Hello Everyone. I recently acquired a 1997 Challenger 1800. The starboard engine starts and runs great. The Port engine on the other hand has since day 1 been hard to start and always idled with a misfire on one or both cylinders. It was rough idling but on the water made good power. Then one time I couldn't get it started at the dock, replaced plugs and barely got it started. I checked compression, 151psi on both cylinders, appears to have good spark on both cylinders, plugs were coming out quite wet at times so I decided to reset carbs to 1 turn out on LS and 1/4 on HS per manual/online suggestions (carbs were set very close to that anyways). Still seemed to run the same, it seemed too rich but I only think that because adding choke never made any positive difference.
I then decided to rebuild both carbs with kits from SBT. Did that on Sunday and everything inside looked good and clean. Reinstalled and set to 1.5 out on LS, and 1/4 on HS. Tried to start the engine and cranked it a LOT but never a hit of fire. Then checked plugs and they were wet so replaced them. Continued cranking (I knew it would need to crank to get gas into the carbs after having them off, but it seemed like an excessive amount). At this point I still had not replaced the air box but did have the flame arrestor in place, I gave it a small shot of starting fluid and it fired up, then died, then I was able to get it to restart on its own. Got it running but it sounded EXACTLY the same as before I went through the carbs. One or both cylinders were having a hard time idling smoothly/consistently. RPM's would fluctuate like one cylinder was loading up or something. If I kept the throttle ahead just a bit it would run OK but when I backed down throttle it would idle rough, drop a cylinder, then die. Idle was set at around 3k out of water.
I then decided to lean the LS screw as it seemed like maybe I was too rich. Leaned both carbs Low speeds back to 1 turn out and engine definitely idled better and I thought I had my problem nailed but then I couldn't get it to restart hot.
My question is, throughout this testing I have been running with the air box off, only flame arrestor in place, is this affecting my idling performance or mixture? It is off because the adjusters are easier to get to. The engine runs great in mid and upper range through to 7k rpm with no issues. Just the low speed idling concern. Also, I thought I had it corrected after I leaned it back a bit more on the low end and closed up the HS's and it was idling well and would restart with a little choke, but after I took the boat out for 15 mins or so, when I came back in, and was idling to do, port motor died again :-(
Sorry to be so wordy but I wanted to be as accurate and upfront as I could be. I have used the search feature and read through 1 million posts on here. Thanks, in advance.
I then decided to rebuild both carbs with kits from SBT. Did that on Sunday and everything inside looked good and clean. Reinstalled and set to 1.5 out on LS, and 1/4 on HS. Tried to start the engine and cranked it a LOT but never a hit of fire. Then checked plugs and they were wet so replaced them. Continued cranking (I knew it would need to crank to get gas into the carbs after having them off, but it seemed like an excessive amount). At this point I still had not replaced the air box but did have the flame arrestor in place, I gave it a small shot of starting fluid and it fired up, then died, then I was able to get it to restart on its own. Got it running but it sounded EXACTLY the same as before I went through the carbs. One or both cylinders were having a hard time idling smoothly/consistently. RPM's would fluctuate like one cylinder was loading up or something. If I kept the throttle ahead just a bit it would run OK but when I backed down throttle it would idle rough, drop a cylinder, then die. Idle was set at around 3k out of water.
I then decided to lean the LS screw as it seemed like maybe I was too rich. Leaned both carbs Low speeds back to 1 turn out and engine definitely idled better and I thought I had my problem nailed but then I couldn't get it to restart hot.
My question is, throughout this testing I have been running with the air box off, only flame arrestor in place, is this affecting my idling performance or mixture? It is off because the adjusters are easier to get to. The engine runs great in mid and upper range through to 7k rpm with no issues. Just the low speed idling concern. Also, I thought I had it corrected after I leaned it back a bit more on the low end and closed up the HS's and it was idling well and would restart with a little choke, but after I took the boat out for 15 mins or so, when I came back in, and was idling to do, port motor died again :-(
Sorry to be so wordy but I wanted to be as accurate and upfront as I could be. I have used the search feature and read through 1 million posts on here. Thanks, in advance.
