At the beginning of this season I arbitraily replaced the rotor and distributor cap.
The unit started up cold fine, when it was hot it was very difficult to start. This problem has a history and has been becoming increasingly worse.
I installed a new fuel filter to see if it helped, the fuel in the old filter was fairly clear looking and didn't appear to have any water. The engine started up cold with the same problems after heating up. The carburator shows good flow at the jets with the linkage disconnected. I initially suspected that the carb might be flooding causing the problem and was considering having the carb rebuilt.
Before rebuilding the carb I figured it was prudent to change the coil on the assumption that it could be breaking down with heat, they are comparatively cheap and the engine is about a 1993 vintage anyway so I replaced it. The new coil would not fire the engine, I replaced the new coil with the old and still would not fire/spark. In both instances I made sure that the coil had voltage available at the primary side of the coil.
Since the wiring in this unit is purple to the positive side of the coil primary and gray at the common side of the coil I am certain that the coil was connected properly.
I started to check the system in total to see if something else had coincidently caused the problem.
The ignition switch circuit seems to be functioning properly as the guages go to the proper positions when on.
This mercruiser is an Alpha gen 1 or 2 so the shift cutout switch was checked out by resistance checks and disconnecting with no improvement.
I disconnected the tachometer wire (grey) to eliminate it. No change.
I tried to get a spark at the coil by intermittently grounding the white/green wire with no change, replaced the distributor sensor.
I pulled the harness at the ignition module and found it to be moderately corroded, Replaced the harness assembly. No change.
As far as I can tell this leaves me with the ignition module. Unless of course you folks can come up with something else.
I have a distributor mounted module with the designation 8V 22A stamped on the front. In my search of the internet I have found modules described as adequate for my engine, 5.7 L merc does anyone know exactly which modules will replace the 8V 22A? There appear to be a lot of options with the price all over the place.
Can anyone tell me if it is normal for these systems to drag the voltage at the coil primary down to 8.6 volts while cranking? I know that some of the older ignitions relayed 12 V to the coil when cranking.
The unit started up cold fine, when it was hot it was very difficult to start. This problem has a history and has been becoming increasingly worse.
I installed a new fuel filter to see if it helped, the fuel in the old filter was fairly clear looking and didn't appear to have any water. The engine started up cold with the same problems after heating up. The carburator shows good flow at the jets with the linkage disconnected. I initially suspected that the carb might be flooding causing the problem and was considering having the carb rebuilt.
Before rebuilding the carb I figured it was prudent to change the coil on the assumption that it could be breaking down with heat, they are comparatively cheap and the engine is about a 1993 vintage anyway so I replaced it. The new coil would not fire the engine, I replaced the new coil with the old and still would not fire/spark. In both instances I made sure that the coil had voltage available at the primary side of the coil.
Since the wiring in this unit is purple to the positive side of the coil primary and gray at the common side of the coil I am certain that the coil was connected properly.
I started to check the system in total to see if something else had coincidently caused the problem.
The ignition switch circuit seems to be functioning properly as the guages go to the proper positions when on.
This mercruiser is an Alpha gen 1 or 2 so the shift cutout switch was checked out by resistance checks and disconnecting with no improvement.
I disconnected the tachometer wire (grey) to eliminate it. No change.
I tried to get a spark at the coil by intermittently grounding the white/green wire with no change, replaced the distributor sensor.
I pulled the harness at the ignition module and found it to be moderately corroded, Replaced the harness assembly. No change.
As far as I can tell this leaves me with the ignition module. Unless of course you folks can come up with something else.
I have a distributor mounted module with the designation 8V 22A stamped on the front. In my search of the internet I have found modules described as adequate for my engine, 5.7 L merc does anyone know exactly which modules will replace the 8V 22A? There appear to be a lot of options with the price all over the place.
Can anyone tell me if it is normal for these systems to drag the voltage at the coil primary down to 8.6 volts while cranking? I know that some of the older ignitions relayed 12 V to the coil when cranking.
