The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.
So I went out last Sat am early and it was wet, I don't mean rainin I mean humid, frog strangling humid, it was as though the very air was dripping and Im running near full throttle with my 2 year old new to me single thumper Evinrude ( tah-hot-sue rebrand) 4 hp 4 stroke and she shut off and there I was pullin that cord and pulling that cord, and she sputters and shut off over and over...
Removed the fuel line and blew out the little fuel filter... pulled the cord and watched the fuel squirt out the fuel pump so I know she's getting gas ( and pumped gas into the internal engine tank so I know she's getting gas. No way to adjust the carb... so I was fit to be tied...
Didn't have anything to get the plug out with ( she's crowded in there ) .....
Limped back to the slip at idle speed... still died right at the end.
Seems I remember a July 4th many years ago with the same weather and the only way I could get the 2 stroke to run was removing the plug and burning a lighter flame on the plug....
So back to stocking a plug wrench, starter fluid, extra plug.... and off to the guys that sold me the engine for this years "servicing"....... who knows the coil may have shorted out ... although she would choke out when I gave her the gas so it sounds like the high speed jet is clogged... ( funny I have 2 fuel filters on the line )... the locals said pull the carb and boil it... ( doesn't that sound like fun )
Distinctive spit like a backfire and quit.....
I may have to go back to a 2 cylinder yammi.... 9.9hp 4 stroke... they look interesting. and you can adjust the carb after drilling out a plug that covers the fuel adjustment screw....
Ray in Atlanta, Ga. "Lee Key" '84 Catalina 25 SR/FK
It seems like the weather has to be coincidence, or somebody on here can teach me more...
Is your gas ethanol-free, or do you use a fuel stabilizer treatment for ethanol gas?
After the last time I cleaned my carb, I started disconnecting the fuel line and running the motor at idle until it dies when we weren't going to use it again for awhile. I know running an engine lean is generally considered a bad practice, but the old timers at my club swear by it. It has worked well for several years now without another carb cleaning and no apparent damage to the engine.
I read you saw the fuel squirt from the fuel pump when you pulled the cord. But the fuel filter might be partially clogged or the fuel pump might not be able to suck enough fuel through it. I ended up removing my fuel filter because the little flapper fuel pump just couldn't handle it and suck in enough fuel.
Are you saying you have both an external and internal tank? So that suggests a switch from one to the other... I'm dubious about two external fuel filters on a 4-horse. But another thing that can cause stalling at higher RPMs is any kind of air leak anywhere in the fuel system, which can break the suction. A bad o-ring in the connector at the tank or the engine, a deteriorated primer bulb, or a crack in a line at a hose clamp can do it. If your fuel line is substantially older than that motor, a new one might be in order.
Dave Bristle Association "Port Captain" for Mystic, CT PO of 1985 C-25 SR/FK #5032 Passage, ex-OUPV Now on Eastern 27 Sarge (but still sailing when I can). Passage, Mystic, and Sarge--click to enlarge.
... but ya know? A “distinctive spit like a backfire” tells me it’s got something to do with ignition timing. Do you have the maintenance manual for the engine?
There are three things I’d check, in the following order: 1. Is there a crank shaft sensor? This tells the ignition that the engine’s crankshaft is at top dead center and when to fire the spark plugs - sometimes it’s going bad, other times something is misaligned. Usually around the flywheel up top. 2. Timing belt skipped a few teeth. This can produce slightly open valves during ignition or pre-ignition. That’ll make it run rough. 3. Last item - bad engine computer? This is a long shot because they’re usually an all-or-none situation. But if a sensor cable is intermittent going to the computer this could give you problems.
Hahaha. You could be right. When I was a kid my mom had and old Plymouth that just would not start in the rain or high humidity. She finally got a can of WD-40 to spray the plug wires and never got stuck again
Going back to my image files I discovered it's been three years... so I feel kinda less surprised... I think it's a clogged high speed fuel jet.. I quit running the fuel out with this engine to see if it made a difference ( we yusta always do that to run the carb dry ) so that was a mistake.
Seth.. always ETOH free, always... Funny they have a small inline fuel filter between the fuel pump and the carb... But it is easy to change out or remove and blow out... but the fuel in it looked clean..
Dave... the int/ext tank actually seems to be a kinda cool feature.. if you turn the valve down and pump the bulb, it brings up the fuel to the pump and if you continue pumping it starts filling the tank in the engine.. so it also makes it easy to diagnose some fuel problems. Turn the valve back and it only pulls fuel from the engine tank. So I could determine it was not a connection problem from the external tank, or if the big filter was clogging....
Anyhoo... new fuel line, new fuel filter, new PRV ( pressure relief valve. ) New fuel, and new stabil ...
AND the engine to the dealer shop and let them diagnose it.
Wish me luck....
Ray in Atlanta, Ga. "Lee Key" '84 Catalina 25 SR/FK
Good luck Ray! I had the opposite issue with my Tohatsu, did not want to idle, figured it was somewhere in the carburetor. Also have an external fuel filter, always use non-e fuel, and used to run the carb dry. I was too lazy to remove the engine off the back of the boat so I found a carb cleaning fuel additive called B-12, thought it was worth a try. I added some to the fuel, ran it at the the dock long enough to make sure the new fuel was in the carb, left it the bowl overnight, repeated the cycle for two more days and problem solved. Now I always add that to my fuel and never run the bowl dry.
We have an old small engine repair guy that hangs around the bar, told me that unless you use the drain screw on the bowl there's always a drop or two left in the bowl and those couple of drops left over time will eventually cause issues.
Again, good luck and let us know what your mechanic says.
So interesting. I have never thought about, or needed a fuel filter for my 9.8 Tohatsu. I have one on my center console with a 115 on her, but just never needed one for Limerick. Do most people have them or???
Peter Bigelow C-25 TR/FK #2092 Limerick Rowayton, Ct
Take an hour to clean the carb. Buy a spray can of carb cleaner, remove the carb, remove the bowl float and valve, and spray everything generously. I would strongly caution against sticking wire in the orifices, enough spraying will safely clean them. Let everything dry completely, gap and install new plugs. That is almost always all you need. If it doesn't solve the issue, then start considering more complex possibilities. I once had a cracked fuel nozzle, part of the jet system, that caused a similar problem, but I took it to a shop where they found the problem. I had a couple of problems with used engines over the years, decades, and now only buy new. As the Admiral said before I bought my 9.9 Begfoot: "For as long as these things last, you might as well get exactly what you want.". A few dollars a year for 15-20 years and fewer headaches is well worth it. Incidentally, I have used ethanol gas for many years without problems and only use stabilizer when I won't use it up in a month or or so. Two 3 gallon tanks instead of one 5 -6 works well for me.
Dave B. aboard Pearl 1982 TR/SK/Trad. #3399 Lake Erie/Florida Panhandle
long story short it was a wet, black, fouled plug.
I was able to get my plugs out with my previous engine with an adjustable wrench... not anymore. Ive added a plug wrench to the boat and now Ive gotta remember to add a lanyard to the plug wrench.
Dealer said turnaround to "service" the engine was three weeks. They apologized. Great, I thought I was finally old enough to pay somebody else to bath in gasoline... Oh well...
I love it when one of your dock mates walks up, stands over you, and asks you hows it going with a cigarette in their hand...
Watched 30 hours of utube videos about this new to me 4 stroke engine. learned lots and impressed with the concept of "servicing" an engine. Don't think about it too much just inspect, clean, repair, replace all systems and crank it and there you go. She runs again.
Changed the plug and she ran.
but NOOOoooo I had accepted the burden of becoming an engine mechanic again ( also with our new to me small block chevy 278hp I/O so the 4hp was not going to push me around ) so I had bought and brought: new fuel line, new tank, new fuel, b12, seafoam, extra tanks, ETOH free fuel mixed with seafoam, fuel filter wrench, new fuel filter, plugs, starter fluid, tubing to drain the engine tank, and my two backpacks of tools/supplies....
It was a lovely day....
I took apart the fuel pump, very interesting, I always thought they were still a rotary system. it is now a diaphragm that runs off a cam on the main shaft.
The "switch" to allow gas from the tank on the engine was most interesting, not at all like ones Ive seen in the past. Its got a little bowl that screws on the bottom with a screen and a gasket, and it does not connect directly from the valve to the external lever but has a screw that holds it in and a spring, and two plastic pieces that appear to interface in some way. I found if the valve was not completely in one direction or the other it shut off. THAT looks like trouble...
If I leave the vent open on the engine tank, water can get into the gas, and if I leave the gas line connected to the engine, and the vent open, water would be able to settle into the fuel line coming from the onboard tank... So my shut down protocol will be close the vent, and shut off the engine tank, and remove the line from the engine. It's so easy to forget to shut the vent if you use the engine tank.
The fuel line I replaced ( 3 years old ) looked good internally, it was some absurdly expensive fuel line I got from the dealership and it had the plastic looking lining inside the line that looked fine. The outside of the line was like a black powder that would get all over you if you touched it.. West marine did not have 3/8 fuel line ( the gray stuff they carry ) and I bought black line from an auto store.
<<< needed a fuel filter for my 9.8 Tohatsu >>>
For me, we have marina gas that is ETOH free but I really don't trust that gas that much, I would not at all be surprised if they had some water in those tanks, they've been in the ground there for so long. I'm trying to get gas at a local station that turns it over always, everybody with a trailer boat fills up there ( including me ) but sometimes I just hit the marina. I've always had a fuel filter on the big boats and I've never had a problem with the fuel in them.. The little engines I've not used external filters until recently ( added one three years ago ) and it seemed like the little engines were always potentially "cranky" and now I'm beginning to think the fuel filter has been a factor. the 2 strokes had a screw in fuel adjustment that you could screw in and then back out that would open up the line. The newer 4 strokes don't have access and have a much smaller jet opening, hence the fuel efficiency so I think more people are looking at adding a filter and hoping they will not have to clean the carbs as often.
So anyhoo... the three take away points I've retained from focusing on the engine for me has been: 1. you run a four stroke at idle a lot and you foul the plug. 2. the little carbs have jets that clog easily, run some seafoam or b12 in the gas. 3. be ready to "service' the engine every year or two and rebuild/clean the carb.
Oh... and the other point...the Florida guys ( the happiest most relaxed people in the world ) if they would tell you they would say "Spray some carb cleaner in there and go"...
Ray in Atlanta, Ga. "Lee Key" '84 Catalina 25 SR/FK
Ray, glad you resolved that issue with your engine to your satisfaction; however I think you situation seems to be somewhat 'unique'.
It has been my experience with the 4hp (a friend's) and the 9.8hp (mine) Tohatsu that they do not foul when run at low speed or at idle - that was a trademark for older 2 stroke engines. I use ethanol free gas either from our marina or a nearby gas station; I can shut my engine off and restart it after months without going through any of the special procedures you mentioned. If I am away for a prolonged period of time I do remove the fuel line from the engine. With the new ventless tanks I have seen two engines being flooded by the pressure formed in the tank that lead to costly services bills.
Regardless, I think it is prudent to know how to remove and clean the carb for the engine on your boat, how to remove and change the spark plugs, how to change the engine and lower unit oils and if you are somewhat adventurous how to change the impeller. If you practice these procedures, say in the winter when sailing is slim you will also find out what tools you need for each task and have them on board if trouble finds you away from your dock.
Nothing really special, just a bit of forward echelon maintenance could safe many headaches; I keep a pair of new plugs and a pair of old plugs and an impeller on board, it is cheap insurance I think.
BTW, I too sail in the Atlanta area in the same humid climate but have not seen any water or moisture issues with my fuel, neither have my friends in this area - you may be on to something that your marina fuel is contaminated - what do other 4 strokers at your place experience? If it is the fuel it should be a wide spread issue...
Another reference: I have done the TennTom Waterway from Mobile to Knoxville in a Catalina 22 with a 5hp Honda , barely above idle to safe fuel and the reverse from Knoxville to Guntersville on a C25 with the 9.8hp, also barely above idel to safe fuel with no issues at all.
How does your 4 hp move your boat through the chop on a busy day at Lanier or when the wind picks up, just curious?
Ray, just a question about the fouled spark plug. Does your engine burn oil?, that is are your piston rings allowing oil past them up into the combustion chamber? Telltale sign is a puff of blue smoke when you first start up the engine, or when you accelerate the motor. I ask because these days, it’s hard to foul a spark plug many other ways... Your carburetor could be running rich - that could also foul it, but you’d smell gas. A stuck automatic choke could cause it to run rich, but your fuel economy would suffer. If you have a buddy with a compression tester, that would tell you about the rings. Of course, you could ignore that problem so long as you have a spark plug wrench. Easy to clean an oil fouled plug
I have an older (1989) Yamaha 9.9, 4 stroke, and yeah it fouls plugs if you idle much. Nothing real quick, but it will foul them. The issue for mine is that I have to run the idle mixture real rich. If I lean it out, it wont restart when cold. My carb has a very frustrating vacuum fuel enrichment system instead of choke.... Works, but not well. Best solution I've found is to run it rich. Fires up within a few seconds every time at the cost of replacing the plugs once a season.
I took it out today. Wouldn't start. Sprayed starter fluid into the carb, nothing. Choke in/ choke out. Pulled the plug and sprayed the plug and starter into the plug hole. Started up after 20 pulls. Ran it a while higher than idle. then it starts dropping down like it was gonna quit, added throttle and it runs... then starts running fast. drop down the throttle and it runs normal then it drops down like its gonna die, then throttle up and it runs for a while and then ir speeds up again.
Over and over.
Got the dock lines off and left the slip running the engine medium speed and it keeps same speed. Got it to my destination.
Thank you for the encouragement Dave I believe you are right, pull the engine take it home and clean the carb. Learn to service the engine every year or two.
I saw a video where the mechanic put in a bigger carb jet in a 9.9 hp engine carb, from a 40hp.
Ray in Atlanta, Ga. "Lee Key" '84 Catalina 25 SR/FK
Notice: The advice given on this site is based upon individual or quoted experience, yours may differ. The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.