I am seeking the collective knowledge of everybody here. Returning back from a sailing trip Labor Day weekend, I was not able to get full RPM. Normally I am able to hold 3200-3400 RPM on my Yanmar 1GM in my 1983 Hunter 27 with an appropriately sized 3 blade prop. All the way back (6 hours) the engine would not go above 2700-2900 RPM. When I returned to the marina that day, I cleaned the prop and changed the primary fuel filter hoping that one of them was the problem. Fuel filter was clean, took some wildlife off of the prop. When I went out today, initially the engine would only do 2400-2600, but eventually got up to 2800. The engine will get up to 3200 in reverse and up to 3400 with no load on the engine, but seems to break up a little at the higher RPM. The engine is rated at 6.5 HP at 3400 continuous. During labor day weekend, I ran the engine at anchor at 2000 RPM for 20 minutes twice to charge the batteries. The engine has the stock 35 amp alternator. When I got back to the dock today, I checked the secondary fuel filter (it was clean), rebled everything, checked the air cleaner (clean), took off the mixing elbow to check it for carbon (only had a light dusting), and the diesel fuel is from a reputable source that many of the Chesapeake watermen use. There has been an increasing black smudge on my transom this year. The only things I can think of is that the engine is not getting enough fuel from inadequate pumping, clogged injectors, or injectors that are dribbling. Can anybody else think of anything else to check/try before I call in the expensive Yanmar service experts??? Any help would be greatly appreciated.
- Status
How many hours?
You didn't mention how many hours on the engine, after all it is a 19 year old boat. It is very possible that it is an injector or injector pump problem. You can have the injectors tested and refurbished at a local diesel shop that specializes in those things. You might also do a compression test. Good luck, it sounds like you did a very good job of checking out all the easy possibilities.
You didn't mention how many hours on the engine, after all it is a 19 year old boat. It is very possible that it is an injector or injector pump problem. You can have the injectors tested and refurbished at a local diesel shop that specializes in those things. You might also do a compression test. Good luck, it sounds like you did a very good job of checking out all the easy possibilities.
check fuel lines?
Before calling in the gold-plated boys you may want to check the fuel flow through the hose connecting the fuel tank to the first filter by disconnecting it at the filter and seeing how fast the fuel runs out. We had an apparent clogging problem in our fuel line this summer which was resolved by blowing a strong air stream through in reverse. In order to avoid excessive foaming one might push clean diesel fuel through with a hand pump or large syringe instead. BTW; you keep saying "the filter was clean" implying that visual inspection is possible and meaningful. However, if some type of bacterial growth clogs the filter the color may not be very dark. The real test of how clean the filter is to measure the pressure drop across it while the engine is running and fuel is flowing. Or is that what you did? Have fun Henk Meuzelaar "Rivendel II"
Before calling in the gold-plated boys you may want to check the fuel flow through the hose connecting the fuel tank to the first filter by disconnecting it at the filter and seeing how fast the fuel runs out. We had an apparent clogging problem in our fuel line this summer which was resolved by blowing a strong air stream through in reverse. In order to avoid excessive foaming one might push clean diesel fuel through with a hand pump or large syringe instead. BTW; you keep saying "the filter was clean" implying that visual inspection is possible and meaningful. However, if some type of bacterial growth clogs the filter the color may not be very dark. The real test of how clean the filter is to measure the pressure drop across it while the engine is running and fuel is flowing. Or is that what you did? Have fun Henk Meuzelaar "Rivendel II"
The onlt thing I havn't . . .
heard mentioned is pulling the pickup tube from the tank and checking that. Good luck Chris s/v Tidesong
heard mentioned is pulling the pickup tube from the tank and checking that. Good luck Chris s/v Tidesong
Re: RPM's
Chuck, I suspect that your exhaust mixing elbow is full of carbon. If you've never cleaned it or replaced it, that is more likely the problem of not getting max RPM's. When a Yanmar mechanic told me I should check the elbow, I removed it and decided to replace it. That will be the best $75 you'll ever spend on your Yanmar. Make sure you clean the elbow at least once a year, twice if you use your engine a lot. Good Luck, Cap'n Brent S/V Elena Lua http://www.elenalua.homestead.com
Chuck, I suspect that your exhaust mixing elbow is full of carbon. If you've never cleaned it or replaced it, that is more likely the problem of not getting max RPM's. When a Yanmar mechanic told me I should check the elbow, I removed it and decided to replace it. That will be the best $75 you'll ever spend on your Yanmar. Make sure you clean the elbow at least once a year, twice if you use your engine a lot. Good Luck, Cap'n Brent S/V Elena Lua http://www.elenalua.homestead.com
DIY
If your bottom is clean, sounds like an injector problem. Why not (since there's only one) replace it with a rebuilt. Easy job. Good luck red
If your bottom is clean, sounds like an injector problem. Why not (since there's only one) replace it with a rebuilt. Easy job. Good luck red
I had the same symptoms
originally, then the injector was replaced and no problem for a while. Got line caught in the prop and bent the shaft and prop. All was replaced, except the yard people used an "on hand" prop instead of ordering the exact same size that came off of it. Within a couple of weeks, developed black smoke and the stern looked like a bad job of trying to dye it black. Kept cleaning while searching for the cause (thought it might be related to the injector issue, above). Not so, finally, pulled the boat, took the damaged prop (which I was now using for a reminder paperwaite in my office) to compare. The diesel mechanic was right, wrong prop size. Ordered a new one - the right size, pulled it out and changed it over. AS SOON AS we restarted the engine, it must have looked like an old Three Stooges comedy skit, the engine started with a huge jolt, black smoke went everywhere (including over both of us in the cockpit)....we coughed and cleaned our sinuses. To this day, NO MORE BLACK SMOKE. Also, the original repair yard has been very quiet since they got "caught".
originally, then the injector was replaced and no problem for a while. Got line caught in the prop and bent the shaft and prop. All was replaced, except the yard people used an "on hand" prop instead of ordering the exact same size that came off of it. Within a couple of weeks, developed black smoke and the stern looked like a bad job of trying to dye it black. Kept cleaning while searching for the cause (thought it might be related to the injector issue, above). Not so, finally, pulled the boat, took the damaged prop (which I was now using for a reminder paperwaite in my office) to compare. The diesel mechanic was right, wrong prop size. Ordered a new one - the right size, pulled it out and changed it over. AS SOON AS we restarted the engine, it must have looked like an old Three Stooges comedy skit, the engine started with a huge jolt, black smoke went everywhere (including over both of us in the cockpit)....we coughed and cleaned our sinuses. To this day, NO MORE BLACK SMOKE. Also, the original repair yard has been very quiet since they got "caught".
- Status