motor wont accelarate

[ibgood]

i have a 1984 150hp Evin VRO. last year i was experiencing a problem with this motor. i was running WOT at about 41mph rpm's was almost 5500, after a while i noticed my speed and rpm's was gradually decreasing. over a period of about 10 minutes, i went from 41mph down to about 33mph. this year i put it back in the water only to find out that it will only run about 7mph WOT. at one time it serged several times, and reached about 15mph, but only did that once. any ideas where to start looking?

 

[CATransplant]

Re: motor wont accelarate

First thing is to check the spark plugs, then check for spark on all cylinders. Sounds like you're dropping cylinders to me.<br /><br />If it's not plugs or lack of spark, you may be starving for fuel. What RPM's are you seeing on the motor now? If they're higher than about 2000, and you're going that slow, you could also have a spun hub on your prop. Use a sharpie or other waterproof marker to mark the prop and hub and see if the marks stay in the same place.<br /><br />But, it sounds to me like you're just not firing on all cylinders or having a fuel delivery problem.

 

[ibgood]

Re: motor wont accelarate

i replaced the plugs, and it actually ran worse, if that makes any sense. i mentioned that it would serge, but not now since i replaced the plugs. at 6-7 mph the rpm's are at about 1100. out of gear it will rev way up, but in gear 1100 is maxxed out at WOT. if a powerpack were bad, shouldnt it still run better than 7 mph? thanks for your reply, any and all help is much appreciated.

 

[fireman57]

Re: motor wont accelarate

It won't run better than that on less cylinders. Do the spark test that CAT suggested and I bet your problem shows up.

 

[Solittle]

Re: motor wont accelarate

Did you try to squeeze the primer bulb when it slowed down?

 

[ibgood]

Re: motor wont accelarate

i checked the bulb and it was still hard. will try the spark test and let you guys know. its dark thirty right now but will do it tomorrow. this motor has two power packs is the reason i asked if it would run faster than 6 mph. on three cylinders. i can see one power pack as bad but both going out at the same time is a little hard for me to believe. im leaning more towards fuel delivery problems than electrical, but will definitely have more info tomorrow. thanks a bunch guys, really appreciate your input.

 

[fireman57]

Re: motor wont accelarate

If a bank of cylinders is not firing then you do have a fuel problem. Too much in one place not burning.