I just acquired an 89 Mariner 135 with a few issues. I just finished replacing the fuel line and primer bulb and the fuel line to the gas tank. I have a bulb that still stays shishy and goes limp after running for a few minutes. I just noticed today that if I prime and prime and prime that gas comes out the prop exhaust. COuld this be my fuel pump? The symptoms I have is that the engine has low power, starts OK but is impossible to start after it has run for a bit. I generally does not idle well and will stall after it warms up. Could it be my fuel pump causing all the problems?
It certainly does sound like a pump gone bad.Depending on how long the motor has had this paroblem, you might consider removing the plugs and shining a flashlight in the cylinders and check for scoring. The problem with too much fuel is that it can wash the oil enough to reduce the lubrication that shuold be taking place. You can also do a compression check at the same time. The spark plugs will be completely saturated on the two holes that provide the pulse signals to the fuel pump.This is an excellent indicator that you have a ruptured diaphram in the fuel pump. Hope the info helps.
Thanks.I will take it apart and get a rebuild kit. I hope this fixes it. Thanks for the heads up on the scoring I'll check it out. I did a compreesion test this year and they all within 1-2 PSI of each other at around 117 PSI. I'll post the results.
Just rebuilt the fuel pump. 1 membrane had a huge tear in it. Felt good to find it. however.... Primer bulb still gets soft. After priming heavily gas and oil comes out the prop exhaust. Motor starts up fine but stalls about 20 secs later. I have to keep it at half throttle to keep it going. I have already replaced all fuel lines and gas was stabilized at end of the season. Last season mechanic rebuilt carbs - although not sure if I trust him
Checked the vent its fine.I have 3 Carbs on this O/B are you talking about the float needle? I just replace the bulb but will swap out with an external tank
I have went through a lot of primer bulbs and have come to find out that the after market has a very high rate of failing even when new.I try and buy only Merc unless your in a pinch and can only find the others. Just my opinion and my experences. DT1
Originally posted by zipperhead: Checked the vent its fine.I have 3 Carbs on this O/B are you talking about the float needle? I just replace the bulb but will swap out with an external tank
the float needle or inlet needle, i'm not sure which is the correct name for it, could be it's leaking, it might be that there is a little dirt that is keeping the needle from seating, if thats the case just flush and clean the needle and reset the float.
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OK, So mystery solved, if anyone cares I know I do....I'm stupid. When I rebuilt the pump and put it back on the engine I swapped the output to the carbs with the top cylinder compression hose. After staring at the thing and contemplating a rebuild of the carbs.... I was trying to kink the hoses to the carbs so I could figure out which bowl needle was leaking. After stopping flow to all carbs by kinking, the primer bulb was still pumping gas out the exhaust and no firm bulb. After I looked at it I kinked the cylinder hose and the bulb got hard with no leaking. I swappped the hoses and all runs pretty well. It turns out that the original; problem I had last year was due to the bad pump, and the latest problem was due to my stupidity....now on to the fuel gauge and trim tilt problems. One day I'll be able to launch the thing...looking forward to it. Thatnk to those who help I can't tell you how much I appreciate it.
89 Mariner 135 primer bulb soft & stalling
I will take it apart and get a rebuild kit. I hope this fixes it. Thanks for the heads up on the scoring I'll check it out. I did a compreesion test this year and they all within 1-2 PSI of each other at around 117 PSI. 
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