'76 Ev 15 runs perfect then loses rpm, quits at wot

[MoeBudz 420]

hey, i picked up a '76 Ev. 15 hp from a friend, very clean, but sat for a few years unused on motor stand. Had a chance to test it awhile ago on a small john boat. Motor started, idled fine, put it in gear, took off. Lots of pep, snapped right up onto plane.After about 1-2 mins wot, rpm's dropped more and more, kinda like throttling down, but tiller still held at wot. Eventually will quit, require restart, same over again. I think the bowl in the carb is being filled by primer ball, then it empties at wot? Engine remains cool enough to leave hand on sparkplugs w/o burning it, good flow out of pressure relief hole (no peehole)<br /> Did not think to squeeze primer ball to check fuel pump pressure. It has to be either that or maube a blockage/plugged filter? Cannot test again till spring. Hoping it's something small!<br /><br />Any help appreciated!

 

[rickdb1boat]

Re: '76 Ev 15 runs perfect then loses rpm, quits at wot

Replace the bulb and fuel lines. New spark plugs. Carb rebuild would be in order over winter. Replace fuel filter as you said. Also, replace water pump impeller, as it will need it after sitting for a few years, even though it appears to be working fine. Drain and re-fill lower unit oil and check for water in fluid. Use fresh fuel and oil at a 50:1 mix(2.5 ounces TCW-3 oil per gallon) Good winter project and not alot of cost to get her going again. Should be well under a hundred to fix her up fine.

 

[MoeBudz 420]

Re: '76 Ev 15 runs perfect then loses rpm, quits at wot

Thanks a lot for the quick advice.. I will have all you mentioned done before spring, should be a sweet little unit! ;-)

 

[JimIslander]

Re: '76 Ev 15 runs perfect then loses rpm, quits at wot

Had the same problem with my father-in-law's 40 horse. Turned out to be water in the oil tank! On low RPM, not much oil (water) injected into the system. High RPM = high oil (water) injected with the fuel. Blew the head right off the motor!<br /><br />Good luck.<br /><br />JimIslander