Pajero timing issue, dies every time

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Artie Fufkin
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Pajero timing issue, dies every time

Post by Artie Fufkin »

92 Pajero, Gen. 2, V44 series, 4d56t

Just installed rebuilt fuel pump and rebuilt injectors. We have fuel up to all injectors, tightened em back down and appears we have all air out.

For timing we had all 3 witness mark points lined up.

Vehicle fires well. Problem is it rev's up a bit higher than normal, then it revs down and dies.

Does this every time.

It's my understanding you can rock the fuel pump a bit to one side or the other to dial the time in ? If so, have no idea how to go about this.

Any insight appreciated.
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Growlerbearnz
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

What you describe sounds like air getting into the fuel line somewhere. A loose hose clamp, split fuel hose, or poor fuel filter seal are the usual suspects, but it might also be a seal in the injection pump- some of those o-rings are tricky to install without damage.

Timing on a 4D56 is critical for balancing fuel economy, power, and engine life, but I don't think there's enough adjustment range to cause the symptoms you're describing. Anyway, to adjust timing:

Loosen the four fuel injection pipe flange nuts on the back of the pump
Loosen the two 12mm nuts that hold the injection pump flange to the timing case (you'll need a long socket extension)
Loosen the two 14mm bolts in the middle of the lower bracket- easiest from under the engine.

You should now be able to rotate the injection pump. Setting your timing accurately requires a dial gauge and special adapter, but if you set the pump's adjustment to the middle of its range you should be about right. When looking at the pump from the front of the car, turning it all the way to the left advances the injection (more power, more cylinder pressure, more knock, shorter engine life) and to the right retards the injection (less power, quieter engine).
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Artie Fufkin
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Re: Pajero timing issue, dies every time

Post by Artie Fufkin »

Growlerbearnz.

I was starting to question if it actually was timing.

This is essentially the problem I had BEFORE deciding to purchase a rebuilt fuel pump and get injectors rebuilt.

Minus the rev'ing higher part.

Had a bad fuel leak at the pump and figured it got bad enough to start sucking in air.... so rebuild/seal test. All the injector lines are pretty new (we tested for leaks before reassembling) and no other signs of where a leak could be to pull in air.

Frustrating process !
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

I suspect the high revving is just because the rebuilt pump's idle speed needs adjusting, which you can really only do once it's running properly. Diesels don't run fast because of mixture or timing problems (unlike petrol engines).

Usually air leaks happen at the rubber lines between the fuel filter and injection pump, where there's a bit of negative pressure to suck in air while the engine's running. The hard lines between pump and injectors are pressurised so I'd expect them to leak fuel out, not suck air in.

Rubber fuel lines love to split at the ends, and no amount of hose clamp tightening will fix it. Try cutting an inch off your rubber fuel lines wherever they have a hose clamp.

If you're getting desperate, you can try fitting transparent hose between the filter and pump, and the return from the fuel injectors to pump. That will let you see if there are any air bubbles. Obviously, the transparent hose won't last long so swap it back out before driving too far.

Bubbles in the inlet line = fuel filter air leak (cracked housing, split prime pump diaphraghm, split water drain fitting, perished filter seals, doubled-up filter seals).
Bubbles in return line only = air leak in injection pump, injector lines, injectors.

Another thing to try is running the pump from a jug of diesel rather than from the filter. That way you *know* air isn't getting into the pump from the filter.

I feel your pain. I've been in similar situations before- I've changed so many things, that the cause of the trouble could be *anywhere*. Just try and eliminate one thing at a time.
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

I've had another thought: the engine only starts after you've bled the injectors, right? And you're using the primer pump on the fuel filter to do that?

Here's a theory: Using the primer pump fills the injector pump. Engine starts, but the vane pump inside the injector pump isn't sucking in new fuel. Fuel level in the injector pump drops, exposing the governor, which speeds up the engine. Fuel level drops more, injectors get air in them, engine stops.

Sometimes the vane pump inside a freshly rebuilt injector pump needs a bit of encouragement for the vanes to move into the right positions. Try pumping the primer pump while the engine is running. If you do it for a minute or two it should/might reset the vane pump. If the engine runs while you're pumping, but stops when you do, you know the vane pump is faulty.

That said, I still think it's air getting into the fuel lines, but this might be something to try that doesn't involve removing fuel lines and getting diesel everywhere.
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Re: Pajero timing issue, dies every time

Post by Artie Fufkin »

Thanks again for the info Growlerbearnz.

Gives me several places to checkout.

Some days I have a love-hate thing with the Pajero ... start having thoughts of pulling out the 12 gauge and trashing it !! But when it runs well it runs well...

Back at er tomorrow.
Last edited by Artie Fufkin on Wed Jul 20, 2016 5:41 pm, edited 1 time in total.
Artie Fufkin
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Re: Pajero timing issue, dies every time

Post by Artie Fufkin »

Growlerbearnz wrote:I've had another thought: the engine only starts after you've bled the injectors, right? And you're using the primer pump on the fuel filter to do that?

Here's a theory: Using the primer pump fills the injector pump. Engine starts, but the vane pump inside the injector pump isn't sucking in new fuel. Fuel level in the injector pump drops, exposing the governor, which speeds up the engine. Fuel level drops more, injectors get air in them, engine stops.

Sometimes the vane pump inside a freshly rebuilt injector pump needs a bit of encouragement for the vanes to move into the right positions. Try pumping the primer pump while the engine is running. If you do it for a minute or two it should/might reset the vane pump. If the engine runs while you're pumping, but stops when you do, you know the vane pump is faulty.

That said, I still think it's air getting into the fuel lines, but this might be something to try that doesn't involve removing fuel lines and getting diesel everywhere.
Ok got it. I see what you're saying here.

Yes, engine only started after bled injectors. Did that with a bit of brake cleaner in the intake to fire it up and pull full. Bled each injector and tightened them down one at a time. We initially used the primer pump, then we used a syringe to fill the pump as much as we could (this was before we discovered the power to pump solenoid was dead). After we fixed the solenoid power issue we just hit it with brake cleaner, confirmed it was actually pulling to the injectors, bled em and tightened. Now it starts great .... for a few seconds !

We did cut an inch off of the fuel line right at the pump intake because it looked suspect and we saw a tiny bit of fuel. Maybe it's time to replace it all just incase.

My neighbour pulled out the primer pump and said the diaphragm looked iffy. Than again, said he'd never seen one with a diaphragm before so could be normal ! Didn't see it myself.
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

Hmm. A split pump diagram on the filter head can be a source of air leaks. I'd replace the fuel hose and try running the injector pump from a container of diesel directly: eliminate the fuel filter entirely.
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Re: Pajero timing issue, dies every time **** new problem !

Post by Artie Fufkin »

Growlerbearnz nailed it.

The higher rev'ing appeared to be air in the vane pump. We replaced the fuel lines just incase and I am ordering primer pump diaphragm just incase.

All air seems to be out, rev'ing is gone and starts well every time. Timing seems good.

Problem now however is throttle needs to be at half way just to hit idle !

If I let go of throttle dies every time. If I try to hit the floor with pedal it will rev up to maybe 2/3 ? and starts to choke out but if I back off to half way it's fine.

So ...

I'm guessing the governor/fuel flow setting is too low to hit idle ? That's the screw on fuel pump everyone says never to touch ?

Don't see what else it could be ..

Any thoughts? Thanks !
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

Neat! Glad it's working a bit better.

The fuel adjust screw *will* change your idle speed, but it should be a last resort. If something else is wrong (and I suspect it is) then using the fuel screw to correct it will only give you grief.

First up, adjust your idle speed screw so it's about halfway along it's range, like this:
20160725_145011.jpg
20160725_145011.jpg (166.49 KiB) Viewed 8899 times
Push the accelerator pedal all the way down, Check that the throttle lever hits the full throttle screw before the pedal hits the floor, and the throttle lever returns to the idle speed screw.

If it's still idling low, then I expect your throttle lever has been replaced a spline or two off.
93.jpg
93.jpg (9.08 KiB) Viewed 8899 times


Remove the throttle lever, position sensor, and return springs (it's a shit of a job. Pay attention to how the return springs are installed and where they go.) The throttle shaft is connected inside the injection pump to a linkage with a bunch of springs. Turn the throttle shaft counter clockwise (as if accelerating) until you feel it take up all the slack in the linkage. Turn it one spline further, and replace the throttle lever in the idle position.

if you have to turn the throttle shaft back and forth to feel the slack in the linkage, try and avoid turning the throttle shaft clockwise too far. It's not usually a problem, but on some pumps the control linkage will fall apart if you turn the throttle shaft too far clockwise (decelerating direction).
(Lots of terrifying pictures of the linkage here: http://gnarlodious.com/Vanagon/Bosch_Pump/-Rebuild)

If your idle speed is still too low, and the idle speed screw won't adjust any further, try turning the throttle shaft one more spline counter-clockwise. if you have to advance the throttle lever more than 3 splines from the initial position (where all the slack in the mechanism is taken up) then it's time to fiddle with the fuel adjust screw.
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Re: Pajero timing issue, dies every time

Post by Artie Fufkin »

Awesome !!! Thanks Growlerbearnz.

Was speaking with my father earlier today and he suggested the throttle lever might be off as well. Your description and pictures will help A LOT !

Like I mentioned, the rebuilt fuel pump was "newly" purchased so I gotta assume the fuel adjust screw was se/reset/left where it is supposed to be. I know it's a touchy thing to mess with.

Will try all your suggestions first.

Thank you very much !
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

I wouldn't be that confident about the fuel screw being correct. Putting the throttle lever back in the right place is pretty fundamental stuff, if they couldn't get *that* right...
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Re: Pajero timing issue, dies every time

Post by Artie Fufkin »

Growlerbearnz wrote:I wouldn't be that confident about the fuel screw being correct. Putting the throttle lever back in the right place is pretty fundamental stuff, if they couldn't get *that* right...
Yeah, I've been wondering about that ....
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Re: Pajero timing issue, dies every time

Post by Artie Fufkin »

Growlerbearnz,

So we are going to get to your throttle lever information tomorrow (neighbour who's helping me couldn't do it today).

I understand how moving the throttle level should get us to idle but what I do not understand is what's happening at the top end.

As I said earlier, we have to hold throttle 1/2 way up to get idle. Let it go and it dies.

When I depress throttle all the way it goes up a touch but basically not much more than idle. Two days ago when engine was at operating temp it would then rev about 2/3 of the way up or so.

I don't understand why it only revs up at operating temp and not at start up ?

The other VERY strange thing is when we could rev it up it would reach the top end and start to conk out every time. Back off on throttle and it would be ok as long as I held it at least half way.

So the two really weird things were not rev'ing higher at start up until warm, and then dying out at top end of rev.

Would that suggest a governor problem ?

This pump was supposedly just rebuilt !

Any help really appreciated. Thanks.


P.S.

Someone is telling the neighbour helping me that if we turn the fuel flow screw it permanently bends something in there that does not recover even if you turn the screw back to original position. Not sure exactly where he's getting that idea but I'm not buying it.
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Re: Pajero timing issue, dies every time

Post by Growlerbearnz »

Welllll.... there's a theory that if you adjust your throttle lever too far (too many splines), or the fuel screw too far, it'll bend the springy linkages inside- or crush the springs, depending on who you're talking to. I've not seen it happen, but I've only ever adjusted a pump in small increments.

I didn't pay attention to the bit about it dying at higher revs earlier, sorry! The throttle lever, governor, and fuel screw all act on the same linkage, and the balance between them determines how much fuel you get. I guess if your max fuel screw was *way* too far out, it might upset the linkage.

Maybe try screwing it in one or two turns (remember how far you turned it) and see if things improve. I know you can turn it about 4 turns in from the factory setting without damaging the linkage.

I'd still check the throttle lever is in the correct place on the splines though. When a pump is rebuilt they're supposed to bench test it in a testing rig, and set everything to factory settings. Do you know if they did this? Or just swapped a bunch of parts and shipped it out the door?
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