onan acting goofy...help

[nor'easter]

I have a 1995 87kw onan that has started to act up. It has 1950 hrs since new, and I really only run it to run it weekly. My boat is not genny dependent, and I run it weekly to keep the cobwebs out and be sure that I catch a problem at the beginning. It is serviced with the mains at 100 hr intervals.
Ran it yesterday and it started fine, and ran great under load. Shutting it down, it would stop right away as it normally does. It took 30-60 secs and sputtered along the way. I checked oil and restarted and it ran rough with/without a load. Trying to shut it down again it acted the same...kind of surging along the way to stop.
Boatdiesel has no info on onan anymore. I assume they were pissed that people air their dirty power generating laundry at their expense.
I am a novice, but willing to learn before calling the 110/hr guys about this. Any suggestions? Where can I read about trouble-shooting this on my own if this is not a common scenario?
Thanks in advance
Paul

 

[chris piazza]

Is it gas or diesel? I would check/change fuel filters first. Whats the exhaust look like?

Chris
Superior Nights 53C

 

[SKYCHENEY]

Since it just started doing this at shut down, I would look at the fuel solenoid or fuel pump. It sounds like a fueling problem. As Chris said, check your fuel filters as well.

 

[Trojan]

Check your exhaust. Is it lean or rich, black or white? Like said, check your shut-off solenoid valve. We need more information.

BILL

 

[REBrueckner]

Is this gas or diesel? sounds like a fuel supply issue. Does it have a compression release solenoid? Look for simple things first...fuel filters, dirt, water in fuel,etc.

 

[nor'easter]

Diesel 8kw.
Filters both new 2 months ago. Wouldn't a fuel supply problem be evident on start up? It runs great first start andunder a load doesn't skip until I try to shut down. I don't know my way around it at all answer other ?s. I will need to spend some time and try and figure out where the pump is etc.
Exhaust looks clean. Very minimal and no change from before this arose.
Thanks.
I'll try and get more info this weekend.

 

[Nonchalant1]

It may be the fuel shutdown solenoid, which could be not closing the fuel supply off at shutdown and not opening it up fully upon restart. The solenoid is usually a small can shaped item with an electric wire going into it and a pushrod going from the can to the fuel lever. When the wire gives it power, it moves the rod to allow fuel to flow. To find it, find your fuel throttle, which is usually the only moving parts visible when it's running. Look at that area when it's not running and then watch it as you start up. You'll see the solenoid lift or push the rod to allow the fuel throttle lever to run. Then on shutdown, the solenoid rod pushes the throttle lever closed again.

Sometimes, a faulty oil pressure sensor or high temp sensor can mess up the solenoid action, because both of those operate by shutting off power to the solenoid in an emergency and the faulty sensor is partially shutting off power.

The same thing would happen if you have a lose or bad connection or intermittent grounding of the power wire to the solenoid.

After you find the solenoid, you might try holding it manually so it's not pushing on the throttle lever. In normal operation, it is held away from the throttle lever by the magnetic solenoid action. If that's where your problem is, manually holding it in the "run" position will fix your problem. Then you just have to find out why (as above) it's not staying fully in the run position.

Doug Shuman

 

[yachtsmanbill]

I agree Doug. The solenoid is the culprit! ws

 

[nor'easter]

The solenoid is fine, BUT the plastic clip at the end of the linkage to the throttle is broken. Couldn't be much more simple.
New part this weekend.
Thanks for the advice.