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74 bravo engine miss at mid throttle

D

dave_s_h

New member
once the engine is warmed up i

once the engine is warmed up it will have a miss while cruising at mid throttle. It's not a constant miss though. engine will be running smooth then it will miss all cylinders for a split second and comes back running smooth again like the ignition shuts off then comes right back on again. plugs wires cap and rotor have been changed. I'm thinking ign module but way too pricey to just through that part at it. ??
 
does the bravo one have a shif

does the bravo one have a shift interupt switch? if so i can't find it anywhere by the shift linkage plate. where would it be? Would the pick up sensor have any thing to do with it?
 
"Not sure; I use an Alpha 1

"Not sure; I use an Alpha 1

What year? MPI or carb?

"engine will be running smooth then it will miss all cylinders for a split second and comes back running smooth again like the ignition shuts off then comes right back on again. plugs wires cap and rotor have been changed."

Check distributor for loose or corroded wires or connectors. Coil may be dying.

item #8 is the ignition pickup coil. In auto engines they are prone to fractured wires that fail under heat randomly. Look for cracks in the insulation; may need a bright light and magnifying glass.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=809994%2098&ivar=images/C RUISER/809994.98/6.png&inbr=2705&bnbr=80&bdesc=DISTRIBUTOR+AND+IGNITION+COMPONEN TS"
 
model year 1997 carb. thuderbo

model year 1997 carb. thuderbolt ign. serial #0k171919. It's a different distributor than the one in that diagram. The ign module is outside of the distributor. I've checked for loose connections everywhere. All look good. It very well could be the coil but i always thought they just died completely. Either good or bad you know. Could they cause a miss?
 
"item 6 is the optic sensor th

"item 6 is the optic sensor that triggers the module to send a signal to the coil to fire a spark plug. Pull the rotor off; it may be stuck. If the optic sensor has rust all over it, that could contribute to your problem. There are some fine wires on the sensor that will corrode.

Yes, the coil will do all sorts of crazy things. Change the coil first since it is cheaper. If it does not improve then change out the optic sensor and reset the timing.

http://www.mercruiserparts.com/Show_Pictures3.asp?dnbr=821723965&ivar=images/CRU ISER/821723.965/4.png&inbr=2345&bnbr=5&bdesc=DISTRIBUTOR+AND+IGNITION+COMPONENTS"
 
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