OMC 302 running horribly! *$$$ BINGO $$$*

[Boomyal]

Out of the blue, my motor has begun running extremely rough at all rpms with constant stalling at lower rpms. It appeared not to be a fuel issue so I checked the voltage to the coil. It only has 4.28 volts to the 'batt' terminal on the coil. It shows no voltage from the terminal on the other side, going to the distrib.(key on but not running)<br /><br />I thought that the lead to the batt side came directly from the battery thru the ignition switch. What could be wrong?

 

[backdraft]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boomyal, Depending on the mfg, you can a ballast resistor ahead of the coil or resistance wiring built in before the coil. When cold there should be 12 to 13 volts leading into the coil. If you have a coil with a resistor built in [it will say it on the side of it] ,there should be the same voltage 12 to 13 going in. After it warms up there will be approx. 8 to 9volts on the output side of the coil. If no output on the coil, I'd try a new coil. nevjb

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Nevjb:<br />I haven't seen any markings on the coil other than on the face where batt is stamped. It is the original coil, 1975. Voltage was checked cold, with key on, motor off. What is a pre-coil ballast resistor supposed to do relating to voltage at the positive side of the coil?

 

[backdraft]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boomyal, A ballast resistor ahead of the coil allows full voltage coming to it to pass through when it's cold. This makes for a hotter spark when cold. To keep the points or electronics from burning out , the ballast resistor heats up causing a resistance in itself restricting the voltage down to 8 or 9 volts. This allows the points or electronics in the distributor to last a lot longer. nevjb

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

NevJB:<br />Sounds like I may have a defective ballast resistor. Sounds like the only thing that could be responsible for low voltage even when it is cold?<br />Thanks<br />JB (Boomyal)

 

[rattana]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boomyal, connect a wire from the battery or any +12VDC source directly to the positive terminal of your coil. This will bypass your ballast resistor or resistive wire of your ignition system. If the boat runs well then you found your problem. You will have to disconnect the wire so your engine will stop.

 

[P.V.]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

In an attempt to troubleshoot a ballast problem, simply use a jumper wire across the two leads on the ballast. It will now have 12 volts (roughly) and should run. Remove the jumper and if the engine dies, the ballast is at fault. Don't run the engine for any length of time with the jumper in place as it will burn points, just long enough to troubleshoot !!!

 

[backdraft]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boomyal, if the coil has a short internally, the voltage coming into the coil will be low because it is shorted internally. Take off the wire coming to the coil and measure the votage to ground. If it's 12 volts, its the coil. If it's less or around the voltage you previously tested , do as the advisors above state and run a hot wire directly to the coil as a test ONLY. The numbers or data I referred to is under the bracket on the side of the coil.nevjb

 

[CRT Skiff Crafter]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Hey Boomyal. This sure sounds familiar!<br /><br />Once you bypass the resistor, you'll know a lot more. Although you already know you've got low primary coil voltage so I'd bet on that resistor first. If it 's not the resistor, there's obvioulsy a voltage loss occuring earlier in the chain, assuming the coil isn't shorted. However, I'm simply stating the obvious and echoing the other dudes who posted. I feel compelled to do so since I spent half the summer chasing such a problem and I want to feel like it made me more aware. <br /><br />If you get the voltage at the coil right and you know the coil is good and there's still a performance issue, don't forget to check that coil secondary (Hi Volt) lead! I believe they become possessed and must be exorcised from time-to-time. <br /><br />As a sidebar, when my coil went bad this summer, I could actually see it arching all over the place when I ran at night! I mean it was like a darn light show! It really was scary in terms of the potential for it causing an explosion. <br /><br />Regards, crt.

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Hey All: Nevjb, P.V.,rattana & CRT, I think you all have got this problem cornered. Now all I need is that hour back and I'd go out and tackle the problem. Thanks Bunches.<br />I want the motor to run right b4 I winterize it and b4 I start tearing out that d*** floor. I've already taken my digital before pictures, I'll be sure to take and post pics as I go along.<br /><br />CRT, it's good to see that you made it back from your Boatin safari. All under your boats own power too. You were like a hound chasin a coon, tearing into all the repairs for you problems. All to be admired.<br /><br />ps, this might be the time to invest in a pertronix type pointless setup w/ hi output coil.

 

[rodbolt]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Hello<br />hiyas moomyal<br /> one other thing before you condem the coil. when using a volt meter and key on engine off method make sure the points are open. if they are closed you will have zero volts.if they are dirty and closed you will have a low voltage just like you described.remember, once the points close you have an electric wire sretching from the distributor to the battery. the points are just a switch. <br /> good luck and keep it wet

 

[CRT Skiff Crafter]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Hey Boomyal. Yeah, it was great to finally have a trouble free day that had my boat in the mix!<br /><br />Hope you get your's figured out quick and look forward to checking out the pics of the floor rebuild!<br /><br />Regards, crt.

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Now I guess I know why they make professional mechanics and all those expensive diagnostic machines. I can't figure this one out. One minute the motor runs at a smooth constant 2000 rpm and the next minute it's missing and running rough, occasionally just stalling out. Plugs are new, points are new (just now readjusted to .19)<br />I tried a different coil and primary coil wire out of my 65 Mustang with no difference. Once the motor was heated up and running I have 13.4 v going to the ballast resistor and about 10.4 v coming out. At the same time the voltage at the input to the coil is 10.4 v and on the distrib side it varies between 8.6v bouncing off of 9v. Doesn't seem to be a problem there. The gas is fresh with a near new spin on fuel/water cartridge. When the engine is running(rough most of the time)it smells a little rich but it's not flooding, it's just not burning it all with the rough running condition. The timing chain has very little time on it. That along with the initial timing could not be an issue because it would never run smooth. The distributor was just checked to make sure the weights were free, the springs were working and the bushings were good.<br /><br />The plugs are new (few hours) but the plug wires are 28 y/o. Two trips ago the motor ran like a swiss watch and this last time out it was a problem from the get go. I appreciate everyones help but it looks like I'm going to have to open my gate, hitch up then open my wallet and go compete with everyone trying to get their boats winterized.

 

[CRT Skiff Crafter]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Hey Boom. I'd change out the plug wires before you sacrifice your finances. No doubt bad plug wires could cause such a problem and at 28 years, they're ready for retirement village. <br /><br />Regards, crt

 

[backdraft]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boomyal, does this motor have a 2 barrel on it? Adjust the mixture screws at the base of the carb. Screw them in and then turn out an equal amount. Usually one and a half to two turns out [both of them ] will put you in the ballpark. Try for the best idle. If this doesn't work, you have never heard of me. nevjb

 

[llerrad]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Change the condensor in the dis.

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

nevJB, I'll check those adjustments.<br /><br />llerrad, I'll change the condenser. Earlier this summer, I had the local Distrib Guru spin my distrib up to check the weights and curve. Just yesterday, when I was checking the point gap I noticed that he had changed the points but that the condensor was the same. The condensor is not as old as the boat but it's at least as old as Methusalah.

 

[Boatin Bob]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boomyal.....never heard of anyone changing points and not the condenser at the same time, any tune kit I bought always comes with both.<br /> btw...I assume those voltage readings you gave above were when the engine was running fine? Are you able to do them again when it's running rough?

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Boatin Bob: That is kinda what I thought about the condensor. But certain he did not change it. It still had the same crimp on connector on the lead that I had on it. The points were definitley different as they were copper colored instead of silver. The voltage readings were when the motor was running rough (most of the time). I'm going out now to pull the condensor and go down the the AP store to try a new one.

 

[Boomyal]

Re: OMC 302 running horribly! *$$$ BINGO $$$*

Well I haven't exhibited the tenacity of tackling this proplem like CRT did, but here is the current non-status. It still won't run!!!<br /><br />After much measuring of voltages between the coil and the ballast resistor I came to no understanding. <br /><br />Whereas the motor ran roughly, with short periods of smoothing out, it finally would not start at all.<br /><br />I pulled the secondary coil wire from the distrib cap, held it 1/2" from ground and cranked the engine. No spark.<br /><br />I went out and bought a Pertronix II ignitor and a Pertronix Flame Thrower II coil. I properly installed them, with the ballast resistor out of circuit, and it still wouldn't start. <br /><br />Back to basics, I pulled the coil wire, aimed it at ground and got a good spark. I pulled a plug wire and plug, grounded it, cranked the motor and got no spark. Down to the autoparts store to order a new distributor cap.<br /><br />Today, with new cap installed, I had proper spark everywhere. Still no start although it half acted like it might. I checked and rechecked for spark in all the right places, determined that gas was entering the carb, used ether. No start.<br /><br />Now I remeasured the key on voltage at the distrib and ran a lead over from the batt just in case. When I crank the motor(turns over well & batt has good charge) the voltage drops to 8.5 v w/o the jumper lead and 9.0v w/ the jumper. No start.<br /><br />Pertronix says it should start with any voltage over 8 volts. I just went out and and cranked the motor, this time holding the plug wire 3/8" from ground (instead of plug to ground) and it threw a huge, consistant, spark across the gap. I did this on two plug wires with equal results. Applied more ether and still no start. It tried to catch but no more than that.<br /><br />I am at a loss. Any further thoughts?