2 stroke boat motor acting up

[ScreamingPotato]

I wouldn't go ripping into the carb yet. If it runs ok once started I'd exhaust some other mentioned items first. Lots of ideas here already shared.

Agree.

Understand that I'm new to boats as I just got this a few months back. It has a 94 Mercury Mariner. The choke activates when you push the key into the ignition. Once I've gotten to my fishing spot and fish a while, I go to start it back up and it just cranks but never starts. Then it'll start momentarily and shut off no matter if I raise up the idle lever. I just have to sit there and give it some time and it will eventually start and run good again after it starts.

OK easy breasy. This is definitely fuel bleeding down and out so the fuel pump is having to ketchup. You've either got that or weak fuel pumps/pressure. Like some others have said, I'd replace the fuel line with good marine ethanol rated line, don't got cheap, that includes the primer bulb and filter because why not. This is an easy task. Run it and see how it goes, if issue remains then you've got weak fuel pumps. Also, be sure the vent on your tank is functional, could be vaporlock creating a bit of a vacuum which the pumps are strong enough to overcome at high RPM but tougher to combat while cranking.

 

[cnelk]

You have 2 fuel filters. The white inline one and the one in the fuel pump assembly

Replace the white one and remove and clean the screen on the other one

 

[Smallie]

Agree.

OK easy breasy. This is definitely fuel bleeding down and out so the fuel pump is having to ketchup. You've either got that or weak fuel pumps/pressure. Like some others have said, I'd replace the fuel line with good marine ethanol rated line, don't got cheap, that includes the primer bulb and filter because why not. This is an easy task. Run it and see how it goes, if issue remains then you've got weak fuel pumps. Also, be sure the vent on your tank is functional, could be vaporlock creating a bit of a vacuum which the pumps are strong enough to overcome at high RPM but tougher to combat while cranking.

This right here as this is something that a lot of new boaters overlook and I’ve been guilty of it too. Vent the gas tank before starting especially after running for a bit and then starting up again or you will get a vapor lock. It may start fine at the launch based on fuel still in the line/ fuel pump. I used to close the valve on my gas tank after stopping as my tank is exposed to water coming over the transom and wanted to avoid water getting in and I would have the same issues you’ve mentioned. Have come across several pleasure boaters out on the lake seemingly stranded and cranking for an hour trying to get the boat to start. Went over the basics and as long as it was turning over and getting spark just walked over to their gas tank and vented it. Started first crank after and then they look at you like you’re a genius lol. I would check all of the mentioned things above related to the gas line and primer bulb before looking into the carb though

 

[Finch]

Is it two or three cylinder?

I honestly have no idea. How do I find out?

I'd suspect the fuel pickup to the motor. The bulb should stay hard after youve pumped it.

How long was your longest run to or from a spot?

Longest continuous run has probably been 30 minutes or so.

Agree.

OK easy breasy. This is definitely fuel bleeding down and out so the fuel pump is having to ketchup. You've either got that or weak fuel pumps/pressure. Like some others have said, I'd replace the fuel line with good marine ethanol rated line, don't got cheap, that includes the primer bulb and filter because why not. This is an easy task. Run it and see how it goes, if issue remains then you've got weak fuel pumps. Also, be sure the vent on your tank is functional, could be vaporlock creating a bit of a vacuum which the pumps are strong enough to overcome at high RPM but tougher to combat while cranking.

Thanks. I assume I should use hose clamps instead zip ties on the new fuel line connections. Pretty sure I saw another motor with zip ties on the fuel lines. Common?

You have 2 fuel filters. The white inline one and the one in the fuel pump assembly

Replace the white one and remove and clean the screen on the other one

View attachment 586362

Thank you sir. You see the other pic with the unconnected wired in my hand? Any clue what they are for?

This right here as this is something that a lot of new boaters overlook and I’ve been guilty of it too. Vent the gas tank before starting especially after running for a bit and then starting up again or you will get a vapor lock. It may start fine at the launch based on fuel still in the line/ fuel pump. I used to close the valve on my gas tank after stopping as my tank is exposed to water coming over the transom and wanted to avoid water getting in and I would have the same issues you’ve mentioned. Have come across several pleasure boaters out on the lake seemingly stranded and cranking for an hour trying to get the boat to start. Went over the basics and as long as it was turning over and getting spark just walked over to their gas tank and vented it. Started first crank after and then they look at you like you’re a genius lol. I would check all of the mentioned things above related to the gas line and primer bulb before looking into the carb though

Genius! Appreciate the info. I'll try everything and report back soon.

 

[CorbLand]

Came back to ask if it does it more when the temps warm up or it sits in the sun. Could be causing to vapor lock, if so.

 

[ScreamingPotato]

I honestly have no idea. How do I find out?

Longest continuous run has probably been 30 minutes or so.

Thanks. I assume I should use hose clamps instead zip ties on the new fuel line connections. Pretty sure I saw another motor with zip ties on the fuel lines. Common?

Thank you sir. You see the other pic with the unconnected wired in my hand? Any clue what they are for?

Genius! Appreciate the info. I'll try everything and report back soon.

Start with the free/easy stuff. For the hose connectors, buy the crimp tool and some proper hose crimps if you've got a few bucks. I'm not vouching for these, it was just the first link I found to show the type. HELIFOUNER 90 Pieces 1/4"-15/16" 304 Stainless Steel Single Ear Hose Clamps with Pincers Kit https://a.co/d/6RCE0IZ

Also, position that primer bulb vertically as well. I had a brand new 4 stroke Suzuki that would vapor lock constantly, run like crazy but after shutting down it was dead. On a hunch I ziptied the fuel lines to position it vertically and never experienced the problem again.

 

[thinhorn_AK]

Fuel filter

In my experience when fuel filters start going bad you sort of lose power under load. Not saying you are wrong just wouldn’t be my first thought.

 

[Gutshot007]

Alot of good info here . Not sure how everyone approaches things . My mariner outboard is a 1993 (old). Sometimes its worth starting at the gas tank, fuel line , bulb, filters , rubber internal lines and carb and just work you way back and replace/clean stuff before problems develop . Found it easier to do before you get stranded. A little preventitive maintenence goes a long way .My outboard is overdue for a new impeller . Just ordered one

 

[KurtR]

Seems everything has been covered except what boat stands for . Bust out another thousand.

 

[cnelk]

I have 2 old outboards - Evinrude 15hp - one is 1978 and the other is 1982.

I know just enough about them

 

[Hill Difficulty]

Couple things:

1) cnelk's #22 answer gets my vote for most useful suggestion.

2) The photo in #13 shows 4 spark plugs.




Other: Prior to 2003, Mercury splash well fuel lines and primer bulbs would harden and become brittle when exposed to ethyl alcohol. If hose and bulb were never replaced, the inside liner has eroded and broken into little particulates that have migrated downstream toward the fuel filter. When you replace the fuel line, cut it open and you'll see what I'm describing.

Tip:
1.Replace the fuel line and bulb in the splash well.
2.Replace the fuel filters.
3.Before you attach the upstream end of the new fuel hose... mix a small can of 1 pint gas and 1 pint Sea Foam Motor Treatment... stick the upstream end of the fuel line the mix and run the engine with a water hose hooked up... run the engine until half the mixture has drawn... let the motor sit for a day or two for Sea Foam to liquefy all the gum residue from the carburetor circuits... test it after it sits and let us know what happens.

Hope this helps!

 

[Hill Difficulty]

Edit - this post duplicated #31.

Very doubtful it's a carburetor issue. Very confident that it's a fuel flow obstruction. Sent a PM to OP.

 

[summs]

Ole 2smokes are easy. Just do the maintenance for $100. Clean the carbs, clean the fuel filter, new spark plugs gapped properly, put a new gas line in and check and possible replace gas lines from the fuel pump to carbs. Should only take half a day and have a basically brand new fuel system.

If that doesn't work, you got a bigger issue and if it does work, well then you got 5 more years of trouble free motor.

 

[Fatcamp]

I have 2 old outboards - Evinrude 15hp - one is 1978 and the other is 1982.

I know just enough about them

99 25hp Mercury 2 stroke
2001 25hp Tohatsu 4 stroke
2007 25 Yamaha 2 stroke
2008 20hp Yamaha 4 stroke

That's just what I have now. My year is divided into mule deer obsession season and boat modification obsession season. They just alternate for top spot, neither really ever goes away.

 

[Finch]

Came back to ask if it does it more when the temps warm up or it sits in the sun. Could be causing to vapor lock, if so.

I noticed it doing this in the early spring when I first bought it. Temps were mild.

Start with the free/easy stuff. For the hose connectors, buy the crimp tool and some proper hose crimps if you've got a few bucks. I'm not vouching for these, it was just the first link I found to show the type. HELIFOUNER 90 Pieces 1/4"-15/16" 304 Stainless Steel Single Ear Hose Clamps with Pincers Kit https://a.co/d/6RCE0IZ

Also, position that primer bulb vertically as well. I had a brand new 4 stroke Suzuki that would vapor lock constantly, run like crazy but after shutting down it was dead. On a hunch I ziptied the fuel lines to position it vertically and never experienced the problem again.

Good tip. Got a set of crimps w/ the tool in my Amazon cart. I've read in a few other places about keeping the primer bulb vertical. I'll be sure to do that when I replace it.

Alot of good info here . Not sure how everyone approaches things . My mariner outboard is a 1993 (old). Sometimes its worth starting at the gas tank, fuel line , bulb, filters , rubber internal lines and carb and just work you way back and replace/clean stuff before problems develop . Found it easier to do before you get stranded. A little preventitive maintenence goes a long way .My outboard is overdue for a new impeller . Just ordered one

I'm all about preventative maintenance. Everything you mentioned is on my to do list.

Couple things:

1) cnelk's #22 answer gets my vote for most useful suggestion.

2) The photo in #13 shows 4 spark plugs.

View attachment 586731


Other: Prior to 2003, Mercury splash well fuel lines and primer bulbs would harden and become brittle when exposed to ethyl alcohol. If hose and bulb were never replaced, the inside liner has eroded and broken into little particulates that have migrated downstream toward the fuel filter. When you replace the fuel line, cut it open and you'll see what I'm describing.

Tip:
1.Replace the fuel line and bulb in the splash well.
2.Replace the fuel filters.
3.Before you attach the upstream end of the new fuel hose... mix a small can of 1 pint gas and 1 pint Sea Foam Motor Treatment... stick the upstream end of the fuel line the mix and run the engine with a water hose hooked up... run the engine until half the mixture has drawn... let the motor sit for a day or two for Sea Foam to liquefy all the gum residue from the carburetor circuits... test it after it sits and let us know what happens.

Hope this helps!

LOL, yeah. I dont have an explanation on why I said that. It is definitely a 4 cyl. Good tip on the gas/seafoam treatment. I'll give that a try.

Ole 2smokes are easy. Just do the maintenance for $100. Clean the carbs, clean the fuel filter, new spark plugs gapped properly, put a new gas line in and check and possible replace gas lines from the fuel pump to carbs. Should only take half a day and have a basically brand new fuel system.

If that doesn't work, you got a bigger issue and if it does work, well then you got 5 more years of trouble free motor.

Appreciate the help.

 

[strousek]

boat​

noun​

ˈbōt
plural boats
Definition : a hole in the water to put your money in

I would have to agree that you are looking at fuel obstruction/vapor lock. I have a Mercury 120 2-stroke that gave me similar issues. Fuel bulb would go squishy after about 30 minutes of sitting and hard to restart. Also had the worst time getting the boat to start when it was over 95 degrees and sunny out. I finally took all the fuel lines apart, replaced what I could and cleaned the hell out of all the rest of the components including the vent on the fuel tank. My fuel was also 2 years old. I always run Sta-Bil but still old fuel will give you fits. Topped her off with new fuel and bam like a brand new motor.

 

[Bluefish]

Sounds like a fuel issue, either no fuel, ie vapor lock or drain back or too much fuel, plugged tank vent, too much choke. If it’s too much fuel, putting the throttle to wide open (out of gear) and then starting will clear the engine.
if not enough fuel, then a dash of fuel down a plug should start it right up. Start by redoing the fuel lines. Common for them to degrade, especially if they are silver.

 

[Fatcamp]

How's it going, Finch? Any progress?

 

[Fatcamp]

Still wondering, Finch. Picking up a 2002 40hp 2 stroke tomorrow.

 

[Finch]

Still wondering, Finch. Picking up a 2002 40hp 2 stroke tomorrow.

Hey, sorry I must have missed the first notification when you asked. I've been meaning to post an update anyway.

I replaced the bulb, fuel line, and fuel filter. I found some rubber orange material when I cut the old bulb open. It was preventing the spring of the check valve from closing all the way. I then realized what it was... the rubber washer/ o-ring of the gas tank lid. There was a bunch of it inside the tank. I went ahead and replaced the tank as the pervious one was very old and pickup tube housing was coming apart from the top of the tank. I emailed the company but they said they didn't carry that part for that old of a tank anymore.

Long story short, I did all these things but it is still doing the same thing on the water after it runs a bit. I don't know what it could be.