Mariner 150 wonbt wind out under load

"Bought a used basscat with a

"Bought a used basscat with a Mariner 150. Took it out for the first time this weekend and discovered a problem. When I push the throttle fwd the engine starts to wind up and I can only get about 5mph. After running like that for about 5 min sometimes it will wind up and really fly. Engine responds fine to throttle advance when in idle, any ideas what might be causing this? The fact that it will really fly when it finally decides to makes me think the motor itself is ok. Help!"

"to big of prop or wrong trim

"to big of prop or wrong trim angle, along with anything electrical"

Have tried most every trim ang

Have tried most every trim angle. Prop is a stainless steel Qucksilver 13.75" 21p. Boat is 19ft basscat with a 90 beam approx. What size and pitch prop would you recommend?

"can't recommend anything

"can't recommend anything without knowing the max rpm of the engine at WOT. There are so many things that could be wrong I was only guessing. Did you check the compression of the engine before buying. Are the carbs clean, running with restricted fuel flow to 1 carb means lack of oil to that cyl or cyl's. Is the timing set correctly. Was it running on fresh gas or old gas. They all sound good without a load on them"

"It was running on some old ga

"It was running on some old gas but I added an additional 10gals with a mix of 50:1. Not sure what the previous mix was. Also can't tell you what the max RPM was as tach is not working, This is turning out to be a can of worms I may have to take to a shop. I'm gonna hook up a hose today and run it in gear. I was told that if the bog down duplicates in gear with no drag or load that it would rule out the prop itself and point to the carbs or gas. I'm just confused as to how smooth it runs at high end in neutral. Also when it finally decided to open up on the lake after being bogged down it ran really sweet. It's hard to believe it could run so good with carb issues or gas unless it;s a choke problem?"

"First, don't rev it witho

"First, don't rev it without a load, bad things happen. If you have a timing light put it on each plug wire while running, no flash and you have no spark on that cyl, check them all. You need a compression test, do it first. No need to waste time and money on a bad engine. It is possible to look down each carb while running to compare the amount of fuel coming out each carb, no fuel means stop. You can also look at each carb while pumping the fuel bulb with engine off, to see if a carb is flooding. Any fuel coming from carb with engine off is bad. Flooding or weak spark would knock you down a cyl, causing performance problems. Don't force the engine to run, damage will happen"

Sounds like a plan. Probably w

Sounds like a plan. Probably won't get to it until Monday evening now due to commitments but I will check your ideas out and get back with you. Thanks!