Dhopper71
Seaman
- Joined
- Jun 12, 2011
- Messages
- 70
Hi all. My brain is fried and i'm in need of your help! I've been reading posts and replies to posts and on and on. I think I've confused myself more than I helped. I'm not a dumb guy, but I feel totally brain dead about this issue right now.
I have a 1974 Mark Twain powered by a Mercruiser 3.0L 140 and pre-alpha outdrive. Just bought this boat a few weeks ago. When I got it the start was a little slow when cold, but not too bad. Once it got going it idled great and seemed to be very throttle responsive. Now, of course this was all on the muffs and not in the water under load(my first mistake).
Got it home, cleaned it up, and noticed a slight milky appearance to the oil, but not horrible. Figured it was primarily from a little condensation and lack of use since the early spring summerization. The po had installed a new plastic 20gal fuel tank and in-line fuel filter, along with new wires and distibutor cap. Did not seem to have any issues, so we took it out to test it under load at the lake.
I warmed it up for just a few minutes prior to heading out that morning so it would be ready to roll at the launch. We backed it down and I lowered the trim and started it it with just a couple cranks. I proceeded to back up and swing around to tie up at the dock to wait for my FIL and as I took it our of reverse and into neutral it sputtered and died. That was the first time I had seen it act that way. When I cranked it to re-start it, it almost caught the first time, but didn't; then didn't even come close to starting after that. I managed to pull myself over to the dock and tie up. Tried several more times over the next 10 minutes to start, but nothing. Kept acting like it flooded, so we let it sit and went to eat lunch.
When we came back it seemed more responsive and finally started after 5-6 attempts. We sat there for several minutes and all seemed fine again. Cool. We tooled around the lake for a while, testing throttle response, handling, etc.; never going more than 2/3 throttle. No worries. I was happy. We anchored for about an hour in a cove to swim and chill. Finally cranked right back up and headed back in. I ran 3/4 throttle for a few minutes, then finally went to wot. Was humming along fantastic. There was a large boat that flew by us in the opposite direction with a huge wake that kind of spooked me and I throttled down to near idle immediately. When I did that, it sputtered a few times, tried to catch again, then died. We never could get it started again. Had to row a while until we got towed by some very nice folks. All the time we were trying to re-start it, it seemed to act flooded to the point it didn't even sound like it was sparking. I really though I overheated the coil.
Got it home and proceeded with inspections and troubleshooting a few days later. Here's where I'm at so far:
Checked gas tank for particles/debrit - none visible - all new gas in tank.
Replaced in-line fuel filter - old one looked like it was collapsing on itself inside the glass.
Flushed oil with new 25w-50 - oil looked better after it had ran, but still slightly creamy and had a definite gas odor
Inspected and cleaned the filter at the inlet to card brom fuel pump - wasn't bad though
Replaced plugs with Bosch SuperPlus 7999 - old ones were wet and smelled like gas
Checked spark from the coil - was strong blue arc
After I had done this we hooked it back up to the muffs to give it a go again. First turn of the key and it fired right up ... for about 15 secs ... then died. Would not start again. Seemed to be flooded yet again. Checking the carb, we thought that the gas seemed to continue to flow into the carb for a few seconds after the cranking had stopped. The flap also seems super tight and for some reason now does not want to open nearly at all unless we hold it open. We broke for lunch and more reading.
After lunch we tinkered with the carb a bit and reset the idle screws. If I hold the throttle wide open all the way, it starts immediately with no hesitation. I can back off the throttle to about half, but any further down from there it sputters and dies again. And at half we need to hold open the flap to keep it running smooth. If we let it go, it wants to close all the way and kills the engine.
I'm at a loss. I can't find a break down or diagram of this particular carb. I see rebuild kits, but nothing with real good images of how this thing should really look. Seems to me that a spring is missing or something is just not set up right in it. The carb appears to be an older rochester 2bbl as it has 2 idle set screws underneath. The carb number is: 7043184
It's getting gas, so I don't think it's a pump problem(unless the pump pressure is too high?). Can't understand the choke on this one. Should the flap be that tight and want to stay sprung closed? Also feels like gas isn't getting down into the cylinder at start unless throttle is help all the way open.
Doe anyone have a manual or diagram for this carb? How about pics all around of one that's running great? Can you think of something stupid I'm not looking at or maybe some adjustments I could make prior to getting a rebuild kit in and tearing this thing down? Could the timing be off that much to make it act this way? Short of taking another few days away and coming back fresh to start over from the begining, I don't know what to do. It seems soooo close to running great.
I have a 1974 Mark Twain powered by a Mercruiser 3.0L 140 and pre-alpha outdrive. Just bought this boat a few weeks ago. When I got it the start was a little slow when cold, but not too bad. Once it got going it idled great and seemed to be very throttle responsive. Now, of course this was all on the muffs and not in the water under load(my first mistake).
Got it home, cleaned it up, and noticed a slight milky appearance to the oil, but not horrible. Figured it was primarily from a little condensation and lack of use since the early spring summerization. The po had installed a new plastic 20gal fuel tank and in-line fuel filter, along with new wires and distibutor cap. Did not seem to have any issues, so we took it out to test it under load at the lake.
I warmed it up for just a few minutes prior to heading out that morning so it would be ready to roll at the launch. We backed it down and I lowered the trim and started it it with just a couple cranks. I proceeded to back up and swing around to tie up at the dock to wait for my FIL and as I took it our of reverse and into neutral it sputtered and died. That was the first time I had seen it act that way. When I cranked it to re-start it, it almost caught the first time, but didn't; then didn't even come close to starting after that. I managed to pull myself over to the dock and tie up. Tried several more times over the next 10 minutes to start, but nothing. Kept acting like it flooded, so we let it sit and went to eat lunch.
When we came back it seemed more responsive and finally started after 5-6 attempts. We sat there for several minutes and all seemed fine again. Cool. We tooled around the lake for a while, testing throttle response, handling, etc.; never going more than 2/3 throttle. No worries. I was happy. We anchored for about an hour in a cove to swim and chill. Finally cranked right back up and headed back in. I ran 3/4 throttle for a few minutes, then finally went to wot. Was humming along fantastic. There was a large boat that flew by us in the opposite direction with a huge wake that kind of spooked me and I throttled down to near idle immediately. When I did that, it sputtered a few times, tried to catch again, then died. We never could get it started again. Had to row a while until we got towed by some very nice folks. All the time we were trying to re-start it, it seemed to act flooded to the point it didn't even sound like it was sparking. I really though I overheated the coil.
Got it home and proceeded with inspections and troubleshooting a few days later. Here's where I'm at so far:
Checked gas tank for particles/debrit - none visible - all new gas in tank.
Replaced in-line fuel filter - old one looked like it was collapsing on itself inside the glass.
Flushed oil with new 25w-50 - oil looked better after it had ran, but still slightly creamy and had a definite gas odor
Inspected and cleaned the filter at the inlet to card brom fuel pump - wasn't bad though
Replaced plugs with Bosch SuperPlus 7999 - old ones were wet and smelled like gas
Checked spark from the coil - was strong blue arc
After I had done this we hooked it back up to the muffs to give it a go again. First turn of the key and it fired right up ... for about 15 secs ... then died. Would not start again. Seemed to be flooded yet again. Checking the carb, we thought that the gas seemed to continue to flow into the carb for a few seconds after the cranking had stopped. The flap also seems super tight and for some reason now does not want to open nearly at all unless we hold it open. We broke for lunch and more reading.
After lunch we tinkered with the carb a bit and reset the idle screws. If I hold the throttle wide open all the way, it starts immediately with no hesitation. I can back off the throttle to about half, but any further down from there it sputters and dies again. And at half we need to hold open the flap to keep it running smooth. If we let it go, it wants to close all the way and kills the engine.
I'm at a loss. I can't find a break down or diagram of this particular carb. I see rebuild kits, but nothing with real good images of how this thing should really look. Seems to me that a spring is missing or something is just not set up right in it. The carb appears to be an older rochester 2bbl as it has 2 idle set screws underneath. The carb number is: 7043184
It's getting gas, so I don't think it's a pump problem(unless the pump pressure is too high?). Can't understand the choke on this one. Should the flap be that tight and want to stay sprung closed? Also feels like gas isn't getting down into the cylinder at start unless throttle is help all the way open.
Doe anyone have a manual or diagram for this carb? How about pics all around of one that's running great? Can you think of something stupid I'm not looking at or maybe some adjustments I could make prior to getting a rebuild kit in and tearing this thing down? Could the timing be off that much to make it act this way? Short of taking another few days away and coming back fresh to start over from the begining, I don't know what to do. It seems soooo close to running great.
