92 Comp misfire/lack of power

[Supra-in-steamboat]

91 Comp, GT40 heads, 1992 Ford 351 PCM ignition (High Altitude specific package). Boat is at 8200ft. @800hrs. New carb, not jetted specifically for altitude. The boat is misfiring intermittently at @2700 and 3200prm. It was doing so prior to the carbs replacement. Does this sound like a timing or advance issue? The reason I question the timing/advance is my 87SunSport has the same carb, same jet, and runs fine (a little rich), on the same lake. Treated gas, changed fuel filter, checked all plugs, wires and no love. Any thoughts or suggestions?

[OUI]

Definitely a timing/advancing issue. Check your timing, also squirt a little WD40 into the screen doors on the distributor if the weights are sticking they won't advance, that should loosen them up.

[Supra-in-steamboat]

The distributor is a PCM with no exterior screen. I removed the cover to have a look t the optical sensor and was/am hesitant to WD it as it a sensor. I will adjust the timing/advance and have a go. Appreciate the help OUI.

[OUI]

Did you check the underside of the distributor, I have a Prestolite system and that's where mine are located.

[OUI]

Do you know Kevin Bennett by any chance?

[92SupraComp]

there are no advance weights in the crank position sensor for the electronic ignition. (where the distrib. should be.) as you can see we have the same boat. whats happening is the ignition pack is going in and out of "limp mode". things that cause limp mode: too high of engine temp (210F), low oil pressure, low battery voltage, bad temp sender, bad oil sender, bad knock sensor, and last the ignition pack is going bad on the inside. ours did similar only it would die shortly after and we would have to wait. turns out smacking the small oil sender(goes to ignition pack) fixed the problem. dont know if it will work for you but the ignition system is acting up.

[92SupraComp]

Limp Mode: comes on after bad readings, limits engine rpm to 2,200 rpm via cutting spark above 2,200 rpm. when cruising above 3,000 and go into limp ignition either cuts spark completely or cuts spark until 2,200 rpm is reached.

[Supra-in-steamboat]

We did speak about the limp mode possibility. The oil sender may be the culprit. It occasionally beeps when returned to idle. Spaced mentioning that piece of info. Very much appreciated 92SupraComp, i will let you know what happens. Thanks again.

[Supra-in-steamboat]

This Comp has a carb. To rule out the knock sensor causing the limp, would i bypass it, or go to ground? or niehter?

[92SupraComp]

This Comp has a carb. To rule out the knock sensor causing the limp, would i bypass it, or go to ground? or niehter?

in order to have fuel injection it would have to be 93 or newer and be gt40 pro boss efi. all Protecs have carbs. but you cant bypass a knock sensor. it is essential to have working. give your sensors a firm but not too hard smack with a small hammer. that fixed our problem 15 years ago.