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300tdi driving me mad


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Sorry for putting this here but the engine is in my series 3 and obviously it is more often found in a defender or discovery.

Anyway, the problem:

The engine has been completely rebuilt, new rings, big ends, mains, head pressure tested and new head gasket, new turbo. The ancillaries are all good used units.

Fitted in the vehicle, it started perfectly first time every time, it's been run no more than 10 minutes since it's been put in. Fired it up the other day, which it did on the first crank as usual, let it idle for a minute then revved it up gently a few times, when the revs came back to idle it cut out. Fired straight back up though. Did it again and now it won't start, it cranks quickly and fires a few times belching out black smoke but will not start. Took the hose off the inlet thinking maybe lack of air but all clear and still wouldnt start which suggests fuel but do injector pumps just give up like that?

Any suggestions welcome

Thanks

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Thanks for the response, I think i have, i've got the feed from the tank to the in arrow on the lift pump, lift pump to filter, filter to injector pump and then the leak off from the injector pump back to the tank which is how it was plumbed in the discovery it came out of.

But a bit more to the story, it started first crank this morning, idled perfectly, wouldn't rev very high (maxxed out around 2500) left it to idle for a while, it just stopped after 30 seconds idling and wouldnt restart. So it sounds very much like fuel starvation. Could it be the lift pump? I've worked on hundreds of 300tdi's and my experience is usually just a lack of power with lift pump or poor starting, never known one cut out.

My other thought is if it is the tank plumbing. The pick up pipe is the original series item which draws from the bottom of the tank, i made my own return pipe which is the same length as the feed to reach right to the bottom of the tank, is this the right thing to do or should the return just drop the fuel in the top of the tank?

Again any suggestions welcome

Cheers

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Step one. Check the lift pump. Disconnect the inlet line to the injection pump and stick it in a bucket. Disconnect the injection pump solenoid wire. Crank and see if you get a good flow of fuel into the bucket. If that is good, come back. If not, fix it....

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Hi Guys, cheers for the suggestions.

I'm fairly certain it's not air in the system, i have clear fuel lines right from the tank up to the engine and there's not a single air bubble in them. The lift pump was tested right before i fitted it and pumped well.

My thoughts are the solenoid, or more precisely the live feed to the solenoid. When it cuts out, often when i turn the key to restart, the starter doesnt engage, leave it a few minutes and all is well again. I therefore think it's probably a failing ignition switch that gets hot and breaks contact. I will run a live feed straight to the solenoid when i get a chance and report back.

Thanks

Dave

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Ok, it fired up perfectly this morning, idled smoothly for about 40 seconds then just stopped as before like someone had turned it off. Restarted and ran for another 10 seconds, then would just crank and fire once or twice but not catch. Removed the pipe from lift pump to filter and cranked, plenty of diesel flowing so not the lift pump. Removed the stop solenoid and took out the plunger, cranked again and still wouldnt start, cracked the pipe to number 1 injector and it's spitting diesel so i'm a bit stuck.

The only thing i can think of that has changed since it's first run (had it running over 10 minutes) is i adjusted the valve clearances because it was a bit tappety, is it possible i've set them a bit tight and when the engine gets warm and bits start expanding that the clearance becomes too small and the valves are being held open?

Cheers

Dave

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If it stops "as if it's been switched off" then that's where I'd look. If it was bad enough to be stopped by air in the fuel, poor compression, valve clearance or a kitten boxing the airbox I'd expect it'd splutter a bit first.

The solenoid is the first place I'd go - keep an eye on the voltage at the spade connector while it runs?

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I've taken the plunger out of the solenoid so it can't be the solenoid. As I said it ran fine when I first put the engine in, the only thing I can think of that's changed is the valve clearances. I think it's worth a try checking the clearances before I condemn the injector pump. Thanks for the suggestion though.

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I can't see that the valves would make it stop as quickly as if it'd been switched off. It must be something on the fuel side. Put a smear of grease around all the banjos and fittings on the low pressure side, on the injector pump and the injectors, see if it's drawing air somewhere.

If you decide the FIP is at fault then I'll happily take it off you for spares?

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Right back to the start, did you put the return line into the tank as in did you make a new hole or use an old one?

Check the pick up pipe to see if it has not picked up some foreign object, I have had a few problems with diesels and never had to remove the FIP. I had some problems in the past with fuel filters, you could try another one if you have one handy.

Next step I would do is get a gallon can with some diesel in it and run a pipe from it to the lift pump and start it up and see what happens, if the problem persists its from the lift pump forward, if the problem goes away the problem is from the lift pump back.

The gallon can will empty very quickly if you leave the return pipe in place connected to the engine/tank, if you want you can run a pipe into the gallon can from the return line on the engine.

Usually a fuel or air problem will cause the engine revs to drop slightly before it cuts out, what's the air filter side of things like no one has stuck a rag in somewhere !

Hope this helps.

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Can you confirm mmgemini's earlier diagnosis of the banjo bolts in the wrong way round please?

Secondly when you pulled off the air inlet, was this at the filter or the manifold? When the short 90ยบ rubber elbow delaminates it also gives the same symptoms but more erratic.

Is there any chance the freshly built engine had a rag or tissue in the inlet manifold that got pushed in before refinement or sucked in afterwards?

You can check the fuel by opening the injector pipes and cranking it. Fuel here would indicate this side of things is OK.

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2 silly things to try,

1) remove the fuel filler cap, vent maybe blocked causing a vacum

2) remove the big air pipe to the inlet manifold, if a pipe is collapsing and blocking air supply this will eliminate it.

3) fit secondary fuel canister above engine, and direct gravity feed to fuel filter, just to eliminate any blockages in pipework. If the lift pump has a small screw on top, undo this, lift off the cap, and clean all the crud from the removable wire gauze.

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Ok, i've checked the banjo bolts and there are correct (i havent disturbed the pipes on the injector pump since the engine was running well in the previous discovery).

I've already removed the inlet hose to the manifold and i am certain there are no foreign objects anywhere in the manifolds etc.

I haven't had chance to get near it recently with work picking up but i will report back when i have it running again, my money is on valve clearances being too tight as they are the only things that i have touched since it was running properly.

Cheers all

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