OX66 LP Fuel Pumps

[fishinAK1]

Great. I’ll go check TPS now.
Yup. I did follow head bolt torque specs and order.

 

[seasick]

I just had a thought about the alarm. It may have been a low oil alarm caused by the main tank getting emptied and not filled up by the remote tank and pump. I though that such an alarm would put the motor in safe mode but maybe it was too short for that to happen. Low oil in the main tank could be due to a clogged oil tank screen, a bad remote pump, sludge in the oil tank and other less common wiring issues. At higher speeds you may have been using oil at a higher rate than the tank was getting refilled. When you got the alarm did you feel the motor drop off at all?
This is another thinking out loud message
I am seriously bored...

 

[fishinAK1]

INTERESTING!

I just checked the TPS. The probes from my DVM don't fit directly into the wire harness so I just stuck a little jumper wire into the harness.

The resistance between the Orange and Pink wire, Which I think is the sensor output starts at 0.98 when in neutral. As the throttle is pressed forward it goes up to about 1.2 at around half throttle end ends at 4.7 at wide-open throttle.

Between the Orange and Red wire, which I assume is the input to the sensor the resistance is a steady 5.02 from neutral to fully open throttle.

SO....

Manual calls for 0.50 with throttle valves fully closed.

When I reinstalled my injectors I noticed that when in neutral my valves appeared to be fully closed. Should I still make go through the steps of disconnecting parts to confirm my throttle valves ARE completely closed? Im not trying to be lazy and save a step, rather I just hate to go adjusting and moving stuff that WAS working (or seemed to be) before.

Also, I am measuring resistance. does the fact that I am measuring this using my little jumper wires affect the resistance?

These numbers, especially the 0.98 in neutral, seem to be out of spec. I think spec should be 0.5 to 5.0. Could this be my issue...slow idle, running rich, increased fuel consump, and loss of top-end RPMS.....

Should I attempt to adjust the current TPS or just replace w new one?

 

[fishinAK1]

plenty of oil in both tanks, remote and onboard. For some reason, Im still thinking once the other issues, fuel and RPM, are solved it wont alarm. Heck it maybe as simple as a water pump getting old (its only 3 yrs old). Yes, tell-tale was peeing. OR its still hovering around freezing here. maybe there was still a bit of ice somewhere that hadnt quite thawed out yet...

Thanks I appreciate your "thinking out loud"!

 

[fishinAK1]

Now my thinking out loud... How do TPS get out of wack? It just seems like something that once in adjustment, it should stay in adjustment...

 

[fishinAK1]

So I was about to adjust the TPS but I was still thinking about the resistance the jumper wires could be causing. So I filed down my probes so they fit into the harness. And also removed the butterfly valve linkage. Now I’m sure #1 valve fully closed.
resistance is 0.76 fully closed and 4.92 fully opened.

since the yellow dummy paint has not been touched, and it doesn’t see too far from spec. I hate to mess w it until I’m convinced this it the problem. What do ya think? Should I adjust?
Also it moves smoothly evenly thoughout throttle, when moving by hand at valve.

 

[fishinAK1]

Fully closed and fully opened Pics attached

 

[fishinAK1]

Ok tried checking resistance between the black and gray wires (these go to the CDI) on O2 sensor. With both sets of wires disconnected (is this how I should test?) I could NOT find continuity/resistance. This is w no ignition. (Pics attached)
W key “on” and white wires attached to their home in fuse box, I would get very erratic resistance between black and gray wires.

more evidence of failed O2?

 

[Toothpick 10]

Isn't there a way to test the O2 sensor by heating it and checking the change in resistance?

 

[family affair]

Yes, there is a flame test method, but if I remember right it isn't absolutely correct.
As for the throttle plates, dont touch them. All you will do is introduce more variables, not eliminate them.
As for TPS, it has to be adjusted with the engine running in neutral, in the water. If it is anything like the 225/250 TPS, it is extremely sensitive. I can actually get the output to change by pushing on the sensor body while it is fastened securely.

 

[fishinAK1]

Thanks Family,
I almost hate to admit it (not sure why) but I did order a new O2 sensor. I guess owe it to 10 yrs of ownership, maintenance, and repairs i have a very strong feeling this is the root cause of the issues. I pray my feeling is right!

I’ll wait to adjust TPS, idle, etc until after I try new O2.

Still open to ANY thoughts.

Hava great night and Thank you all again!

 

[family affair]

I would still do a strong shock treatment decarboning before you put that sensor in to avoid contamination.

 

[WiltonGrady232]

I had a pair of ox66 engines for 5 years. I've been in your situation a few times. Every time the problem ended up being the LP pumps. It'll be a good idea to always keep an extra set on hand. With ethanol gas, they don't last much more than a year or so.

 

[seasick]

The key is that the resistance changes with out spiking to a high number while the actuator is rotated. The wires you used to make connection are not a problem.
Based on your results, the TPS seems fine.


The resting value is the number at idle setting. That number is not as important as making sure that when installed, the TPS changes value across the full throttle movement. For examples, if you have a reading at 3/4 throttle but it doesn't change as you increase the throttle, the adjustment is incorrect. Note that the throttle plate adjustments and synchronizing) have to be done before the tps is adjusted. In addition, the throttle cable has to be disconnected at the motor. You don't need to do any of that at this time.
Do not buy a new TPS

The throttle plates should be closed. Do not adjust the individual throttle screws unless you are absolutely certain there is an issue and you are versed in their adjustment. The only throttle screw you should possible need to adjust is the one that adjust the idle speed .

You replaced the plug wires and boots I believe. Did you measure the resistance of the old wires and boots?

 

[fishinAK1]

Thank you all!
I did install new plug boots.
next steps:
1: shock treatment (how ya doing this?) (seafoam)
2:LP fuel pumps
3: O2 sensor

Whatcha use for shock treatment? Concentration? How much? In bucket ok?

where would there be crud that I haven’t already cleaned?

 

[seasick]

So I was about to adjust the TPS but I was still thinking about the resistance the jumper wires could be causing. So I filed down my probes so they fit into the harness. And also removed the butterfly valve linkage. Now I’m sure #1 valve fully closed.
resistance is 0.76 fully closed and 4.92 fully opened.

since the yellow dummy paint has not been touched, and it doesn’t see too far from spec. I hate to mess w it until I’m convinced this it the problem. What do ya think? Should I adjust?
Also it moves smoothly evenly thoughout throttle, when moving by hand at valve.

No!

 

[fishinAK1]

Phew. Good. I did NOT adjust.

 

[seasick]

I am going to slow down on suggestions. My head is spinning.
For now, I am much more concerned about the alarm than the WOT issue. It could be something simple or at the other extreme something very bad.

 

[family affair]

Thank you all!
I did install new plug boots.
next steps:
1: shock treatment (how ya doing this?) (seafoam)
2:LP fuel pumps
3: O2 sensor

Whatcha use for shock treatment? Concentration? How much? In bucket ok?

where would there be crud that I haven’t already cleaned?

Use sea foam in a 2-3 gallon fuel container for shock treatment. You will need to look up the ratio. I dont know it off hand. You will actually run the boat under load off this container. I simply disconnected the fuel line ahead of the ball and used an extension to draw from the container.
I can only speculate on the fuel pump issue. Maybe having them off the power head allows for a valve to hang open allowing fuel to flow.?

 

[Sparkdog118]

The pumps have multiple sections. Some bolts hold the two sections together and other bolts hold that assembly tight to the block.Those bolts if I remember also squeeze the sections together so Make sure the bolts that don't hold the assembly to the block are tight. Pumps can suffer tears/leaks in the internal diaphragms. If that happens, you may see gas leaking out of the back. There are check valves that can go bad but when they do, you wont see any leaks. You can have an internal leaky diaphram that affects pump pressure but also doesn't leak out the rear.
Note also that the pumps are connected in series so if one is bad, if affects the whole set ( 2 or 3 pumps).
What exactly are you trying to diagnose?

Those pumps wear out and depending on the model year and when if ever the pumps were replaced, they may need replacing. Older lp pumps used a different material for the diaphragms that didn't hold up as long as the newer diaphragms.
On the edge of the pump assembly you should be able to see a small plastic tab that is part of the diaphragm. You may see either a black or clear plastic tab. Now for the kicker; I don't remember 100% what the newer parts are, black or clear but if I had to guess, I would guess that the older ones were black.

The defective ones are the clear ones.