1990 US Marine Force 15 Carb Enigma -HELP!

timmeraw

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I recently picked up a nice clean 1990 Force 15 but am having a heck of time getting it to run. I can't get the float/needle to work properly. I pump the fuel line ball and when the bowl fills fuel starts to squirt out of what I assume is an overflow port on the side of it and the ball will not harden. I have cleaned and cleaned the carb, replaced the inlet needle (the seat is pressed in and not replaceable). The plastic float is not taking on fuel and sinking and the needle appears to be moving in and out of seat properly. What is strange is that with the carb off and using a piece of fuel line to blow into it seems to completely stop the air when upside down but when turned right side up it is VERY hard to get air to flow unlike when I have done this before. I have blow air with a compressor thru the fuel inlet with the carb apart air is flying thru the inlet seat properly. I have ensured to have the strange bowl articulated properly so the deep end is opposite the float pin etc and the float is set to level with the carb rim as it should.

Any ideas? I am at a point of attempting to find a replacement carb but have not had any luck online at ebay etc and most sites list it as NLA.
Anybody have a Force or Gamefisher 15 carb from about 1990 or newer? Model number is 153F90D which I have found means it is a 1990.

Thanks
Tim
 

jerryjerry05

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May 7, 2008
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Did you replace the float or needle?
The replacement stuff is usually the wrong stuff.
Pics of the float? Is it adjustable?
Some seats have an o-ring in the base.
It can deteriorate and leak(magnifying glass).
The needles, some have a rubber tip it can get a grove in it and it will leak.
Close up pics of all parts.
 

foodfisher

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Closes when inverted leads to problems at the float. Improper adjustment or soggy float,
 

timmeraw

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Thanks for the responses Gerry and Foodfisher.

Let me answer (and reiterate)

Did you replace the float or needle? I replaced just the needle...the float is fin and NO it is not soggy and adjusted per speck.
The replacement stuff is usually the wrong stuff. I verified the part number and drove 45 mins each way to get the $8 needle
Pics of the float? Is it adjustable? Yes ...it is plastic with a small metal tab that I have adjusted to level with carb body
Some seats have an o-ring in the base. Not sure if the seat originally had an O ring (it is pressed it) but I suspect it is the issue
It can deteriorate and leak(magnifying glass). Will try that to see how the hole looks at the bottom of the seat
The needles, some have a rubber tip it can get a grove in it and it will leak. New needle but I may have mixed them up comparing...original was rubber tip..
Close up pics of all parts. Will try and get some good pics and respost
 

timmeraw

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Ok spent a bit more time today trying to figure this out. It is a real strange issue. I have the carb off and have removed the bowl off the carb....when I hook the fuel line up and pump the ball with the carb oriented correctly ...fuel squirts out through the inlet seat as it is supposed to. If I lightly lift the float ...as it would when bowl is full.... the needle seats fine and the ball is hard as it is supposed to be and stops the flow. I have floated the float in fuel and it is floating as it should and I don't see how it can be getting stuck in any way inside the bowl (even have the offset bowl lined up properly with the deep end opposite the pin fulcrum of the float to let it raise higher.
When I put the bowl on the fuel runs out the overflow like the needle is not seating.

This has me totally stumped. Sorry still now pics but take my word that the needle is seating properly based on my tests.

More ideas most welcome... still no pics but will work on that if it might help but we all know how these carbs work and everything seems fine. It does not appear to be a needle/seat issue that I can tell.

Weird to say the least. My hands are pruny from all the gas now and I give up for another day. Sure wish I had a spare carb to try like I usually do with the older mercs I work on.

Thanks
Tim
 

foodfisher

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Feb 18, 2009
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From your description, it's got to be the float. Not bouyant enough to lift the needle. Be sure the float is empty (warmth and time to dry) and not damaged, allowing fuel inside. Reseal it. Good luck.
 

pnwboat

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Oct 8, 2007
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I've found on occasion with the replacement parts, you have to play with the float level to get the needle valve to seal properly. Try this. With the carburetor inverted, adjust the free end of the float so that it is slightly higher (maybe 1/16") than the pivoting end of the float. You have to experiment with the float height.
 

timmeraw

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The float is plastic and sound with no leaks and floats like a bobber in fuel. As far as I can tell it is not getting hung up or rubbing or anything to prevent it from rising and closing the needle. I have been playing with the metal brass tab to change the level but no luck yet. I am going back to out play with it some more shortly and have been looking for a used carb but not having much luck.
 

jerryjerry05

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The float "plastic" does it have a metal tab for adjusting?
Someone along the way designed a plastic float that was real pretty.
Absolutely useless but real pretty.
Post a pic of your parts.
 

timmeraw

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Jerry... yes it is plastic with a single metal tab that can adjust the level only ....drop is not adjustable cause the other tab is plastic. In any case after playing some more with different needles and different adjustment on the float I got it to seal and all the ball to harden. Then I put it back together and tried to start it but it would not start. Checked spark and for some reason now I've only got spark on top cyl. I know it had spark on both before when it would run for a short time.
So I am now trying to get this stupid design of a flywheel off. Who designs a flywheel with no threaded holes for a puller? I know I worked on one of these before and recall prying it off I believe somehow from underneath. I think I may have read somewhere once someone just drilled and tapped holes for the puller?
 

jerryjerry05

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If you can, buy a 3 jaw puller.
Some use the 3 holes in the top but I always seem to screw up the threads.
For some reason the Force/Chrysler seems to hold on to the taper better than the other outboards.
Before they "improved" the site I used to have a ton of pics that showed how a 3 jaw being used.
 

kimcrwbr1

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Oct 23, 2014
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Be sure and rebuild the fuel pump while your at it the one I am working on the diaphram was delaminating and had a small hole in it. Replace the fuel lines also.
 

timmeraw

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No Title

I got back at it today at lunch a bit and finally got the flywheel off. Had to use a pry bar under while giving the protected crank spindle a good few wacks with a ball peen hammer.

As you can see in these pics... everything appears to be pretty good under there but for some corrosion on the under side of the flywheel. Strange ignition to me though.... has the two prestolite coils (or I think they may call them modules or something). Strange part to me is though the armature plate appears to have spots for condensors and point sets etc and even has a stamp saying set points gap to 20, none of that is there? Since one side is not firing I need to figure out how to test I guess....any ideas on that?
 

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Nordin

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Jun 12, 2010
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Your engine has the ignition system with BIM coils. They look like a regular magneto coil but this system does not have any points and capacitors.
The system operates the same way as a magneto system but there is a built in SRC electronic switch which act as points but in electronic way.

Check for broken or frayed lead wires, check sparkplug boot, change sparkplug.
If this does not help change BIM coil.
These BIM coils are pretty expensive.... about 80 dollar at ishopmarine. CDI Electronics has a replacement kit but then you have to change both BIM coils.
This kit costs about 270 dollars !!!!!!!!!!!!!!!! (maxrules.com)
 

timmeraw

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Thanks Nordin... I did some research figured out the BIM coil thing and yea they are pricy. I cleaned up the flywheel and magnets are good and strong and fine. Plug wires seem just fine from boot to coil. I am gonna clean and reconnect all of the coil wires and grounds and go over the kill circuit. The emerg lanyard wires were disconnected and tied up inside the motor etc.
Question... I know that CID ignition can get in trouble if checking things with plug wires off and not grounded......are BIM coils succeptible to the same thing? I usually always ground plug wires when disconnected to check spark etc but may have missed it once with this carb issue I was playing with.
 

timmeraw

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Jun 10, 2008
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Played some more before dark. Spark issue solved.... just removed and cleaned all connections on the armature plate, Sanded and cleaned up the faces on the coils and the magnets in the flywheel. Put back together and strong spark on both coils. Began by checking full line ball hard again.... squirted a bit of pre-mix into the plug holes and she kicked off for a sec or two but died after that quick burn. Squirted some pre-mix into throat of the carb and it started for maybe 2-3 seconds and died. So now I am back to the fuel issue.

THought maybe I had the float set so high maybe nothing was filling the bowl. Nope...pulled the carb and the bowl had lots of fuel in it. Whey the heck is it not getting into the jets and into the combustion chambers? Even if it was a hole i fuel pump diaphram it would run longer and maybe just crappy. It has to be the carb.

Sure wish I could find a replacement to test? I will send some pics tomorrow when I tear it apart again in the daylight.
Thanks
TIm
 

timmeraw

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Jun 10, 2008
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That older Chrysler Carb I found online..that looks very similar in pics is on the way and estimated to be here by Thurs. Hopefully it solves my prob. I have restored and tuned up probably over a 100 motors now and once had the same kind of enigma with a Merc 9.8. Gave up and found a carb on ebay and as soon as I installed it the motor ran like a top. Carbs seem pretty simple and similar but can be a real bear to figure out when probs ensue.
 

jerryjerry05

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This post is 5 years old.
The mods are gonna kill this.
Start another with the problem, including the year, model serial#

Almost all floats are set even when turned upside down.
The drop is it almost hits the center post when turned right side up.

Depending on the model/year the needle seat and cleaners and soaks don't work well together.
I use Dawn to clean then air dry.
 
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