Hello
So, here's the breakdown.
I took the boat and motor into a shop to have the lower unit sealed properly, and to get a new water pump impeller installed. I figured that was a reasonable investment, as the lower unit has 20-some seals.
The first time I took it out, I had motor issues. Engine was bogging down, not getting above fast idle, some other issues. I traced that one down to bad fuel flow. Squeeze the primer bulb, things got better. Lower end was leaking, though. So much for that $400.
Got it back in, ran diagnostics on it. Cyl compression betw 20-135, fuel pump diaphragm was kinda crunchy, carb needles and seats were leaking a bit.
Electrical/ignition system is doing fine. Did a complete check on the coils (fine), ignition box ohm readings all in spec. Stator is within spec on high and low sides.
I checked the fuel lines, and they are old, but still clean and no kinks/bends/blockages. Fuel filter/strainer is new.
I replaced the fuel pump diaphragm, needles and seats on both carbs, cleaned out all the carb passages, and did some driveway testing. Checked spark, and it seemed fine. It starts great, goes to high idle just ducky. Throttle travel is full, and the ignition timing (low end) was great. All three cylinders were producing spark, and had rpm drop when disconnecting the plug. When warm, it starts in a half crank. When cold, it takes a couple cranks.
Took it out today to test some other things. Got the fuel mixture set, got the timing all set to 28 BTC (as in manual), checked fuel pressure (1.5 psi idle, 2.5 psi WOT), but had a fuel line connector that was funky/temperamental. I spliced that out, and the thing is not having any fuel supply issues, except when the tank runs out of fuel.
But still, the engine does not get above 3200 rpm. Had it running there for 20 mnutes straight. Last fall, before putting it away for the winter, it was getting to 5300 rpm. No prop change from last year, using new gas bought last month.
What could be wrong here? I'm out of ideas. Compression is good, spark is good, fuel is good. What else is left?
So, here's the breakdown.
I took the boat and motor into a shop to have the lower unit sealed properly, and to get a new water pump impeller installed. I figured that was a reasonable investment, as the lower unit has 20-some seals.
The first time I took it out, I had motor issues. Engine was bogging down, not getting above fast idle, some other issues. I traced that one down to bad fuel flow. Squeeze the primer bulb, things got better. Lower end was leaking, though. So much for that $400.
Got it back in, ran diagnostics on it. Cyl compression betw 20-135, fuel pump diaphragm was kinda crunchy, carb needles and seats were leaking a bit.
Electrical/ignition system is doing fine. Did a complete check on the coils (fine), ignition box ohm readings all in spec. Stator is within spec on high and low sides.
I checked the fuel lines, and they are old, but still clean and no kinks/bends/blockages. Fuel filter/strainer is new.
I replaced the fuel pump diaphragm, needles and seats on both carbs, cleaned out all the carb passages, and did some driveway testing. Checked spark, and it seemed fine. It starts great, goes to high idle just ducky. Throttle travel is full, and the ignition timing (low end) was great. All three cylinders were producing spark, and had rpm drop when disconnecting the plug. When warm, it starts in a half crank. When cold, it takes a couple cranks.
Took it out today to test some other things. Got the fuel mixture set, got the timing all set to 28 BTC (as in manual), checked fuel pressure (1.5 psi idle, 2.5 psi WOT), but had a fuel line connector that was funky/temperamental. I spliced that out, and the thing is not having any fuel supply issues, except when the tank runs out of fuel.
But still, the engine does not get above 3200 rpm. Had it running there for 20 mnutes straight. Last fall, before putting it away for the winter, it was getting to 5300 rpm. No prop change from last year, using new gas bought last month.
What could be wrong here? I'm out of ideas. Compression is good, spark is good, fuel is good. What else is left?
