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r_d
 
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Default 87 OMC carb/ignition problems

Hi all,



Thanks to the help of some great members, I have been able to get my 87
OMC into the water and running. Unfortunately, I have hit a snag. I
converted the point's ignition to a petronix electronic system with the
diode/resistor patch for the shift interrupt. I am having two primary
problems:



(1) When I hit the drive trim it kills the engine (a Chevy 350).?. I cannot
figure out how the systems are connected, the mechanic thinks the trim pump
is pulling too much power and starving the coil but it has two batteries and
with they engine running the volt meter shows about 12 volts with the pump
running. So I do not totally believe him because if is did pull too much it
would blow the fuse and in addition I have wired the Hall Effect sensor to a
battery source so it should be seeing 12 volts regardless...



(2) I also seeing the engine cutting out or stumbling above idle, although I
believe this is due to a carburetor (Rochester quad jet) problem. I had the
same mechanic rebuild the carb and I honesty think he made a few mistakes
(he also put a new pump in the drive and did not bother to clean the gasket
surfaces. Pump sucked air (no water) and left me rowing back to the dock).
Anyway, the engine starts easily but also stalls easily (unless you are
pumping the throttle), and back fires if you try to kick it above 2500rpm
(high-speed jets). The kicker is that when I first put it into the water it
ran perfect for about 20 min and then started to stumble and has been
getting worse ever since.



Anyway, has anybody had any problems with this system? The mechanic thinks
these problems are all associated with the petronix system (they have no
help line) and not with the carb. I have checked all the wiring, the
resistor wire that feeds the coil is within specs and I cannot find fault
anywhere in the electrical system. The timing (using a timing light is rock
steady and set correctly). It has fresh fuel and I have replaced the fuel
pump, fuel lines, fuel filters, plugs, coil, wires, rotor and distributor
cap. My vote is for a problem carb but I do remember somebody saying they
had an issue with this petronix system and their mechanic added a resistor
but it already has the proper amount of resistance in the system.?.



Sorry this is so long but I though background info would be helpful.



Thanks for your help, it is appreciated.

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