Hey Gang:
1988 Glastron 233 SSV
5.7 Merc. Engine, 1169 HRS on the engine
Alpha 1 Outdrive
Recent appearance of an engine surging problem. The engine surges down in RPMs and then returns back up to where it was. A down and back surge takes about 1 second and goes about 800rpm down, then up.
Each time it has happened, the following were true:
1. The engine was hot. Typically had been run for more than 1 hour
2. The fuel tank was less than 35% full (87 gal tank)
3. The lake wasn't completely calm. Some degree of chop, but not insane.(3" to 2' chop)
4. The throttle lever was not in the process of moving. it was stationary. boat had been running at maintained RPM for at least 10 sec.
Surging seems to happen above 3300 RPM when problem first happened. If you back the throttle down, usually to 2900 or so, the problem goes away. If you go wide open, it still happens.
First time this ever happened, it was after fuel was added from a Houseboat Reserve Tank. My theory was that there was water in the fuel. So I changed the fuel filter (didn't find water when I dumped it in clear container). I also changed the only old section of fuel hose that was older than 2 yr. old.
New filter, new hose. Topped off the tank with brand new fuel. Problem still happened when engine was hot.
Next trip:
I bought enough HEET water remover to treat my fuel. Added it to the tank. Sloshed it around while driving boat on trailer to mix, topped off tank with fuel. Fuel spilled out the vent, so I do not believe that the vent is clogged. I changed Water Separating Fuel Filter Again, didn't find any water. Problem happened again when the engine was hot. This occurrence was more interesting to me because we used the boat 3 straight days. Days 1 & 2 we drove the boat for more than an hour at 3000-3200 RPM. Problem did not occur. On the 3rd day, it did, when the fuel level was lower than it was on day 1 and 2.
THEN on the third day, problem occurs at 3200, If I back the throttle down to 3000 it goes away, and runs for about 5 more minutes just fine. Next, it starts surging at 3000, so I have to back down to 2500. It runs fine there for 2 minutes. Then it surges at that RPM. This process keeps repeating until I end up at idle in forward gear, with no surging. I ran like this for 10 minutes. Then for kicks, I gave it throttle to try and get on plane. It accelerates to 3500 RPM and planes out. Stays there for a minute. Then the surging happens again.
I had an extra water separating fuel filter in the boat. Spun the old one off and dumped it in a friend's gatorade bottle. No water visible after we let it sit. Problem happens after the new fuel filter is installed.
So, I feel water in the fuel has been ruled out.
New in 2009: Carburetor
New in 2010 Distributor Cap, Rotor, Plug wires, distributor sensor, ignition coil, Fuel Pump, Heads (old ones cracked)
What needs to be investigated next?
Thanks,
Dave
1988 Glastron 233 SSV
5.7 Merc. Engine, 1169 HRS on the engine
Alpha 1 Outdrive
Recent appearance of an engine surging problem. The engine surges down in RPMs and then returns back up to where it was. A down and back surge takes about 1 second and goes about 800rpm down, then up.
Each time it has happened, the following were true:
1. The engine was hot. Typically had been run for more than 1 hour
2. The fuel tank was less than 35% full (87 gal tank)
3. The lake wasn't completely calm. Some degree of chop, but not insane.(3" to 2' chop)
4. The throttle lever was not in the process of moving. it was stationary. boat had been running at maintained RPM for at least 10 sec.
Surging seems to happen above 3300 RPM when problem first happened. If you back the throttle down, usually to 2900 or so, the problem goes away. If you go wide open, it still happens.
First time this ever happened, it was after fuel was added from a Houseboat Reserve Tank. My theory was that there was water in the fuel. So I changed the fuel filter (didn't find water when I dumped it in clear container). I also changed the only old section of fuel hose that was older than 2 yr. old.
New filter, new hose. Topped off the tank with brand new fuel. Problem still happened when engine was hot.
Next trip:
I bought enough HEET water remover to treat my fuel. Added it to the tank. Sloshed it around while driving boat on trailer to mix, topped off tank with fuel. Fuel spilled out the vent, so I do not believe that the vent is clogged. I changed Water Separating Fuel Filter Again, didn't find any water. Problem happened again when the engine was hot. This occurrence was more interesting to me because we used the boat 3 straight days. Days 1 & 2 we drove the boat for more than an hour at 3000-3200 RPM. Problem did not occur. On the 3rd day, it did, when the fuel level was lower than it was on day 1 and 2.
THEN on the third day, problem occurs at 3200, If I back the throttle down to 3000 it goes away, and runs for about 5 more minutes just fine. Next, it starts surging at 3000, so I have to back down to 2500. It runs fine there for 2 minutes. Then it surges at that RPM. This process keeps repeating until I end up at idle in forward gear, with no surging. I ran like this for 10 minutes. Then for kicks, I gave it throttle to try and get on plane. It accelerates to 3500 RPM and planes out. Stays there for a minute. Then the surging happens again.
I had an extra water separating fuel filter in the boat. Spun the old one off and dumped it in a friend's gatorade bottle. No water visible after we let it sit. Problem happens after the new fuel filter is installed.
So, I feel water in the fuel has been ruled out.
New in 2009: Carburetor
New in 2010 Distributor Cap, Rotor, Plug wires, distributor sensor, ignition coil, Fuel Pump, Heads (old ones cracked)
What needs to be investigated next?
Thanks,
Dave
