mariner 50 no idle; climbing rpms; have to smash primer bulb

siebertl · #1 March 28th, 2009, 10:59 AM

I have an 80 something mariner 50 horse. I replaced all the rubber in both carbs. Did not look at needle valves on floats though.

Engine starts fine and runs at full throttle out of gear. But not at proper rpm. When I try to idle it dies. I got mad the other day and squeezed the **** out of the primer bulb, till i had fuel spewing out of the carbs. Started it and it ran like a champ!!!!

After fishing for an hour I started it again w/out priming. RPMs will climb and then all is fine.

Why would smashing the primer bulb fix the problem? Is there a needle stuck somewhere? Why does the rpm climb?

matt9923 · #2 March 28th, 2009, 12:34 PM

Maybe some dirt in the fuel system or something and when you smashed the bulb it moved. I would buy a fuel pump kit. Their cheep. Then blow out all the fuel lines.
Are you saying it is running fine now?
Matt

siebertl · #3 March 28th, 2009, 01:27 PM

No, it isn't really running right. I can get it to run right if I pump the heck out of the bulb. She'll fire and idle fine. If I shut it down for an hour or so and restart at fill throttle, it will start and slowly climb in rpm, then it will idle fine.

If I let sit for a couple days, I will have to pump the ball hard again in order to get it to idle right.

Where is the fuel pump located, I thought I replaced the diaphram fuel pumps in the carbs.

Just went out and pumped the primer bulb, It sounds like there is air in the system and eventually fuel will squirt out of the top of the lower carburator. What is that port anyway?

CharlieB · #4 March 28th, 2009, 03:48 PM

Rubber in the carbs?

Sounds as tho this is the model that each carb has its own fuel pump.

Squeezing the primer and fuel coming out the vent of the lower card indicates the float needle is not sealing and the carb is flooding, richening the mixture and causing the fast idle.

Once the needle seals then the fuel level lowers to normal and the motor idles.

Clean both carbs COMPLETELY, carefully check float height settings.

It wouldn't be a bad idea to go ahead and replace the float needles on both carbs while you have them apart, just to be sure that they seal properly.