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150 Mariner will start missing after running great?

C

cricket4462

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My 1995 150 Mariner outboard will run great start great every time since I bought it in 1995. Although I have replaced spark plugs throughout the years it has always ran great. I started having an issue with it as of late. Here is the problem....after running it for seems like a 20 minutes or 30 minutes it will all of the sudden bog down and almost stall out at high speed. Then it will be missing terribly. I then will try to get back on plane and it trys too but stalls out again while trying.

I do notice after letting it sit for a half hour or so it will run fine again. Seems like this is an issue with something miss firing after heating up or after running for a longer period of time at higher speed. Could it be a bad ballast resistor or ignition coil or control module?

Please help with some information on what it might be or what I can try in fixing this.

Thank you
 
The stator and trigger coils can heat up and begin to fail. Were you able to check for good spark when it bogs down? The next time it happens push in on the choke assist to see if it is a fuel issue. If pushing in on it makes it run better then the fuel pump may be quitting.
 
guyjg said:
The stator and trigger coils can heat up and begin to fail. Were you able to check for good spark when it bogs down? The next time it happens push in on the choke assist to see if it is a fuel issue. If pushing in on it makes it run better then the fuel pump may be quitting. http://issuu.com/cdielectronics/doc...t.xml&backgroundColor=000000&showFlipBtn=true
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Tahnkyou for your input! I did not check for spark when it bogs down. Not quite sure how to test that when it happens. I will be taking my boat out of storage and running it this weekend. I will first try and see if the choke assist help it when this happens again . If so then it looks like I will be replacing the fuel pump. If not then I will check into the stator and trigger coils. I will post after I get results.
 
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you can check the resistance on the stator and trigger too. Easy way to eliminate them as a problem.
 
emac said:
you can check the resistance on the stator and trigger too. Easy way to eliminate them as a problem.
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Could you please tell me how to check the resistance on the stator and trigger? Also do you know how to check for spark when it bogs down and starts missing?
 
or using an ohm meter you can measure the resistance. The readings you are looking for will be in your manual, assuming you have one.
 
Okay,, Here is what I diagnosed so far doing trial and error with everyones advise. I do have spark and also timing is all good when my boat bogs down after running it for about 5 to 10 miles. Wht I noticed is my primer bulb will completely collapse when it bogs down meaning it is getting no gas at that time meaning* there must be an obstruction between the gas tank and the primer bulb. I noticed that there is two check valves* or* anti siphon valves between the primer bulb and my 30 gallon gas tank. I took the fuel line off both valves and shot compressed air through them and they were free and clear of any objects that might be logged in the line. I also took both valves, one that is in line and the other that is connected to the fuel tank and see that they are not check valves or anti siphon valves They are just straight through connectors and are completely clean. I did disconnect my fuel vent hose and blow compressed air through that hose as well and it was clean meaning it isnt causing vapor lock.

Im still stumped what is causing it to starve from fuel after running for 5 to 10 miles.* I did notice that the primer ball will slowly un-collapse on its own and I then prime the bulb again and it will run again. Could it be something in my gas tank plugging it?
 
Pull the suction line out of the tank...it may be clogged...check the anti-siphon valve where the hose connects.
 
guyjg said:
Pull the suction line out of the tank...it may be clogged...check the anti-siphon valve where the hose connects.
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I did check the suction line that goes into the tank and it was perfectly clean.... Also there really isnt a anti siphon valve. What I thought was an anti siphon valve is actually just an connector that connects to the top of the tank and its a straight through connector is all, with no valve and its clean as well.

I must admit I am stumped unless there is something in the bottom of my gas tank that is obstructing the gas flow at times.

I wouldnt think it was the fuel pump as it sucks the bulb completely flat most the time when this happens which to me means that its trying to suck the fuel to the engine and working.
 
The last two responses got me to thinking about a similar problem I had a long g time ago. I had Mercury factory couplings (or quick disconnects) on both my tank and engine. There's a spring loaded ball inside those couplings, and some type trash had lodged in the ball area. I hooked the hose up directly to the tank and to the engine and have not had a fuel problem since...BF
 
BIGFLAT said:
The last two responses got me to thinking about a similar problem I had a long g time ago. I had Mercury factory couplings (or quick disconnects) on both my tank and engine. There's a spring loaded ball inside those couplings, and some type trash had lodged in the ball area. I hooked the hose up directly to the tank and to the engine and have not had a fuel problem since...BF
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My connections from my the primer bulb to the gas tank is not quick disconnect coupling and are connected directly by the gas hose to a straight through L shaped connector no ball or spring. Nothing to fault in between.
 
guyjg said:
Replace the primer bulb...the only thing left w/a valve in it.
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I did replace the primer bulb after this first happened at the end of 2011 before winter and that never solved the problem. Although who knows if this primer bulb can be bad as well. My conclusion is if this primer bulb collapses that means no gas is passing through anymore which means a bad primer bulb and or something in the fuel tank plugging gas flow.
 
Next time this happens, have someone pump the bulb and see how the motor reacts. If it picks right back up, you have a fuel supply problem (air leak, bad pump check valves, dirt, etc.) If pumping the bulb does nothing, start looking into ignition problems (as stated above).

Jeff
 
fastjeff said:
Next time this happens, have someone pump the bulb and see how the motor reacts. If it picks right back up, you have a fuel supply problem (air leak, bad pump check valves, dirt, etc.) If pumping the bulb does nothing, start looking into ignition problems (as stated above).

Jeff
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It definetally is being gas starved as the primer bulb will collapse and bog down engine . Everything is clear and clean all the way to the gas tank. No check valves or anti siphon issues as there is no valves in between.
 
Awhile back a guy had the problem of the primer collapsing, turned out there was something floating in the tank that would make it's way to the pick up,then when the engine sat awhile,the debris would float away until next time.
 
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