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Discussion Starter · #1 ·
Hi all

I have a 1990 90TD and I am encountering the following problem.

When I drive at speeds in excess of about 45mph for more than a few minutes
(ie speeds when the turbo should be in operation) the car loses all power
and comes to a halt with the engine giving up entirely, I solve this by
undoing the fuel filler cap when pops off like a morter bomb leaving what
fuel is visible bubbling like lemonade. The vehicle runs fine after this.
This is becoming a real pain for all but the very shortest or slowest
journeys. I was told before that there could be a leak in the diaphragm in
the plenum chamber on the injection pump (whatever that is) but it occurs to me that instead of the turbo charging the mixture it is charging the fuel tank instead. I've unblocked the breather tube to the tank and bought a new filler cap (which according the landrover is only vented on the way in anyway). The pressure is building up inside the tank and not creating a vacuum as should be the case.As i can only go a few miles it is hard to tell but it doesn't seem like the turbo is working on the engine either.

Any help would be greatly appreciated. Thanks
 

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turbo

Hello,
The injector pump detects the turbo pressure so it can alter the fuel ratio as the air pressure from the turbo increases,it does this by means of a small pipe that runs from the turbo to the injector pump.It is possible that the turbo is pressurising the fuel and also causing air to be forced into the pump but I wouldnt expect the fuel tank to pressurise in the way you say as the breather should eliminate the pressure.

Are you 100% the breather is ok and clear if so try running without the fuel cap on to see if the symptoms of poor running and low power still occur.

Cheers ONz
 

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Discussion Starter · #4 ·
I've checked the breather and it is completely clear. According to Land Rover the breather only vents on the way in through the filler cap (so as the fuel level lowers there is no vacuum inside the tank). I seem to have the opposite problem - the tank is pressurising and the filler cap isn't vented for this - It runs fine with no cap on but is sluggish as though there is no turbo pressure. Even if I were to cobble something together to let the pressure release I still can't understand why there should be a build up of pressure inside the fuel tank when the fuel level goes down....
 

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Hi.

I just had the opposite problem so did some research and pulled my cap apart.

The breather will go both ways as it has two valves but they are small and can only deal with soo much preasure.

The suggestion in your first post is probably the correct one. If the bladder inside the injector pump fails preasure/air from the turbo can go to the tank via the fuel return line as it is diesel that is lubricating the pump. This would also explain the bubbling fuel; I think heated air from the turbo could have that effect on diesel fuel.

Is this problem related to speed only or could it be RPM/load related? You could try plugging the turbo to pump line and see if that eliminates the preasure build up in the tank. With out that line though I would expect your mixture to be lean at higher RPM so watch out for overheating. Someone please correct me if what I'm saying is too dangerous.

IMOA take it to someone who really knows their stuff. Playing with a really good hair dryer and diesel fuel can't be overly safe.

Good Luck.

Mike
 

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Discussion Starter · #6 ·
Thanks for all your advice. In the end I bit the bullet and took it to Lucas UK (the elctrical and fuel injection people). £369 and a day later it runs fine, turbo is working again and tank is remaining unpressurised. Thinking back, the very first symptoms were sluggishness uphill on even the slightest gradients and that the engine sometimes raced when I pulled up after a longish stretch at constant speed. Although it now sounds funny - the problem really came to a head when it packed up at the M25/A21 junction and I was forced onto the hard shoulder, walking around the driver's side I heard the telltale hissing from the fuel cap so I undid it, next thing the fuel cap complete with the keys flew across three lanes of motorway onto the central reservation to where I had to dodge traffic to recover it. Perhaps next time I won't be so cheap about getting things fixed.....
 

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Discussion Starter · #8 ·
It was the diapragm in the fuel injection pump which was split causing the turbo to find the path of least resistance and turbo charge the fuel tank. Apparantly, if you know what you are doing it's not too difficult a job. Unfortunatly I have a bad habit of starting a job, getting in trouble and then paying for a lowloader to take it someone who really knows. The bit that put me off was the use of two different LR "special tools".
 

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I know the feeling. I just had an electrical fire in my truck. After having dealt with other issues, I just went screw it, and had it towed to a shop. I let them deal with melted wires and inspecting the harness. Unfortunately after looking at the repair they did I'm going to have to spend some time and sort it properly.
 
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