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Hello knowledgeable people,

 

200Tdi 110 1990

After years of starting the engine with one flick of the key, all of a sudden it now takes two or three turns of the key and with the help of a little pedal. I don't have to continuously crank it, it fires up but only for a split second. Puff out the exhaust. The vehicle had been left for a few months.

I have done : New fuel filter (genuine), new lift pump (all makes (I can't get the primer arm to pump in any rotation of the cam but appears to be pumping)), new lift pump to filter hose (genuine), new stop solenoid connector and cleaned the terminal, new stop solenoid, even though I could hear the click (Bosch), checked fuel cap breather (ball bearings free), tried with fuel cap off (same), replaced spill hoses and pump return (3.2 mm int.), bled from the filter, checked filter is full (yes), checked lift pump has fuel at the output (yes), checked for leaks at the injector pump and injectors (none), adjusted tappets.

Once it's running it's normal and stays.

I have a new sender which I will do when the tank is empty enough, there may be an obstruction in the pick up pipe but why would it only obstruct on start up? The low fuel light is on and the needle is in the red but there is 3/4 of a tank in there so could be connected to that. The old genuine lift pump seems ok but left the new one on anyway. The new one has a different primer, it's sprung and there is no slack point in it, feels exactly the same no matter what. I've taken it off and refitted to make sure it's on the lobe.

There is a slight hiss from the fuel filler cap after a run but I can't understand why. It doesn't hiss when I remove it and it comes off normally. Can't see that the tank has sucked in.

I am now scratching my head....??

 

Any ideas or advice would be greatly appreciated. 

Cheers thanks.

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50 minutes ago, Stambecco said:

Yes I have replaced the fuel filter. I can't see signs of any leaks but i will look yet again. There must be a leak somewhere. Would diesel come out of the same place air is getting in?

Fuel may not be coming out, if the leak is on the pick up side it will just slowly drain the line back to the tank, may only be a very small leak as you are having no issues whilst actually running, on a series vehicle I had a small rust hole on the pick up pipe in the fuel tank that took ages to find.

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1 hour ago, Stambecco said:

Yes I have replaced the fuel filter. I can't see signs of any leaks but i will look yet again. There must be a leak somewhere. Would diesel come out of the same place air is getting in?

Not necessarily, but might show as a slight weep.

If vehicle has been left for a while, I would have a look at the fuel hoses on top of the tank. Mice might have been nibbling.

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Check for air leaks in the fuel system very methodically starting from the injectors as suggested above.

One additional thought, has this started to happen since it started to get colder? A healthy 200tdi should fire up with little to no glow plugs, but an elderly tdi may need the glow plugs to be in good order to fire up on the first spin. Worth a look if you don't find any air leaks in the fuel system. 

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1 hour ago, steve b said:

Just a random thought, is the tank only pump diesel as veg oil will settle out if stood? 

Once it is running, cracking the filter bleed screw while running is a good check for lift pump function.

Steve

No, only diesel. Yeah, I've undone the bleed screw while running, a few small bubbles then clear.

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1 hour ago, monkie said:

Check for air leaks in the fuel system very methodically starting from the injectors as suggested above.

One additional thought, has this started to happen since it started to get colder? A healthy 200tdi should fire up with little to no glow plugs, but an elderly tdi may need the glow plugs to be in good order to fire up on the first spin. Worth a look if you don't find any air leaks in the fuel system. 

Not not really since it's got colder, it's been doing it a while and I now am trying to get to the bottom of it. I've got a feeling there could be some dregs in the tank.

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