Fuel pressure.

[Turner326]

Twin optimaxs serial #2b362048

Just put the motors on the boat after some work to them. Seem to run great on the muffs and I ran it in the water for about 5 minutes cause it was so windy. Everything seems normal except for a hanging idle on my port motor but I believe that was a throttle cable problem. I just got my gauges set up so I figured I would go check the motors. My starboard motor is running fuel at 100psi and air at 88 psi. Switched gauges and got the same result. The manual says it should be air pressure 94.3-96.3, fuel pressure 108.1-110.1. I also notice when I turned the motor off both fuel and air dropped pretty quick. With in about 30 seconds the air was at 0 and the fuel was holding at 15 psi. I tested the port motor after that and both air and fuel was in spec. And when I shut the motor off they seem to hold pressure. Air at 90 and fuel at 100 for at least 30 seconds until I walked away. The book says to hook a air compressor up to the air inlet and inspect for leaks. Where exactly am I looking for leaks, just at hoses and connections? Should I be soap testing for leaks? "Leaking air through the compressor indicates bad reeds". Should I hear air leaking through the reeds? I also want to note that I punched off the air and fuel line and they both spiked to 120 psi or higher. If Don or anyone else has a starting point for me I would appreciate it. Thanks

[Turner326]

I also notice the book say .043 for the spark plug gap. Is this still accurate? Thanks

[lpugh]

use a pressure relater set to 93 psi to test with

[lpugh]

use a pressure regulator, set to 93 psi to test with

[Turner326]

use a pressure regulator, set to 103 psi to test with

Set my compressor to 103 psi??

[Savage]

Shop air

[Turner326]

Shop air

Yes that's what I meant lol. Should have been more specific. Would I know if my reeds are broke? Would I hear anything or would the air be blowing back through the compressor intake? Thanks

[Turner326]

I also notice a quick plume of smoke from the prop on start up. The port motor does not do that

[EuropeanAM]

Let's work on one item at a time here. Air Fuel should indeed be 94/108 if you have GRAY direct injectors (verify this please as I've heard of a few stragglers that made it out).

Need pressures:

-At idle
-Under Acceleration
-5/10/15 seconds after shutdown (you can restart for each).

[Turner326]

Let's work on one item at a time here. Air Fuel should indeed be 94/108 if you have GRAY direct injectors (verify this please as I've heard of a few stragglers that made it out).

Need pressures:

-At idle
-Under Acceleration
-5/10/15 seconds after shutdown (you can restart for each).

Thanks for the response don. The injectors are the gray ones. Are they problematic? I cannot do a acceleration test right now because the boat is on the trailer. I could probably get it in the water by Monday but I also wasn't sure if it's safe to drive the boat with this problem. I don't want to do any harm to the motor. I will get pressures again tommrow. As mentioned earlier in the thread right when I turn the key off it is a steady decline for both air and fuel. I will do the 5,10,15 tommrow though and report back.

[EuropeanAM]

Skip the acceleration. Be sure we get both pressures at precisely the same time (quite important)... that first 15 seconds is what tells us the most.

[Turner326]

Skip the acceleration. Be sure we get both pressures at precisely the same time (quite important)... that first 15 seconds is what tells us the most.

Ok I will check them tomorrow and let you know what I find. Thanks are there known problems with grey injectors?

[EuropeanAM]

Not based on their color. Direct injectors (regardless of color) are extremely expensive, and are a high-mortality item (especially where carbon, debris or metal fragments are involved).

[lpugh]

Set my compressor to 103 psi??

93 psi, head up but, air pressure should not be bypassing thru the regulator, listen for leaks around the di injectors, fuel pressure regulator vent hole. air lines
pull the spark plug and check there as well as the exhaust

[Turner326]

Ok so I just got don't doing more diagnosing. I did the key off and honestly I forgot what my results were cause it's been a long day. All I can tell you is that air and fuel just fall steady and air is at 0 with in 30 seconds. Fuel held at 15. I hooked shop air to it and pulled all plugs. Didn't hear anything and was still dropping air pressure. Then I took the outlet hose off the compressor and blew air into the compressor and it dropped just like when it was connected to the rest of the system. Then I plugged that hose and pressured the rest of the air system and it held perfect. So I'm assuming it's bad compressor reeds or a o-ring in the compressor. While I had the system pumped with air I turned the motor over briefly and my fuel pressure then held at 40 psi. That was just a quick crank and didn't start the motor obviously. Now that I'm looking in the book I see that I was not suppose to cut that oticker clamp off the compressor outlet so I will have to deal with that.

[JOE54]

pull the reed plate check it out the tiniest speck can cause reed stuck open

[Turner326]

pull the reed plate check it out the tiniest speck can cause reed stuck open

Ok. Are the o-rings reusable or should I just order o-rings before I pull it apart? If I find dirt should just clean and reassemble? Or should I just get a new reed plate? Thanks

[JOE54]

recommend replacing all components, inspect cyl closely for any scaring also

[Turner326]

recommend replacing all components, inspect cyl closely for any scaring also

Ok sounds good. Hopefully everything looks ����

[Turner326]

Ok took the compressor apart. Reed plate o-rings are shot and reed plate is a little corroded. Going to replace the reed plate and o-rings. Piston and cylender look perfect. Is 835088A10 the right part number for the reed plate? Thanks