Yanmar 3jh3e rpm's up and down

[Gary Ryan]

Well my son and his buddies took out out Hunter for a voyage to Lake Erie. Coming back today the weather whipped up and they were in 6' swells and waves. Getting tossed around, the diesel engine started revving up and down. He didn't want to damage anything, so they got a tow from TowBoatUS. I have a membership with them. They're still on the way in. I can't believe the prop was coming out of the water on a 40' boat. I'm thinking being so rough that it stirred up impurities in the diesel?

 

[kloudie1]

I think you are correct that you are seeing the classic symptom of plugging in the fuel system. First change the primary; if it doesn’t look too bad, then the pickup tube in the tank would be the next logical suspect. If non of those then very small air leak .

 

[sail sfbay]

In 6 ft swells with the prop coming out of the water it does not surprise me that the diesel engine started revving up and down. If was due to impurities in the diesel the engine would have stopped due to fuel line plugging based on the experience a sailing friend's boat had on a new used boat to him (he had to replace the fuel line). When the boat gets back to the marina check out the engine operation, fuel filters, etc. Hopefully, you will not find an issues.

 

[Gary Ryan]

They got towed to Lake St Clair ( where our marina is). At that point they fired up the engine and all is fine. I'll have to replace those fuel filters this week.

 

[sail sfbay]

Thanks for the update, glad everything is OK and that was a good decision by your son to get a tow vs. risk engine damage!!

 

[Stu Jackson]

Check this, too:

Fuel Starvation and The Obscure Check Ball Valve
Fuel Starvation and The Obscure Check Ball Valve
and
Fuel Starvation and The Obscure Ball Check Valve

 

[Gary Ryan]

Just to update. TowboatUS got them back to Lake St. Clair. At that point the operator informed them that he was now out of his jurisdiction....they'd have to call TowboatUS again to get another tow from there. My son decided to try the engine again, and fired right up. They were able to power sail the rest of the way back to our slip. Good news! Once they got off Lake Erie, the waves settled down. I'll have to get on those filters this week. Thanks all!