Thread: Disco TDI not getting fuel sometimes

Matt

Firstly... welcome to the forum. There are a lot of very knowledgable people on here. Hope they can help you ......

This maybe could be a turbo boost problem .... maybe a leak or split in on of your hoses to or from the turbo. I had a similar problem and found the hose clip on one of the hoses had come loose, would sometimes leak and kill the boost pressure.

They should be able to test the lift pump.

It can be removed and just connect some short hoses and pop the 'in' tube in a container with fuel in it, then pump it by hand.

Not full proof but it will show if it's pumping.

..............but from what I understand that the lift pump isn't really nessesary...........and thus when running the injection pump should be enough

cant test the lift pump my ass...

remove the hose runing from the outlet side, manually hold the fuel shut off valve in the off position (zipties, is there nothing they cant do) and crank er over on the starter you should get a nice pulsing of fuel with every second turn of the crank. Got that, cool put on a rubber glove, put your finger on the hose and do it again, got pressure? pumps ok.

It sounds a little like loss of supply to the injector pump... change your fuel filters and blow back the lines with the filters off and the lines disconnected from the tank... Dont forget there is at least one gauze type trap filter in the system and its usualy on the inlet side of the lift pump.

whats happening in your engine (if my opening guess is right) is that at low fuel demand your pump can keep up fuel through the restricted lines. when you go for the noise the engine begins to burn off the fuel, the pump cant keep up the pressure and the injector pumps dont get a full load to push to the injectors.. and you get a progressive power loss as the supply fuel pressure decreases. Lifting off temporaily will let the pressure build and you will get a brief return of full power.. It should be worse when your in cold ambient temps.

IF you do a filter service and that doesnt fix it, take heart there are still some very cheap to fix things that can be wrong with it.

You can test the lift pump, but it'll probably die while you're testing it.

Easy to test, crack open the bolt on top of the fuel filter - the one that looks like it is there for no reason. Reach your arm in to the left of the fuel injection pump and to the right of the air filter - don't wear a white shirt. Well that's how it's placed on a Defender. There's a lever under the lift pump. If it does nothing crank the engine over to make sure the cam is in the right spot. If it still does nothing put a new one in. Costs about $75 from karcraft. Takes about an hour to fit, isn't difficult, just dirty and a long reach. You have to take off a couple of fuel lines and move the air filter.

Before you do that undo the screw on top of the lift pump and check the gauze for sediment. Apparently not all lift pumps have the gauze. When the gauze cruds up after a dirty load of fuel it can cause fuel starvation and show up exactly the symptoms you are describing.

Been using bio diesel recently? Or visited a Volume Plus servo? VP sell bio diesel and I've had a couple of tanks of dirty diesel from them.


Now, to start from the beginning:

Fuel cap dirty and stopping air from entering tank as fuel leaves - pull apart and clean.
Gauze on fuel outlet line inside tank dirty - very carefully pull out fuel level sender unit and clean gauze.
Tank full of crud - drain, flush, etc.
Sedimenter dirty - pull off, drain, and clean.
Lift pump problems - clean gauze, replace lift pump.
Fuel filter - change fuel filter.
Fuel lines - blow out with air, check for cracks in lines to lift pump.
Fuel injection pump - You don't want to know $$$.

hth

Cheers
Simon

Originally Posted by Roadrunner

Hi,

I've posted this in a UK forum (before I found this one) and one person suggested it could be the lift pump and that you can't really test the lift pump. Has someone heard of a problem like this ?

I've got a 96 TDI Disco and some trouble with the engine.
Sometimes it feels like the engine is not getting diesel. You drive along and everything is fine then after a sudden rpm's go down and the car slows down. I put the foot on the throttle nothing happens. I take the foot off the throttle car get's slower and slower and after a few seconds everything is fine again.
I was driving 5000KM no problems then it started doing it within 300KM it did it 3 times.
I have the car at the repairer at the moment but they can't find anything. They had a look at the injection pump and if there was something in the fuel tank but they don't know what it could be new fuel filter was done as well.
I can't reproduce the problem. It just happens while you're driving.

Any suggestion would be great.

Matt

HI, It could be sucking air through a bad or loose fitting, or at sediment trap, or filter head Maybe

Cheers Sumo

To continue Blknight.aus's post. My theory is that the surging supply/intermittent fuel supply is that the blockage isn't completely stopping fuel from getting through, just stopping fuel from getting through at 100% demand. What I reckon happens is that you get a load full in the fuel filter chamber, the injection pump sucks it up, the fuel filter chamber is empty, you get fuel starvation until the demand drops and the fuel filter chamber gets a chance to fill again.

Cheers
Simon.

and most of those cheap things to fix are in abaddonxi's post... but he forgot collapsing fuel lines, and a cracked supply line inside the tank... both cheap to DIY but time consuming and swear word inducing to actually do.

If youve checked all of them things out and they seem smicko its time to look at things like wastegate control problems...

if your any good with the spanners dont by a new lift pump, repair the old on the a generic repair kit should only cost you $25 or so, save the extra $50 and buy a rattler type electric pump and make up a bypass for the engine pump, then yovue got something to get you out of trouble when it dies on the road.

Originally Posted by Blknight.aus

repair the old on the a generic repair kit should only cost you $25 or so, save the extra $50 and buy a rattler type electric pump and make up a bypass for the engine pump, then yovue got something to get you out of trouble when it dies on the road.

Good oh, just happen to have a spare lift pump lying about, where do I get the kit?

On a slight hijack.

I went looking for a filter funnel today.

I like using the bio diesel, first because it makes me feel very smug when I get those looks about my environmentally unfriendly big 4wd.

And 'cos the closest servo sells only bio diesel and it's cheaper than any of the other local servos.

So, I went off to local Whitworths and asked after a filter funnel. They showed me some very sad looking things with gauze of varying fineness.

I said I want a proper fuel filter in a funnel.

Nope.

I want something that will make sure the fuel isn't full of floaty stuff before it gets into the tank. I read about a filter like this on the internet, but no luck.

I used a stocking in the filler, which does the trick, but a little expensive, and what will I wear?

Suggestions?

Cheers
Simon.