Logo

bad primer bulb?

Jstep89

New member
hi. i have been having problems with my mercury 200 20hp outboard. if doesnt want to stay running. i first changed the fuel pump and it needed to be done but it didnt eliminate my problem. i then noticed the original float in the carb was cracked and hanging up on the side of the fuel bowl so i replaced that. now the motor rus good but stalls after about a minute of running. i can watch the fuel in the fuel filter (inline filter that i installed) run down as the engine runs.

i will add that when i prime the engine, the bulb gets firm and the filter fills up, but then it looks as if the fuel drains back into the tank shortly after. the bulb only remains firm for about 30 seconds before there is no fuel left in it. is this normal and if not, would it cause my symptoms?

thanks
 
The primer bulb will NOT stay hard with motor running--that is normal.

I suspect your fuel pump is not set up correctly (easy to goof up--don't ask!) or the gasket between the carb and block does not have the hole in it (for vacuum) aligned correctly.

On the fuel pump: The "check valves" consist of a thin rubber sheet that is supposed to be backed up (like a spring) by that gold fabric piece. Leave either one out--or assemble them assbackwards--and the pump doesn't work right.

Jeff
 
the fuel tank is venting, that was the first thing i checked

im pretty sure i did the fuel pump right (did it twice) but ill look at it again. as for the carb gasket, i replaced it when i did the fuel pump because it was damaged and i made sure the holes were alligned but ill re check that too.

as for the primer bulb, it will run completely empty back into the tank (engine not running) in less than a minute after primimg. is that normal?
 
Try this (which saved my butt last year): Replace your fuel hose with clear plastic hose (the reinforced type sold at True Value). You will then be able to SEE what's happening in the fuel system--it'll be very obvious! If you see the fuel "falling" back to the tank before the primer bulb, that says there's an air leak in that area.

Note: The pump won't pump with a bunch of air in the hose--that too can be seen with the transparent hose. Also, the hose MUST go uphill continuously from the tank to the motor (as I learned the hard way). Any down dip in the line will screw up fuel delivery.

Jeff
 
Last edited:
okay i may try that too. it makes sense to be able to see if you have air in the line. i may go ahead and replace the primer bulb and connectors anyway. i can tell for sure that when i pump the primer it does squirt fuel back into the tank when squeezed (it is installed correctly lol). i think i may have an issue with the quick connector leaking as well so ill just replace it all and see if that fixes it
 
well, i took the carb apart again and it turns out that the fuel pump was incorrect (i have no idea why i assembled it that way but whatever lol). a did go ahead and replace the quick connector but i left the primer bulb. i got it out on the lake and finally got to drive it lol. i bought it back in january and ever since then my life had been a rollercoaster (replaced intake manifold gasket on truck, got a new job, left new job because it wasnt for me, realized that it wasnt the intake manifold gasket on my truck...it was the head gaskets, guy working on truck went to jail after tearing it all apart, then after all that i graduated college.) 6 months later, i finally got a chance to use the boat. my girlfriend and i might just be bitten by the boating bug. she didnt seem too excited about my buying it at first but i think her smile speaks for itself lol.
 

Attachments

  • 0607120926.jpg
    0607120926.jpg
    49.1 KB · Views: 434
  • 0607120925.jpg
    0607120925.jpg
    79 KB · Views: 694
Back
Top