ZD30 fuel issue [SOLVED]

[shagsta22]

Hi guys,

"Little Red" (D22) has developed a problem. A month or two ago I filled up at a BP and went on an hours drive. It was running fine before hand but part way there, whenever the engine was under load it would give a bit of a cough as if the engine was starving for diesel. Once I got home, I changed the filter and dropped and drained the tank. After a refuel with some fresh diesel (from a 7/11 this time) I thought the problem was solved. However it still is presenting itself. I don't think it's as bad but it's still there.

Does anyone have any suspicions as to what this could be?

My next options are to check for air leaks, check injectors or maybe get the injector pump checked.

On top of this it's decided to throw the seal on the transfer case. Poor "Little Red". At least the seal is a reasonably easy fix.

Is it safe to drive the truck with a leaking transfer case?

 

[Old.Tony]

Was up your way at Easter, working at Mt Panorama for the BMF. Awesome racing. Absolutely had a hoot watching the historic cars, but really enjoyed the Production Sports.

Anyway ... your car might have just gained a little dirt/varnish/cobwebs on the injectors. Revving the hell out of the engine might be the first backyard attempt to "clear out the cobwebs" but in reality it could also cause damage.

A $25 (Supercheap Auto) can of Liqui Moly Fuel System Treatment in your next tank of fuel is a good first step. It will clean all of the fuel system out - not as effectively as a Diesel Purge (Liqui Moly) but I've used this several times with excellent results. It never hurts to do!

There are other things to consider, but before exploring them it would be interesting to follow the car while you're loading it up, to see how much smoke comes out. If you're getting lots of black smoke, it's getting more fuel than it needs so maybe it's an air problem. Check the filter, the intake path, the turbocharger. Know that your intake manifold is probably rather chocked up with gunk as a result of EGR + oil vapour in blow-by gases.

Which brings up another possibility - excessive blowby (always increases under load) with an unblocked EGR will reduce engine performance. You'll see a marked increase in black smoke as well as the loss of performance. Perhaps a stuck piston ring? Blocking the EGR to see if it makes a dramatic improvement will give you the answer.

Now, can you drive for long distances with a leaking transfer case? I wouldn't leave it TOO long. Certainly not more than a few hundred km.

 

[shagsta22]

Thanks for your advice Old Tony. I'll give it all a try and see what comes from it.

The truck has never had any smoke. I've always thought it remarkable that an old diesel would never blow much smoke at all. And the performance hasn't actually been affected.

You mentioned that the intake manifold is probably choked up, is there any way to easily clean out that gunk?

I'll let you know how it goes once I've tried it!

 

[Ben_W]

Are you sure it's fuel related? Faulty Neutral Position Switch can also cause surging or rough running symptoms under acceleration. There are plenty of threads on here about disconnecting the NPS.

 

[shagsta22]

I'm not 100% but it had a bad fuel blockage when I first bought it and the symptoms mirror that.
So I assume it's either fuel or air related.

When I bought it 8 years ago, it was surging so I pulled the tank out and the fuel intake hose was almost completely blocked up with grass seeds. The numpty who owned it prior to me must have filled it up with jerry cans (with seeds in them) or left the fuel cap off when he was driving around in it.

 

[Old.Tony]

Grass seeds? Could have been a farmer transferring fuel from his own storage tank or his tractor. I've seen how well some of those tractor tanks seal - you wouldn't want to roll one, you'll have diesel everywhere!

 

[shagsta22]

So I eventually ended up discovering the cause of the problem. After living with it for a while, suddenly the accelerator started acting up by cutting out as well.
Thinking it was an all new problem, I pulled out the accelerator assembly and gave the Throttle Position Sensor a blow out. It has been back to running like a dream ever since, no cutting out, no surging. Thanks everyone for your help and suggestions.

 

[Ben_W]

Glad you got it sorted. Good stuff.