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50hp mercury (3cyl) bogging down

N

nairboading

New member
Hey,

I am new to the forum, i have a 1050412 mercury OB motor, believe it is a 2001 or so.
Has always been a great motor, but this season i am having an issue.

i don't think i have ever had to squeeze the primer bulb, this season it seemed i had to, to get it to start. which may be totally unrelated, but figured i would mention... After starting it seemed great. After getting up to speed, it started bogging down, and loosing power, i was expecting it to die, then suddenly it will pick up and power again, and continue to do this.
I can let off the throttle and it seems ok, until i rev it up again and it will eventually start to loose power again.

It seems to be like its starving for fuel possibly? I started reading about the fuel pump diaphragm, but before i go that route i was curious if anybody had anywhere else i should look first?

thanks in advance
 
nairboading said:
Hey,

I am new to the forum, i have a 1050412 mercury OB motor, believe it is a 2001 or so.
Has always been a great motor, but this season i am having an issue.

i don't think i have ever had to squeeze the primer bulb, this season it seemed i had to, to get it to start. which may be totally unrelated, but figured i would mention... After starting it seemed great. After getting up to speed, it started bogging down, and loosing power, i was expecting it to die, then suddenly it will pick up and power again, and continue to do this.
I can let off the throttle and it seems ok, until i rev it up again and it will eventually start to loose power again.

It seems to be like its starving for fuel possibly? I started reading about the fuel pump diaphragm, but before i go that route i was curious if anybody had anywhere else i should look first?

thanks in advance
Click to expand...

also, when it surges, it seems to slowly loose power and slow down on RPM's, then like a jolt it picks back up for a second or two and slows down rpm's again.
 
"i don't think i have ever had to squeeze the primer bulb, this season it seemed i had to, to get it to start. which may be totally unrelated, but figured i would mention"
usually you have to prime the motor every time you start it, since now you do maybe the fuel pump components are dirty or the diaphragm has a hole in it - when did you check/replace it last?
 
racerone said:
Run with timing light hooked up one cylinder at a time.----Observe the light when motor acts up.
Click to expand...
Very difficult to do this, but did yesterday when i took the boat out. I couldn't tell any difference in the flash of the light while it was bogging down. However i was holding on trying to not fall off as the boat starts surging :)

Quicksilver said:
"i don't think i have ever had to squeeze the primer bulb, this season it seemed i had to, to get it to start. which may be totally unrelated, but figured i would mention"
usually you have to prime the motor every time you start it, since now you do maybe the fuel pump components are dirty or the diaphragm has a hole in it - when did you check/replace it last?
Click to expand...

I was leaning to this as well. I have had the boat about 5 years or so and have never replaced it. having trouble deciding the kit i need based off my SN, so will be making some calls today.

thanks!


I was able to get all around the lake yesterday as long as i stayed at a slow speed, "trolling" speed it never cuts out, but giving any sort of gas and holding speed it will start to bog and surge after a minute or so.
 
Last edited:
Update:

waiting on fuel pump rebuild kit to come in as well as the main fuel line from tank to engine.

Still had the same problem this weekend with full tank of new 100% gas.

Noticed after getting home and pulling long white fuel filter (only one i find) it was full of gunk that looked almost like sand. so started up in driveway ran it 5 minutes and pulled filter again, same thing full of gunk.

I have a plastic tank, where should i start, obviously the gunk is stopping things up!
 
faztbullet said:
Cut the fuel line from tank in two...if it has the liner inside it sounds like its degraded and comming apart..
Click to expand...


bingo, thanks for the help it was coming apart or was full of tarnish.... it was almost completly stopped up! new line and changed filter and runs like new again.

does the main gas line need a check valve? i bought OEM mercury line and i dont believe it has one.
 
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