2005 Honda 5hp bogging down hard start brand new carb.

[tsawyer123]

Hi guys hope someone will chime in I really could use some help. I bought a 5hp from an old guy had been sitting for years in his garage thing looks brand new. I put it on my 9 ft boat and went for a test run first off was hard to start got it running and idling went to throttle up and it just boggs down. I took the carb off and it was clean as a whistle but I cleaned it anyway same thing. I have been an auto tech for years and did all the testing had good spark good compression and clean fuel. The carb was 100 bucks on amazon so I gave it a shot same thing hard start idles ok no power have no clue .

 

[Sea Rider]

Welcome to Iboats,

Put a new plug gaped to factory specs. Go for a wot run and report back if booging down has been resolved. If not, probably it's an electrical failure, component heats up, shorts and OB fails. That model has individual ignition coil and CD, or it's one sole piece IC/CD unit. ?

Happy Boating

 

[tsawyer123]

Thanks for the response .It has a brand new NGK bp5es gapped to specs compression test results were 110 psi after 3 pulls carb is brand new. It does this on start up cold or hot getting very frustrating I would think if electrical it would be worse hot after heat soak but it does it right away. I can hand throttle it with no lad and get to about half throttle then dives on it's face. The plug looks a little rich when removed but I would expect that . I build and restore classics so I know my way around engines but this one is starting to chap my but. Any help would be greatly appreciated.

 

[Sea Rider]

When OB is running on muffs while in forward gear, as you open throttle, does OB gives exact same symptoms ? Would you say that while OB is under load, that's powering a boat, the symptoms gets worse ?

Happy Boating

 

[tsawyer123]

Pretty much exact same thing maybe a little worse in the water I am at a loss have checked valve clearance 10 int 15 exh good they sent me another carb doing same thing they also allowed me to remove the air fuel mix plug . I removed the plug and tried to adjust the mixture made no difference I could bury the mixture screw and mad no diff in running backed it out no diff . I have been building engines for years and this is driving me crazy I get to half throttle then it fall's on it's face there are no repair shops close so I'm stuck with no out. This thing has very low hours on it and is clean as a whistle inside it has been sitting but will start right up idle fine and run to half throttle open it up and blahhhhh any ideas ?.

 

[Sea Rider]

If you are sure all mechanical parts are working 101% spot on, could be an electrical failure, component heats up, shorts and OB misses, gets worse at load. That OB uses independent Ignition Coil, CD units or it's a dual single pack unit ? Seems will have to troubleshoot that OB electricaly with a good multimeter. Do you have the electrical specs of each component to do so ?

Happy Boating

 

[tsawyer123]

No I just ordered a manual I would think if it were electrical it would only fail after heat soak it does it cold or hot driving me nuts as this thig is like brand new just sits allot

 

[Sea Rider]

If it's brand new and with manufacturer warranty, send to dealer. Let him blow his head out..

Happy Boating

 

[isaksp00]

Maybe take a look at the fuel pump?

 

[Sea Rider]

Is it an internal, internal & external fuel tank or only external tank model ? If external and suspecting it's a fuel pump related, prime fuel bulb gently while having issues, if issues continues, it's not a fuel pump failure. Is complete fuel circuit tank to fuel pump immaculate clean ?

Happy Boating

 

[tsawyer123]

Is it an internal, internal & external fuel tank or only external tank model ? If external and suspecting it's a fuel pump related, prime fuel bulb gently while having issues, if issues continues, it's not a fuel pump failure. Is complete fuel circuit tank to fuel pump immaculate clean ?

Happy Boating

​I have tried using the primer bulb while eng is running no difference I opened the fuel bleed off while running has a steady stream of gas has had three carbs all new all same thing I am at a loss and the closest dealer is 2 hrs away it is not brand new but has been used very little. Good compression good spark good fuel delivery doesn't make sense to me.

 

[Sea Rider]

Does OB misses same when not at load, say on a stand and running geared at idle/fast idle speed ? If running OK without load does not means will run same while pushing a boat.

Electrical components can fail at any time, have 3 conditions: Works spot on, are kaput, or have erratic intermittent issues, which are the worst to diagnose if not having electrical parts to swap, test and confirm.

Happy Boating

 

[tsawyer123]

This thing cant be that complicated I can't imagine anything electrical to cause a bogging issue is there anything that controls timing advance ? they want a 100 bucks an hr to work on it crazy it's just a lil 5 hp.

 

[Sea Rider]

You'll be suprised how an electrical issue can bog an OB down when full electrical requirements are needed to run around or wot range. That 5 HP should have a fixed timing advance.

Happy Boating