At a loss continued

1990 25hp evinrude, tiller, pull start.
Rebuilt fuel pump, rebuilt water pump, cleaned and replaced needle vale on carb,had a new power pack installed. and was told the coils are ok.
Took it out today. It ran fine until after a long troll ;1/2 hour or so . I throttled up to go back up river,the motor got up to speed fine and then
started to run slower and slower until I was at 1/2 speed or less. Stopped for 15 30 minutes. Started the motor it ran fine.


Additional info
Rebuilt the carb,water pump, and fuel pump myself.
Had a shop replace the power pack. Their diagnoses
Today I replaced the tank. All hoses and bulb have been replaced.
While running pulled each plug wire. Made some difference but still ran.
Took it out to the closest impoundment to run it. Idles around for a few minutes ran great. Then wot and back to a little less than wot ran fine.
Idles again for 10 minutes then wot ran fine made a turn to go back to the landing. Hit wot motor started to sag twisted the tiller back a 1/8 to 1/4 and ran fine.Good stream of water out the pee tube.
Still at a loss
TJ

Re: At a loss continued

Never read word one about Thermostat???

Water circulates (on bypass) until the t-stat opens. If it is starting to stick (fail closed)it will present the symptoms you described.

Re: At a loss continued

crxess said:

Never read word one about Thermostat???

Water circulates (on bypass) until the t-stat opens. If it is starting to stick (fail closed)it will present the symptoms you described.

Click to expand...

If that motor overheated to the point of loosing 1/2 it's RPM he should have smelled it burning up, that baby would have sizzled spit, but it could have gone undetected I guess.

Does your motor have a high speed adjustment, sounds like She could be leaning out, fuel tank vent.

Re: At a loss continued

What was your fuel/oil ratio?

Re: At a loss continued

Don't know if my motor has a thermostat. Or where it's at. If it was shutting down as a result of overheating why would it run sag run all in a period of 3-4 seconds. Can't cool that fast. My motor has good discharge through the pee tube. A steady syrem.
I will retard the top rpm as it does seem a little high. No way to check.
I use a 50-1 mix with just a little extra oil in the mix with premium gas.
Back to the shop on Mon.
Thanks for the ideas
TJ

Re: At a loss continued

stupid as it may seem but did u put in the carby float the right way up? if u didnt this will let the carby fill up so much so slowly allowing u to throttle up untill the carby is empty than slowly replenishing the fuel supply

Re: At a loss continued

Yeah caught the float notch and made sure it's the right way. Also tested it by blowing through the line. Worked like it's supposed to.

Re: At a loss continued

Doesn't really sound like fuel, sounds like an intermittent spark problem. Have a buddy in the boat with a timing light, and when it starts doing this, have him drive while you check the spark with the light. Plug wires as well, could be just one has a minor crack and shorts out once in a while.

Re: At a loss continued

OK I appreciate all the help and sugestions.
I'm going to replace the thermostat because of the slowing down to about half speed. Also am going to adjust the carb so the motor doesn't turn to high an RPM and cause the limiter to kick in.
If that dson't work I'm going tp put 4-5 sticks of dy no mite under it and blow the hell out of it and buy a pair of oars.
Take care
TJ