?? Fuel problem or not ??

[alandchris]

'04' Merc 9.9 HP electric start.

New Carb, new fuel filter.
Original boat fuel lines and bulb primer.

Issue: starts perfect, idles perfect, but bogs down with any amount of throttle.

I let the motor idle, and took the fuel hose off that feeds the carb - the fuel appears to be coming out with a healthy amount - however - the fuel amount "pulsates" - I thought this was a normal condition. Question - should the fuel come to the carb in a consistent flow or pulsate?

I've read contradicting opinions in other posts - reason for my question. Things like spongy hoses create a pulsating fuel issue. I believe my fuel vent is thru the fuel cap and that filter is clean - I even opened the cap to vent 'better' - no change.

I plan to change the fuel hoses along with the primer bulb as well has rebuilding the fuel pump with a new diaphram - I would think that I would get a bog in a higher "throttle position" rather than all throttle positions, given that there is fuel getting to the carb.

Please,,, your thoughts on the above.

Thanks - and... happy Monday.

 

[rickdb1boat]

Re: ?? Fuel problem or not ??

The fuel flow will pulse. That the nature of the pump. since it works off of crankcase pulses. To eliminate the pump as the problem, try pumping the bulb when you accelerate and see if it helps. Do you have good strong spark at the plugs?

 

[alandchris]

Re: ?? Fuel problem or not ??

yes - i have spark on both new spark plugs with the correct gap - the symptom seems like it points to the parts in the float bowl - ie no gas getting into the chamber when throttling up. There is the plastic float that rides on a small bar that is screwed to the bottom of the inside of the carb and freely moves up and down - also attached to this is something I think is called a pin float - looks like a miniature silver sharpened pencil in shape ( now that's a technical description by the way )

All the jets are clean etc... I wonder if the float should have some spring on it - it just moves freely up and down...

the speed jet is new - it's a '45' size and it's fully seated under the main jet. Knowing motorcycles that have this jet set at a certain "clip" which varies the depth of the jet - I thought there might be an issue there - but the carb does not appear to have this - it just screws all the way down, then the main jet screws all the way down as well.

 

[alandchris]

Re: ?? Fuel problem or not ??

As a side note to my previous post - the pumping of the bulb while accelerating does not change the problem - I may change the carbueretor - but ... if for whatever the reason the carb is NOT the issue (yes I know it sounds like it) can it possibly be a timing issue or ignition issue - would I check the stator or something else - I do have spark while idling - holding the spark plug about a 1/2 inch from the block shows a spark jump.

 

[alandchris]

Re: ?? Fuel problem or not ??

ttt