5.7 Omc Cobra...misfire In 4 Cylinders..ideas?

[billb83]

I have a 1987 Chris Craft Scorpion with a 5.7 OMC Cobra. There were new points put in before the winter and ran fine before taking it out of the water last year. When i put it in the water this year it starts fine, idles fine but when trying to accelerate it bogs down and cant get out of its own way. Ive checked the spark and it apears as though 4 out of 8 cylinders arent getting spark at all. Ive checked the cap as well and everything seems to be fine there. Anyone have any ideas as to what can be wrong?

 

[HT32BSX115]

Re: 5.7 Omc Cobra...misfire In 4 Cylinders..ideas?

Howdy,

Assuming your dist cap is not wet inside, you have good plugs, wires, connections etc....It sounds like the classic ESA activation.

You may have a lower shift cable that is corroded/defective/out of adjustment causing additional force to move it, activating the ESA. It'll seem like several cyls not getting spark....


If you're trouble-shooting problems your best bet is to get an OEM service manual and read the following. http://www.hastings.org/~stuart/cobra/

regards,


Rick

 

[CWBIF1234]

Re: 5.7 Omc Cobra...misfire In 4 Cylinders..ideas?

WELL I SAY ITS THE RESISTOR WIRE RUNNING FROM YOUR ALTANATOR TO THE COIL ITS A RESISTOR WIRE . THE FIX IS CUT 21 INCHES OFF THE COIL END PUT NEW END. I REPLACE MY MOTOR FOR SAME REASON ONLY TO FIND IT STILL HAD SAME PROBLEM WHEN TAKE BOAT OUT WHILE TRING TO GET UP ON PLANE RUM METER ON 12 VOLT SETTING TOUCH POS AND NEG POST ON COIL YOU WILL FIND YOU DON'T HAVE 12 VOLT ANY MORE omc service bulletin 4091 REV 1 DATED JAN 1993 HOPE THIS WAS HELPFUL OTHERWISE YOU HAVE TO BUY NEW WIRE HARNES AND GOOD LUCK WITH THAT

 

[billb83]

Re: 5.7 Omc Cobra...misfire In 4 Cylinders..ideas?

thanks.. it seems like it could be the esa activation and that was my first thought, but when the motor is at idle i have used a test light on all eight of the wires coming off of the cap and four have nothing.. i am going to look into the second suggestion. Thanks again guys.

 

[billb83]

Re: 5.7 Omc Cobra...misfire In 4 Cylinders..ideas?

Anybody else have any thoughts on my problem? No spark at on half of the wires in the distributor cap. i believe its cylinders 1,3,5,6 that are dead.. three on one side and one on the other side.