1982 Johnson 70 takes off strong then falls on face

[safetysam1]

my 70 horse Johnson takes off great for a short while then it "loads up" and falls on its face.
It seems to start and idle just fine but under load it just doesn't take off.
I don't think that it is a fuel problem because I use the same tank for my trolling motor and it seems to
run correctly and the fuel is fresh and mixed correctly.
Any help would be great!
Thank-You in advance

 

[racerone]

Re: 1982 Johnson 70 takes off strong then falls on face

What happens when an assistant operates the manual fuel pump ??

 

[boobie]

Re: 1982 Johnson 70 takes off strong then falls on face

What happens if you hit the choke ??

 

[safetysam1]

Re: 1982 Johnson 70 takes off strong then falls on face

Thanks for the reply,
If I hit the choke it dies right away.

 

[safetysam1]

Re: 1982 Johnson 70 takes off strong then falls on face

I'm not sure if this got posted but I am not aware of any manual fuel pump.
Would you please inform me of where I can locate it on a 1982 Johnson 70?
Thank-You.

 

[kbait]

Re: 1982 Johnson 70 takes off strong then falls on face

Manual fuel pump would be a reference to the primer bulb..

 

[emdsapmgr]

Re: 1982 Johnson 70 takes off strong then falls on face

When the engine bogs on the water next time, try a test. Have a buddy constantly prime the fuel hose bulb. This will force extra fuel into the carbs. If the engine runs normally and ok at WOT as long as you constantly prime the fuel hose bulb, you have a fuel supply issue. Possibly a weak fuel pump, but it could be a bad fuel hose.