Seem like starving for fuel?

[halfor]

Looking for some info, I believe I am not getting enough gas to the motor. My reasoning is that with muffs on I start and idle nice, rev up nice. In the lake it was same thing except at WOT I?m doing trolling speed with a little bog down (no spitting or sputtering), if I increase throttle slowly you can fell it start to increase then kinda give out and hold the slow speed. I had my wife pump the ball while we were going and there was no change, she mentioned the ball didn?t fell hard. I also had noticed this or thought I did after she mentioned it. I also switched gas tanks in case the vent wasn?t working and no change (both vents were open). The weather was not so good so we just pulled it out and parked it. While parked I put the muffs on and as before all seems good, but the ball is not hard, there was no leaking fuel or any smell of fuel after many pumps on the ball (not sure if this is common). I pulled the line at the motor and pumped the ball no change in firmness, I pushed in the stopper ball and let some fuel out from the motor end of the hose then pumped the ball, it went hard like I remembered. Could I have just fixed the problem? I have to trailer to a lake to see if this is fixed, not fun if it?s not. Has anyone ever had similar issue?
Other questions are: this is last years gas it was treated with stable but would bad / old gas fit the description? When my motorcycle has carb issues like high jets plugged, I don?t just loose power I get popping and chugging wouldn?t this be the same or an outboard?
This is a 78 mercury 700 70hp

Thanks in advance.

 

[ajgraz]

Re: Seem like starving for fuel?

From your description, presumably the tank, fuel lines and primer bulb are OK.

Sounds to me like the inline fuel filter may be totally clogged, or (more likely) one or both of the needle valves in the carbs are sticking shut. When's the last time the carbs were disassembled and cleaned?

 

[hotrod53]

Re: Seem like starving for fuel?

If you can't get a hard primer ball, something is wrong right there. Ethanol eats up our rubber fuel lines, I would start with new fuel lines and a primer ball. Without the ball getting hard it has to be air in the line, otherwise the fuel has to be going somewhere. Once the carb bowls are full, the needles rise and shut off flow, either that or it runs over somewhere which sounds like you're not. Another possibility is that the floats are sinking but that would flood the engine or run the carbs over.

I'd start with all new rubber ....

 

[halfor]

Re: Seem like starving for fuel?

Thanks for the info, I have had the boat in the water 3 times over the last year, this is the extent of my boating experience. Last season it ran fantastic after a few wiring issues but nothing has been done to this boat in several years, it spent the last 10 years mostly in a garage getting out once or twice a season. The fuel lines do look older than the ball. I could not get the ball hard until I disconnected the fuel line from the motor, depressed the stopper and forced gas thru by pumping the ball, after some gas came out the ball got hard (don’t remember if I tried just pumping after disconnecting). The mention of the ball can’t get hard because of air in the line makes sense, but now the tank line disconnected has a hard ball leads me to believe it doesn’t leak and I need to look at the fuel lines inside. I do recall thinking the lines look stiff and rigged. Having never seen them before I did'nt think much of it, now I am guessing this is not what they should look like. I did some searching and I cannot find the part numbers that my parts list suggests, so does one just buy bulk line? A few post here mentioned that they are pre-formed and will kink unless they are??
Thanks