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Bleeding 12j 2.5 NA Diesel


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Wondering if anyone can help. Have rebuilt a 2.5 nad on a very good recon bottom end.

But cannot get it to run! Basically can bleed to the filter no probs (in fact a lot of pressure there) but cannot get anything from the bleed on the top of the injector pump.

Seems to be getting to the pump and the solenoid (which I have tested and works) as I get diesel bleeding if I loosen either.

One suggestion I found was to blank the return (tbh there was a lot more diesel in there than expected) but that doesn't seem to have helped.

The pump is apparently OK and was with the bottom end which still had the hone marks on the bores and piston rings that gapped pretty much as new, therefore assuming the pump is similarly good...but realistically is an unknown.

Any ideas anyone?

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If I understand correctly,
When you loosen the filter bleed screw you can get diesel 'leaking' when you operate the lift pump manually.
When you loosen the stop solenoid on the Fuel Injection pump you can get diesel 'leaking' when you operate the lift pump manually.
When you loosen the pump bleed screw, no diesel leaks when you operate the lift pump manually.

I can't see it being anything other than an internal blockage (waxing?) in the pump, but just on the off chance, if you loosen the fuel pipes at the injectors, can you get fuel leaking from those pipes, when you operate the lift pump manually?

How long was the High pressure pump stood and not used?
Was the fuel system sealed (and full of fuel) during that time?

Regards.

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12Js have a stupid fuel routing design.  The return line goes to the filter and air can't get out...  One day, plan to fix that.

Anyway, first crank the engine with the injector bleed screw open.  Forget the hand pump.  See if it comes out then.  If that is okay, crack all the lines at the injectors and crank.  As fuel comes out, tighten one at a time.

As Les says, a tow start is usually the quickest.

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Hi All, many thanks for the swift reply's

Basically yes, leaks from solenoid if loosened, have done a bit of manual pumping but mostly on the starter, filter primed really quickly so I guess the lift pump is Ok (ir's new but!!!!)   Had it jumped across to another car so it has had a lot of cranking!

No diesel seems to be getting beyond the pump so yes, I think the pump is gummed up as it may well have been left for a while empty.

I have syringed diesel in through the bleed port yesterday in the vain hope that it may loosen up but not optimistic!

Any way to ungum other than sent to a specialist!

Towing not really an option sadly as we are in a busy estate and the nimby's would moan.....

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Thanks for all the info, didn't have much time on sunday but squirted some diesel and cleaner into the pump bleed port, turned it over and had bubbles at the port and fluid coming from the pipes at the injectors, but the pump appears to be empty at the bleed port again now....does this move me on at all?

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Any new fuel you can get in will help free it up.

There is probably a fine nylon filter down inside the inlet fitting on the pump, maybe that is gummed up because if the pump pistons are gummed up you should still be able to get fuel up to the bleed screw.

Until you can get the pump body full of fuel and sqirting out when you prime the lift pump then I don't think you have much chance of a start.

If you filled the body up by the bleed port and then it pumped that out the injector pipes then it looks like the pump is working but just not getting any fuel.

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You have a blockage or an air leak somewhere.  The system takes a few minutes to bleed, but is not hard - you bleed the filter until no bubbles appear, then the injection pump, then the filter again and your'e done.  The return line goes through a banjo on the top of the filter casing to allow any air in the filter to be automatically bled back to the tank.  Only if air is being sucked into the system will you get more air after that first round of bleeding, and that source of air has to be from the lift pump or upstream of it.  Favourites are bad or doubled-up o-rings on the filter, worn olives on the lift pump unions, a holed pickup pipe int he fuel tank (only sucks in air once the fuel level reaches a certain level) or a worn, chafed or loose pipe.  Lift pump diaphragm failure can also do it, but you're likely to have diesel leaking out of the witness hole near the priming handle or into the sump, raising the oil level (if it's not using oil) and making the oil smell of diesel.

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You mention that you checked the solenoid - have you got power to the stop solenoid as you are pumping the lift pump handle so that it is open and allowing fuel into the injection pump? The advice in the post above coupled with plenty of fuel in the tank should get the air out. If the pump has lots of air in it then it will take a few minutes to bleed out. I find it better to use slow, full strokes on the lift pump to produce a constant and steady flow of fuel rather than a series of spurts.

Also make sure that all of the unions are sound so that air isn't leaking back in after your efforts. I'm sure the 12J system is the same as the 19J. When I beld my system on my 19J a while ago, I forgot to properly tighten the joint where the injector spill rail connects to the return pipe to the top of the filter and had to do the job again when it wouldn't start again in the morning!

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Thanks for the helpful advice all, left the Landy for the week with diesel cleaner syringed through the bleed port.
Charged battery, connected to Wife's Jeep with jump leads and a very slow turn over, swapped to Daughters jump leads and fired on the 3 try, running on the 4th.
Yay..............
Probably would have fired last week with the different jump leads.......oh well.......should have noticed really.
After a little while settled down nicely....quiet (for a 12j) and the smoke cleared quickly.
But all is not great sadly......
Have a steady drip of diesel from the timing case........I suppose this means the front seal on the diesel pump???
I guess to sort this is a pump rebuild??????
The lift pump is new and doesn't seem to be dumping diesel into the sump so don't think that's the cause...which is a pity as that would be a simple fix.
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33 minutes ago, gbmoto said:
Have a steady drip of diesel from the timing case........I suppose this means the front seal on the diesel pump???
I guess to sort this is a pump rebuild??????
The lift pump is new and doesn't seem to be dumping diesel into the sump so don't think that's the cause...which is a pity as that would be a simple fix.

See here: 

 

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Quote

Have a steady drip of diesel from the timing case........I suppose this means the front seal on the diesel pump???

I guess to sort this is a pump rebuild??????

have a read of these 

http://forums.lr4x4.com/topic/18997-replacing-a-fuel-injection-pump-on-a-25-na-or-td/

http://forums.lr4x4.com/topic/5260-replacing-the-injector-pump-seal-insitu/

 

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  • 3 weeks later...

Many thanks All, seal replaced today with pump insitu and no leaks :)

Big job tho' (for me!) and setting up the timing is way more difficult when the engine is installed, ended up taking pictures end on to make sure it was all lining up!

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