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View Full Version : Replaced the kill switch: Now what?


TonyB
06-22-2008, 07:11 PM
Last Friday heavy rain storms forced us to seek personal cover at a lake side tavern. The boat however remained exposed to the rain. Three - four hours later we charged back toward the boat launch during a lull in the foul weather.

While underway at near full throttle the boat shut down and would not restart. I suspected the kill switch at that time but regardless of what I did to switch (jiggle, push, pull, etc) it would not run.

Got towed by to safety by the last water craft on the lake, a PWC. Oh the shame. Next day was able to restart while on the trailer but only ran for short time and shut down again. It appeared to shut down when I accidently jiggled the kill switch. Replaced the kill switch today (and bypassed as well) and still will not run.

Coil perhaps?

91 Prostar with EI. Appears to be original coil. Positive and negative posts on coil could use a bit of cleaning.

(Have now cleaned posts on coil and applied dielectric grease. No change)

jmmcalpin
06-22-2008, 09:23 PM
I had the same problem and it was the coil...

TonyB
06-23-2008, 10:43 PM
I applied a test light to the positive post on the coil. Turned key to on position and light came on. Cranked the engine and the light remained on. I'm thinking that eliminates the coil and I'm now down to distributor cap or electronic module.

Am I wrong?

cbryan70
06-23-2008, 10:54 PM
try taking the dis cap off and letting it air out. If moisture is in there the thing wont fire or will mise fire. happend to me last season

jmmcalpin
06-25-2008, 11:14 PM
When you turn the key to on do you get the alarm and warning light on ? If so can you hear the electric fuel pump turning on , it should make a wirring noise when you turn the key on for about 10 seconds. If both of them are working it may be your coil or electronic module. Even though you get electricity to the coil it still may be a bad coil.

TonyB
06-27-2008, 05:14 PM
It is a 1991. The fuel pump is mechanical and there is no alarm or light. The guages do activate when the key is turned on. I am sort of back to thinking it is the coil. Does anyone know what the resistance (ohms) is supposed to be on the low voltage terminals?

Gonzo
06-27-2008, 05:51 PM
I say the distributor cap too, it needs to dry, but I couldnt tell you how it got that wet to begin with.

JimN
06-27-2008, 06:36 PM
Look at the star wheel that rotates and causes the pickup to cause the module to open and close. If it's too far from, or close to the pickup, it won't necessarily work. It needs to see a definite signal that approximates a square wave and if the wheel is too close, it can be hard for it to sense the "edges" of the waveform. If it's too far, it just won't pick it up. Also, if you can measure the resistance from the distributor's bottom plate to the block, it should be very low.

Now that I realized what motor you have- replace the coil wire. For some reason, I had to replace a lot of them on 351 motors. If you don't have a new one, just use any kind of wire to try it. It won't hurt anything to try it for a little while. Since you have been cranking it with no spark, it's probably flooded, so go WOT until it catches and back it down immediately.

east tx skier
06-27-2008, 08:41 PM
You just can't get these things wet.

Sorry, Tony. Got nuthin'

TonyB
06-30-2008, 11:09 AM
Look at the star wheel that rotates and causes the pickup to cause the module to open and close. If it's too far from, or close to the pickup, it won't necessarily work. It needs to see a definite signal that approximates a square wave and if the wheel is too close, it can be hard for it to sense the "edges" of the waveform. If it's too far, it just won't pick it up. Also, if you can measure the resistance from the distributor's bottom plate to the block, it should be very low.

Now that I realized what motor you have- replace the coil wire. For some reason, I had to replace a lot of them on 351 motors. If you don't have a new one, just use any kind of wire to try it. It won't hurt anything to try it for a little while. Since you have been cranking it with no spark, it's probably flooded, so go WOT until it catches and back it down immediately.

When you say "Coil Wire" I'm assuming you are referring to the high voltage coil wire. I also see troubleshooting references to sticking an insulated screwdriver into the distributor end of the coil wire and grounding to the block. If you get lots of sparks then the coil (and wire) is good. Hesitant to try that sort of thing. FYI-I replaced all spark plug and coil wires last year.

Regardless, since they were old (never replaced during my ownership) and somewhat inexpensive, I've replaced the kill switch, coil, distributor cap, and rotor with no success.

JimN
06-30-2008, 12:39 PM
Right- the one that goes from the coil output tower to the center of the distributor cap. The problem I have with using a screwdriver is that a spark plug doesn't cause a dead short to the block when the voltage is discharged- it arcs and there's resistance in each spark plug. Better to use a regular piece of wire to substitute for the coil wire.I have used speaker wire, stranded wire for lights and other kinds and as long as it conducts better than the bad one, it should start running. Strip an inch of insulation off and fold the end over so the wire stays in place. You may need to wrap it around the posts, but it's better that you don't try to hold it in place unless you want a handful of high voltage.

Re- new wires- I have had bad coil wires in a new set and for some odd reason, it was always on Ford engines and it didn't matter what brand of wires. If you have a timing light, you can out it on the coil wire, to look for a regular pattern of flashes. If it's intermittent and your starter is cranking at a steady speed, there's something odd happening, somewhere.

Do you see the tach move when you crank it? You should. Remove the gray tach wire to the dash and see if it runs. If it does, that wire or the tach is shorting to ground.

I don't know if this link will help but check it out. The coil primary is low resistance, usually in the single digit range.

http://www.nurex.com/article.asp?Month=1&Year=1994&ID=24

TonyB
07-02-2008, 11:16 PM
Received my replacement ignition module from skidim today.

Removed the old one; put in the new one.

BoooooYah!!

Fired right up. And just in time for the 4th of July.

Thanks everyone, especially JimN who is always the fountain of expert knowledge.

JimN
07-02-2008, 11:57 PM
Fountain? This is a MasterCraft site.

TonyB
07-04-2008, 02:16 PM
Fountain? This is a MasterCraft site.

Oops. JimN is a master(craft) of expert Knowledge.