ofmusicman
Recruit
- Joined
- Jul 23, 2016
- Messages
- 1
I have a '89 model OMC "Mark Twain" 190 boat powered by a GM 4.3L engine and a 2 jet Rodchester Carbuertor. It has been sitting with a boat cover over most of it for about 10 years without seeing the water. We started it up in the yard for a couple of seconds before we first dove into this project to make sure it still ran, which it did just fine. I've spent the past two months restoring it, replacing everything that's wood on the boat. So far, that was the easiest part of this project. With the engine, I replaced the fuel line with another A1 fuel line, the fuel filter (which the old one had the bottom rusted out of it and was the original), the mechanical fuel pump (with a Airtex 60201 mechanical fuel pump- the guys at NAPA cross referenced the original fuel pump to this new pump and this one looks identical to the original, including the Carter name stamped into the side of it), and rebuilt the Carbuertor with automotive parts.
The first time taking the boat out on the lake, it ran beautifully for 45 minutes to an hour at full throttle and at 35mph. After dropping anchor and swimming for over an hour, we decided to pull people on the tube. We did so for another 30 or so minutes until we hit a 1.5-2 foot wake coming off of a pontoon. It immediately started to bog down and act as though it was flooding out. My guess was that the after market float in the Carbuertor got stuck somehow. We managed to get about a mile down the lake by running it until it flooded out, then letting it sit and evaporate out, then running it again, until it finally didn't start and we got towed into dock.
We replaced the float with the original when we got back and took it out again, this time it would idle perfectly but not get above 3000rpm's or on plane without dying. Now it was acting as though it was starved for fuel. So after taking it apart once more, we replaced the needle and seat with the old ones, which were much bigger than the automotive needle and seats (they looked brand new, which if memory serves me correctly, they have less than 2 hours of use on them from 10+ years ago). We tried this out and it ran great for a few minutes and then acted up again. This time it sounded as though it was starved for fuel again.
Thinking something was clogged in the line somewhere, I took the sending float until for the fuel gauge out and looked into the tank. The fuel looked fine, especially since half of the 30 gallon tank has brand new fuel mixed in it, there wasn't anything that was on the bottom of the tank that looked as though it was getting sucked up into the feeder line and blocking anything. I blew out the lines just to make sure and nothing came out. I did the same for the rubber line as well with the same result. I checked all of the fittings, including the anti siphon check valve, for anything clogging them with no result.
I then replaced the fuel filter one more time today and a bunch of black soot looking stuff came out of it along with some rusty looking stuff, which makes no sense as the fuel tank is aluminum and all of the fittings are brass.
After replacing the filter, it ran fine for about 5 minutes when it then bogged down and died. This time, after taking the flame arrester/air filter off of the carburetor and cranking it over to restart it, there was no fuel getting to the top of the motor. We disconnected the fuel line going from the fuel tank to the fuel pump and found there was no suction. After reconnecting this line and disconnecting the fuel line from the carburetor and cranking it over again, fuel started coming out of the fuel line. We reconnected it and were able to idle back to the dock. This time, though, it started to flood again like it originally did on the lake, which my father thinks is because the float was bent a little too far and the fuel is filling up the bowl just a little too much.
So since the fuel pump, fuel filter, and carburetor are all new and it ran perfectly for 20-25 minutes at full throttle, we think that when the electronics on the motor finally got to be warmed up they started to fail on us. We replaced the coil and the control module on the distributor tonight and haven't had it out to test it out, but we don't think this will ultimately fix it.
So this is just the short version of where we are now:
After rebuilding the carburetor with the original needle, seat, and float, it should be fine. The fuel accelerator works just fine too. We're on the second filter after the first one was clogged up by some mysterious black soot looking stuff but even after changing it, it didn't work very well. It won't run past an idle without dying.
We plan on attaching a fuel pressure gauge to it to monitor the fuel pressure on the line above the fuel pump and we've changed and need to test the coil and ignition control modual on the distributor. Does anyone have any idea what we could do next or have any idea of what it could be?
The model number on the plate on the outside of the outboard part of the engine reads 985685
The first time taking the boat out on the lake, it ran beautifully for 45 minutes to an hour at full throttle and at 35mph. After dropping anchor and swimming for over an hour, we decided to pull people on the tube. We did so for another 30 or so minutes until we hit a 1.5-2 foot wake coming off of a pontoon. It immediately started to bog down and act as though it was flooding out. My guess was that the after market float in the Carbuertor got stuck somehow. We managed to get about a mile down the lake by running it until it flooded out, then letting it sit and evaporate out, then running it again, until it finally didn't start and we got towed into dock.
We replaced the float with the original when we got back and took it out again, this time it would idle perfectly but not get above 3000rpm's or on plane without dying. Now it was acting as though it was starved for fuel. So after taking it apart once more, we replaced the needle and seat with the old ones, which were much bigger than the automotive needle and seats (they looked brand new, which if memory serves me correctly, they have less than 2 hours of use on them from 10+ years ago). We tried this out and it ran great for a few minutes and then acted up again. This time it sounded as though it was starved for fuel again.
Thinking something was clogged in the line somewhere, I took the sending float until for the fuel gauge out and looked into the tank. The fuel looked fine, especially since half of the 30 gallon tank has brand new fuel mixed in it, there wasn't anything that was on the bottom of the tank that looked as though it was getting sucked up into the feeder line and blocking anything. I blew out the lines just to make sure and nothing came out. I did the same for the rubber line as well with the same result. I checked all of the fittings, including the anti siphon check valve, for anything clogging them with no result.
I then replaced the fuel filter one more time today and a bunch of black soot looking stuff came out of it along with some rusty looking stuff, which makes no sense as the fuel tank is aluminum and all of the fittings are brass.
After replacing the filter, it ran fine for about 5 minutes when it then bogged down and died. This time, after taking the flame arrester/air filter off of the carburetor and cranking it over to restart it, there was no fuel getting to the top of the motor. We disconnected the fuel line going from the fuel tank to the fuel pump and found there was no suction. After reconnecting this line and disconnecting the fuel line from the carburetor and cranking it over again, fuel started coming out of the fuel line. We reconnected it and were able to idle back to the dock. This time, though, it started to flood again like it originally did on the lake, which my father thinks is because the float was bent a little too far and the fuel is filling up the bowl just a little too much.
So since the fuel pump, fuel filter, and carburetor are all new and it ran perfectly for 20-25 minutes at full throttle, we think that when the electronics on the motor finally got to be warmed up they started to fail on us. We replaced the coil and the control module on the distributor tonight and haven't had it out to test it out, but we don't think this will ultimately fix it.
So this is just the short version of where we are now:
After rebuilding the carburetor with the original needle, seat, and float, it should be fine. The fuel accelerator works just fine too. We're on the second filter after the first one was clogged up by some mysterious black soot looking stuff but even after changing it, it didn't work very well. It won't run past an idle without dying.
We plan on attaching a fuel pressure gauge to it to monitor the fuel pressure on the line above the fuel pump and we've changed and need to test the coil and ignition control modual on the distributor. Does anyone have any idea what we could do next or have any idea of what it could be?
The model number on the plate on the outside of the outboard part of the engine reads 985685
