Yanmar 1GM10 Fuel Delivery Problem

[conks01]

Hi.

I'm not overly mechanical so please bear with me on this one.

I've bled the engine as there was an air lock via the 3 bleed points/screws etc.

It wouldn't start still so I then took the fuel injector apart as there didn't appear enough fuel coming out when I loosened the nut on the top. Once I took out the spring and needle (?) and put it back together again it fired and ran but the problem I'm now having is that it starts every time but cuts out after say 20 seconds.

Would this be a problem with the fuel injector perhaps?

Would you have advice if it's something else perhaps.

Thanks.

 

[black mercury]

More likely a fuel problem somewhere. Do you have to bleed the system again to get it going or do you do nothing and it restarts immediately? There should only be a drip of diesel coming from the top union on injector when engine is running only. You haven't replaced this back leakage union with an ordinary bolt have you? Because it would give your symptoms. Air seems to collect at the injection pump on those yanmars and it may need bleeding a couple of times here to get rid of all the air, especially if the return is piped to the filter and not the tank. Try bleeding it again at the injection pump using the lever on the lift pump, see if any air comes out. Unlikely to be injector.

 

[conks01]

More likely a fuel problem somewhere. Do you have to bleed the system again to get it going or do you do nothing and it restarts immediately? There should only be a drip of diesel coming from the top union on injector when engine is running only. You haven't replaced this back leakage union with an ordinary bolt have you? Because it would give your symptoms. Air seems to collect at the injection pump on those yanmars and it may need bleeding a couple of times here to get rid of all the air, especially if the return is piped to the filter and not the tank. Try bleeding it again at the injection pump using the lever on the lift pump, see if any air comes out. Unlikely to be injector.

Thanks - No it starts first time every time without having to bleed but then dies after approx 20 secs.

No parts have been replaced. I'll certainly bleed it again to see and I think that the return is going back to the filter as there's no return pipe to the tank etc.

I've uploaded here a pic of the exploded diagram of the fuel injector from the Yanmar service manual. The 'bits' I've pulled out to clean & replace are those from the top; Delivery valve spring holder to roughly the delivery valve (which I called the 'needle' earlier in this post). I'm wondering if I've done something when I replaced the delivery valve but it is grooved and could only go in a certain way?

 

[black mercury]

Ok, that's not the fuel injector, that's the injection pump. No, don't think you have put anything back together wrong. Try to bleed it again at the injection pump, then crack open the fuel pipe union at the injector (at the top of the engine), the union is at the end of the steel pipe where it screws into the injector. Crank engine over with this loosened until you see fuel squirting from it with no air, tighten it and start engine. I think you have air trapped in the system.

 

[conks01]

Ok. Great. Thanks for the advice. Like you I'm hoping it's an air lock.

 

[pioneer]

If the spill pipe returns to the fuel seperator/filter air can get trapped in the system. After bleeding the system from tank to on-engine filter, then to the injection pump and then to the injector, back bleeding the system from the seprator to the injector can work. Worked for me a couple of times, once I found out what the problem was. Finally solved the problem for good by routing the spill pipe to the main tank allows the air to vent into the tank and doesn't suck air back into the system.

 

[peteK]

If its cutting out after 20seconds it could be the fuel pump not working and just relies on gravity to give you the 20 seconds run and then fuel starvation. Try rigging up a separate supply above the engine to give a head of fuel.