140 mercruiser missing after it gets warm

[dubs283]

Re: 140 mercruiser missing after it gets warm

The Resistor wire comes from the key switch, it is aluminum, or white metal of some type, so it becomes a resistor automatically,,, not delivering the full 12 Volts.

The only thing I can think of, is that someone monkeyed with, and switched the wires on the ignition switch?

i have never seen a resitor wire coming off the key switch, all mercruiser resistor wires are part of the engine harness

in any case the location is arbitrary, he's not geting the proper voltage drop

 

[splatter]

Re: 140 mercruiser missing after it gets warm

That don't matter much now,,, I'm trying to establish a baseline here.

Did you take off the solenoid wire at the coil, and test IT for voltage when in cranking/starting mode, then in Run mode, of the key switch?
and did you happen to test the voltage on the Resistor wire using the same method?

I took the solenoid wire off at the coil and tested it with the engine running . I had 0 volts . I didn't test it while cranking . I figure it has to have 12v then or the engine wouldn't start . I tested the voltage on the OLD resistor wire with the engine off and it on the coil . I get 5v . If I take it off the coil I get 12 v . I tested it with it running (old and new wire) and I get 11.5 to 12v.

 

[splatter]

Re: 140 mercruiser missing after it gets warm

that is very strange, especially with the wire's resistance, i guess you could daisy chain the old and new, see if that drops the voltage enough...sounds like your doing everything as you should

I tried this and it dropped the voltage to about 10.5v

 

[splatter]

Re: 140 mercruiser missing after it gets warm

The resistor wire was wired in the harness to 2 purple wires . one coming from the alternator and one coming from the carb. This should be correct because the it appeared to have a factory splice . Also even if it came from the switch wouldn't it still have the same voltage as what is coming from the alternator ? If it was wired wrong before I wouldn't think it would have ran good for the last 3 years .

 

[splatter]

Re: 140 mercruiser missing after it gets warm

I'm thinking seriously about going with the pertronix ignition,use their coil which needs 12v and this would eliminate the points and condenser also .I took the day off today to work on this and other things . I'm going to the lake in a few and try it . I don't expect and different results but I i have to try it . When it starts running rough I'm gonna daisy chain the 2 wires and see if that helps. At this point I wish I had insurance on it then I would just sink it .

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

I took the solenoid wire off at the coil and tested it with the engine running . I had 0 volts . I didn't test it while cranking . I figure it has to have 12v then or the engine wouldn't start

Okay, That sounds right!

I tested the voltage on the OLD resistor wire with the engine off and it on the coil . I get 5v

That sounds right, but is this with the ignition on, or off?

If I take it off the coil I get 12 v. I tested it with it running (old and new wire) and I get 11.5 to 12v.

This I don't understand?

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

The resistor wire was wired in the harness to 2 purple wires . one coming from the alternator and one coming from the carb. This should be correct because the it appeared to have a factory splice . Also even if it came from the switch wouldn't it still have the same voltage as what is coming from the alternator ? If it was wired wrong before I wouldn't think it would have ran good for the last 3 years .

One purple wire might have been for the electric choke?

By the way, setting the points with a feeler gauge will get the engine to run, but setting them with a dwell meter will get the engine to run better! Did you happen to check inside your Dist. to see if there's any play, side, to side movement, (wear) in the shaft? And that your mechanical advance is working, and working properly, so that the Pertronics would work right?

A common generic Ballast Resistor:

 

[wrench 3]

Re: 140 mercruiser missing after it gets warm

With 5V at the coil with key on and engine off you must have lots of resistance in the wire. Getting 12V with the wire off of the coil is like I said "no current flow, no voltage drop".
The purple wires at the splice go to the choke heater and the alternator exciter terminal.
It mite be worth while to recheck the point gap.

 

[splatter]

Re: 140 mercruiser missing after it gets warm

since I still had the same voltage on the coil I just went ahead and bought a pertronix electronic converter and their 3 ohm coil . I buy passed the resisitor wire and put a new wire on from the splice .This way I don't have to worry about the voltage at the coil being correct.
At 30 minutes it started sputtering again . However this time it wasn't as bad as before . So I had my son drive and I took the engine cover off to see if I could figure something out . as soon as I took the cover off the boat started running like it should . I had done this with the previous coil with points and it didn't matter it still ran like crap .Any way so I'm thinking heat is the problem . So I felt around and the only thing in the ignition system that was hot was the coil .
I don't know why its suddenly to hot in the engine compartment .The temp gauge shows I'm running around 165 degrees . The only thing I can think of is the new out drive which is an SEI 106 may not pump as much water as the old mercruiser causing the engine temp to rise just enough to cause the coil to over heat
So now I'm gonna insulate the coil from the engine as much as possible and see if this solves the issue . I certainly hope so . May not get to the lake again till sunday or monday but I will post the results after I go .

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

Maybe there's not enough air circulation getting to the engine compartment, choking the engine out?

 

[AKPilotnboatman]

Re: 140 mercruiser missing after it gets warm

I don't know a whole lot, but it seems that the correct ohms, volts, and all that is in the mercruiser maintenance book. So test those accurately. if not, maybe there is some unusual build up of exhaust gas or something. it is hard to say exactly but it has to be fuel, spark, air, or compression. Most of those sound like they check out. Don't get discouraged. It will work out

 

[splatter]

Re: 140 mercruiser missing after it gets warm

Maybe there's not enough air circulation getting to the engine compartment, choking the engine out?

I was thinking this also but when it starts I can still make it worse by hitting the trim switch so it has to be electrical .

 

[splatter]

Re: 140 mercruiser missing after it gets warm

I don't know a whole lot, but it seems that the correct ohms, volts, and all that is in the mercruiser maintenance book. So test those accurately. if not, maybe there is some unusual build up of exhaust gas or something. it is hard to say exactly but it has to be fuel, spark, air, or compression. Most of those sound like they check out. Don't get discouraged. It will work out

I'm already disgusted but thanks for the encouragement .

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

Something else to consider, A poor power, or ground, connection somewhere can play havoc on the whole electrical system. Have you cleaned up all your electrical connections recently? The sudden current drop, or draw can kill your engine if bad enough, hence the power trim motor issue.

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

Check out this link I just found:

http://forums.iboats.com/mercruiser...ting-your-engines-starting-system-167035.html

 

[splatter]

Re: 140 mercruiser missing after it gets warm

I re connected all my connections ,cleaned and lined with dielectric grease .
I've moved the coil away from the engine and plan on putting a couple of clam shells on the engine cover to improve ventilation . Don't have the clam shells yet though . Gonna try and go to the lake today and see if moving the coil changes anything

 

[Speakrdude]

Re: 140 mercruiser missing after it gets warm

Remember, Ohms law only applies if used in the continental US. Outside of that, international laws apply!
-)
Happy Mothers day, moms!

 

[wrench 3]

Re: 140 mercruiser missing after it gets warm

Remember, Ohms law only applies if used in the continental US. Outside of that, international laws apply!
-)
Happy Mothers day, moms!

It applies in Canada too.

 

[MikDee]

Re: 140 mercruiser missing after it gets warm

IMO, If you're getting 12V from the solenoid with the ignition on, engine running. Then it might be bad? That may also be causing the current drain, because it shouldn't be doing that?

One thing to check, If you take off the resistor wire, does the engine run on the solenoid wire alone?

 

[splatter]

Re: 140 mercruiser missing after it gets warm

IMO, If you're getting 12V from the solenoid with the ignition on, engine running. Then it might be bad? That may also be causing the current drain, because it shouldn't be doing that?

One thing to check, If you take off the resistor wire, does the engine run on the solenoid wire alone?

No I only get 12v when the engine is running . I get 5v with the ign on