940 td wont start

[argosy960]

Originally Posted by Paddy Wagon

Argosy, I'm not being funny but there's absolutely no point asking someone for advice if you wont follow the advice given. The reason I said to run it WITHOUT the plunger is in case there is dirt inside the solenoid hole, if there is dirt in the hole then putting a new plunger in is NOT going to fix it, is it,,, and as you say, after running it for a minute it wont turn off, then obviously there is a problem there, so you have to find out what it is, and you do that by FITTING THE SOLENOID WITHOUT THE PLUNGER so that if there is dirt or some other obstruction in the hole, the new plunger is not blocking it off again.
The shut off solenoid is the heart of the fuel supply, that is what allows fuel into the pump, and if that is not working correctly due to a blockage then the pump is not going to get the correct amount of fuel for the engine to run properly. YOU HAVE TO MAKE ABSOLUTELY CERTAIN THAT THE SOLENOID HOLE IS TOTALLY CLEAR OF OBSTRUCTIONS BECAUSE IF THERE IS AN OBSTRUCTION IT WILL RESTRICT THE FUEL FLOW AND NOTHING ELSE WILL WORK PROPERLY, and the fact that the plunger was stiff coming out indicates there is some form of obstruction, the plunger should come out with no resistance at all. Throroughly clean the solenoid hole, use some cotton buds soaked in diesel and use a circular motion to clean the hole, keep doing that until the cotton buds come out clean, then fit the solenoid WITHOUT THE PLUNGER AND SPRING (there could also be wear in the hole causing the plunger to stick) and see if there is any improvement in the running of the engine. If there is not, then at least you have eliminated that and you can then go on to checking the rest of the fuel supply system, but you have to make certain that side of things is working properly before checking anything else.

Yes i should have followed your advise, just its putting it together taken it apart over and over, need to remove injector pipes to remove solenoid, just its a pain, cant get near solenoid with out removing injectors,
When i take out solenoid i can see into hole, looks clean,i,m not sure how deep the plunger goes but it can only be about and inch,
I will take apart again, and clean it and run it without plunger,
i'll let you know what happens,
i need this engine to put into my 740 saloon,,I was going to just give up and take engine out of 940 and fit to 740 and worry about fixing it then,
i,m trying to renew a 740td saloon, and this has been huge delay,
740 is up on stands and not a lot i can do with it until i have engine fitted,
if fitted then i could clean up body work interior,fit new wheels, get it looking good,and if be drop it into garage to get this problem repaired,
at moment i cant drop 940 in any where as its just a wreck with a great engine, i know engine,,,,

[Paddy Wagon]

I fully appreciate it's not the easiest job to get the solenoid out and I know it seems like a lot of work but it is part of a process of elimination that will help to find the cause of the problem in the shortest possible time. I've attatched a diagram of the injector pump, as you can see it's a very complicated piece of equipment that performs several functions, even the slightest blockage will affect the operation of every item in the pump, that is why it is so important to find out if the correct amount of fuel is getting into the pump to start with.
If you look at the diagram you will see the shut off solenoid (marked as fuel valve) Under the plunger is a smaller hole, this is the hole that the plunger closes, thereby stopping fuel getting to the rest of the pump, that is the hole that must be clear of obstructions. Once you've cleaned the solenoid hole, get a soft piece of wire (a paper clip is ideal) and gently insert it into the plunger hole to see if there is any obstruction. It's worth noting that if there is dirt etc in the hole it may well have got into the inside of the pump through the plunger hole so be prepared for that, but try cleaning the solenoid and plunger holes first, refit the solenoid without the plunger and see what happens. If it runs ok, then great, if it doesn't make any improvement then you know with 100 per cent certanty the problem lies further along the line.
If there is no improvement, then the next item to check is the emergency shut off lever (note that not all pumps have this lever) it could have got moved and will esentially cause the same result as a blocked solenoid hole. The bottom of the lever (marked in green) must be fully back to get full fuel flow, if it moves forward it will restrict the fuel flow, when fully forward it will completely shut down the fuel flow so make sure that is pushed fully back.

[argosy960]

Hi
Ran it without plunger, Still very same, Looked at that lil hole inside where plunger is, its clear, stuck piece of wire into it, spent a while looking carefully at this, no blockage,
Started car with out plunger,1500 rpm, Wont rev more,, i turn key off,,Of course it wont turn engine off,, but it didnt jump rpm up to 2100 when i tunred key off, like it does when plunger is fitted,
I will now look at stop lever,
Is it hard to fit a new pump?

[argosy960]

Stop lever ok,
At what point should i admit pump is screwed?
I,m gonna take engine out, Fit to 740 td saloon,
I'v noticed a lot of lil vacuum pipes on 940 td that are not on 740 td,
Will it matter, there is small vacuum pipe coming off injector pump on 940,, it goes to a lil fitting on inside of bonnet just above the battery, No where on 740 for it to go to, >//?

[Paddy Wagon]

ok, at least you've eliminated that part of it. The pump is not the easiest thing to change plus you'll have to retime the new pump so before attempting that, do one last test on the pump. The fuel pin diaphram, thats the one that sits on the top of the pump. As the engine speed increases, the pressure in the inlet manifold increases, a small pipe on the inlet manifold sends pressure to the diaphram and pushes it down, which moves the fuel pin down against the fuel flow lever and allows more fuel into the engine. If the diaphram is faulty or stuck then it will prevent sufficient fuel getting to the engine. To test it is quite simple, but you will need some way to get compressed air into the diaphram, if you dont have a compressor you can jury rig a foot pump to do it. Disconnect the pressure feed pipe at the diaphram end and connect a compressed airline, or your footpump, to the pipe connector on the diaphram cover. Get someone to start the engine and give it full throttle, then apply air pressure to the diaphram, not too much though as the diaphram should fully open with 10 psi pressure. If the diaphram and fuel pin/lever are working correctly, the engine will suddenly speed up to full revs when air pressure is applied to it, which means the diaphram is not get pressure so check for a blockage in the feed pipe or manifold connection. If the engine does not speed up, then either the diaphram is leaking or seized,,, or the fuel pin or lever is siezed.
If the engine does speed up when doing this then it's just a matter of finding out why the diaphram is not getting pressure so check the feed pipe and connectors, also check the induction pipes from the manifold back to the intercooler and to the turbo. If they are all ok, check for a turbo wastegate siezed open, it's very rare but it does happen. If the wastegate is stuck open it will prevent pressure from building up in the inlet system.
If the engine does not speed up, then switch off the engine, connect a lenght of pipe to the diaphram inlet connector and blow into it, if you get no resistance then the diaphram is split so fit a new diaphram. If you do get resistance then the diaphram is ok but something is preventing it from opening, either the pin or lever are stuck, you can check these by removing the diaphram cover, but be carefull how you do this.
If after this things are still the same then your probably looking at a pump strip down so you'd be better off just fitting a another good pump as stripping down an injector pump is a job that you really do need to know what your doing before attempting it.

[Paddy Wagon]

opps, pressed the wrong button, anyway,,,, that pipe your talking about, if it's the yellow one shown in the photo, dont worry about it, it's an EGR valve vacumn pipe. A solenoid on the bulkhead next to the battery applies vacumn to this pipe to open the EGR (Exhaust Gas Recirculation) valve. On a petrol engine with a carburattor, you need this valve to improve cold start running, on a diesel turbo, especially with an intercooler, it's a complete waste of time, in fact it makes the engine run worse because it allows hot gases into the inlet air flow which totally defeats the operation of an intercooler, so just pull the yellow pipe out of the solenoid and blank off the solenoid connector with a self tapping screw or similar.