Yamaha F115TLRA power loss

[Mulletman]

I have a 2002 Yamaha F115 tlra 4 stroke that won't plane my 19' Key West. It idles reasonably well but develops no power under load. I have been working this issue since Feb after a 6 month storage. I have replaced all filters, cleaned vst, replaced plugs, pulser coil, tps, thermostat, injectors, fuel pressure regulator, rectifier, primer bulb. Compression checked good as well as fuel pressure. I drained tank and am running on auxillary 6 gallon tank. Please help.

[99yam40]

Just because you say it all has been checked does not mean a lot, it may help to post what all these tests/readings were
Has it been conected to a computer to see what it has to say?

[Mulletman]

Yamaha F115TLRA power loss

Thanks for the reply. The compression tested 138psi on all four cylinders and the fuel pressure was 38-40. The computer diagnostics indicate all are normal.

[TownsendsFJR1300]

What's the max RPM your getting out of the engine now?

Is the idle DIFFERENT NOW than it was before (rougher?)

How many hours on the engine?

Is it used in salt water and if so, flushed religiously?

Any alarms?

Have you looked closely at ALL FUEL LINES/vacuum lines for splitting, cracking?

If you can, run the engine to max RPM (under load), then TURN OFF IMMEDIATLY. Let it cool down some and pull the spark plugs. Inspect them closely, they should all look the same. Water injestion won't show on the computer.

A leak down test, if all the above pans out would be next. Its much more comprehensive than just a compression check. If a cylinder isn't sealing correctly, you'll find it with this test..

[Mulletman]

Thanks TownsendsFJR1300. Max rpm is 3700. Idles about 700-750 slightly rough. 215 total hours, no salt, no alarms. All lines look good/ no splits or cracks. Haven't done a leak down test. How do I do it? Any special tools required?

[TownsendsFJR1300]

Thanks TownsendsFJR1300. Max rpm is 3700. Idles about 700-750 slightly rough. 215 total hours, no salt, no alarms. All lines look good/ no splits or cracks. Haven't done a leak down test. How do I do it? Any special tools required?

Tks, yes there are some special tools..

This is the leakdown tester I use and am very happy with the unit;

Amazon.com: OTC 5605 Deluxe Compression Tester Kit: Automotive

You'll also need an air compressor.

Basically, you bring the cylinder your testing to TDC on the compression stroke. You have to lock up the flywheel somehow or the in-coming air will spin over the engine.

Once the the engine is correctly set and locked down, air is added to the cylinder thru the spark plug hole. The second gauge will show how much (how efficent) leakage the cylinder has..

IE, if you have broke, stuck open, etc, intake valve, you'll see on the gauges the drop in pressure and literally hear air flowing out the intake manifold.

Air flow into the crankcase leans towards bad compression rings or block.

Its a very efficient way to determine the health of the internals of an engine W/O a tear down...

It can be used on most any 4 stroke and some very limited use on a two stroke (can't check how well the lower end crank case, reeds, etc, seal)..

[Mulletman]

Thanks for the info. I will order it and see what happens.