20 hp Honda outboard starting issues

[8ntruck 6,998]

We've got a 20 np Honda outboard on our small pontoon.  This season, it has been hard to start when it is cold.

 

It usually fires right up when cold, then runs 15 or 20 seconds and stalls.  A shot of carb cleaner into the intake is then needed to get it going.  Once warmed up, it starts at the touch of the key.  

 

Yes, I do squeeze the fuel line bulb until it is firm before I try to start the engine.

 

It seems to me like the fuel pump is losing its prime.   We've been busy enough this summer that I have not had a chance to pull it out of the lake to do any disassembly and trouble shooting.  Probably ought to chase the issue down before the boat is put into storage.

 

Anybody got any other ideas of what to look for?

Edited September 5, 2023 by 8ntruck

[OutdoorEnvy 1,522]

Couple ideas…Change the fuel filter or clean it out if you can.  Water in the fuel can cause those kind of problems.  Maybe drain the tank to ensure all fuel is good in it with no water or debris.  Next would be check the fuel lines at their connections for the loss of pressure.  Those get weird angles and can wear over time around the clamps and they aren’t as tight.  Last might be carb cleaning, or if it’s fuel injected run some Lucas injector cleaner with the gas on the next fill up.  
 

keep us updated!  It’s gotta be something!  

[wh500special 2,168]

Choke linkage or electric choke working ok?  
 

Also it’s worth checking or replacing the fuel line quick connector. The O-ring eventually wears out and it can suck air letting the fuel leak down or the pump lose prime.  And they don’t always drip fuel when they leak either. 
 

I was an Evinrude diehard until BRP pulled the plug on them in 2020, but I’ve been won over by the 90-hp Honda on my boat. They are rock solid reliable…which is a good thing considering how few dealers are around for them.  
 

Good luck!

 

Steve

[ri702bill 8,311]

9 hours ago, OutdoorEnvy said:

or if it’s fuel injected run some Lucas injector cleaner with the gas on the next fill up

Good advise - Lucas makes quality products. I am not a believer of "Miracle Mechanic in a Can" addatives, but, B12 by Chemtool does live up to its claim as a fuel system cleaner. Been using it for years.

Bill

[Ed Kennell 38,113]

Signs of a Bad Outboard Fuel Pump & How to Troubleshoot (bornagainboating.com)

[peter lena 8,604]

@8ntruck   first thing I thought was a fuel check valve ,https://www.amazon.com/Mesee-2-Pack-Return-Petrol-Aluminium/dp/B09L1H4JH4/ref=asc_df_B09L1H4JH4/?tag=hyprod-  you can get these in any line size you need , would also add the valve in a VERTICAL  spot  so fuel will always be holding to intake. personally would , swap out the pump also , overkill on starting insurance is what you want . used to have related  horse  starting issues , have these in all my small engines , instant starts , just a suggestion . Pete

[lynnmor 7,303]

Chickanic has a recent Youtube video showing small engines that refuse to start because of bad gas.  It appears that the overpriced canned fuel from the big box stores is useless.  She would simply try to start customers equipment, then swap out the gas and they worked.  In the case of the OP, perhaps he should try fresh gas first thing and see if that helps.

[Ed Kennell 38,113]

16 hours ago, 8ntruck said:

20 np Honda outboard

2 or 4 stroke?          If 2, oil injected or mixed gas?

[stevasaurus 22,713]

Was just talking with my fishing buddy, Ray.  He had a problem like yours with his 9.9 Honda.  Changed the fuel filter and disconnected the gas line at the carb...sprayed carb clean in there.  Also pulled the jet screw out and sprayed in there and the screw.  It ran great after that.  

[wh500special 2,168]

1 hour ago, Ed Kennell said:

2 or 4 stroke?          If 2, oil injected or mixed gas?

4-stroke.  Honda has only ever made 4-stroke outboards.  
 

Steve

[8ntruck 6,998]

It is a 4 stroke.  I am running the same rec. fuel that I run in my horses - non alcohol premium fuel mixed with Seafoam at 8oz to 5 gallons.  After seeing the starting issues, I added another ounce or so to the 3 gallon boat tank.  It has a carb with an electric enrichment system - no choke butterfly.

 

I think the 9.9 hp engine is in the same family as my 20hp.

 

Took the pontoon out this afternoon and discovered that there is a time issue to the problem.  It starts much harder after it has not been used for several days. We had the boat out yesterday.  Needed a shot of carb cleaner to start yesterday.  Today, it fired right up, then died after 15 or so seconds.  Tired cranking it again and got acough and a sputter.  Same thign on the 3rd try.  Was able to catch it and keep it running on the next try with the fast idle lever - no carb cleaner shot needed today.-

 

Research on the internet is pointing in the same direction that your fishing buddy went @stevasaurus.  When I get a chance to pull it out of the water, I am planning on checking the fuel lines, changing the fuel filter, emptying the fuel chamber, and checking the output of the fuel pump.  While I am in the fuel system, I might as well empty and clean the gas tank.

 

The fuel chamber is a do-hicky that lives between the carb and fuel pump that mixes cool fuel from the tank with warmer under hood fuel to prevent vapor lock somehow.   They are said to collect water and cause hard starting.

 

Thanks for the ideas

[8ntruck 6,998]

OK, here is an update.  I asked the boat dealer to take a look at the engine web  I dropped the boat off for storage last fall.  This spring when I picked the boat up, they told me they could not replicate the issue.  Translation - they didn't do any troubleshooting, since the engine runs and starts fine once warmed up.

 

While prepping the boat for this year, I installed new plugs, and fuel filter.  It still had difficulty with a cold start, needing a couple of shots of carb cleaner to get it going. This was happening on alcohol free gas doped with Sea Foam at 8oz per 5 gallons.  Out of desperation, I added a 1/4 cup of ATF to about 2 gallons of gas in the boat.  For several days, I did a cold start on the engine and let it warm up at idle, figuring this was the best way of getting the doped gas through the idle and enrichment circuits with the hope that it would clean them out.

 

It seems to have worked.  I no longer need a shot of carb cleaner to get the engine started.  It usually stalls a couple of times on a cold start before it settles into a steady idle.  Even better, the engine can sit unused for 10 days or 2 weeks and still starts with minimal fuss and no carb cleaner.

 

Still trying to decide if I want to get a spare carb.  I'd install the spare as part of the spring prep, then clean and rebuild carb I removed to be ready for installation at the start of the next boating season.

[wh500special 2,168]

10 hours ago, 8ntruck said:

…  Out of desperation, I added a 1/4 cup of ATF to about 2 gallons of gas in the boat. …

 

Still trying to decide if I want to get a spare carb.  I'd install the spare as part of the spring prep, then clean and rebuild carb I removed to be ready for installation at the start of the next boating season.

if a spare carburetor is cheap, might as well get one to have as an insurance policy that you won’t need it. 
 

The ATF trick is interesting. Is this something of your own making or is this a common thing?   I know the couple of WH hydros that I’ve had apart that had ATF in them were way cleaner than those that had motor oil, so maybe there is something to this…

 

I just picked up a new-ish Yamaha 6-hp 4-stroke that was left with old gas in it for a few years.  Replacement carburetors are cheap for this single cylinder engine but I am tempted to try your ATF trick to see if it will save a teardown…maybe I’ll get lucky if i can get it started then just let it run in a barrel all day to purge it. 

 

The Honda BF20 is a well regarded engine.  It’s one of the lighter 20’s and is apparently has more torque than most.  I’ve met people up in the BWCA who claim the weight penalty incurred by bumping up to the 25 hp class on modern 4-strokes offsets the 5-hp power gain.  Dunno, but seems plausible. 
 

Happy boating!

 

steve

 

 

Edited August 4 by wh500special

[wallfish 16,994]

I've read many things about using the ATF because of the detergents in it. BUT, I've also read that ATF contains much less detergent than motor oil does. I wonder if motor oil would be a better thing to use vs ATF. Probably use dino oil over synthetic. The old 2 stokes specify using 30w motor oil mixed with the gas for them so doubtful it could cause any more problems than ATF.