Optimax 225 fuel rail problem / misfiring 😩

[miagonz85]

Hi everyone, 06’ 225 Opti misfiring. Barely idles, turns off if I give it throttle. Smells like fuel, sounds like it’s running rich. New plugs. Comp test good, air 80 psi fuel 90 psi. I can hear pumps when open ignition. Tested spark, all 6 spark. When I press the Schrader valve on the air side, it lets out air mixed with fuel. Checked all 3 valves on fuel rail and they’re good. I believe the issue is in the fuel rail. Somehow fuel is getting on the air side. Any ideas will be help and appreciated.

[miagonz85]

When turn key on fuel press only goes to 15-20psi, air side goes up then drops right away. Should fuel / air hold pressure ?

[stoker2001]

fuel in air-rail is symptom of bad tracker valve

[miagonz85]

fuel in air-rail is symptom of bad tracker valve

That was my first thought, but checked all 3 tracker valves and they’re good.

[stoker2001]

That was my first thought, but checked all 3 tracker valves and they’re good.

I believe they came out with a modern upgraded material for tracker valve and it was distinguishable by the color but can’t remember which color.?Pretty sure the only way Raw fuel l or fumes can get in there is on those diaphragms are bad even though they look good

[InjectorService]

The tracker valve is that green one on top, the purple one with the small spring is the fuel pressure regulator. Both of these valves have fuel on one side and air on the other. Both are potential leak areas, although the tendancy is for it to be the tracker valve.

Did it start leaking suddenly, or what set it off?

You can put everything back together, install it on the boat and use the schroeder valves to put air in the system, hear for leaks. Don't put more than 90 psi in either, but if you have a cracked rail or something it should show up then.

[stoker2001]

The tracker valve is that green one on top, the purple one with the small spring is the fuel pressure regulator. Both of these valves have fuel on one side and air on the other. Both are potential leak areas, although the tendancy is for it to be the tracker valve.

Did it start leaking suddenly, or what set it off?


You can put everything back together, install it on the boat and use the schroeder valves to put air in the system, hear for leaks. Don't put more than 90 psi in either, but if you have a cracked rail or something it should show up then.

Don correct me if I am wrong,STBD side is tracker valve and port is fuel pressure reg?Merc came out with better material for tracker that is purple color?

[Motv18]

It should hold 14-20psi on fuel side. Or 10-15 per spring weight in the regulator. For a leak down test. If it goes to 0 you have a leak.

fuel can get in during the initial start when the air side backfills. If any is in the bore. It shouldn’t be gushing out but it can smell oily from the compressor. Their is no dryer on the Air side so water is sometimes an issue. Why the regulator isn’t at the lowest point possible for letting water out is beyond me.

[miagonz85]

Thanks to all for the input! The 2 purple tracker valves in the picture are new, I replaced them recently, the 1 green I didn’t replace cause it’s still in good condition. I checked all injectors with the multimeter testing ohms resistance. On the air side, 5 air injectors measured 1.5 ohms and 1 measured 2.0 ohms. On the fuel side all 6 measured 2.2 ohms. Will only 1 faulty air injector cause such misfire? Is there another test I should perform to confirm this injector is faulty?

[InjectorService]

Don correct me if I am wrong,STBD side is tracker valve and port is fuel pressure reg?Merc came out with better material for tracker that is purple color?

The purple are the updated ones. The top rail in the picture with the green valve is the starboard rail.

[InjectorService]

Thanks to all for the input! The 2 purple tracker valves in the picture are new, I replaced them recently, the 1 green I didn’t replace cause it’s still in good condition. I checked all injectors with the multimeter testing ohms resistance. On the air side, 5 air injectors measured 1.5 ohms and 1 measured 2.0 ohms. On the fuel side all 6 measured 2.2 ohms. Will only 1 faulty air injector cause such misfire? Is there another test I should perform to confirm this injector is faulty?

If you want to double check if the valves are leaking you can take the air dump hose off and see if fuel is coming out during running condition. If that is the case you still have fuel & air mixing in the air side, most likely the valve you have not replaced yet then.

EDIT: As far as the injector goes, I would rule that out until you know 100% that the air and fuel is not mixing.