Yanmar loses power, slows down & kills

California · Jan 30, 2008

Is there a banjo fitting where the fuel line meets the injector pump? Has it ever been removed?

Seems to me that's the last place air could enter, if it sucks air regardless of which tank is feeding it.

YanmarFever · Jan 30, 2008

California,
He has never removed the fitting so the copper washer should still be there.

With all the tests he has done, Im thinking the injection pump, or the lines that feed the injectors

But he does not want to look inside the inj pump, (dont blame him)

Tomorrow I will go out and look at our 1802 for a refresher of thoughts

Underwaterdog · Jan 30, 2008

Talleyho8,
What is the model number of the engine in your 1802?

rock2610D · Jan 30, 2008

My gut is telling me that dirt got into the fuel system. In my 2610 there is a spring that holds the fuel filter up. Does your filter bowl have a spring to hold the filter up? If not it probably fell down and dirt got into the pump.

I would bet that there is dirt or something in the top part of injector pump and once engine deplets the reisivor the dirt prevents the fuel from being used by pump..

I know its expensive but aside from rebuilding my engine, and my turbo, the best thing I did for my tractor was to replace all fuel lines to and from injectors and pump, AND rebuilding my pump. It cost me $550 but now its good for another 20 years. Pump rebuilder told me the pump was working but poorly, and was VERY worn.

Its just my opinion but ANY refurbished tractor should have at the minimum pump testing done to confirm correct operation. A poorly functioning/dirty pump and cause alot of issues.

rock2610D · Jan 30, 2008

Wanted to also mention, air! Are you absolutely sure nothing is blocking intake??

Maybe govenor linkage. Springs and stuff in there. Maybe the heat from oil is affecting springs.

dieselgeek · Jan 30, 2008

rock2610D said:
Wanted to also mention, air! Are you absolutely sure nothing is blocking intake??

Maybe govenor linkage. Springs and stuff in there. Maybe the heat from oil is affecting springs.

I doubt it's an intake blockage. I shut mine down once (practice) by covering the intake, the engine starts to knock LOUDLY when starved for air.

The video seems very telling to me: fuel starvation.

I still doubt it's the pump. The motor sounds healthy when it's cold. I doubt it's compression or anything internal to the engine, because when he cranks the starter you hear nice, even compression. A low compression cylinder is easily spotted when cranking the starter...

Has he confirmed fuel flow to the injector pump, during the stalling?

tallyho8 · Jan 30, 2008

UPDATE.....
I had loosened the fuel lines at the injectors while the motor was cool and running well. When I did that it slowed a lot on each cylinder that I loosened. Today was the first time that I loosened the fuel lines when it was WARM and RUNNING BAD.

When I loosen cylinder 3 it starts to kill immediately.
When I loosen cylinder 2 it slows a little but continues to run.
When I loosen cylinder 1 there is no difference.
When I loosen cylinder 1 and 2 at the same time it just slows a little.

SailorBob · Jan 30, 2008

tallyho8 said:
UPDATE.....
I had loosened the fuel lines at the injectors while the motor was cool and running well. When I did that it slowed a lot on each cylinder that I loosened. Today was the first time that I loosened the fuel lines when it was WARM and RUNNING BAD.

When I loosen cylinder 3 it starts to kill immediately.
When I loosen cylinder 2 it slows a little but continues to run.
When I loosen cylinder 1 there is no difference.
When I loosen cylinder 1 and 2 at the same time it just slows a little.

I am no expert but, it seems to me that cylinder 3 is probably running normally (it keeps the engine running) , cylinder 2 marginal, and cylinder 1 not working at all. Obviously it is fuel related but, whether it is the pump or not I have no idea. I believe you said that you had the injectors tested and replace all of the fuel lines, etc. That kind of leaves the pump as suspect. It may be worth taking off and having it tested at least. (I know that is not a simple job.)

tallyho8 · Jan 30, 2008

Underwaterdog said:
Talleyho8,
What is the model number of the engine in your 1802?

3T80U-NB

Underwaterdog · Jan 31, 2008

That bleed tank that you set up is a little puzzling, and it is true that it is a gravity feed to the pump, but, my manual says that the injectors take 2276 psi to open. That means there is a pump in the injector, and if it pumps out, it must also pump (suck) in. It wasn't designed to pump air, just diesel. There would have to be a heck of a restriction to cause negative pressure on the fuel line, and suck air, since it is much larger than necessary to meet the fuel requirements of the engine. But it is possible especially with rubber lines and primer pumps. I hole can act like a one way flapper valve. I read one of your earlier post about a primer pump:

I have a primer pump by the filter and one by the pump. When I pump the one by the filter it shoots out a good stream of diesel. When I pump the one by the injector pump it shoots out only a little dribble of fuel but this finger pump may not be working well.

Are you talking about the type of pump that is on an outboard motor tank? Is that original? I don't understand why you would even need one with a gravity feed supply. I have seen them stop up and get air leaks on outboards and shut them down. While my manual does not specifically address your engine, this is what it says about the injector pump:
"Yammar PFR2K two plugner fuel injection pump is used on all two cylinder models and Yanmar PFR3K three plunger fuel injection pump is used on all three cylinder models. The nozzles inject into swirl type precombustion chambers. Because of extremely close tolerances and precise requirements of all diesel components, it is of utmost importance that clean fuel and careful maintenance be practiced at all times. Unless necessary special tools are avaiable, service on injectors and injection pump should be limited to removal, installation and exchange of complete assemblies. It is impossible to re-calibrate an injection pump or reset an injector without proper specifications, equipment and training."
If you are going to have to have the pump rebuilt or replaced anyway, it wouldn't hurt to blow the fuel inlet on the injection pump out with air. There may be a piece of trash (rust, rubber line, a piece of o-ring) in there that is stopping the flow. So these ideas are my last shot. If this is something you have already tried or doesn't work, there is nothing left but the pump. I wouldn't think it would be that hard to find someone willing to work on a Yanmar injector pump. They are very common in marine and generator applications.