Force 120 #1 cylinder not firing

[leej]

i have a 1991 force 120 outboard and the number 1 cylinder has not gotten fire ever since i have had it...Performed a compression check on all cylinders and they were 120 psi...next put an inline spark tester on each cylinder to confirm I was getting spark on all other cylinders....number one cylinder was only one that had no fire....i ohmed all the coil packs from wire from switch box to spark plug wire and got 1.047 Kohms (meter was set to that) on all four.....next I swapped the non firing coil pack with one I knew was firing and the coil pack that wasn't firing started firing on that cylinder and the other stopped firing on cylinder 1.....so now I know the coil pack is good I ohmed the trigger to make sure the readings were good on it....I found a site that said the ohms should be 48-52 mine was 53.2 ohms wire to wire (1-1, 2-2, 3-3, 4-4) .....then i ohmed the stator and got 327.4 ohms wire 1 to wire 2 and 327.4 ohms wire 3 to wire 4....was kinda think that i had a bad switch box but am unsure because i am new at trying to work on outboards....Any help would be appreciated to know if i am heading in right direction (since the switch boxes are not cheap) or if i have messed up on my troubleshooting...also boat starts great and revs out of water fine but once it is in water its top speed is approx 10mph based on gps readings...this boat sat for a year and never cranked...the site i used for my wire diagram is......http://http://www.maxrules.com/graphics/force/wiring/120_125_thru91A_CD.jpg

 

[Jiggz]

Re: Force 120 #1 cylinder not firing

You seem to be on the right track with your troubleshooting. The ohmmeter readings on both stator and trigger are within specs. Unfortunately, 91-120HP comes in two flavors one with switchboxes and the contemporary CD modules which one do you have? The link you provided doesn't work and they never do by the ways. If you can post the wiring diagram even better.

 

[leej]

Re: Force 120 #1 cylinder not firing

I have the motor with the two switch blocks....as i investigated further today after i posted...i was fixing to swap out the switch boxes to see if i could isolate the problem and get it to swap cylinders....as I went to disconnect the first wire on the wire block i found that the white yellow wire from the switch box was broke at the crimp under the heat shrink as it came apart in my hand as i pulled it off the terminal...i recrimped a new end on the wire and fired the motor up and had fire on all cylinders....now that i had that fixed i took it to the water to test it....motor ran awesome and came on plane for about 100yds then acted as if it was flooding out.....i readjusted the carbs thinking that they were my issue and put the boat in gear and off again i go....then the exact same thing happens motor floods....had hard time starting then once it started again it would only go in gear but would not take any fuel or it would flood out....carb cleaner would give the motor life but still wouldn't improve after the cleaner....i messed with it for about an hour or so on water and found if i let it sit not running it would plane again....but then would flood out again and was also acting as if it was knocked out of gear....motor would rev real high but boat would stop..done that twice...then i trolled back to ramp since motor would stay running now....figure i would take carbs off and clean them tomorrow because i did have a blocked fuel line the other day but that has been fixed with a new fuel line and an in line fuel filter between tank and water seperater..the blockage was causing my primer bulb to collapse when motor would run...hopefully there are some ideas on this fix because i know it is a fuel issue just not sure where.....leaning towards ventilation on the prop and possible diaphram problems on the fuel pump....any ideas?????

 

[leej]

Re: Force 120 #1 cylinder not firing

this is the wiring diagram

 

[Jiggz]

Re: Force 120 #1 cylinder not firing

this is the wiring diagramView attachment 210519View attachment 210519

Those two units are referred to as CD modules which provide power to the coils. Each unit or CDM has two ckts connecting to two coils for two cylinders. A switchbox is an integrated module. Yours are the CD Module version and not switchbox.

As for the fuel flooding problem, double check the idle mixture screw setting to make sure they are both set at 1 turn out. If problem persists, then it is time to at least check the bowls and floats and make sure the chokes are not engaged or are at least fully horizontal when choke is not in use. If problem still persists make sure the vent holes on the carbs are not blocked or plugged.

 

[leej]

Re: Force 120 #1 cylinder not firing

I checked into it after thinking about it last night and figured it wasnt flooding the engine it was starving it....i opened the carbs and found the black sandy material that was in the fuel lines before i replaced them and i found it in the fuel pump...I cleaned everything thoroughly this time and even had to replace my diaphram in the pump because it had a small hole in it....so now everything is new from fuel tank to carbs and i even installed a inline fuel filter between fuel pump and carbs for easy troubleshooting on future fuel problems....After adjusting the carbs and making sure i had clean gas coming through primer i started the motor......then cleaned up and headed to the lake for a test....good news the fuel problem was solved and it planed with out a problem and never shut off....bad news is the prop was spun and that was why it kept reving high and not going....so i took it to the prop shop and they fixed it so tomorrow is the big test...hopefully i have gotten all the gremlins out....i will post an update tomorrow evening...thanks for all the help and advice so far

 

[Jiggz]

Re: Force 120 #1 cylinder not firing

Congrats and enjoy!

 

[leej]

Re: Force 120 #1 cylinder not firing

ok update for today....went to lake today and it ran great for about and 1.5 hrs...came on plane and ran flawless ....then it started acting like it was running out of gas and i knew there was a full tank of gas in it(gas is kinda old and am trying to run it out because tank is a pain to get to, which I know old gas isn't good but i did put gas treatment in it)....i took the cover off the motor and saw the inline filter from pump to carbs was bone dry...my filter from tank to water seperater was completely full....i knew i was having fuel pump problems so i filled the line again using the primer and ran as far as it would let me till it shut off again....did this all the way back to ramp....i came home and opened the pump and it appeared the diaphram was still good but may have slipped or something...I notice gas on the x gasket between the pump and engine block that seals it to the engine, which to my knowledge should remain dry of gas since it is behind diaphram...i replaced it and added a little sealer to the gasket to help it stay....after waiting for it to dry good i primed the motor and started it with muffs on and ran it for a little while to see if it would drain the filter....after it did not drain the filter i took it back to the lake...i opened throttle and planed no problem...ran for about 100yrds and then started shutting down i brought it back to neutral and the motor kept running so i removed the hood and inspected the filter..it was completely full....so i tried again same thing happened except this time in would do it right before plane...the filter never was dry anytime i looked at it even when it did die a couple of times...almost acts like i am picking up trash or something and it is blocking my flow but both of my filters remain full....this baffles me and any ideas would b helpful as i plan on working on it tomorrow...hoping to have it ready for the weekend.....thanks

 

[Jiggz]

Re: Force 120 #1 cylinder not firing

With the fuel filter staying full it's obvious the problem is with the carbs. I recommend opening the carb bowls again and cleaning and setting the floats properly. Double check the inlet needle valve make sure it is not sticking. In short, you need to thoroughly clean the carbs and properly set. If problem still persists, it is time to check the reeds visually.

 

[leej]

Re: Force 120 #1 cylinder not firing

I opened my carbs and set the floats to just above horizontal when they r upside down....when I opened the bottom carb bowl and the main nozzle that has the four jets in it that covers the siphon tube fell out in my hand so i figured this was my problem as everything else looked great in the other carb...I could not replace it because it had been broke before i got the boat right at the ears for the screw driver to fit...I had noticed this before but had no way of getting it out....so i guess it falling out was a blessing...I have ordered a new one along with new gaskets for them both....So i am awaiting the parts which should be here sometime this coming week hopefully....

 

[Jiggz]

Re: Force 120 #1 cylinder not firing

Goodluck and hopefully this is the end of the road for you and start enjoying your boat before the weather really turns nasty for a very long time.

 

[leej]

Re: Force 120 #1 cylinder not firing

thanks again for all the help..i will repost after my part gets here and i install it...

 

[leej]

Re: Force 120 #1 cylinder not firing

Finally got parts in and back from vacation...installed carb nozzle and new gaskets....started the boat with muffs on and it fired right up ran for about a minute or so then died....i noticed the muffs had slipped off the motor and the lower had gotten a little warm ....replaced muffs and let it cool off....no alarms went off so i dont think it got too hot.....motor will start and run for about 5-10 secs then just shut down and wont run any longer but will start right back up....not sure what it is now as i have never had it to do this before....carbs have been adjusted and fuel is in the lines