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5.7 260h/p Alpha1 lack of power/miss

stretchmanPA.

New member
I have an '86 Wellcraft 23 NovaXl with a mercury 260 alpha1 (5.7 liter) TB ignition syst. The distributor cap cracked and had to be replaced. In the process, one of the cap screws, (rearmost) broke off. I had to remove the distibutor assy. to drill it out. In the process, I damaged the ignition sensor and had to replace it. New ignition sensor, cap, rotor. Reinstalled distributor. I don't have a manual so going off gm/mechanical experience, preset the timing to 8' BTDC. Engine starts fine, but now has a complete lack of power, misses. Won't run up over 3000rpm. The odd thing is, if I hold the trim button, say down, with the trim all the way down, so it is maxed out, the enging smooths out and gains 500rpm. As soon as I let the button go, the miss comes back and engine slows down. I went thru most of the electrical syst. trying to find a short. Can't pin down a problem.
What is the correct initial timing setting, and any ideas at all on the miss, running issue, and why would putting a load on the trim pump make the engine run fine??
Help.
 
8 deg BTDC is whats in the manual...I'd start with the firing order...and then check the wires you moved prior to pulling the distributor....I doubt that the engine runs fine with the electrical load applied...

BTW, you will getting more responses if you post the mercruiser issues in the mercruiser forum
 
Firing order is correct. Only 2 wires removed were to the ignition sensor, and they are color coded.
I had someone with me who witnessed the running issue and the engine response to electrical load.

Thanks, but I thought I was on Mercruiser forums.
 
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