G'day everyone.
Firstly, thank you for your hosting and input on such a valuable site.
Secondly, I dont know alot about boats. I bought a Haines Hunter V16C 16ft Half Cabin that is powered with a 115 Merc. I got the boat as i am building an aeroplane and the wife was getting upset that all of my hobbies are only enjoyed by me, and not the family (she hates flying). So i got this boat that was in need of a transom replace. I got it from a local boat shop that has been there for years and has an excellent reputation.
On inspection, all was as described.
After the transom replace, I took the boat out and it ran brilliantly. 5500 to 5600 WOT. It was dark and was only out for about 20 mins.
Second time, it was raining, and while i was out, the boat started losing power, like it was fuel starvation. If the throttle was backed off, it could be caught before it would die. If left open, it would die out over about 5 seconds. Prime the bulb up, and away it would go again, and repeat the proceedure.
I noticed that some clamps were missing off the tank fittings, so replaced them, also the fuel/water separator and took it out. I also noticed that fuel was dripping from the throat of the bottom carb when priming to hard. Manually closed off the enricher valve. Took it out, did the same thing, just less severe.
Replaced the bulb/line and the female fuel fitting, and now it will run all day with only one problem - it will want to sit at about 4500rpm WOT. It runs very smooth at all RPMS's, no smoke, no pingingor coughing etc. It is capable of more RPM, and i have seen it do that. Fuel has been flushed from the tank and is fresh. It is running standard unleaded with 50:1 mix. Plugs look a little back / oily?
The things in the fuel line that are left are the fuel pump, the male fitting at the lower cowling, the anti siphon valve at the tank (the vent is not clogged). I was also thinking of maybe a carb rebuild?
I have had experience with vintage 2 stroke motorcrossers (which i know are only one cyl), but i always found that a well seasoned 2 stroke, or even the factory new ones did not have perfect plug burn indications when they were pulled. I always found it beneificial to performance and WOT RPM to make adjustments to the carb such as lowering the needle into the seat (leaning) dropping a jet size and adjusting the float bowl settings. All three of these were needed to make the ordinary engine turn into the machine it is supposed to be AND also achieve the correct tan/brown burn colour. We also used to upgrade the original plug for a hotter race plug. We never lost an engine doing any of these enhancements, and always made sure the plug were right. I know i'm comparing apples to oranges here, I'm just trying to figure out what the cause of the RPM loss is. I dont have easy access to a dial indicator for the purpose of a timing check as per the Seloc Manual, nor a timing light, So i'm wanting to run a process of elimination before taking it to a Merc dealer to have them strip me of funds. It also idles at 500rpm in neutral in the water, and taking off in either forward or reverse takes a quick jab of the throttle to make it go without stalling once load comes onto the prop.
Another possibility is that when the outboard is tilted out a fraction past optimum trim position for planing at WOT, the revs jump right up. I am assuming that that is due to the load being off the prop. The boat feels as though it gains no speed at all by doing that, probably slows down. I made sure that during that test, water was being pumped through the powerhead. For good measure, I also replaced the whole water pump assembly. Maybe i mounted the engine too low / too high? It seems though the anticavitation plate is in the right spot, so I'm probably going to rule that one out.
Oh, and the dealer who sold the boat said that the compressions were good. He went to look for where he wrote them down, but couldnt find them. This venue has a great reputation, so i am trusting their word. I dont have easy access to a compression guage.
Any thoughts would be greatly appreciated, I'm sure i've given sufficient detail!
Firstly, thank you for your hosting and input on such a valuable site.
Secondly, I dont know alot about boats. I bought a Haines Hunter V16C 16ft Half Cabin that is powered with a 115 Merc. I got the boat as i am building an aeroplane and the wife was getting upset that all of my hobbies are only enjoyed by me, and not the family (she hates flying). So i got this boat that was in need of a transom replace. I got it from a local boat shop that has been there for years and has an excellent reputation.
On inspection, all was as described.
After the transom replace, I took the boat out and it ran brilliantly. 5500 to 5600 WOT. It was dark and was only out for about 20 mins.
Second time, it was raining, and while i was out, the boat started losing power, like it was fuel starvation. If the throttle was backed off, it could be caught before it would die. If left open, it would die out over about 5 seconds. Prime the bulb up, and away it would go again, and repeat the proceedure.
I noticed that some clamps were missing off the tank fittings, so replaced them, also the fuel/water separator and took it out. I also noticed that fuel was dripping from the throat of the bottom carb when priming to hard. Manually closed off the enricher valve. Took it out, did the same thing, just less severe.
Replaced the bulb/line and the female fuel fitting, and now it will run all day with only one problem - it will want to sit at about 4500rpm WOT. It runs very smooth at all RPMS's, no smoke, no pingingor coughing etc. It is capable of more RPM, and i have seen it do that. Fuel has been flushed from the tank and is fresh. It is running standard unleaded with 50:1 mix. Plugs look a little back / oily?
The things in the fuel line that are left are the fuel pump, the male fitting at the lower cowling, the anti siphon valve at the tank (the vent is not clogged). I was also thinking of maybe a carb rebuild?
I have had experience with vintage 2 stroke motorcrossers (which i know are only one cyl), but i always found that a well seasoned 2 stroke, or even the factory new ones did not have perfect plug burn indications when they were pulled. I always found it beneificial to performance and WOT RPM to make adjustments to the carb such as lowering the needle into the seat (leaning) dropping a jet size and adjusting the float bowl settings. All three of these were needed to make the ordinary engine turn into the machine it is supposed to be AND also achieve the correct tan/brown burn colour. We also used to upgrade the original plug for a hotter race plug. We never lost an engine doing any of these enhancements, and always made sure the plug were right. I know i'm comparing apples to oranges here, I'm just trying to figure out what the cause of the RPM loss is. I dont have easy access to a dial indicator for the purpose of a timing check as per the Seloc Manual, nor a timing light, So i'm wanting to run a process of elimination before taking it to a Merc dealer to have them strip me of funds. It also idles at 500rpm in neutral in the water, and taking off in either forward or reverse takes a quick jab of the throttle to make it go without stalling once load comes onto the prop.
Another possibility is that when the outboard is tilted out a fraction past optimum trim position for planing at WOT, the revs jump right up. I am assuming that that is due to the load being off the prop. The boat feels as though it gains no speed at all by doing that, probably slows down. I made sure that during that test, water was being pumped through the powerhead. For good measure, I also replaced the whole water pump assembly. Maybe i mounted the engine too low / too high? It seems though the anticavitation plate is in the right spot, so I'm probably going to rule that one out.
Oh, and the dealer who sold the boat said that the compressions were good. He went to look for where he wrote them down, but couldnt find them. This venue has a great reputation, so i am trusting their word. I dont have easy access to a compression guage.
Any thoughts would be greatly appreciated, I'm sure i've given sufficient detail!
