Help with running rich 7.4L 300 hp
 

I have 87 Pachanga with 7.4L Alpha combo. All stock. At the end of last season my fuel pump failed. I replaced that with a genuine Merc pump. When I restarted the boat it was running rich so I started looking things over and found what I thought was water inside the ignition coil tower so I dried it out put it back and the ext day it was wet again. Well this time I felt it and it was oily not water (clear in color) so I replaced the ignition coil again new Merc stock coil and replaced the plugs MR43T's and it was still running rough. I pulled the cap & found the cap and rotor to be pretty badly pitted I waited until today to put the new cap and rotor on fired it up and it still is running rich as I could not get the boat to stay running under 900-1000 rpms it would just load up and start to stumble and stall. I pulled all the plugs and they are all def black sooty. I did not replace the plugs again as they were run for not even 20 min in the fall. The wires are a couple seasons old but look to be in good shape and there was ZERO corrosion at either the plug side or the cap side when I looked in the boots. My question is should I try a new set of plugs again? Can anyone tell me which wires should be going where on the ignition coil I am 99% sure when I replaced the coil that I was careful to keep everything in the right place but I am not overlooking it. When I replaced the rotor I did notice that the sensor assembly where the stainless part at the bottom of the rotor spins through has some light surface rust from condensation/sitting over the winter-- I am not sure if this could cause this type of problem. I kinda feel that that part would either work or not work at all. Any suggestions/help would be greatly appreciated.

To start I would make certain you have the plug wires on correctly. The firing order is 18436572. Your cap should be marked. Looking at the engine front to rear you can trace each wire going to the proper plug/cylinder. The right side bank is 1,3,5,7, and the left bank is 2,4,6,8. It also wouldn't be a bad idea to check your timing to make sure it didn't get moved. Also it is possible with the new install of your fuel pump that your pressure is high. Doubtful however if you could put an inline pressure gage in that would rule that out. I have a feeling your wires got crossed though. I wouldin't change the plugs right away unless they look wet. Who installed the plugs? It's also possible you may have cracked a couple during the install. Hair line cracks are sometimes difficult to see unless you run it in the dark and see the spark jumping over to a ground. You can also check the wires with an ohm meter for consistancy.

Hope this helps a little.

Wires are installed 100% correct. It is not misfiring or backfiring just running very rich. I thought about checking the fuel pressure but I don't have a gauge for carbureted I do have a gauge for fuel injected though. The plugs were not dripping wet with gas just very black and soot covered. I pulled them after running it about 10 min on the hose letting it get up to temperature.both risers were warm not scalding hot to the touch and all water hoses were warm. I have not yet pulled the fuel/water separator to check and see if there is any water from the tank but it was near full when winterized and used stabil to close it up.

The plugs will soot up pretty good/bad idling. It may be a combo of things. Take it out and run the **** out of it for a bit and see what happens. LOL... Seriously I wouldn't concern myself to much with it until you take it out and run it.

New plugs & wires, and rebuild the carb. The failed pump could have thrown pieces ynto the needle and seat.