Honda carbed 75 help!

JackCB

Cadet
Joined
Oct 20, 2009
Messages
25
I have a 1996 carbed 75 Honda. It looks new and I keep it as good as I can. Did have an issue with ethanol last year and had carbs rebuilt, tank pumped clean and now use regular gas and run a 10 micron filter. The motor was running the best it ever has......until today. Was out on the river when she idled down on her own, ran rough and almost stalled. My first thought was fuel because of the previous issue. Had wife hold onto dock while I unscrewed filter and emptied into container. Fuel looked clear and fine. Was able to get started and headed back to dock. Got her up on plane but at wide open throttle would only do 24mph [normally 50]. Once in a while she would surge to wide open and run fine for a few seconds then cut back down again. I could tell she was running rough like on 3 cylinders instead of 4.

Back home I first checked the plugs. There was one that was not snapped on tight but did not make any difference in running when I snapped it in fully. I pulled all plugs and they looked fine. I then pulled one at a time with engine running. For some reason the bottom plug caused engine to stall when others did not. Not sure why.

Then I drained each carb into a glass jar thinking some crap got into carbs from the line between filtyer and engine. All fuel was clear. There was one strange thing. I started at the bottom carb and worked up. When I got to the top carb there was no fuel to drain. I don't ever remember that happening before. Is it possible one of the fuel pumps is to blame? It looks like one [there are 2] pump handles 2 carbs. Would appreciate any suggestions from those with a pay grade higher than mine before it goes to the shop.
 

mark b1924

Recruit
Joined
Jun 1, 2011
Messages
3
Re: Honda carbed 75 help!

can only be fuel ,spark, bottom crank shaft seal or lack of compression. test spark, then spray fuel into carb see if it picks up if no compression test.
 

hondon

Lieutenant Commander
Joined
Jun 11, 2001
Messages
1,922
Re: Honda carbed 75 help!

You will need to isolate the problem from fuel to ignition.When this is happening take a timing light and CAREFULLY run that inductive pickup up and down the plug wires and the light pointed at your face and your wife,girlfriend,buddy,teenage kid,holding on to your belt.We do'nt want to see you rolling off the back of that boat.Ignition failures are rare with these engines so keep that in mind.Fuel pump may be more of a focal point but much easier to troubleshoot.At the point of failure pump the primer bulb and see if things bouce back.If so you know you have a fuel pump or delivery issue.
 

JackCB

Cadet
Joined
Oct 20, 2009
Messages
25
Re: Honda carbed 75 help!

Well, I sucked it up and took it to mechanic today. He called and said that I needed a new coil. Could not find it locally so had to order over internet. I did ask why there was no fuel in the top carb when I drained them but he basically said, one thing at a time. I find it hard to believe that two things happened simultaneously so am hoping he is right on his diagnosis. Coil was $104.
 

Solmar

Cadet
Joined
Jun 1, 2011
Messages
6
Re: Honda carbed 75 help!

Ignition promblems rare on fourstroke hondas from my experience. IF You drained your carbs and the one carb bowl was empty the needle could be stuck not allowing fuel to enter carb bowl. I wonder how he came up with the coil "diagnosis"? Dont letem tell you later it was a coil and a bad hose or some B.S. Its fuel or ignition...
 

JackCB

Cadet
Joined
Oct 20, 2009
Messages
25
Re: Honda carbed 75 help!

I will be honest that the diagnosis is a concern as a Honda mechanic on another forum has stated that these coils must be tested properly or else it will appear as if they have failed.
 

JackCB

Cadet
Joined
Oct 20, 2009
Messages
25
Re: Honda carbed 75 help!

Well, I had the coil replaced and everything is running fine. Could there have been nothing wrong with the coil and the problem was a stuck needle valve. I suspect that I will never know.
 
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