15 hp 1997 evinrude 4 stroke

Okay. I hope someone has the answer for me. I have a 15 hp 1997 evinrude 4 stroke it's a electric start. When I put it on the water it cranks up. It is on a 17 ft flats skiff thin wall fiberglass hull. when I open it up it will not get on plane maybe 10 mph max. then the primer ball will go soft. So I replaced the primer ball 3 times. after the I get to my fishing spot and then crank it up again to come back to the ramp it will go maybe 5 mph max. then it will sut off. I would start it back up after a few attempts and it will run 2 mins then it will shut pff again. Then a knocking sound will start while running. Then it will run all the way to the ramp but very slow. I have to keep priming the ball so the motor doesn't shut off because lack of fuel. But even then after running the motor trying to get back to the ramp that doesn't always work. The motor has excellent compression. The primer ball is good. Has new plugs. I don't know what the knocking sound is. Could it be a bad fuel pump? Under the Flywheel is a exhaust looking thing with a hose going to it. It releases smoke evey now and again . Well a few times when I trying to crank it up brief flames would come out of there. Please if anyone has any info please help me out

Re: 15 hp 1997 evinrude 4 stroke

are all clamps on fuel line tight?
i think air is sucking somwhere, maybe at conectors join?
take of the cover, conect fuel line to fuel pump diectly to avoid conectors and run motor on lake

Re: 15 hp 1997 evinrude 4 stroke

If the primer bulb is going flat then it sounds like you have a restriction in the fuel tank or a vent is not open; maybe an anti-siphon valve is stuck in the tank or the fuel pick-up hose is blocked in the tank. Good luck

Re: 15 hp 1997 evinrude 4 stroke

Could have a bad fuel pump if you have to keep pumping the primer bulb to keep it running.

Re: 15 hp 1997 evinrude 4 stroke

Misread it thought he said the bulb went flat; but he said soft.

Re: 15 hp 1997 evinrude 4 stroke

The primer bulb is supposed to go soft once the motor is primed & running. At that point in time it just acts as a section of normal hose as a fuel pass-thru.

As for it not running up to speed, could be electical/only running only one cylinder OR the timing belt may have jumped a tooth, OR the flywheel key may be partially broke allowing the flywheel to be slightly missaligned effecting the timing

Re: 15 hp 1997 evinrude 4 stroke

friend run yamaha 40 hp, 4 stroke and he could reach only 3000rpm becouse timng belt jumped 1 teatch

Re: 15 hp 1997 evinrude 4 stroke

Thank you for all your responses. It timing was off one notch. I put it on the water today. It started fine on the trailer. But when i put it in the river under a load it took a while to start. And when it did and i put it in gear it would boggle down and shut off this went on for about 15 mins. Got it to start kany times but when i pit it in drive and accelerate it would kepp boggling down.i got it to stay on while in drive but can only go slow speed. When i increase the speed it will only increase by a little when i open the throttle up it will rev up but still go the same speed. When i pulled the boat out of the water someone ask me if i adjusted the lean sitch. Have you guys ever heard of that?

Re: 15 hp 1997 evinrude 4 stroke

Sorry trying to post this through voice control. I meant to say the lean Switch.

Re: 15 hp 1997 evinrude 4 stroke

Oh yea h we did adjust the timing and the flywheel key is fine