25 HORSE MERC

[Floridian]

At high power setting the engine bogs down real bad. Rebuilt carb, new plugs & wires. Could it be timing? It ran good until I bought a bigger tank and accidently sucked the primer bulb closed because I didn't open the vent. I replaced all the fuel lines on the engine and to the tank, including the primer bulb. <br />I'm lost from here.

 

[Trent]

Re: 25 HORSE MERC

Try pumping the bulb when it does this. If problem goes away replace the fuel pump diaphram.

 

[Floridian]

Re: 25 HORSE MERC

I've replaced the fuel pump diaphram. I tried squeezing the bulb while it's running, and it feels empty. I also slowly put a rag in front of the carb and the engine dies. A marine mech told me if it picks up RPM it's gas and if RPM's drop it's ignition???<br />It starts and runs perfect except for higher power settings.<br />Thanks for the quick reply. I'm tired of only being able to go 7 MPH pushing a 20' pontoon boat.

 

[Bear]

Re: 25 HORSE MERC

I think so too. This is an exploded view of your carb:<br /> Diaphram item #25 <br /><br />Edit:<br /> Have you tried the old gas tank again?

 

[Floridian]

Re: 25 HORSE MERC

Thanks BEAR. I have a manual. I've already replaced the fuel pump diaphram.<br />What does the trigger coil do?<br />I stuck the fuel hose in a different tank. No good.

 

[Bear]

Re: 25 HORSE MERC

Was the new gas tank clean and filled with fresh fuel and no water? Have you checked the fuel filter? I would drain the carb and look for dirt and water. Use a clean and dry glass bottle or similar. <br />I would also check the fuel pickup in the new tank.<br />The new tank might not be new as in NEW, but it's shorter than the larger tank or second tank. Was it new as in newer used?

 

[Floridian]

Re: 25 HORSE MERC

Brand new tank. I tried a different tank. I'm a retired Aircraft Mech so I know how to work with tools I just don't know boat motors. I can remove and reinstall the carb now in less than 10 minutes. It runs the same no matter what I do.

 

[Bear]

Re: 25 HORSE MERC

Retired and now this You should be cruising that pontoon all day long. <br />Good to know that you are not completly lost around tools.<br /><br />I'm almost out of ideas here. As it happend when you forgot the air went i still think it has to to with fuel supply. Not ignition.<br /><br />Still wonder a few things.<br />Did it ever run properly with this brand new tank or did you forgot the vent the very first time you tried it?<br />Is i possible that you got an air leak somewhere between the fuel pickup in the gas tank and the cylinder? I'm thinking of the fuel fitting o-rings or carb gasket.<br />The arrow on the bulb facing the engine, getting firm after squeezing it a couple of times?<br />Do you still have the old tank and fuel lines? Can you switch them again?<br /><br />Yeah, just questions, no answers. Yet.

 

[Floridian]

Re: 25 HORSE MERC

I appreciate all the ideas BEAR. The local marine mech is scratching his head too. I just may have to take it in to the repair shop. It's not the cost as much as knowing I'm a mech, I should be able to fix it. It's an ego thing now. When I do figure it out, I'll be sure to share the info.

 

[mellowyellow]

Re: 25 HORSE MERC

here's a guess... when the pressure built up, it<br />collapsed a fuel supply hose (inside part).<br />definately sounds like a restriction somewhere.<br />pull the hose from pump to carb and see if she's<br />pumping. if hoses are'nt new, change 'em.<br />good luck,<br />M.Y.

 

[Floridian]

Re: 25 HORSE MERC

Well I finally found out what it was. It was a bad STATOR. It runs great now.

 

[TXredfish]

Re: 25 HORSE MERC

Mr. Retired Floriadian may I ask what year your 25 merc is because 2 days ago I just bought a 25 2stk 2003 merc and hearing this worries me.

 

[dmessy]

Re: 25 HORSE MERC

Not to worry Txredfish. Your motor will go strong for years to come. You don't hear of many stators going bad on Mercs(this has been MY experience, I know some will disagree) <br />My 2000 25 HP Merc runs great always as does my 1969 20 HP Merc and my 1967 9.8....you made a good choice. Keep the lower oil changed yearly,run good oil and fresh gas,keep the fittings lubed and ,flush the motor for at least 5 min. at slightly over idle immediately after salt use PS-Academy or ?

 

[Floridian]

Re: 25 HORSE MERC

It's a 1989 and I use it ALMOST every day. Knock on wood, no complaints. You have to expect some repairs.