Hey folks. I'm up against the limits of my understanding and need some guidance.
Twin crusader 327s circa 1965ish. Dual control stations. Mallory distributors with electronic ignition. Mechanical fuel pump and Rochester 4gc carb freshly rebuilt. I'm getting fuel and I have compression, but there is a spark issue I'm trying to track down.
Starboard engine is running great. Port engine was running fine but recently changed behavior. Would only start and run from the fly bridge switch, but the main helm switch also had to be in "run" position.
Replaced the helm switch with new. No change.
Tested both coils (port and stbd) and they read the same for primary and secondary windings. Swapped coils to confirm, starboard engine still runs great and no change to port engine. Rules out the coil.
Today, I discovered that the Ammeter light on the fly bridge instrument panel tested high for resistance. Replaced the light with new. While under the instrument panel, replaced several other loose terminal connections.
Turned the key at the main station and it started up when given enough throttle. Ran fine over 1500 rpm, but died below that.
With the key at the main helm in run position, started the engine from the fly bridge switch and it started much easier and ran fine above about 1000rpm, but then died when I pulled throttle below that. With both keys in run position, started the engine again, let it run at 1200rpm, then shut off the fly bridge key, engine died immediately. Tried the same thing again but switched stations (fly bridge key in run, then turned off the main helm switch) it ran for about 5 seconds then died.
I suspect a weak spark at low rpm, which is exacerbated when only one switch is in the run position. This makes me think it is a poor ground somewhere.
Am I on the right track? What should I do to further isolate the problem?
I'm really new to DC electrical and just feeling my way through, so any help is greatly appreciated.
Twin crusader 327s circa 1965ish. Dual control stations. Mallory distributors with electronic ignition. Mechanical fuel pump and Rochester 4gc carb freshly rebuilt. I'm getting fuel and I have compression, but there is a spark issue I'm trying to track down.
Starboard engine is running great. Port engine was running fine but recently changed behavior. Would only start and run from the fly bridge switch, but the main helm switch also had to be in "run" position.
Replaced the helm switch with new. No change.
Tested both coils (port and stbd) and they read the same for primary and secondary windings. Swapped coils to confirm, starboard engine still runs great and no change to port engine. Rules out the coil.
Today, I discovered that the Ammeter light on the fly bridge instrument panel tested high for resistance. Replaced the light with new. While under the instrument panel, replaced several other loose terminal connections.
Turned the key at the main station and it started up when given enough throttle. Ran fine over 1500 rpm, but died below that.
With the key at the main helm in run position, started the engine from the fly bridge switch and it started much easier and ran fine above about 1000rpm, but then died when I pulled throttle below that. With both keys in run position, started the engine again, let it run at 1200rpm, then shut off the fly bridge key, engine died immediately. Tried the same thing again but switched stations (fly bridge key in run, then turned off the main helm switch) it ran for about 5 seconds then died.
I suspect a weak spark at low rpm, which is exacerbated when only one switch is in the run position. This makes me think it is a poor ground somewhere.
Am I on the right track? What should I do to further isolate the problem?
I'm really new to DC electrical and just feeling my way through, so any help is greatly appreciated.