Good afternoon everyone, hoping someone can help me out as my local mechanic is stumped.
So a little back history. Last year I bought a 1997 Sprit 19' Bass Boat with a Evinrude Intruder 175 hp. First time I took it out I couldn't get it up on plane. Took it to local garage and he cleaned/rebuilt all of my carburetors. He told me he found a bunch of crap in them. I took it out on the lake and it would shoot right out of the hole. Motor ran great and could easily achieve 55 mph. Well about a month later the motor started acting up again. This time it would bog out when I would try to get up on plane. Eventually I figured out that if I feathered the throttle I could get it up on plan. Also if I had a full tank of fuel it didn't seem to do it. Once on plan it would run like a champ. Feeling like this was more of a nuisance than a real issue, I waited till this spring to take it back to the shop. However, being spring I also wanted to go out and do some fishing.
First time I took it out in 2017 it performed the same. I had to feather the throttle to get it on plane. Now the second time I took it out it was getting up on plane with no issues, however when I got up to between 3500-4000 rpm I would get a surge. Original I though I had some water in the fuel. The next day I dropped it off at the shop. The mechanic called me Saturday after having the boat for two weeks and said he was stumped. He told me he had over 30 hours of troubleshooting into it with 6 hours on the lake and couldn't figure it out. Said he even called a fellow tech that was a wiz on Evinrudes and he didn't now either. They went through and cleaned/rebuilt all the carbs. Checked compression (110-115 all cylinders), and spark. All good. He did say that my timing was advanced a little and the idler screws were turned way out (13 turns). He said he tried to put it back to factory but the motor would run. He said he bypassed my fuel tanks and used an external and still had the same issue. He said his next step would be to start replacing parts one at a time to see if it would go away. Not wanting to do a bunch of recreational maintenance I told him to hold off. Great thing is he didn't charge me anything since he didn't fix it. Tried to give him some money but wouldn't take it.
So now I'm stuck. Not sure what to do. Motor starts up great even shoots out of hole good and the rpms will go up to 3500-4000 while getting on plane. But once up on plane the rpms drop to between 2500-3000. It's almost like something is telling the motor not to go any high on rpms while on plane like a governor. If I give it more throttle and try to go faster it will cut out. Motor will start immediately back up.
I find it odd that I had an issue with bogging at take off, which has completely gone away to now having this surge.
I welcome anyone's advice. Would love to get it running normal
So a little back history. Last year I bought a 1997 Sprit 19' Bass Boat with a Evinrude Intruder 175 hp. First time I took it out I couldn't get it up on plane. Took it to local garage and he cleaned/rebuilt all of my carburetors. He told me he found a bunch of crap in them. I took it out on the lake and it would shoot right out of the hole. Motor ran great and could easily achieve 55 mph. Well about a month later the motor started acting up again. This time it would bog out when I would try to get up on plane. Eventually I figured out that if I feathered the throttle I could get it up on plan. Also if I had a full tank of fuel it didn't seem to do it. Once on plan it would run like a champ. Feeling like this was more of a nuisance than a real issue, I waited till this spring to take it back to the shop. However, being spring I also wanted to go out and do some fishing.
First time I took it out in 2017 it performed the same. I had to feather the throttle to get it on plane. Now the second time I took it out it was getting up on plane with no issues, however when I got up to between 3500-4000 rpm I would get a surge. Original I though I had some water in the fuel. The next day I dropped it off at the shop. The mechanic called me Saturday after having the boat for two weeks and said he was stumped. He told me he had over 30 hours of troubleshooting into it with 6 hours on the lake and couldn't figure it out. Said he even called a fellow tech that was a wiz on Evinrudes and he didn't now either. They went through and cleaned/rebuilt all the carbs. Checked compression (110-115 all cylinders), and spark. All good. He did say that my timing was advanced a little and the idler screws were turned way out (13 turns). He said he tried to put it back to factory but the motor would run. He said he bypassed my fuel tanks and used an external and still had the same issue. He said his next step would be to start replacing parts one at a time to see if it would go away. Not wanting to do a bunch of recreational maintenance I told him to hold off. Great thing is he didn't charge me anything since he didn't fix it. Tried to give him some money but wouldn't take it.
So now I'm stuck. Not sure what to do. Motor starts up great even shoots out of hole good and the rpms will go up to 3500-4000 while getting on plane. But once up on plane the rpms drop to between 2500-3000. It's almost like something is telling the motor not to go any high on rpms while on plane like a governor. If I give it more throttle and try to go faster it will cut out. Motor will start immediately back up.
I find it odd that I had an issue with bogging at take off, which has completely gone away to now having this surge.
I welcome anyone's advice. Would love to get it running normal