97 40hp Merc. stalling out 5-10min into a run.

[marmarr1978]

Its a 97 40hp merc. motor on my bass tracker this motor has appr. 50 hrs on it. Everything is as it came from the factor as far as parts are concerned except filters and general maint. It starts fine but while on the way to the honey holes approx. 5-10 minutes of running at full throttle it completely loses power and rpms all of a sudden. Once the boats comes to a stop the enigine after a few seconds chokes itself down. Eventually it will start but it takes maybe 2-5 minutes of cranking. It cranks then shuts down cranks then shuts down and eventually it will crank and ride on like nothings wrong till a few minutes later then it does it again. The last time it did this, once i got it back goin, as i gave it more throttle it began to bog down as it was gonna choke down i could only give it about 25% of throttle. If i gave it anymore it would start dieing out again. Any suggestions would help i dont know much if anything about outboards. Is it a easy fix? Is it worth fixiing. This motor is to new still imo as far as the running hours are concerned to be haveing troubles like this. This is my first merc. and im not impressed. Had an evinrude on my last boat and never once had a problem ever. Please help prime fishing is coming in... Thank you in advance for any help..

 

[rndn]

Re: 97 40hp Merc. stalling out 5-10min into a run.

When this happens in the fuel primer bulb sucked flat?
If you squeeze the bulb when it bogs down will it start going again?

 

[StarznBarrz]

Re: 97 40hp Merc. stalling out 5-10min into a run.

sounds like a shortage on either fuel supply and/or air, check the fuel lines and make sure they arent clogged or anything and also check the carb. also take a look at the fuel pump! hope this helps

 

[marmarr1978]

Re: 97 40hp Merc. stalling out 5-10min into a run.

No the fuel line and bulb is normal it doesnt collapse and if you press the bulb when it bogs down it doesnt help, originally i thought this was the problem that is maybe was vapor locking or there wasnt enough line presure, but the lines seem to be fine. I have also changed gas tanks and gas though havent messed with the carb. Not much of a mechanic specially when it comes to outboards. I havnt checked out the fuel pump though that maybe next on my list. Other people have told me it could also be the stator or the coil pack may have minut cracks. Im to the point to were i dont know were to begin anymore and i dont want to get raped at the boat shop. Thanks for the advice i will definatly put it to use fellas.

 

[Yamajoe]

Re: 97 40hp Merc. stalling out 5-10min into a run.

Your problem is likely to be blocked main and pilot jets or stuck float valve; ensure all fittings from tank to fuel pump, to carb are tight (airleaks); clean your carbs thoroughly, do a link and sinc; what are your compression numbers? good luck

 

[Yamajoe]

Re: 97 40hp Merc. stalling out 5-10min into a run.

Usually you can tell if your fuel pump is playing up by squeezing the primer bulb when it starts to bog at wot, if power returns then you can suspect the fuel pump; to check for main jet problems, fill a spray bottle with premix, at wot when the motor starts to bog, shoot premix into each carb one at a time, if you get full power then suspect main jet/carbs. always clean all carbs not just the one with the problem.