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.

mark

"r_d" wrote in message
roups.com...
Hi all,


I converted the point's ignition to a petronix electronic system with the
diode/resistor patch for the shift interrupt.
(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. 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.?.



When installing an electronic ignition, you remove the resistor wire as the
new module runs at 12volts all the time. That may also be part of your
problem as most electronic modules go "off line" at 9.5 volts or lower.

RFI interference from the trim motor can also affect the ignition module,
either thru the air or thru the boat wiring.

Bill Grannis
service manager

"Billgran" wrote in message
om...

"r_d" wrote in message
roups.com...

When installing an electronic ignition, you remove the resistor wire as
the new module runs at 12volts all the time. That may also be part of your
problem as most electronic modules go "off line" at 9.5 volts or lower.

RFI interference from the trim motor can also affect the ignition module,
either thru the air or thru the boat wiring.


Thanks for the response. The electronic ignition is wired to the accessory
side of the ignition switch and then to the negative coil lead; the coil is
wired to the electronic ignition and tachometer on the negative lead, and
the positive lead is wired to the alternator (voltage regulator) though a 2
ohm resistance wire and a shunt line (no resistance) to the starter solenoid
(I assume to supply full voltage to the coil while the starter is engaged).



Thanks again for the help, it is appreciated.

mark

"r_d" wrote in message
groups.com...

"Billgran" wrote in message
om...

"r_d" wrote in message
roups.com...

When installing an electronic ignition, you remove the resistor wire as
the new module runs at 12volts all the time. That may also be part of
your problem as most electronic modules go "off line" at 9.5 volts or
lower.

RFI interference from the trim motor can also affect the ignition module,
either thru the air or thru the boat wiring.


Thanks for the response. The electronic ignition is wired to the
accessory side of the ignition switch and then to the negative coil lead;
the coil is wired to the electronic ignition and tachometer on the
negative lead, and the positive lead is wired to the alternator (voltage
regulator) though a 2 ohm resistance wire and a shunt line (no resistance)
to the starter solenoid (I assume to supply full voltage to the coil while
the starter is engaged).

If anybody is following my exploits... it turned out the tach was shorting
once it read above a certain rpm it would cut out and miss like crazy. Once
I cut tach wire it ran like a dream...

Thanks to all who responded to my posts. I was sure we where going to have
to change out this engine but with a little work and a lot of questions it
is running very well now.

thanks again
mark