Bleeding Yanmar 4JH3

[Porthandbuoy]

I've bled through to the secondary on-engine filter with sparkling clean diesel.
Engine won't start.
Cracked the inlet line to the HP fuel pump. Diesel there okay.
Cracked the supply pipe on the injector nearest to the pump.
No diesel.
Cranked the engine over for 20 seconds a few times.
Still no diesel at injector.
Bypassed the engine lift pump and put electric pump in the circuit because my fingers were developing callouses pressing that damn priming lever..
Diesel is flowing through the HP pump and back to the tank via the excess fuel line.
Still no diesel at injector.
Clamped excess fuel line to force diesel up injector pipe.
Still no diesel at injector.
Moved throttle to various positions.
Still no diesel at injector.

Stop solenoid seems to be operating and releasing okay, but no fuel is getting past the HP pump/governor to the injectors.

What could be the problem? The system is now pressurised, so I'm not sucking air in.

 

[QBhoy]

Sounds a strange one, given what you have done...but I would likely crack open all 4 of the injector fittings a few turns. loose enough that you can move the fitting up and down to make sure they are definitely breaking their seal, but not enough that the fitting becomes undone. Then turn her over a few times. no reason you shouldn't get fuel through otherwise, that I can think of. Forgive me for asking...but I take it, you have tightened up the bleed screw again, when trying to get fuel to the injector by cranking ? Presumably you would have.

 

[Porthandbuoy]

Yes, bleed screw on filter tight. No bleed screw or bolt on HP pump. Tried slackening off and cracking the seal on all four injector pipes.
Nothing. Not so much as a weep.
I’m thinking there’s something to do with the fuel cut-off jammed inside the pump/governor.

 

[QBhoy]

Yes, bleed screw on filter tight. No bleed screw or bolt on HP pump. Tried slackening off and cracking the seal on all four injector pipes.
Nothing. Not so much as a weep.
I’m thinking there’s something to do with the fuel cut-off jammed inside the pump/governor.

No worries.
is there a chance that the primary filter isn’t or wasn’t quite full, meaning there was a void of air between that and the secondary filter before injectors…and the pump is dry ? Mayne needs more priming ?

 

[Porthandbuoy]

No worries.
is there a chance that the primary filter isn’t or wasn’t quite full, meaning there was a void of air between that and the secondary filter before injectors…and the pump is dry ? Maybe needs more priming ?

I've put an electric pump in the circuit instead of the on-engine lift pump. Fuel is getting through the secondary filter and the HP pump and is spilling back to the tank via the excess fuel line. The HP pump will have been flushed through with clean diesel. Everything I loosen on the LP side pisses clean diesel, definitely no air.
The stop solenoid pulls the lever back on the governor and when released it springs back to the run position.
Cracked all 4 injector pipes, cranked the engine over several times and still nothing at the injectors.

I should mention the engine hasn't run for about 5 years, and if the state of the fuel tanks was anything to go by, god alone knows what state the HP pump internals are like, and by extension, the injectors.

Reckon I'll give Yanmar a call tomorrow. Time to call in the pros. £££

 

[Porthandbuoy]

Found this guy on YouTube.

Worth trying?

 

[jamie N]

I should mention the engine hasn't run for about 5 years, and if the state of the fuel tanks was anything to go by, god alone knows what state the HP pump internals are like, and by extension, the injectors.

Reckon I'll give Yanmar a call tomorrow. Time to call in the pros. £££

I think that's going to be the case.
Good luck with Yanmar.

 

[Bilgediver]

Found this guy on YouTube.

Worth trying?

I haave had to do something like this on my MD2B when the pump wuld not free the air in the HP barrel. There is NO NEED to remove those fittings. Just slacken them and the air will rise up past the threads. once fuel flows re tighten.

 

[QBhoy]

I've put an electric pump in the circuit instead of the on-engine lift pump. Fuel is getting through the secondary filter and the HP pump and is spilling back to the tank via the excess fuel line. The HP pump will have been flushed through with clean diesel. Everything I loosen on the LP side pisses clean diesel, definitely no air.
The stop solenoid pulls the lever back on the governor and when released it springs back to the run position.
Cracked all 4 injector pipes, cranked the engine over several times and still nothing at the injectors.

I should mention the engine hasn't run for about 5 years, and if the state of the fuel tanks was anything to go by, god alone knows what state the HP pump internals are like, and by extension, the injectors.

Reckon I'll give Yanmar a call tomorrow. Time to call in the pros. £££

such a strange one this...youd think if it has fuel making it's way past the HP pump and the stop solenoid is definitely not to blame, there can't be much else to stop the fuel getting to the injectors, other than a failed fuel pump...but you'd think a mechanical fuel pump, should it fail, would be making all sorts of bad noises when turning her over perhaps. So you think that without using your added in make do pump, it isn't pumping fuel up and through the leak off pipes ? or is it ? Wonder if it would be interesting to take the fuel pipe off at the outlet side of the primary fuel filter or before the pump and dip it into a fuel can or source you can visually check if its actually sucking fuel ?

 

[Bilgediver]

such a strange one this...youd think if it has fuel making it's way past the HP pump and the stop solenoid is definitely not to blame, there can't be much else to stop the fuel getting to the injectors, other than a failed fuel pump...but you'd think a mechanical fuel pump, should it fail, would be making all sorts of bad noises when turning her over perhaps. So you think that without using your added in make do pump, it isn't pumping fuel up and through the leak off pipes ? or is it ? Wonder if it would be interesting to take the fuel pipe off at the outlet side of the primary fuel filter or before the pump and dip it into a fuel can or source you can visually check if its actually sucking fuel ?

I explained elswhere that the fuel IS NOT making its way past the HP fuel pump to return to the tank. It is only flowing through the fuel pump body cavity ie the suction side of the fuel pump.

What has happened here is that air got into the high pressure plunger barrels and as air can cpmpress that is what this air is doing as it is not reaching a high enough pressure to lift the spring loaded delivery valves .

The OP should be able to cure this by slackening off the delivery valve bodies which allows the air to escape and fill the HP pumps with fuel. Do not remove the deliver valves as there is the risk of dropping wee components in the bilge.

I have had the same problem on occasion with my MD2b when I have been a little careless and allowed air into the HP Pump.
This is only a problem when a higher spring loading exists on the delivery valve and not all elderly Volvo engines suffer from it. I have one cylinder that does and the other does not.

 

[QBhoy]

I explained elswhere that the fuel IS NOT making its way past the HP fuel pump to return to the tank. It is only flowing through the fuel pump body cavity ie the suction side of the fuel pump.

What has happened here is that air got into the high pressure plunger barrels and as air can cpmpress that is what this air is doing as it is not reaching a high enough pressure to lift the spring loaded delivery valves .

The OP should be able to cure this by slackening off the delivery valve bodies which allows the air to escape and fill the HP pumps with fuel. Do not remove the deliver valves as there is the risk of dropping wee components in the bilge.

I have had the same problem on occasion with my MD2b when I have been a little careless and allowed air into the HP Pump.
This is only a problem when a higher spring loading exists on the delivery valve and not all elderly Volvo engines suffer from it. I have one cylinder that does and the other does not.

I would say that makes more sense of it, to be fair.