Mercruiser 3.0 no spark

[bobskilton]

Just had 1984 140HP 181 c.i. engine rebuilt and installed but no spark. All new parts. The engine was turned over in reverse (battery was hooked up backwards for a minute!) Still have 12V at both sides of coil. I'm thinking the problem may be in the ignition switch wiring. Any ideas would be appreciated.

 

[Trent]

Re: Mercruiser 3.0 no spark

Check for voltage at the + side of the coil while cranking. What is the voltage then?? Also try removeing the gray wire from the neg. side of the coil and then try cranking. One other thing that can be a problem is the shift interrupter is grounding out.. Disconnect it (port side of engine)

 

[bobskilton]

Re: Mercruiser 3.0 no spark

Thanks Trent for getting back to me. I measured the voltage on the + side of the coil while cranking - it drops to 6 volts or less. Disconnected the gray wire and then the shift interlock. Still no spark. Is it possible I fried the coil by hooking the battery up backwards? Do you have any info about the ignition switch hookup? I appreciate your help!

 

[Trent]

Re: Mercruiser 3.0 no spark

Dont worry about the switch! You got voltage at the coil..Its working <br /><br />Six volts is not enough. DO this. Connect a jumper wire from the + side of the battery to the + side of the coil. Then crank..Does this help? If not I will give you the specs on the coil and you might have to replace the condensor.<br /><br />Trentcr@hotmail.com

 

[bobskilton]

Re: Mercruiser 3.0 no spark

I'm once again trying to get my new engine to run. I get 12V at the coil and it drops to just under 10V when cranking. I replaced the starter solenoid, coil, condensor and ran down all the wiring I could. The shift interlock seems to work OK. The only electrical part I have not replaced is a solenoid-type switch that feeds into the ignition and main breaker. Since I accidentally ran 12V reverse polarity, could that (or something else) be damaged?

 

[spinakersheet]

Re: Mercruiser 3.0 no spark

Bob I had this same thing happen. You burned out your points. If your getting 12 volts on both sides thats what it is. I had a so called mechanic reverse the + and - on my coil and he couldn't figure out why we were getting 12 on both sides. I got rid of this guy after he also broke my rotor. I then put in new points and presto I had 10.5 on + and less than 1 on - when you turn your key on.<br /><br />You should be getting 10.5 on one side and less than 1 on the other. There is a resistor wire conected to your alternator that brings down the volts from 12 to 10.5 by design.

 

[tuanp]

Re: Mercruiser 3.0 no spark

spinakersheet,<br /><br />I have the same problem as cap'nbob; I have no spark but have voltage from the coil. In fact, I have 11.x on both the + and - sides of the coil. According to your reply, the points are burned and you replaced them. Is it possible to replace just the points? or do I have to replace the whole distributor?

 

[KiLer]

Re: Mercruiser 3.0 no spark

you can replace just the points...but I'd change the condensor too....make sure you have the dist. at the high point shen setting them...and that they are set to the right gap....too much gap...no spark.

 

[Hunky Dory]

Re: Mercruiser 3.0 no spark

Points open and close regularly during engine rotation so there is no predictable static measurement. Points open= 12v both sides of coil; points closed = 0v (ground) one side of coil. If you meter while cranking one side should show reduction. If not points aren't closing or are fouled with non-conducting material...

 

[tuanp]

Re: Mercruiser 3.0 no spark

Thanks. I replaced the points and that fixed it. There's spark now and the engine fires, but now I'm having problems starting, or when it starts, keeping it running. I have some more questions in my original post (...is it coil?) if you care to look. Thanks again.

 

[Kelsey]

Re: Mercruiser 3.0 no spark

I am having a simpler problem with my 140 Hp mercruiser I/O 1986 Thundercraft. Some details are: I was having a charging problem, so I ended up replacing the alternator. When I installed the new alternator I put the wires back on the same as the old one and without knowing the plug that goes into the side of the alternator was reversed. I think I then noticed a little smoke coming from the opposite side near solinoid etc.... Now when the boat sits for any longer than a week or so the battery is dead. The battery by the way is brand new marine deep cycle type. Is there any ideas out there on what could be causing this problem or maybe someone had same problem.<br /><br />Thanks