I'm getting ever closer to fixing an F80TLRA that died on the water 2 seasons ago and wouldn't start at all last season. So far I have done the following...
1 Replaced all of the fuel lines on the tank side of fuel pump
2 Pumped out all old gas and replaced with Startron treated gas
3 Replaced the 10 micron in-line filter
4 Cleaned the on-engine fuel filter
5 Dissembled and cleaned the fuel pump
6 Removed carb/intake manifold assembly
7 Cleaned float bowls / jets with carb cleaner
8 Replaced in-line filter at each carb
9 Installed carb/intake manifold assembly w/new gasket
10 Confirmed all bowls receiving fuel by opening bowl drains
At this point I was able to get the motor to start by pumping the throttle before cranking. The engine would only run rough at about 1/2 throttle, but not idle at all.
11 Pulled all 4 plugs & inspected. Plug 2 & 3 electrodes are black.
I suspect an ignition problem w/clys 2 & 3 so I made up a spark test jig to hold two grounded plugs. Unfortunately I couldn't see spark in the bright sun. I even tried one of the suspected good wires, & still couldn't see spark.
12 Disconnected & reconnected connector on hot side of both coils.
13 Swapped the two black end plugs to cyls 1 & 4 & clean plugs in 2 & 3
At this point the motor started, but again only after pumping the throttle. I was able to get it to run near 600RPM and it seem pretty smooth. After about 10 minutes of run time it coughed (backfire?) and then started to run rough again, requiring more throttle to keep it running.
As it runs at fast throttle, it seems like the missing cylinder wants to fire, but it won't keep firing - kind of intermittent. The intermittent part makes me pretty sure this is an ignition problem, not a fuel problem. It's very possibly a loose connection somewhere.
Next I will pull and clean the grounds at the coil packs. If that doesn't work I need to pull of some covers so I can find the other connectors on the ignition system.
If anyone has other ideas what might cause the intermittent fire please comment.
1 Replaced all of the fuel lines on the tank side of fuel pump
2 Pumped out all old gas and replaced with Startron treated gas
3 Replaced the 10 micron in-line filter
4 Cleaned the on-engine fuel filter
5 Dissembled and cleaned the fuel pump
6 Removed carb/intake manifold assembly
7 Cleaned float bowls / jets with carb cleaner
8 Replaced in-line filter at each carb
9 Installed carb/intake manifold assembly w/new gasket
10 Confirmed all bowls receiving fuel by opening bowl drains
At this point I was able to get the motor to start by pumping the throttle before cranking. The engine would only run rough at about 1/2 throttle, but not idle at all.
11 Pulled all 4 plugs & inspected. Plug 2 & 3 electrodes are black.
I suspect an ignition problem w/clys 2 & 3 so I made up a spark test jig to hold two grounded plugs. Unfortunately I couldn't see spark in the bright sun. I even tried one of the suspected good wires, & still couldn't see spark.
12 Disconnected & reconnected connector on hot side of both coils.
13 Swapped the two black end plugs to cyls 1 & 4 & clean plugs in 2 & 3
At this point the motor started, but again only after pumping the throttle. I was able to get it to run near 600RPM and it seem pretty smooth. After about 10 minutes of run time it coughed (backfire?) and then started to run rough again, requiring more throttle to keep it running.
As it runs at fast throttle, it seems like the missing cylinder wants to fire, but it won't keep firing - kind of intermittent. The intermittent part makes me pretty sure this is an ignition problem, not a fuel problem. It's very possibly a loose connection somewhere.
Next I will pull and clean the grounds at the coil packs. If that doesn't work I need to pull of some covers so I can find the other connectors on the ignition system.
If anyone has other ideas what might cause the intermittent fire please comment.
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