Re: I just don't get it....at a complete loss
Around 2500 or before it will backfire, sometimes it will return to idle if I let of the throttle at that point, other times it will just dies, but in either case it won't run rev'd at all. Before all of this work was done it just wouldn't start at all, literally ran good one day wouldn't start the next. It's the weber 4 bbl carb and yes when I cleaned it, I broke it all the way down and gave it a good soak, I feel confident that I did it correctly, I've done this same carb a dozen or more times on different boats in the past. When I disconnect the throttle and give it a pump it will squirt a healthy stream into the venturi, however I certainly believe it's a fuel issue by the way it smokes and hisses if I pump fuel in there after it backfires and dies.
I was reading in the manual and it states that if the timing chain was ever serviced (I don't know if it was or wasn't) that the engine MUST be set to #4 cylinder TDC. Again I don't believe it to be timing. Wouldn't it backfire just while idling if it was timing and/or run much rougher at idle? In the manual it doesn't state which way is bow or stern when it gives you the cylinder layout, but I matched it up in relation to where the dist sits and I had a few others confirm this is correct (starting from port bow side 1,3,5 starboard side starting again bow 2,4,6) and firing order as Don stated 1,6,5,4,3,2,. I inspected the ignition module and dist cap and rotor...I suppose it could be replaced but I've seen MUCH worse run considerably better.
This is the motor however that has the car starter on it, I asked about the wire for it in a previous thread and I haven't swapped that out yet. The purple w/yellow wire that runs over to the third post on the starter (runs the oil switch and fuel pump) I have running instead over to the + on the coil. I don't see how this would cause this particular problem unless it's burned up the points between now and the last time I checked them, but I suppose if everyone here agrees it's what I will redo next....planned on doing it right anyways.
Back to the gas, if I can run the fuel pump disconnected into a gas can from the gas tank and it has a continuous undisturbed stream, does that mean I can eliminate gas tank air locking, bad pickup from tank, and anti-syphon as being the issue? I was reading a thread on here concerning these issues for people that were rebuilding carbs unsuccessfully. Lastly, on the IV Thunderbolt you do NOT have to ground out the purple lead on the ignition module to set into base timing correct? I read it to be only the Thunderbolt V and later or models with a knock sensor which I don't believe I have that need to follow this procedure. If I was supposed to, I didn't and I'd guess that to be the problem.
