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1993 Force 40 won't start

InstaGator

Contributing Member
I've got a 1993 Force 40hp outboard that I'm working on for a friend. Sometimes it starts right up but won't idle. You have to have the idle level way up even after it's warm and to put it in gear you have to be quick to lower the lever and put it in gear... thats when it wants to start. Sometimes after we have been running it and stop somewhere we will go to start it and it will start for a split second and shut off and it does this about 10 times before it will stay running and then you have to put it in gear and get the RPMs up to keep it running. I've cleaned the carb and put new plugs in but I cant figure out why it's doing this. Anyone had a problem like this before?
 
The carb adjustment screw is at 1 1/2 turns out. I tried doing a spark test by pulling the plugs and holding it against the block and turning it over but I didn't see a spark, this engine uses surface gap plugs so I wasn't sure if it wasn't getting a spark or if you can't do that test with a surface gap plug. I will do a compression test on it today and see how that turns out. Thank you
 
Just got off the lake trying to adjust the idle with it in the water. it started but as soon as you lower the idle to put it in gear it shuts off and won't start again. the starter is old and gets hit easily so it only has about 10 times of trying to start before you have to let it cool down for a while and the teeth are shot anyway. Never got it running after that, even with trying starter fluid(I know you're not supposed to use that in a 2 stroke but it was a desperate time). The owner has decided she just wants to sell it and get rid of the headache. I'll do a compression test just to check but without a starter it will be hard for her to sell. How do I check for a spark if it has surface gap plugs?
 
Surface gap plugs spark just like the regular plugs.
Undo it and hold it against the block.
Or change it for another plug with an electrode(if your just looking for spark from the coil)
Very rare the surface gap plugs go bad.
I had a set in an outboard for over 8/9 years.
 
I'm waiting on a new starter to come in so I can check the ignition system. Until then, how would I check through the ignition system to see if the coils are good if I don't have a spark on both cylinders? How would I check the points on this? Do I check the gap with a feeler gauge? Thank you again for all of your help. As you can see by me only having one wrench on my profile, I'm very new to working on outboards and boat motors in general.
 
No points on this motor.
It's an electronic discharge.
It has a something like a basic computer in the pack.

In some tests, all you need ia an analog meter.
Others you need the starter and the meter and other tests you'll need a special DVA/Peak Reading Volt Meter.
CDI ignition has test procedures for most motors past 1980.
They also have a tech line if you need help, they have some real good techs working there.

I've got a few wrenches and still need to ask questions:)
 
Thanks Jerryjerry05. I figured it had points. How would I go about testing the coils? Would I need to buy the peak reading meter to do this? I've only worked on a 1973 18hp evinrude before so I am pretty new to this type of motor with all the electronics.
 
Update...Well the starter came in, I got that put on pretty quick and got to checking the spark. Both plugs get a nice blue spark, which leaves me baffled. It's got fuel it's got spark, but the only time it will run. is if the idle is way up. Anything else I can check? At this point any advice is helpful. Thank you in advance.
 
Over on iboatsdotcom there is a Chrysler/Force forum.
The first 3 post have tips on setting up the linkage.
it's called a Link and Synch.
That might help?

Does it backfire?
Try a can of starting fluid sprayed around the intake side of the motor.
Spray around the fuel pump base too.
If that makes a difference in the way it runs? then it's sucking air and needs new gaskets or sealed??
 
It does not backfire. I will have to try the starting fluid trick and see if that changes anything. when I rebuilt the carb I adjusted the float so it was parallel with the base of the carb, and it now has fuel all over the bowl. Could it be flooding? Do I just keep adjusting the float and see if that changes anything?
 
I believe I have found the problem. I did a compression test(which I should have done in the first place) and found the top cylinder only has 25 psi. The bottom cylinder has about 118 psi. Jerryjerry05 you hit the nail on the head with that one. Is there a way to see if it's just a gasket or something simple without tearing the motor apart? I would hate to out new gaskets just to find the motor is shot. Thanks in advance for your help, you have saved me a lot of time on this project.
 
Just remove the head and check for damage???
It could be just a blown gasket?
These are fairly easy to rebuild if needed.

The parts are all over, the hard part will be the boring of the block.
Not all machine shops are [FONT=Arial, Helvetica, sans-serif]equipped t[/FONT]o do that kind of work :(
 
The lady who owns the boat does not want to put much money into it. She would rather just get a new motor for it. I'm guessing with only having 25 psi if there were any damage to the cylinder it would be pretty obvious.
 
Oh yea if there was any damage it would show pretty quick when the heads removed.
It might only be a 35$ gasket or a 1000$ rebuild??
 
Update! The head gasket was shot. Had no gasket through the upper and lower cylinders. Put a new head gasket on, both cylinders have 145 psi. She cranks right up and idles like a dream. Thanks for all of your help... especially Jerryjerry05. I'm sure I'll be posting here soon with another project and I'll do my part to help others on this site.
 
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