocked breather, that combination could be the cause of your problem.
Here's hoping you cure your RR
Cheers, RB
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Hi again!
Just one more thought, related to another problem I had once, this time on a Peugeot 309 (petrol) - but to do with mechanical fuel pumps. We had problems with intermittent stalling, a bit like on the lorry I mentioned earlier. I fitted a new pump, but that made no difference. In the end I diagnosed that the actual cam that operated the pump must be worn. There was a thick gasket, or spacer, between the pump and the cylinder block. I removed that, refitted the pump and the problem was cured.
If you find a similar problem, and there's a spacer between the pump and block (like I say I'm not familiar with VM engines!), bear in mind that removing the spacer could cause damage or excessive fuel flow - best consult an expert! It might be possible to fit a thinner spacer or skim the existing one. Anyway, it's worth investigating wear on the cam or the pump rocker arm.
A full tank, as you probably realise, will have a bigger 'head' of fuel pressure feeding into the outlet than a half-full one.
Cheers, RB
"Lee_D"
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noted
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<snip>

consult
pump
Well the pump arrived this morning. Removed the old one quickly and in the process noticed that the feed pipe had a copper washer missing , h'mmmm! Anyway fitted the new pump...went for a world tour to find a replacement copper washer x4 and took it for a test drive for around 20 minutes duck'in and div'in around the local estates, great excuse for a good old nosey!
Anyway seems thus far to be ok and was only running on 1 jerry can of fuel :-)
So thanks Prof Rollerball for the suggestion...If it weren't for that I'd be under ripping the tank of by now convinced there was a holed take-up pipe.
Also thanks to George at VM Specialist who I know is a very busy guy but got the bits out to me in a next day order...so he should to the amount I spent there in February ;-)
He's at..... http://www.courtfield.co.uk/vmspecialists /
for info of anyone doing a similar job on a VM engine in the future, can't recommend them enough and don't rip you off.
Cheers all!
Lee D
-- Project Percy - Jaguar 4.2 and Auto in to Series IIa 88 see it @ www.lrproject.com 101Ambi '76 / IIa - Percy '64 / Rangie TD '90
alt.fan.landrover hall of fame - http://lobster.dynip.com/afl/index.htm
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