300TDI revving problems

Hi there,

Ok, first of all thanks for even looking at this post, second sorry for the huge length of it. It should be information that might be helpful. Thanks in advance

So my issues started when I started my Landy to go to work. Started up fine, drove out of my driveway and up the hill. I got half way up when it decided to die on me. I tried starting it up again but had no luck. I then checked the fuel lift pump as i have had some issues with it not pushing fuel through as there is grit and dirt in the fuel (even though its a new fuel tank i fitted).

Anyway, so I let the Landy roll back down the hill until it was just above my driveway where i left it to get a ride to work.

I then towed it into my driveway and left it in one of our bays. I lifted the bonnet and fiddled around with things to see what the issue could be, cancelled out everything until I found the injection pump was the issue. I couldn't see any reason it wasn't working apart from the fact that there was no fuel getting out of the pump to the injectors.

For some reason, I decided to take out the injection pump and took it apart to see if i could see any issue with the inside of it. I found nothing, so i tried testing the new Solenoid I had put in, by attaching it to a battery, nothing happened. So i took it out and tested it again and the pin fired up and down. put it back in and tested it again and it worked. I i thought that this would've been the issue.

Today, after a week of screwing around, I managed to get the injection pump back in and connected up. The plastic fuel line snapped, so i tried using another fuel line but its leaking.

Anyway, it still didn't fire up, and with the ignition on i removed the solenoid positive and touched it back to the connector, nothing happened. this told me that I never had to take out the Injection pump as it was an electrical problem.

So I have been trying to work out what the issue is. After a lot of fiddling with wires and relays the solenoid finally worked and there was fuel getting through!! SUCCESS!!

NO! It started up, but went straight to full revs, even though the throttle lever wasn't pressed down.
I tried to start it up again and went straight to fuel revs so i decided that i couldn't continue doing it.

The question I guess i am asking is why is it going straight to full revs??

I apologise for the long Post but thought that the all the information I gave could help.

Thank you in Advance!

Tom

How far did you go with stripping the pump?

Hi there, i took off the bottom end of the injection pump, where you can see inside it with all the rollers.

I then put it all back together after realising there wasn't an issue there. Thanks for the reply

We you in a cleaner than hospital operating room environment when you disassambled the injection pump, and even when you removed the injector pipes etc

Hi, yes the conditions were pretty close to that. And I had cleaned my injection unit before taking it apart.

Have you looked at the throttle position on the pump. Is it right back at the stop, when it revs up is it still at the stop. Cable might be caught, sticky etc. Forget the pedal, look at the pump.

Hi there, yes it is where is it meant to be against the threaded stop screw...

Unless you really know what you are doing stripping injection pumps is not a good idea. Possibly reassembled incorrectly with governor not connected.

Have you popped the diaphragm and boost pin out, then had a look in the hole, opened the accelerator and witnessed the fuel pin pop out to meet where the lunger used to be?.....just to make sure that is working correctly....then popped the pin back and replaced the plunger in the correct orientation?

Also, have you adjusted the maximum fuel screw on the back of the pump?

Hi Wammers, what does the governor look like?

Hi Saint V8. I'm going to do that check tomorrow, I took off the accelerator linkage again today, and with the whole unit connected in the engine bay, trying to re-attatch the Spring is nearly impossible so I may have to take the injection pump out again.

How to I witness the fuel pin pop out? Are you talking about the one on the coned shaft with the diaphragm or on the solenoid?

Which screw is the one you are talking about? Is it the one that stops the throttle linkage from going too far back? Or the one between the injection line outlets?

As said, never a good idea to mess with the internals of the FIP, unless you know your way around how it all works. Remember, this unit is doing stuff with mechanical innards that modern ones are doing with electronics now....in my mind, stuff that's best left alone or to the experts to deal with. I would advise you take the pump out and have it serviced and recalibrated for you by one of those diesel service places...all the best with it.

Have a look on YouTube for VE pump disassembly (or similar wording), there are a couple of good vids there and also shows what test equipment is needed to properly calibrate one post rebuild.....................and no I don't think you will be wanting to buy the kit

Here you go for a calibration one

The pin is connected via a spring to the accelerator mechanism.

The pin rides on the boost plunger - there should be a witness 'streak' on the cone of the pin to show where the pin has been riding. In the mage below I have coloured the pin in red and the plunger in green.

As boost pressure increases, this moves the plunger downwards by the pressure acting on the diaphragm above. As the Plunger moves down, this pin is allowed to move inwards due to the profile of the cone.

As the pin moves in, it automatically increases the fuelling to compensate for the additional air being inducted due to the increase in boost pressure. without the need for accelerator pedal to me moved.

You can see this pin, if you remove the top of the boost diaphragm chamber, carefully lift out the diaphragm and plunger and look down the hole. If you then actuate the accelerator lever, the pin should pop out into the hole you are looking into. You have to use a screwdriver or similar to push the pin back in to refit the plunger, the actuate the accelerator lever again to ensure it pops back out to meet the plunger.

I am not saying this is the issue, but it is a further check to ensure the accelerator mechanism has been refitted correctly.

It certainly sounds like a governor issue.

The governor uses a set of weights on a rotating shaft, the weights have a keyway in them that locates onto the rotating shaft. As the shaft spins up, centrifugal forces take over and the weights move outwards, as they move outwards they pull the shaft with them and this acts on an assembly that controls the maximum fuel flow through the pump and stops the engine from running away with itself. It has a preset gap on the governor assembly that allows a small amount of extra fueling when starting (hence why you always get a puff of black smoke when you first start it up) and then as the pumps starts spinning, the governor takes over maximum fueling at maximum RPM control.

Diagrams below:

The governor assembly:


The weights and the shaft:


The weights:


The governor assembly:

Hi Saint, ok yes I saw all of that when I took it apart, then put it back together exactly as I saw it. I didn't take to much of it out, but what I did I then out back together again. I will use your photographs to have another good look and see if I can spot any issues.

So I will check that the weights are seated properly yes?

Kwakerman thanks for the vid I will take a look once I have the pump out. Thanks guys. I'll let you know how I get on. Any additional information that may be useful would be greatly appreciated.

Hi Saint, so that pin doesn't move out when I fiddle The accelerator linkage. How can I make it move?

Flailbasher said:

Hi Saint, so that pin doesn't move out when I fiddle The accelerator linkage. How can I make it move?

Click to expand...

Take the plunger etc out and move the accelerator link to full throttle - the pin should then pop out.....you should then be able to push it back with a screwdriver so you can put the plunger back.

Hi yeah I inderstand how to make it move when it works, but unfortunately moving that accelerator linkage doesn't make it move. I can make it move when I undo the governor top housing cover with it all connected inside, but as soon as I close the cover it stops working? Any ideas?

I'm not sure how it looks like inside when it's put back together properly...