OMC CDI shift interrupt question.

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SCORPIO

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I recently installed a Sierra electronic conversion kit into my Mallory dostributor on my 260HP OMC. I also installed the Rapair CDI shift interruptor unit compatible with the electronic conversion kit. I timed the engine and set the idle on muffs in the driveway and everything seems to be working OK but I find that if I don't shift very briskly into foreward, the engine will occasionally stall.
I have idle set to 550 rpm in gear and the timing is set to 10BTDC. I have no trouble with the stalling going into reverse gear. The info with the unit instructs to be sure the coil resistance is 1.5 ohms, which mine is, and also to be sure the external ballast is 1.5 ohms. On my engine, that is a violet/red wire on the positive coil. My shop manual says to check the resistance between the coil end and the 20 ga. purple wire on the alternator. Trouble is, I have a two wire alternator and no purple wire, one is yellow about 14 ga.and the other is brown about 6 ga.
Does anybody have any ideas?
Anyone have a similar experience with stalling?
Maybe this is normal and I just need to adapt to a quicker shift stroke?
 
Sounds like your lower shift cable isn't adjusted properly and your ESA is activating during the shift to forward. The ESA should only be turned on during the shift out of gear.

The problem could also be a worn and binding lower shift cable.

Try shifting without the ESA connected to see if you have the same problem.

Do you have this problem in the driveway on muffs?
 
Idle should be set in forward gear which you did (550-650)RPM. Have you tried increasing the idle to the 650 rpm range to see if this would help.
 
quote:
Originally posted by bruceb

The ESA should only be turned on during the shift out of gear.

Click to expand...

That's what I used to tell people too until someone called me on it - I looked in my OMC manual - it says it's actually supposed activate going into gear too, unlike Mercruiser's system, but your right about the lower shift cable as the likely culprit.
 
I didn't have the stalling problem with the old points setup and ESA module, only since the swap to electronic. Yes it does this in the driveway on muffs. I have not tried setting the idle higher yet as I was afraid it would make shift efforts higher.
Since this problem only surfaced after the electronic swap, I thought that perhaps I have a problem with one or more components involved in the swap.
 
It's not normal as far as you question about needing to shift more briskly. Did your old ESA work? A lot of those original ESA boxes only lasted 10 years or so. Maybe you need to adjust the switches that trigger the ESA. If the old one was dead, the switch adjustment wouldn't have mattered.
Whatever you do, don't raise the idle to mask it.
After that - maybe call Rapair and make sure it works with the Sierra setup - it works with Pertronix, but Sierra....hmmmm
And if it's Cobra drive, it's probably the lower shift cable dragging going into gear and causing the ESA switch to stay closed after the shift.
 
The old ESA worked fine (with points) and I had no shifting or stalling issues with it. I replaced my points with electronic to get away form the maint. of points. I replace my old ESA with the CDI unit so I could use the electronic kit. I doubt the shift cable has anything to do with the stalling. It sounds to me like the new ESA is occasionally grounding out all the spark and stalling the engine. There is a trouble shooting page with the unit explaining that coil resistance needs to be stock (1.5 ohms) and the stock ballast resistor needs to be 1.5 ohms. This keeps coil current at 12/3=4 amps. More than that and the CDI units will cause stalling. My origional post was about how to determine if the ballast resistor is OK. This is a Stringer drive using a violet/red wire of 1.5 ohms. The factory shop manual says to disconnect it from the coil + and from the alt. and read the impedance. I have no purple 20ga wire on my alt. so I cannot determine how to check to see if I have sufficient resistance for this ESA to work correctly. I don't want to add another ballast and find out the problem is worse.
 
Talked to GVP and he recomended readjusting the switches and trying it again.
 
we gave up on the omc stutter box when switching to eletronic we convert it to a merc style kill system like used on alpha ones with very good results
 
Kevin, can you elaborate on that, what parts were involved (sources?) also how difficult was it and exactly what all did you have to install to make this work?
Thanks
 
Suggest you convert back before you cause big buck damage to your drive. Conversions have given a lot of people problems.
 
Try adding a .8 ohm ballast resistor(AutoZone $6.95) to the positive side of the coil (purple wire in 1991). If the voltage is to high going to the ESA it will cause the engine to stall when the ESA is activated.
John
 
the trip switch is already there just rewire it to ground the minus side of the coil instead of the stutter box.... a little water testing to adjust and it works the same as every merc alpha one out there
 
Readjusted the overstroke switch and staling problem seems to be fixed, thanks George!
 
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