YSE8 issue. Only runs at high idle. Please help.

[Brodiesel710]

I'm a diesel mechanic, with no experience with these smaller inboards. My friends YSE8 will only start at high throttle, once throttle decreases it dies. Fuel filter is clean, valves are adjusted, it's getting air, regulator valve needle is clean/working. I have removed Governor lever/linkage and am throttling it by rotating regulator shaft. Basically, it will only run at max throttle anything lower the engine shakes/stalls out. Meaning, we can't moved the boat. Am I missing something? Experienced YSE owners please help!

Thanks

 

[anchorclanker]

Something in the governor/injection pump. Your going to have to dig farther.

Heres a manual. Reading some of it regarding your problem, it could be as simple as disassembling the pump and cleaning it.

http://sailingboatefaki.gr/Engine Manuals.htm

 

[NYSail]

Try looking at the mixing elbow where exhaust is mixed with fresh water. Maybe clogged abusing engine to cut off.. Remove and inspect replacing if necessary. Yanmar suggests replacing these every 5 years.

 

[Brodiesel710]

Something in the governor/injection pump. Your going to have to dig farther.

Heres a manual. Reading some of it regarding your problem, it could be as simple as disassembling the pump and cleaning it.

http://sailingboatefaki.gr/Engine Manuals.htm

Yeah your right, governor/injection pump. Pump only works whens needle valve is fully seated, once backed off even a hair it loses it's ability to pump. I'll disassemble and clean pump first if that doesn't work I'll find another one. Thanks for manual link, I actually have that paper manual. It doesn't give much info regarding serious troubleshooting though, the engine is so basic, they just leave it up to you to figure it out.

 

[Brodiesel710]

Try looking at the mixing elbow where exhaust is mixed with fresh water. Maybe clogged abusing engine to cut off.. Remove and inspect replacing if necessary. Yanmar suggests replacing these every 5 years.

Great I'll check it out.

 

[anchorclanker]

I actually have that paper manual. It doesn't give much info regarding serious troubleshooting though, the engine is so basic, they just leave it up to you to figure it out.

It is real basic, I think if you take it apart apart youll see whats going on. Probably a chunk of crud hanging it up somewhere.

 

[We2Sail12113]

High Engine RPM, no Idle on Yanmar YSE8/SB8

I'm a diesel mechanic, with no experience with these smaller inboards. My friends YSE8 will only start at high throttle, once throttle decreases it dies. Fuel filter is clean, valves are adjusted, it's getting air, regulator valve needle is clean/working. I have removed Governor lever/linkage and am throttling it by rotating regulator shaft. Basically, it will only run at max throttle anything lower the engine shakes/stalls out. Meaning, we can't moved the boat. Am I missing something? Experienced YSE owners please help!

Thanks

By the way, YSE8 and SB8 are close siblings.

Hi, I just spent 5 weeks waiting for my diesel mechanic to repair my Yanmar SB8 diesel. He found three problems. High pressure fuel pump, low pressure fuel pump, and replaced the return line from the injector to the low pressure pump. (The big problem, I think, was finding the repairable parts).

As background, I had the engine rebuilt in 2001 in a local shop, which is (was?) the Yanmar Regional Dealer. Silly me, when they said they rebuilt the engine, I assumed it would have included the pumps. (Crazy idea, huh). My symptom was almost identicle to the one you describe. I had bought a Tach* from TSC*, and my "idle" was about 1200 rpm, and when i engaged the prop shaft, it would die to zero. Basically, a good half of engine operation was shifting between Forward and Neutral.

The people who fixed it for me (of course they charged!!) is Niemiec Marine in New Bedford, MA and I highly recommend them.

Now, not only is my idle set at 750 rpm, but I can also "cruise" at that speed (basically 0.4 kts, flat water, not much wind).

If you need any additional information, feel free to contact me directly.

Robert

* Tach is TinyTach, from Design Technology, Inc. I think they are located in Chicago, but TSC (Tractor Supply Company) used to carry these, They are in fact a Tach, Hour Meter, and can be set as a third parameter.