omc 2.3L when motor gets to temp stumbleson take off at 3000 rpms like bad plugs

[freedom170]

i am at witts end on this one. first some back ground. i bought this boat last year, a 170 freedom 4-winns with aa 2.3L ford motor, omc drive. the first time i took it out it was fine u could pull skiers and all. then the next time i took it out after about 2 hrs when i starting to take off then at about 3000 rpms it would start to miss like a bad plug. so i took it back home and tuned it up( i have been a mechanic for 35 yrs.) plugs wires, cap, rotor, gas filter, points, conds. the works. take it back out it runs fine for half the day then starts it again. i take it back and double ck every thing. dwell timing wire routing.put a nother set of points and conds. same thing. replaced the coil no help. tried a differnt gas tank when it started, no help. alternator, had rebuilt because of a noise bearing so help(didnt think it would but needed it any way.)disconneted wire to tach same problem. rebuilt carb. same thing. it only acts up when its get up to temp and get worse if u keep trying to get going. if u let it set for a hr or so (go swiming or something it run like a new boat and if u stay crusing it keep going but as soon as u slow down to a idle and try to take off it wont go just starts jerking,feel electric but cant find anything. even sprayed it with water in the dark with it running but not uder a load and all was fine. im down to the fuel pump but its 280 bucks and dont want to replace if it not that. the only thing else i can think off it to hook up a fuel pressur gauge and try it. if any body has a clue of whats happening it sure would make the wife happy and as we know keep the happy and we can be happy. thanks dave

 

[superbenk]

Re: omc 2.3L when motor gets to temp stumbleson take off at 3000 rpms like bad plugs

Check/replace all fuel filters (including the screen in the carb). Check/replace the anti-siphon valve in the tank pickup. Make sure your tank vent is clear & breathing.

Do you have a fuel/water seperator? Could be bad/wet gas.

Testing fuel pressure is a good idea.

 

[freedom170]

Re: omc 2.3L when motor gets to temp stumbleson take off at 3000 rpms like bad plugs

hi, i do have a water/fuel seperator, i changed the filter and checked for water. none found. i also tried when the problem started to use a differnt fuel supply(differnt can of gas) it did not help so i wonder if the anti-siphon valve could have any thing to do with it. to me it just do not feel like a fuel problem, it does not bog or cough its like if u had bad wires and sprayed them with water. but i have check and recheck every thing wires and replaced every thing twice and still have the same problem. the other thing is if u can get it up to speed after it sets for a while it will run great for as long as u keep going,but if u slow it down to idle and then try to take off it starts to stumble and wont let it gain any rpms. is there any way the interupter switch could have anything to do with this or is it out of the loop when its in gear? i am going to try the things the was on the testing fuel systems on here next.

 

[rainy lake boater]

Re: omc 2.3L when motor gets to temp stumbleson take off at 3000 rpms like bad plugs

I was having sort of the same problem with the exact same boat, 1990. I'd take off and it would stumble and discovered that the choke on the right side of carb was staying open. I just tied it so it was closed and it solved that particular problem.

 

[freedom170]

Re: omc 2.3L when motor gets to temp stumbleson take off at 3000 rpms like bad plugs

well i could not get to the water today but did hook-up a fuel pressure gauge to the system between the fuel pump and the carb. ran it with the muffs on it for 30 minutes and i got to act up a little and when it did the pressure was in spec. 6.5psi. dont think its the pump, but i still want to take it out on the water, also the vent is clear. sure could use some ideas.