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2003 Honda 90hp Never starts on key turn have to push throttle down even when warm?

B

Baltimore Dave

New member
I have a 2003 90 hp that runs like a top. Recently it has become more difficult to start as I always have to push the throttle down to start it. In the past this was always the case when it was cold but after the first start I was always able to start by just turning the key for the remainder of the day. I did notice that I have a "PRI" diaphragm assembly attached to the throttle that I believe controls the priming for starting. It has what looks like a vacuum hose on the top and should pull up the throttle when the engine is cranked. Do these go bad? Is there a way to test the part or the vacuum level of the hose? Any help would be greatly appreciated.
Thanks,
Dave
 
The diaphragm you are referring to is a dash pot, it causes the throttle to return to closed position slowly as opposed to snapping shut and causing engine to stall, this does not have any effect on idle quality unless the diaphragm ruptures. To test, simply suck on the hose and see if it holds a vacuum. Your cold start is enriched by mechanical butterfly valves. The early 90's had a problem with the bottom choke butterfly spindle corroding a seizing, check and make sure that all the chokes are opening fully as you may be getting a rich mixture at start up when hot thereby requiring throttle to allow more air into the intake.
 
Thank you very much for your response and info. I did not quite understand how the engine primed itself for starting. I will check that vacuum line as you suggested however that now does not sound like the cause of my problem. I just had my carbs removed, cleaned and rebuilt for the first time in June of this year because I was experiencing a rough idle. I had it done by a authorized Honda dealer and when it was returned the engine ran fine top end and at idle. However I have noticed now that even if I turn off my engine for a very short period of time (minutes) it will not start by just turning the key. I must now manually give it gas by pushing down the throttle first before turning the key. I did not have this problem before my carbs were rebuilt. In the past if I stopped to fish for a hour or two and went to restart I would have to give it gas as I believed the engine cooled and maybe lost some pressure in my gas supply but if I turned it off momentarily it would always start just by turning the key. That is why I thought it just maybe a adjustment required that was possibly altered during the carb rebuild process. I would assume that the dealer would have noticed corrosion on the butterfly spindles but I cant be sure of that. Can I inspect the chokes on the carbs without removing the entire carb manifold? Can the air intake cover be removed to see the front of the carbs and the butterfly valves?
 
Thank you very much for your response and info. I did not quite understand how the engine primed itself for starting. I will check that vacuum line as you suggested however that now does not sound like the cause of my problem. I just had my carbs removed, cleaned and rebuilt for the first time in June of this year because I was experiencing a rough idle. I had it done by a authorized Honda dealer and when it was returned the engine ran fine top end and at idle. However I have noticed now that even if I turn off my engine for a very short period of time (minutes) it will not start by just turning the key. I must now manually give it gas by pushing down the throttle first before turning the key. I did not have this problem before my carbs were rebuilt. In the past if I stopped to fish for a hour or two and went to restart I would have to give it gas as I believed the engine cooled and maybe lost some pressure in my gas supply but if I turned it off momentarily it would always start just by turning the key. That is why I thought it just maybe a adjustment required that was possibly altered during the carb rebuild process. I would assume that the dealer would have noticed corrosion on the butterfly spindles but I cant be sure of that. Can I inspect the chokes on the carbs without removing the entire carb manifold? Can the air intake cover be removed to see the front of the carbs and the butterfly valves?
 
If a Honda dealer gave it back to you like this then I would be taking it back to them. Those motors should not need any throttle to start once warmed up. To check the chokes you simply flick the choke link bar up and down and carefully watch to see if they all snap open freely , focus on number 4 ( bottom one) which is the one prone to seizing.There are other factors that can cause your issue such as valve clearance, running cold ( thermostat stuck open ) , fouled spark plugs as well as fuel.
 
That is interesting that they should not need to be pumped to start. My 1998 BF90 often needs a couple pumps on the throttle when starting. If it does not start within a second or two, then I pump it once or twice while the engine is cranking and it fires right up. I recently rebuilt and balanced the carbs, as well as new fuel pumps , fuel lines, fuel filters, fuel couplers, and fuel tank.

This is my first Honda engine so I really don't know what it is supposed to do. Also, I my engine may be a special case since it had not run in 12 years, before I bought it and got it on the water this summer.

I had always just racked it up to being carbureted rather than fuel injected, but it sounds like this is not the case?
 
Your choke is activated by a switch in the control box which in turn is activated by lifting the warm up lever all the way up, when doing this you should here the choke engage, pumping the choke mechanism activate
 
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