1988 force 125

[L.J.]

I took the whole thing apart and cleaned it. I did not remove the crankshaft or pistons, just cleaned around them. I have verified spark on all cylinders and fuel is getting to carbs. I cannot get it to fire, it just cranks. I spray fuel mix 50:1 into cylinders and get a pop but that's it. It has compression and exhaust is clear. Why won't it at least try to fire off?

 

[Jiggz]

Did you install back the reed blocks? Are you getting fuel into the cylinders? To test for this you will have to remove one of the plugs and place a dry white napkin or paper towel in front of the said cylinder about 3~4 inches away and crank over the engine. If fuel is getting into the cylinder, you will see a spray pattern on the paper towel. Test all 4 cylinders.

If there's fuel getting into the cylinders, did you mess up the timing? Also, need to make sure the carbs idle setting is set correctly. If not, the throttle valves will be shut and no fuel mixture will get in at idle. Check timing and idle setting then post back results.

 

[L.J.]

I have the idle screw at 1 1/4 turns out from lightly seated as specked in manual. I folded a napkin over the plugs and screwed them back in and cranked it several times, they all came back dry. The reeds are in, if the block is the term for the whole assembly yes, if not then what are the blocks? Aslo I shined a light thru the carb to see if the reeds were sealing last night and i can see just the slightest amount of light outlining 3 of the reeds. Is that enough to allow fuel to blow back out?
i don't have a timing light but have set top dead center of top piston to the single line on the flywheel. That should get it close enough to at least cough, shouldn't it.
I've rebuilt fuel pump and cleaned the two plates hooked up to the vacuum tubes that have a screen at bottom and top as well, sorry don't know what they're called.

 

[Jiggz]

Check the carbs bowls make sure there is fuel in both. As previously mentioned, check the idle screw (one located at the bottom of the towershaft) make sure it's screwed in (against the engine block) to set idle speed. The 1 1/4 turn you mentioned is the air screw or technically, air-fuel mixture screw. This doesn't set the idle speed. You can initially (air screw) set that up to 1 1/2 turn out from seated.

As for the idle screw (bottom of towershaft, initially set it to touch the engine block and then about 3 turns more. If it still would not fire, give another turn or two. Watch the cam pushing against the roller opening the throttles. This will push the cam against the roller and will open the throttles for idle setting. As soon as you get it to fire, then set it to around 1000~1200 rpm on muffs in neutral. Final setting should be 700~750 RPM, idle in gear in water. Thereafter, set the air screw to around 1 1/4 ~ 1 1/8 turn out from seated.

 

[Jiggz]

"I've rebuilt fuel pump and cleaned the two plates hooked up to the vacuum tubes that have a screen at bottom and top as well, sorry don't know what they're called."

Contrary to common beliefs, there are no vacuum hoses in this engine. The hoses you are referring to are fuel recirc hoses which collects unburned fuel from the cylinders and feeds it back to the intake manifold. But these hoses should not stop you from starting and running your engine, albeit it can cause rough running after a while due to over rich air mixture in the cylinders.

 

[jerryjerry05]

Sounds like the flywheel key's sheared??

 

[Nordin]

Yes as jerryjerry says (took the words out of my mouth), check the flywheel key.

Check that #1 piston is at TDC (with a screw driver in top hole) when TDC 0 mark lines up with zero at timing plate.

 

[L.J.]

Sorry, had to go coach some softball practices.
set the idle screw and kept trying and turning it more and trying again but no dice. I know all of the common issues, saftey lanyard, neutral switch, shear pin, and I can assure you it is none of those. Both bowls are full and fuel even runs out the front of them after attempting to start with choke on. I blew air through carb and everything seems clear but no fire. I am getting consistent fart bubbles as I crank, I assume that means air is running through the engine. I have it lowered into an 80gal cooler. If air is going through why won't it take fuel with it? Before I took it apart all it did was start and idle and easily. Any throttle would bogg it and kill it.

 

[Jiggz]

Get a 2nd person to do the cranking. Place fuel oil mix in a spray bottle. Remove the air covers on both carbs. With one hand, hold the tie bar (between the two carbs that holds the throttle levers) all the way down, meaning the throttles are wide open. Have another person crank it. If it still would not fire up, while cranking spray fuel oil mix into each carb and it should cough or fire momentarily. If it fires momentarily but not continuously, can you post a pic of the carbs linkages focused on the tower shaft, adjust rod that connects to the cams and rollers and tie bars.

 

[L.J.]

Held tie bar up, both flaps horizontal and had the kiddo turn the key while I sprayed. The cranks progressively sped up sounding like it was about to fire off and then 1 POP! water blew up out of the tank. We tried again an same thing, 1 POP!
I'm trying get these pics on here for you now.

 

[L.J.]

I have created an idea book with the pics in it but have no clue how yo attach them to a comment.

 

[Jiggz]

If it popped only once after spraying fuel oil mix into the carbs, there could be more than just one problem. First, fuel delivery to the cylinder and that it could be out of timing. As mentioned, check #1 cylinder matches the TDC mark on the flywheel. To do this:
1. remove all plugs
2. locate the TDC marking on the flywheel, it's the single mark right of the three markings
3. Insert a screw driver on #1 cylinder
4. Manually rotate the flywheel clockwise direction (looking down on flywheel)
5. Watch the TDC marking on the flywheel passing the static or stationary timing marker and it should coincide with the screwdriver on #1 cylinder at its top most travel. If not, then the flywheel key is most likely sheared.

 

[jerryjerry05]

That's what Nordin and I suggested.
Unless he's sucking huge amounts of air somewhere?

You change the flywheel?
Check the magnet?

 

[L.J.]

As I mentioned before, I have no timing light so I am only able to do tdc. It's been set at 0 and tdc the entire time. I popped the flywheel off last night and the key is rounded on one side, straight on the other and in place.

 

[Jiggz]

Zero'ing the TDC marking on the flywheel with #1 cylinder ensures the key is not sheared. But you still need a timing light to verify timing. You can either lease or get a loaner from auto stores. You do not need a sophisticated one, just a plain inductive timing light with a bright light (approx. $30) will suffice. There's a youtube video on how to do this without going out on the water. It's called "static timing" or cranking timing at WOT.

 

[jerryjerry05]

If the keys in place? then you might not be getting fuel?
The floats stuck after cleaning.
Unscrew the float bowls and squeeze the ball making fuel drip out the bowl.

Or like I said earlier it's possible your sucking lots of air??

It's also possible you've been turning and turning the motor over it's flooded.
Remove the plugs and let set over night.
You are using the choke to start?
Holding the key in while the motor turns?

 

[Zink357]

I thought I read somewhere on here about not using carb cleaner on some of the orings in the carb or something like that because the rubber swells up and blocks the fuel... Is that a possibility here? Just a shot in the dark but I swear I read it here somewhere.

 

[jerryjerry05]

Yes you probably heard that from me.
The soaks, not so much the spray cleaners can swell the o-rings and rubber in the carb.
Usually letting it air dry for a few days it will shrink back the regular size.
But a carb that has that problem the rubber won't shrink as long as there is no air getting to the parts.

I use Dawn soap and a spray cleaner for the hard jobs.
Then blow dry and install.
Don't use any silicone sprays or WD
Those things can gum up and stop the needle/seat working right.

I try not to use any additives other than StaBil.

 

[L.J.]

Ok long story short.
It was mentioned "sucking in lots of air". That led me to redo the compression test, head gasket was leaking. Replaced it again and sprayed fuel mix into wide open carb while kiddo turned the key. It fired off. Reving very high the kid turned it off. Then I tried a normal in neutral idle start, it fired up. I killed it then retired, 2 more times with success. I then fired it up and let it idle for 2min, killed it, waited 5 min did it again.
took it to the lake and nothing.
Found bottom carb bowl leaking, fixed it and it started. It idled, it putted and it ran nicely for about half a mile and died.
next day fresh charge on battery it fired first try and again made it half a mile and died.
I know it did not over heat, I felt the metal on powerhead with bare hand both times.
now i replaced the starter and it cranks and sneezes, then cranks and tries to fire off, then it cranks and backfires. The cranking seems to weak to turn it over unless I run jumper cables from the truck even though the battery shows over 13volts on meter.
prime bulb stays hard and spark exhaust fuel and compression have all been confimed.
I borrowed a timing light and it doesn't work.
I've cranked then turned timing adjustment a 1/4 turn from all the way in to all the way out and there is a sweet spot but still no fire.
so much for a long story short.

 

[jerryjerry05]

First thing do a compression test and post the #s
That ok? Check the flywheel key.

What "timing adjustment screw" did you turn?
Outboards don't jump time like a car motor.

Top posts read and find the linc and sync and then the static timing.

Backfire or sneezes??? it's sucking air somewhere, or the flywheel key's sheared.

One tiny backfire can blow the port cover gaskets.

How to test: mix up some soap and water in a spray bottle.
Remove the plugs, rotate the piston so it's as far away from the hole as possible.
Then shoot some soapy water on the top port cover and hit it with compressed air in the plug hole.
Don't need a lot of air, or you can blow the gaskets.