Pontoon Boat & Deck Boat Forum

Ok folks I need some input here. I have a 90 Merc 2 stroke that has been invaded by gremlins. You can run the boat all day at various throttle settings and no issues. However, you hook a tube to it and run it hard: hole shots WOT or near WOT, it we run for about 5 min or less and then it just QUITS. Will restart run about 3-4 sec and dies. Happened three times on sat two runs to the lake. Had it towed in the first time and the marina replaced the fuel filter, plugs , bottom end oil and impeller. Might as well do some maintenance when it's out of the water
, right! They said the fuel filter was bad. Flash forward to this weekend...
Took it out ran it up the lake 4-5 miles at anywhere from 3000 to 5000 rpm. Ran like a top. Anchored, ran some more, anchored and then the kids wanted to tube. Hooked it up, took off d and it ran for maybe three minutes and quit again. Fire, run for 3 sec and quit. Drug it back to the marina and they couldn't figure it out either. Fire ,run 3 sec and die. Pulled gas cap off fired it and it ran like nothing happened other than a lot of fuel smoke... Thought cap on gas tank not venting. Bought a new cap thinking it's fixed. Fast forward to Sunday.....took it out. Same thing as Saturday. Hooked up the tube, 3 minutes and nothing!!!!. By now I'm out of my mind. Wife convinced me to calm down and wait about 30 minutes.....we did. it started!!! Ran it back to marina at varying speeds and was fine. Even went to watch fireworks on it last night. Ran fine. Didn't run it wide open , maxed out at nice slow cruise@ 4000 rpm and 15 mph.
I'm at a loss why putting loads on the motor which is common in pulling a tube would cause this.
Fuel starvation? Power pack going bad? Float sticking in carb? Vapor lock? Carb kits needed ? It's not the fuel, as it's 100 percent real gas. It put out a healthy stream of water so overheating shouldn't be an issue. For the love of God , someone point me in the right direction as the wife is to the point she won't get on it unit it's fixed and I'm ready to pump three slugs in the toons and sink it .HELP!!!!!!!!!!!!!!!

Sounds like a heat thing to me. Have you checked the thermostat?


Frustration I understand. After the issue with mine a month ago not being able to kill motor we got the loose wire fixed and now it fires but won't start. 3 week wait to get it fixed. Finally getting it in Tuesday

Next time it dose it look and see if you have spark, it sounds like it may be in the early stages of a heat break down component.

Get yourself a 3 gallon fuel tank, fuel line, fuel ball and a murcury fuel coupler and hook it straight up to your motor. If it run fine then you know the problem is with your fuel delivery. If not you know the problem is on the motor.

Sounds like a fuel issue. Basically it is running out of gas long enough to kill the motor. You can restart it pretty because that doesnt take much fuel.

The ethanol in fuel is causing a lot of problems with fuel lines. Go to bass boat central and do a search on fuel line. I would also change out the fuel filter. If you dont have a 10 micron fuel filter I would install one.

I've owned at least a half dozen Mercs with zero probs.. My current one a 2009 90hp Optimax has broken down 5 times in 5 yrs----all blamed on ethanol except last time---bad kill switch.

FYI---just got back from a few days in Belize. Almost every motor down there is a Yamaha. Few Hondas-almost NO Mercs.

wwind3 wrote:I've owned at least a half dozen Mercs with zero probs.. My current one a 2009 90hp Optimax has broken down 5 times in 5 yrs----all blamed on ethanol except last time---bad kill switch.

FYI---just got back from a few days in Belize. Almost every motor down there is a Yamaha. Few Hondas-almost NO Mercs.

Yup, Yamahas all over the Carribbean.

Well good news , folks. I replaced the fuel line this morning and sure enough, the damned thing runs like a top now!!!! The interior liner had pulled away from the tubing and under full throttle, would collapse the liner . Obviously the previous owner had run some damned ethanol thru it. Can't believe a new bulb and 6 ft of line cost me 50.00 but it solved the problem. Just glad to have the gremlins out . Shoulda thought about it first thing off the bat ...oh well.

Good fix!

Soonertoon wrote:Well good news , folks. I replaced the fuel line this morning and sure enough, the damned thing runs like a top now!!!! The interior liner had pulled away from the tubing and under full throttle, would collapse the liner . Obviously the previous owner had run some damned ethanol thru it. Can't believe a new bulb and 6 ft of line cost me 50.00 but it solved the problem. Just glad to have the gremlins out . Shoulda thought about it first thing off the bat ...oh well.

word-------VST tank. Optimax has about 3 or 4 fuel pumps---ethanol eats up the rubber...fuel pump throws craps. wouldn't hurt to have that stuff checked too----speaking from experience. Also the 1st time I broke down---my hose was bad also--Quality in Onalaska replaced it at my xpense with the new and improved model. Last month new and improved model and bulb showing signs of deterioration--replaced with a newer and more improved model-----at my xpense----again........-just sayin'...

Well, if it's got tits, tires or toons, it'll give you trouble.

Glad to hear you're fixed and toonin.

The exact thing happened to me once down in Florida. Loyd was onto something. The engine was overheating, and it partially seized. I'd run fine until it heated up again. Your problem could have just as easily been overheating. Fortunately it wasn't my boat.

Piece of shit Mercury quit on me again!!!! As you know I've been having issues with this POS for about a month now. Thought it was the fuel line so replaced it and thought all was well. Today my son and I were out. Ran it up and down the lake at close to WO for at least 8-10'miles . Ran like a top. Then it just friggin Quit. Would fire back up run 4 -5 sec and die. Same story as last times waited about 30 min and it fired up and we limped back to the marina at 15 miles an hr. Pissing steady steam of water and ran smooth when it did run. I've checked fuel sender, fuel filter replaced, new fuel line, plugs (just for the hell of it) . Pulled cover, doesn't feel hot so don't think it's heat related unless it's ignition module which would be a stretch since it re fires pretty quickly. It's almost like its flooding itself out, but what the hell do I know...maybe fuel pump?

Now I'm faced with dragging the sunuvabitch 40 miles back to Tulsa and waiting 3 weeks for one of these crooked ass merc dealers to take a a look at it. I AM READY TO SINK THE SUNOVABITCH.. does anyone have any experience with this? KIds and wife won't get on it and the wife threatened me with death if I trade it off for another one. AAAARRRRGHHHHH!!!!!!

I am having similar issues with my 115, just dropped it off at the mercury dealer today. If I have to spend a few bucks to get back on the lake so be it...