Omc 3.8 lite dieing spark

[Troy Adams]

I've lost all spark, will not fire. Two weeks ago it r a n perfect. Then the following week I launched the boat, let it warm up. I proceeded through the no wake zone with no problem. When I attempted to throttle up it it ran like it was running out of fuel. Then I noticed the smell of unburnt gas, like the choke was stuck. It wasnt, so I pulled the boat out of the water. Since then I replaced the fuel pump, rebuilt the carb. Now it will barely idle,and chugs like it has performance cam. I checked the timing off the crank and it was kinda bouncing around. Between 6 and 12 degrees BTDC. I then changed the points condenser and coil. Now it won't even fire. The only thing left that can think is the resistor. From what I understand that's built into the wire harness. I'd hate to change that out. I hope someone can help. Thanks

 

[southkogs]

Are you getting spark at the plugs? And are they firing in the right order?

 

[Scott Danforth]

When you replaced the points, you did clean them, and set the dwell, correct?

 

[Howard Sterndrive]

is the distributor rotor turning?
there are still lots of things besides the resistor wire.
I would try unhooking the tachometer.
Then, if tach not the issue, unplug the ESA module. (if your boat is 1982 -1985)
but unhook things ONE at a time.

do a compression test - you could be onto something with the lumpy cam. Your timing chain coulda skipped a tooth or a valve spring broke - compression test will eliminate the mechanical issues like that. You can also check for water on the spark plugs while at it - could be a manifold failing or riser gasket water can put a "damper" on things when sparks are trying to start fires in the cylinders.

still 50 other things. even seen a bad ignition switch cause spark problems, or a corroded fuse, or bad alternator, bad grounds or wiring issues in general. old boats need lots of things checked sometimes.
if it's a 2BBL, also check the heat choke tube. they like to rot off and create a vacuum leak

 

[Troy Adams]

I made sure the contacts on the points were not flawed, but didn't really clean them. I didn't check the dwell cause it wouldn't fire. It should be close enough to at least sputter. The rotor is turning. I'll try disconnecting the tac, my boat is a 1984. I don't know what the Esa module is. I pulled the plugs they were all black. It didn't appear to have any sign of water. I did check the timing chain it looked brand new, no slippage. I pulled the dizzy to check the gear, it looked really good too.( I did mark the rotor so it went back right). I'll do the compression check and if that's good I'll try disconnecting the tac. Thanks for the help, I rescued this boat from the crusher, it was pretty wiped out. I replaced the motor, outdrive, seats, floor, paint,carpet,ect. It's only been in the water 4 times. It's a 17 ft Conroy. I'll post my progress. Thanks again

 

[Howard Sterndrive]

my boat is a 1984. I don't know what the Esa module is.

esa=electronic shift assist. 1984 has it

it's a module that stumbles the ignition to assist shifting from gear into neutral - safety related, so disconnecting it should only be temporary for test purposes. your shift cable adjustment can cause it to interrupt spark while underway.

 

[Troy Adams]

Is that module on the shifter or back on the engine. I'm going to try your suggestions tomorrow, thanks for your help.

 

[Howard Sterndrive]

by the engine - sometimes on a bracket on one of the exhaust manifolds, sometimes on a bracket on the intake manifold or rear of block. google up " [h=2]OMC Stringer Test of Switches and Electronic Shift Assist Operation[/h] I don't think iboats lets me link to a crowley site, but they have the test procedures there

 

[Troy Adams]

I'll give it a shot. Thanks I'll let you know what happens. Thanks alot

 

[Troy Adams]

I check the compression, they all consistent right at 125 or so. The mechanical timing is right, I put rotor on the #1 cylinder and the timing mark on the crank was at 10 degrees BTDC. I checked the wiring under the dash all tight and pretty clean but one. I cleaned and tightened it. I disconnected the Esa switch and no change. I disconnected the tach. No change, what's weird is it ran at idle until I changed the points, now nothing. The coil reads 4.2 to 4.6 volts when I open and close the points. Im completely stumped. I'm thinking oar locks at this point, ha ha! Tubing would be slow though.

 

[Troy Adams]

I checked the resistance wire, according to the book. I tested the purple wire from the altinator and the purple and red from the pos. Side of the coil. It should read 1.5 to 2.5 ohms. I got a count down to 0.00. I'm not sure if I tested right, if I did can I get a working harness. Or can I by pass that stupid design.

 

[Scott Danforth]

Checking dwell during cranking will tell you if the points are firing at all. Then again, so would a test light

 

[Howard Sterndrive]

my guess is you're not doing a lot of good work with that multimeter. Maybe a couple youtube vids on the basics. But if checking resistance of something, that has to be a BENCH test with the part removed from the system. I suspect you are trying to check that wire still installed.I wouldn't worry about it's resistance. A visual is as good as anything. If the wire looks good, and isn't smoking or super hot, it probably is fine in this case.
As far as the coil, you are probably checking voltage at the 2 coil terminals which tells you nothing but is a pretty common error.

You want to put the red meter lead on the + coil terminal, and then stretch that black one all the way over to the battery - terminal.

You should see 10V or so key on, also 10 or maybe 11 or so cranking depending on how strong your battery is.

If your key on voltage is way low, you can go back to worrying about the resistance wire. It's actually a pretty decent design in my experience.

 

[Troy Adams]

Your right about my work with a multimeter, Iam much better with mechanical than electrical. That's why I struggle with this stuff. I'll recheck the coil, if it does read 9 volts then I'm still stuck. I should have spark. Anyway, thanks for your time. I really appreciate it. I'll post what I find.

 

[Troy Adams]

I checked the voltage at the coil, with ignition on. Red to positive post on coil negative to neg. Post on battery. It came up 4.8 volts, bad ignition switch?

 

[Howard Sterndrive]

or a bad connection somewhere. or a bad coil. or a weak battery. or a bad resistance wire.