1976 merc 165 horse hard to start, runs solid but bogged with speed loss

[Bonafide]

Heres the lowdown. Ive had the boat out all summer and ran fine.
Had it out last weekend, ran perfect all day then at the end of the day i had to crank it forever to get it started . Checked the gas and we were very low so i just figured we were out of gas. Trailored it until the next weekend when i filled her up and put her in again. This time we probably cranked it for five minutes before she would start. I figured out if i hold the key for about 20 seconds while giving throttle she will start. When it does start ive got to give her throttle to keep idleing. but then when i throw her in drive she will putt all day long at 2100 rpm, when i try to increase throttle it makes a "motorboating" sound slightly increasing rpms but not speed. If i shut off warm shell start right back up, but when we sit and fish its back to cranking.
Oil pressure and temps are golden, she ran like a dream the week before.
Does anybody know what might be goimg on, any help would be greatly appreciated
Thank you.

 

[Don S]

Re: 1976 merc 165 horse hard to start, runs solid but bogged with speed loss

Sounds a lot like water in the fuel. Do you have a water separating fuel filter? If so, remove it and empty the contents into a clear container and see what's in the flter. DO NOT reuse that filter element, install a new one.

 

[Bonafide]

Re: 1976 merc 165 horse hard to start, runs solid but bogged with speed loss

Sounds a lot like water in the fuel. Do you have a water separating fuel filter? If so, remove it and empty the contents into a clear container and see what's in the flter. DO NOT reuse that filter element, install a new one.

Thanks for the reply Don. Im guessing the thing (with the screw on top) below the distributor is the fuel filter ? how do I take it off ?

Appreciate the help thanks. -Corbin

 

[Bondo]

Re: 1976 merc 165 horse hard to start, runs solid but bogged with speed loss

Thanks for the reply Don. Im guessing the thing (with the screw on top) below the distributor is the fuel filter ? how do I take it off ?

Appreciate the help thanks. -Corbin

Ayuh,... Welcome Aboard,.... I'm guessin' yer describing a 6 cylinder 165 hp motor, a Chevy,..??

That would be the fuel pump, which does have a filter inside it, though not a water separator type...

There's probably another filter in the carb's inlet too...

Ya oughta Add a canister type like Don's talkin' 'bout....

 

[Bonafide]

Re: 1976 merc 165 horse hard to start, runs solid but bogged with speed loss

Ayuh,... Welcome Aboard,.... I'm guessin' yer describing a 6 cylinder 165 hp motor, a Chevy,..??

That would be the fuel pump, which does have a filter inside it, though not a water separator type...

There's probably another filter in the carb's inlet too...

Ya oughta Add a canister type like Don's talkin' 'bout....

Yea chevy 250, do I still need to change the filter in the fuel pump.
Do I just add the canister type to the gas line before the pump?

Also there is a vent just below my fill cap that has a line running to the tank, I think this might be lettin the water in. common sense says cut the line under the deck where water cant get down it, good idea or not? or somethin Dont want fumes...