At home: The motor generally starts very well in the driveway on muffs. Pump the bulb, choke with the key, turn over a few times. It may stall the first couple tries, but generally catches and runs pretty easily.
At boat ramp: (an hour or so after starting at home) I back it down the ramp, go through the same procedures, and I have to crank it, and crank it, and crank it. When it grabs, it typically stalls right out. Takes a few of these start, stall sessions before it will stay running. Sometimes acts like this at the end of a beach day too.
One thought I had was the angle of the boat/motor. In the driveway the motor is generally trimmed down and is fairly perpendicular to the ground, or trimmed slightly up. At the ramp, the angle is generally not the same because of the ramp angle. Could the change in angle be causing be causing fuel flow issues? Other suggestions?
depending on were the fuel pickup is in your gas tank but manufactures take that into consideration when building them. maybe next time trim your motor up so it is perpendicular with the water before starting it up, more like it would be at home. could be an issue with the fuel in the bowls on the carbs, maybe. or possibly tilt your whole boat back at home more like it would be at the ramp and see what happends. then adjust from there the trim.
Try starting it first with out choking it…the drive to the ramp, bumps, being trimed up the carbs could be leaking alittle gas into the engine already priming it and when you choke it, it might be flooding it. My 25hp 1993 model motor after starting it I don’t choke it again unless it has sit for several hours…1 pull…it’s running…
dont choke it, after its already started, but my next question, after you take it to the ramp, do you pump the primer bulb again?
back pressure does make a difference
I’ve had afew motors do that, the answer has always been the back pressure. Question is, what does the back pressure do to the motor; answer from some mechanics has been older motors with low compresion don’t have enough compression to overpower the back pressure. Some have blamed the coil for not enough spark, or timing being off and back pressure overloads the electrical system or something like that. Good luck on a monster problem…
You should try running it in a flush tank/barrel at home to get the idle speed, fuel mixture and timing close and then fine tune it in the water. I had a similar problem when trying to get my 70 'Rude adjusted, and the service manual said it had to be in the water, not tied to a dock or on a trailer to get the best results.
I had a Chrysler do that same thing,went fishing one day and it started cuting off and would not start for a while,basically left me stranded,needless to say it became a reef.
dont choke it, after its already started, but my next question, after you take it to the ramp, do you pump the primer bulb again?
back pressure does make a difference
Typically yes, I will pump the primer bulb at the ramp. It generally only takes 1-2 pumps.
Should I try starting it with the foot barely in the water (just covering the water intake) then trim down once it starts? Will that lower the back pressure?
No more choking at the ramp either.
1996 Sunbird Spirit 170 - 112 Johnson
15’ Ocean Kayak Scupper Pro
My 1995 88spl Johnson (simmilar age and configuration) likes to be trimmed flat/level when cranking. If it is trimmed up a little, I think it has a little trouble pulling fuel from the carbs and is slower to start. She will crank when trimmed up… it just takes a few more tries.
I also pulled, cleaned, and re-gapped my spark plugs this past weekend and it made a significant difference. They were new last season… so I did not expect much or any improvement. She went from spinning a time or two and spitting (but not cranking) for a few iterations before starting to turning about 1/2 a turn and firing right up. But, that might be kinda’ like changing the oil in my car. I’m sure after I do it that the car is substantially stronger… really pulls through 3rd gear a lot better… (not).
I have an older 150 Evinrude that does the same thing and I know that the carbs are horribly nasty and in need of rebuild. Start just fine on the hose and was like pulling teeth at the ramp…let us know what you did to fix this!
