Randy Barrett

I have an early 80's Mercury 25h.p. outboard that has a problem with bogging down/out. It has been doing this for a few seasons now but is getting worse. It starts OK and idles fine and accelerates fine but after running WOT for a while it just loses RPM (and power obviously) and will drop back almost to an idle. It will sometimes stall and be difficult to start again (although it always does) but usually just runs low for a bit and you can accelerate partially and usually find a point around 1/4-1/3 throttle where it is happy and will sometimes let you go to WOT again but after a while will drop back. I'm spending less and less time at WOT and it sucks. It first started when the boat (14' tinny) was under most load - hauling camping gear and guys - but now happens, well, all the time.

I CAN keep it at WOT by pumping the ball every few seconds so it seems to be a fuel supply issue.

I've changed plugs, cleaned plugs, changed the fuel line, used carb cleaner and gas line antifreeze, cleaned the filter. What about this magic SeaFoam stuff? Where to buy in the GTA, ideally somewhere between south Etobicoke and BassPro?

Any suggestions as to what may be the issue would be most appreciated.

Just because the vent is open doesn't mean it is working.

Next time out run it till it starts to lose power, once this starts,loosen the gas cap and see if it clears up. Sounds like a vent problem and the tank is going to a vacuum pressure preventing proper fuel supply. Once you are back at an idle it allows the vacuum presure to release allowing it to run better again until you increase fuel demand again.

You can try Harris roofing 328-3051, he does good work and is a fellow fisherman. He is ussually pretty busy so not sure how quick you need it done.

Balsam = 3 walleye with a regular license and 1 with conservation ,nothing between 37-55 cm.

Rest of the zone 17 = 4 with regular 1 with conservation, must be between 35 -50 cm.

http://www.mnr.gov.on.ca/stdprodconsume/groups/lr/@mnr/@letsfish/documents/document/mnr_e001336.pdf

Gelling is a common problem with deisels in cold temps.A snowblower is gas powered and it was pobably water that froze.If its a 2 stroke then oil and water froze upin the fuel bowl.Kinda like a slushi.No gelling or anything like that.No water in the gas at all.The tank was cleaned out entirely.

A carb prob im sure,it bogs.

Old fuel will create some gel,it wasn't water. It was meant as an example,dirt will do the same thing as I don't figure your fuel is old enough to gel. It could be someting as simple as when they had the motor apart the fuel lines were diconnected,when one of the rubber lines was reconnected a small peice of the rubber line was broken off on the inside of the connection and made it's way into the carb. It's a cheap and simple check to ,if nothing else rule it out.

I don't have any experince with inboards but have a fair bit of experience with older cars and trucks an alot of carb problems come down to a little bit of dirt in the carb. Just trying to help!

Keep in mind when I said under load, It was meant while in the river or lake.On my driveway I can throttle up no problem.There is though a little hesitation if I throttle up slowly.At the same time the water pump and impeller(pick up pump(new))are working fine.Lots of pres on the outlet end of the pump.And she pees like a race horse.

When it's not in the water it's not under load so not using as much fuel. I know it's not the same equipment but at the start of last winter with my snow blower I could start it up it would idle fine,go to full throttle it would run fine but as soon as I got into the snow it would die after about 5 sec.It would restart right away but just die under load. Pulled the fuel bowl and found gel in it.(had just bought the blower and don't know how long it sat with that fuel in it)Once I cleaned it out and put it back together it ran great the rest of the winter.

Sounds like dirt or gel in the fuel bowl,at idle and not under load it's not drawing enough to suck the dirt up to the jets. As soon as it's under load it draws alot more fuel and sucks the dirt up to the jets,once it stalls it fall back away allowing it to start again.

Try pulling the fuel bowl and cleaning it out,remove, check and clean the jets while your at it.