2003 225 Optimax fuel/air problems

**velox** · 08-04-2023, 10:19 AM

I have dual 225 Optis with under 190 hours and the boat has been sitting for long while due to personal problems. After cleaning and fixing several small problems I have one engine that is running pretty good and has the correct air and fuel pressures of 80/90. The other engine barely runs for 20 seconds or so and has 20# of air and about 40# on fuel. I have removed and checked the tracker diaphragm and it looks perfect. I am thinking with such a low air pressure it is probably the air supply, ie, the compressor. It could be the reed valves stuck from sitting. I know the fuel regulator diaphragm could be shot, but because there is such a huge drop I would think it may be something other than the diaphragms. The last time I started it, a couple of years ago, it ran fine.
I do have a DDT and a set of gauges, but it’s been so long since I worked on them I would like some ideas from those that are skilled and current before I start ripping it apart and finding it was something simple. PS I did see a small amount of free from the Schneider (sp?) valve but only a very small squirt of a couple of drops.

**XstreamVking** · 08-04-2023, 02:43 PM

If you want it to be reliable change out the rubbers and clean out the fuel pump tanks and pumps. These parts if original are 20 yrs old. Check the air lines with soapy water for bubbles (leaks)

**velox** · 08-05-2023, 07:08 AM

I did clean the fuel pump reservoir and found it to be very clean. I pulled the tracker valve and found it to be in good I removed the compressor head and it seemed normal. All the hoses and electrical lines are in very good shape. I always kept the power head clean and used anti corrosion spray on it after each use. I have all new filters for air and fuel. I plan on checking the air regulator as the fuel pressure is regulated to be 10psi above the air pressure and the air pressure is quite low. It’s so low that even a small leak in an o ring would not account for such low compressed air. I will check the air regulator. I am very slow as the boat is outside and it’s over 100f with bright sun!

**XstreamVking** · 08-05-2023, 09:21 AM

I'm sweating too. It's hot man! The rubbers wear with age. The fuel pressure valve failure will raise the rpm's very hi on start up. (leaking fuel) Air press one will do what you seem to be looking at. Tracker will often cause a very ruff idle and then will die when throttled up. You are going at it systematically, you will find it. new rubber compound is purple. Tan or green is original. Spray some soapy water on it and check for leaks.

**InjectorService** · 08-05-2023, 01:09 PM

Have someone run the motor, check if there is air coming out of the drain holes on the air regulator.

But your issue is definitely on the air side. Your either losing it or not building it.

Bad compressor, fuel reg diaphragm, tracker, or oring on a fuel or air injector. Could be stuck open injector too.

**Tcatrett** · 08-05-2023, 03:10 PM

`With your gauges on crank the engine and pinch off the air dump hose. Connects to the exhaust plate. Should go over 200 fast. You can test the fuel seal the same way by pinching the fuel return to the vst.

**InjectorService** · 08-05-2023, 07:39 PM

Tcatrett is right those are both good tests.

**velox** · 08-06-2023, 11:23 AM

I did determine or thought I did, realize that the air pressure has to be high enough to make the fuel pressure high enough to keep the engine going. I used my shop compressor to force air into the inlet of the engine compressor. The engine started right up and went to 80/88.5 air to fuel pressure and kept running. Evidently there was something blocking airflow and cleared itself. The big problem is I will never really know what was wrong. The good thing is now I know what is involved in R and R the tracker valve, the air pressure regulator and the fuel pressure regulator. While I understood the basics of the air pump/fuel flow, I now have a much better understanding of using the gauges, checking for fuel in the air port and the proper use of the gauges. My son had put the oil filled gage manifold years ago, but this was about the first time I have actually used them to trouble shoot.