OK, another WOT problem.
The long story:
Bought 1994 Bayliner Capri 2050LS with Mercruiser 4.3LX and Alpha One Gen 2 in 2006. Ran it in 2006 and 2007, then wife got pregnant and got deep into a kitchen remodel. Had gotten on our town marina's waiting list when we first bought the boat. Well, our name came up this year, so that gave me the kick in the pants that I needed to get Sunshine Daydream running again. In 2007 had filled the tank full with gas to try to minimize the ethanol issues, not knowing then that I'd not run the boat for 3-1/2 years.
Fast forward to 2011, I pulled the plugs, squirted about 1 oz of MMO into each cylinder (let it sit for about 1-1/2 weeks), put new NGKs in gapped to .035", charged the battery, changed the impeller and drive oil, changed the t-stat, added octane booster and fired her up. Ran okay on muffs - we've got issues with our well so I didn't let it run for more than about 10 minutes. Splashed her and headed out with wife and daughter, figured we'd just burn through the 40 gallons and fill it up with fresh. Got about 3/4 way to where we were going at about 3000 rpms at WOT and started backfiring through the carb. headed home at 2000 rpms and no more backfiring, but our day was done. In planning my startup I consulted this and another board and stocked up on fuel filters. So the next morning I headed down to the marina, changed the filter and headed out. No backfire, but low WOT - about 3400 rpm with just me and the boat trimmed out nicely. Repeated the early morning cruises and afternoon family time until the gas was gone. Was now getting excited that the problem may be fixed! ....but no such luck. WOT RPM remained the same. Next morning I went out and changed the filter again just to make sure, and no change. Changed the anti-siphon valve - no improvement. I read through Don S's low WOT list - I have a feeling it's fuel related. Initial kick keels right, but once she gets up to about 1800- 2000 rpm she just poops out and it then takes forever to get up to 3200. ALso, changed the cap and rotor this past weekend. Had a neighbor aboard this weekend, and he said he could smell raw gas sitting in stern seat.
The short story and other info
Symptoms:
1. Low WOT (3400-35000 rpm when alone, 3200 with wife and daughter and stuff, 2800 rpm with a full boat of people)
2. OK initial acceleration, then it poops out.
3. Not backfiring anymore - fair amount of water in first filter. Not as much in 2nd. Currently on 3rd of the season
4. Raw gas smell when running at WOT, but not at lower rpm.
5. She's been stalling sometimes when pulling her out of gear.
Done so far:
1. Burned through about 38 of 40 gallons of old gas and filler her up with fresh. Burned that down to about 20 gal and filled up again this weekend.
2. Changed fuel filter 2x (maybe 3x, don't remember)
3. changed anti siphon valve
4. Changed cap & Rotor
Questions:
1. I feel pretty stupid asking this, but how do you get to the fuel pickup in the tank? Do I just turn the hex fitting that the anti-siphon valve is attached to? does it just screw in to the tank?
2. Should I check the filters in the carb inlet? I've done zero carb work, but am a fairly proficient shadetree mechanic when it comes to cars, its just that everything I've had has been FI. I did rebuild a carb on a leaf blower, but I don't think that comes close to the complexity of this one ;oP
3. Could this just be a throttle cable/linkage problem? How would I go about diagnosing that?
I plan on getting a fuel pressure gauge and making up the test apparatus that Don recommends.
Thanks in advance,
Don
The long story:
Bought 1994 Bayliner Capri 2050LS with Mercruiser 4.3LX and Alpha One Gen 2 in 2006. Ran it in 2006 and 2007, then wife got pregnant and got deep into a kitchen remodel. Had gotten on our town marina's waiting list when we first bought the boat. Well, our name came up this year, so that gave me the kick in the pants that I needed to get Sunshine Daydream running again. In 2007 had filled the tank full with gas to try to minimize the ethanol issues, not knowing then that I'd not run the boat for 3-1/2 years.
Fast forward to 2011, I pulled the plugs, squirted about 1 oz of MMO into each cylinder (let it sit for about 1-1/2 weeks), put new NGKs in gapped to .035", charged the battery, changed the impeller and drive oil, changed the t-stat, added octane booster and fired her up. Ran okay on muffs - we've got issues with our well so I didn't let it run for more than about 10 minutes. Splashed her and headed out with wife and daughter, figured we'd just burn through the 40 gallons and fill it up with fresh. Got about 3/4 way to where we were going at about 3000 rpms at WOT and started backfiring through the carb. headed home at 2000 rpms and no more backfiring, but our day was done. In planning my startup I consulted this and another board and stocked up on fuel filters. So the next morning I headed down to the marina, changed the filter and headed out. No backfire, but low WOT - about 3400 rpm with just me and the boat trimmed out nicely. Repeated the early morning cruises and afternoon family time until the gas was gone. Was now getting excited that the problem may be fixed! ....but no such luck. WOT RPM remained the same. Next morning I went out and changed the filter again just to make sure, and no change. Changed the anti-siphon valve - no improvement. I read through Don S's low WOT list - I have a feeling it's fuel related. Initial kick keels right, but once she gets up to about 1800- 2000 rpm she just poops out and it then takes forever to get up to 3200. ALso, changed the cap and rotor this past weekend. Had a neighbor aboard this weekend, and he said he could smell raw gas sitting in stern seat.
The short story and other info
Symptoms:
1. Low WOT (3400-35000 rpm when alone, 3200 with wife and daughter and stuff, 2800 rpm with a full boat of people)
2. OK initial acceleration, then it poops out.
3. Not backfiring anymore - fair amount of water in first filter. Not as much in 2nd. Currently on 3rd of the season
4. Raw gas smell when running at WOT, but not at lower rpm.
5. She's been stalling sometimes when pulling her out of gear.
Done so far:
1. Burned through about 38 of 40 gallons of old gas and filler her up with fresh. Burned that down to about 20 gal and filled up again this weekend.
2. Changed fuel filter 2x (maybe 3x, don't remember)
3. changed anti siphon valve
4. Changed cap & Rotor
Questions:
1. I feel pretty stupid asking this, but how do you get to the fuel pickup in the tank? Do I just turn the hex fitting that the anti-siphon valve is attached to? does it just screw in to the tank?
2. Should I check the filters in the carb inlet? I've done zero carb work, but am a fairly proficient shadetree mechanic when it comes to cars, its just that everything I've had has been FI. I did rebuild a carb on a leaf blower, but I don't think that comes close to the complexity of this one ;oP
3. Could this just be a throttle cable/linkage problem? How would I go about diagnosing that?
I plan on getting a fuel pressure gauge and making up the test apparatus that Don recommends.
Thanks in advance,
Don
