Fuel starve need help

[wavefisher]

I need help diagnosing a problem, here are the symptoms. The engine runs fine at lower speeds but won't run full speed. If I slightly choke it the motor runs better but still not quite full speed. While the motor is running the bulb is completely soft, not sure if that is normal. After shutting down I can pump up the bulb, it seems to restart fine. It came on suddenly, I ran from one end of the lake just fine, fished an hour and when trying to return it started doing this. I have a new fuel pump on order and am considering replacing the fuel line and bulb. Any suggestions?

 

[tinkerguy70]

Re: Fuel starve need help

I would suggest you share a little more info so others can help you.
To start with, what make and model the motor are you talking about.

 

[wavefisher]

Re: Fuel starve need help

It's about a 87 40hp 2cycle mariner outboard

 

[Chris1956]

Re: Fuel starve need help

Check the antisiphon valve in the fuel tank pickup, for clogging. Check/clean/replace all fuel filters. Check/clean the fuel tank vent. Retest.

 

[wavefisher]

Re: Fuel starve need help

I cleaned the carbs, fuel lines, and put a new fuel pump in and it ran great for about a mile, then it slowly lost rpms and would bogg down at full throttle. At least the primer bulb seems to be holding its prime now. When running full throttle it runs pretty good at about 1/4 choke but no choke it Boggs down and seems to "pulsate" or will pick up briefly then bogg down again constantly. Not sure what to try next. I did try to adjust the jets( 1 on each of 2 carbs is all I found) but only made it idle worse. Any other ideas?

 

[bgc]

Re: Fuel starve need help

Is the fuel fresh? Like that week?
Check compression. Get manual.

 

[quicktach]

Re: Fuel starve need help

Check for air leaks between carb and manifold ....tighten if loose .... Is your linkage moving the throttle plates to full open ..and holding them there ?

 

[wavefisher]

Re: Fuel starve need help

I'll check all that in 2 weeks when I am up north at my boat. I did, without it running open the shifter up and a couple of times the throttle plates did seem to slowly close on their own, then I would back the throttle off and push it forward all the way and they would fully open and stay there. Then I had my wife drive it, with the cover off, and I looked inside, the throttle plates are fully open and stay there. I can get it go 22-24mph, 27-28 was tops, just when I give it that last push, when the throttle plates fully open, in gear with resistance on the motor, out of gear it winds up just fine. It doesn't seem to have quite the pick up either.