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.
I have a Honda 8hp, starts fine then quits after a few minutes and starts right back up, over and over. Was in the shop a few months ago for the problem, mech found no problem and I had it fully serviced. I don't believe it's a fuel problem, entire fuel system from the carb to the tank has been replaced including the tank but not the carb. The motor is on the boat in the water so it's not like I can take it back to the shop without paying someone to pick it up and deliver it to the shop.
Try the emergency cut off switch. That's the one with the wrist lanyard clipped to it. See if you can get some WD40 on and into the backside of the switch then work the switch by pulling and pushing it in and out. It could be a corrosion causing the intermittent engine cut out. Costs nothing an worth a try. Also try the main fuse. Take it apart and clean it. It too can have corrosion causing a connect disconnect.
Scott-"IMPULSE"87'C25/SR/WK/Din.#5688 Sailing out of Glen Cove,L.I Sound
Ok that's different. The suggestions I made were if it just instantly shut down. You could possibly have an Ignition Coil going bad. The Ignition Coil sends the spark through the spark plug wires then through the spark plug. it could be working intermittently. Honestly it could be many other things like Emergency Stop switch, Neutral Switch, exciter coil, Pulse Generator, New Plugs, Ignition coil etc. See where i'm going here? You could end up with 100 different suggestions without any of them working. I would suggest a different mechanic but it is very hard for them to figure it out unless it happens right in front of them.
Scott-"IMPULSE"87'C25/SR/WK/Din.#5688 Sailing out of Glen Cove,L.I Sound
Thanks for the advice. Until today it would sputter for a few seconds then quit. Today it would just stop. I'll find a different mechanic and get his input.
On my Honda 8 I had a problem with the fresh water hose adapter on the thermostat housing. It has a spring and ball valve that normally keeps the port closed, however, the spring loosened up and some seawater leaked out of the port right onto the spark coil. One spring a few years back I noticed I wasn’t getting spark, so I investigated. The coil was rusted out and shorted, so I replaced the coil, the retainer bolt and the thermostat housing, ball and spring. Worked fine thereafter but it was pretty obvious what the original problem was. Do you have the Honda maintenance guide books? Pretty darn helpful.
Thanks Voyager, I had a similar problem a few years ago with seepage from that fresh water input on the thermostat housing. Rather than replace the housing I keep a bolt with an O ring there to prevent the seepage when I'm not flushing the motor. I'll take a look at the coil. I've bookmarked that link, good website.
Just a thought ... Honda sells a carburetor rebuild kit. I did a rebuild about 7 years ago. Before rebuilding the carburetor it would not idle, however, it would run at normal driving speed. Afterwards, the engine idled just fine. It’s still working 7 years later.
That said, there are several systems built-in to this engine that could make it spuriously behave in this manner. The kill switch lanyard switch may be going bad. The circuit feeding to the spark coil could be intermittent. The magnetic “Hall Effect Switch” on the flywheel that tells the engine computer where top dead center (TDC) is could be bad.
You could sell the engine for parts (I might be interested) or just scrap it, but if the crankshaft mechanism is still tight and she’s not burning oil, I’’d be inclined to repair it. Aside from bringing it to the shop, you might see if you can still obtain the maintenance manual. I. Inherited one and it quite literally shows you each functional section and discusses the methods for disassembly and reassembly in the manual.
Troubleshooting may take some effort. Looking for electrical faults with a multi-meter in an engine that’s running without a cowl over the side of the transom is a sign of insanity. I see a few denizens of my harbor doing this each year. Having an engine that weighs over 100 lbs is also nuts if you want to remove from the boat and test it in a barrel.
The things we do for love ...
Bruce Ross Passage ~ SR-FK ~ C25 #5032 Port Captain — Milford, CT
I hear ya Bruce. I have over $2000 into this repair on a motor I paid $2800 for new 15 years ago, has less than 500 hours on it, I've maintained it as per the manual. I've reached the point where I don't want to keep throwing parts at it, if the carb isn't the problem I'll see what the repair shop will give me for it on a trade in. It's been fully serviced at the shop and a new bottom end put on so the only problem is it won't run properly. I've been dealing with the problem since August and I'd really like to get out sailing.
That’s a completely different story, I didn’t realize that you’ve been dealing with a constant problem with the engine. I’d agree that if the carb doesn’t do the trick, it’s time to move on. Life’s too short! Good luck with however it turns out.
Bruce Ross Passage ~ SR-FK ~ C25 #5032 Port Captain — Milford, CT
Problem finally solved. Local dealers have told me that new motors are almost impossible to find due to the covid shutdowns this year but I located a new Honda 9.9 at Outboards Online. It's in my garage awaiting transport to the marina to be put on the boat. It's not easy removing an outboard and installing a new one while the boat is in the slip but I'll find some help. Never have discovered why the old Honda 8 won't run but it will be in the garage on a stand and easier to work on, not putting another cent into it though.
Thanks for the follow up. So many of these posts just end up without an ending. I suppose with the shortage of new engines it makes engines hanging on the back of boats very tempting.
Scott-"IMPULSE"87'C25/SR/WK/Din.#5688 Sailing out of Glen Cove,L.I Sound
I just saw this thread... A competent mechanic can figure out whether stalling is due to fuel or spark. It's one or the other. These engines aren't rocket science. Hondas and other 4-strokes are also prone to stalling at low throttle because of a clogged (very small) idle jet in the carb, but that doesn't sound like your situation.
The apparent predictability of this stalling suggests to me air leaking into the fuel delivery system at one of many connections inside or outside of the motor. This problem causes stalling after a brief period (length depending on the leak) followed by restarting after a period, and then repeating. Electrical issues are generally less predictable--especially in the ability to re-start.
Sorry you got to the point of buying another motor... I think there's a good chance you can make your "old" one a working, salable Honda--possibly with the replacement of a clamp, hose or gasket.
Dave Bristle Association "Port Captain" for Mystic/Stonington CT PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired), Now on Eastern 27 $+!nkp*+ Sarge
Dave, that was my first thought when I read Steve’s post, however, he reported that “ I don't believe it's a fuel problem, [the] entire fuel system from the carb to the tank has been replaced including the tank but not the carb. ”
This would include the fuel hose and the fuel connectors where air can easily ingress...
Bruce Ross Passage ~ SR-FK ~ C25 #5032 Port Captain — Milford, CT
Yup, but all it takes is something like a damaged or missing O-ring on a connector. No need to ask me how I know...
Dave Bristle Association "Port Captain" for Mystic/Stonington CT PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired), Now on Eastern 27 $+!nkp*+ Sarge
My Honda 9.9hp is about 15 years old and running fine right now. During it’s lifetime, I have had 1 minor and 1 major issue. Of course, all issues are major until resolved. The first issue occurred perhaps 10 years ago and turned out to be a hairline crack in the face of the hose line fuel connector that plugs into the outboard - Replaced the connector solved that issue. Last year, my outboard was plagued with hard starting. Oftentimes, it would inially start okay and I would leave the marina and go sailing. But then when returning to the marina, that was usually when it would be hard starting. Then weeks later, it was hard starting initially as well. I had a mechanic work on it at the dock and after changing out spark plugs, fuel filter, draining the carb, etc things, the outboard still had issues and so the carburetor was then replaced. The outboard seemed better for a few weeks but I started having the same issues again. This time, I decided to bring the outboard into the Washington Marina, oldest marina in the DC area and also where I initially bought my outboard. They ultrasonically cleaned the carburetor (which supposedly was new...maybe rebuilt?). In any case, that solved the issue. There are so many issues that can eventually plague these outboards and sometimes very hard to resolve.....and especially if it turns out to be the electronics which hopefully is very rare an issue. Anyway, just sharing my experiences. It has been running fine this past season - Just moved my boat further south on the Potomac River and motor ran flawlessly for 6+ hours.
Thanks everyone for the input. I hope to get it on the stand in the garage soon and take another look at it. All an engine needs is fuel, air and spark in the right combination, I hope to resolve the issue and put it on Craigslist.
You know, it’s funny that if you have 1 problem with an engine (or computer or car or any complex device), it’s generally easy to repair the damn thing. You just have to figure out, or take a lucky guess, at what the root cause problem is. But, if you have two (or more) problems at the same time, solving the problem become 4 times more complicated. For example, you have a kill switch intermittent plus a fuel air leak. You can spend countless hours and dollars working on this. Hopefully Steve demand for used engines is strong enough that even a partially running engine will be saleable.
Bruce Ross Passage ~ SR-FK ~ C25 #5032 Port Captain — Milford, CT
I’ll just stick with my 31 y.o. 8hp oil injected 2-stroke Suzuki that starts on the 3rd pull every time. Might smell a little if the winds just right but it’s been very reliable.
BTW... unlike most, I’ve always liked the smell of 2 strokes. Reminds me of being a kid and being on the water with my dad.
Big-throated carb, 3 simple moving parts... what can go wrong?
Dave Bristle Association "Port Captain" for Mystic/Stonington CT PO of 1985 C-25 SR/FK #5032 Passage, USCG "sixpack" (expired), Now on Eastern 27 $+!nkp*+ Sarge
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.