SX150TXRY Idle / Stalling

[FabricGATOR]

I've had some time to attend to her. Still trying to work out my poor idle and stalling issue with the starboard engine. Luckily I have the port engine and can swap some parts to see if the symptoms follow the part.

The engine runs poorly at idle and exhibits the symptoms of missing spark or intermittent fouled plug(s).

Yesterday and the day before, I have tried to identify which cylinders are misfiring using the DIS/Kv high voltage tester. Not having any definitive results, and reading here about the majority of problems are fuel related, I have cleaned/changed the filters (onboard water seperator, engine bowl type, cleaned VST filter and ran quicksilver powertune in the electric pump). I swapped all six ignition coils, then spark plugs. I swapped VST tanks from engine to engine. Port engine continued to run well Stbd, not so good. I am aware that #2 and #5 are designed to drop out at idle. What tells the engine to deactivate those cylinders? TPS? RPM?

When starting STBD, I need to raise the idle manually. Just off idle sometimes she'll bog under and quit and others she'll get a spark or two kicking in. After a period of intermittent jumping/fouling and warming up, sometimes she'll idle normal for a while, other times for several minutes. After coaxing her to run good, I can shut her off then right back on at idle and she runs like I want. When I shut her down for 5 minutes, back to the same poor idle and missing.

Back to the factory manual. At least it has some cartune pictures.

Compressions are within 5-10 PSI of 130 PSI in 5 revolutions. (warm)

[FabricGATOR]

R&R removal and reinstallation.

Thank you Captain,
What is entailed in removing, inspecting, cleaning and re installation.

I appears that I remove the air box, and then the fuel rail. Appears they are captured with an o-ring by the fuel rail and what is the probability that I will be able to salvage the o-rings. Not being cheap, its just availability. Is it something I can probably do today or should I secure two full sets of o-rings prior to dis-assembly.

Maybe I am being cheap, looks like $30.00 dollars per injector for items 15, 16, and 17(o-ring, gasket, and rubber)

Are there screen filters at the fuel rail inlet and outlet or at the VST?

What is the procedure for releasing the wire clip on the FI wiring harness plugs.

[99yam40]

I am aware that #2 and #5 are designed to drop out at idle. What tells the engine to deactivate those cylinders? TPS? RPM?

I thought it dropped cylinders in neutral , so neutral switch would be my thought.
Edit Rodbolt17 said the OX66 does not drop cylinders in normal operation so pay no attention to what I wrote

Did you ever get any fuel pressure readings?

If they staying in spec, then have the injectors been flow tested and cleaned?

[FabricGATOR]

Going in

I just reviewed the Illustrated Parts Catalog and maintenance manual. Answered all my previous questions. I'll pop it off and inspect for debris in the injector filter screens.

[FabricGATOR]

neutral switch

Hey 99yam40, thank you.

It is exhibiting the low idle and stalling in both neutral and in gear.
I have not created a good fuel pressure gauge yet (I have to gather supplies from the airport), so I swapped VST tanks, assuming that if there were low fuel pressure issue it would follow the tank, pump and regulator. It did not.

I also did a rough LP fuel flow test. It appeared to fill half a 20oz coke bottle in about three seconds at idle. Again, I assume that volume should be plenty to sustain operation at idle.

[FabricGATOR]

Not the Fuel Injectors...

I swapped FI's from port to stbd engines. 1 to 1, 3 to 3, 4 to 4 etc. Cleaning the FI screens. Minor minimal detritus seen but nothing that would inhibit fuel flow to any great extent. No change. Cleanliness in the FI system is paramount when fishing deep in the Bermuda triangle.

Having swapped VSI assy's yesterday and only three screws, I swapped resistors. No change.

I'm going bezerker now. There is no reason why with two identical motors that I shouldn't be able to find this. Swap CDI's... No change. No corrosion on terminals noted.

Previously swapped all six ignition coils 1 for 1 no change. Even swapped spark plugs 1 for 1. No change.

I've not failed even once... I've discovered several things that it is not.

[FabricGATOR]

For Sale, Pair of SX/LX150TXRY

For sale, A pair of 2000 OX66 150's with 470 hours. One runs real good, the other has been fingered by a back yardigan.

Swapped the crank position sensor and the atmospheric pressure transducer.... I know, I know, I'm grasping at straws. If nothing else, I'm learning the engine, what everything is and verifying the connections and grounding.

For my last trick of the evening, I verified the TPS voltage. Not having the test adapter for the three conductor plugs, I did have a jumper cable for the fuel flow sensors. I was able to test the voltage on both engines I/A/W the Manufacturers Maintenance Manual. Found them both a bit low, re calibrated to 5 vdc +/-.02 with the throttle linkage disconnected.

About the only thing left is the Pulsar Coil and I just didn't have a big enough wrench to go after that today.

No fishing tomorrow,
Caio

[rodbolt17]

splatter gunning leads to technician induced failures plus the original issue.
where did you get the idea that it drops cylinders ??

[FabricGATOR]

Splatter gunning

Rodbolt, thank you for your interest and splatter gun concerns.

When started, she'll run rough between 400 to 500 RPM's and stall. With an occasional kick, like a plug trying to fire. If I manually raise the throttle to 600 to 800 RPM's she maybe will continue to run and sometimes jump up to 12, 16, 1800. kick, kick, kick

I have found that if I hold her up 800 to 1200 , that the suspect, begins to fire more than miss and when brought back to neutral sometimes she'll idle at 7-800 relatively smooth.

Out in the creek, other than the stalling annoyance, she seems to run like the other. Sometimes when stepping down she'll idle others she'll be rough and eventually stall.

What do you think?

[FabricGATOR]

SX150TXRY - YouTube

I don't know if this is any good. 39 second video, audio does not do it justice.

This is after manually advancing throttle to aprox 800 RPM to maintain running.

[rodbolt17]

the 2.6L ox66 does not use CCS and does not drop cylinders in normal operation.
have you tested the plug caps lift pumps and O2 sensor outputs?

start back over with the basics.
compression.
can all 6 coils spark across a 7/16ths gap?

from there you can either monitor it with the diagnostic test lamp OR measure each and every sensors reference and output voltages.

[FabricGATOR]

Rodbolt,

I put the scatter gun away, thank you.

Plug caps all six between 4.36 and 4.79 I believe spec is 4-6 ohm.

Lift pumps. Was able to measure aprox 10 oz fuel to the vst within 4seconds at idle. Lift pumps being the vacuum diaphragm pumps on the motor (2). How else should I test them?

O2 sensor output. Today, pulled the o2 sensor, bracket, and joint. Tested I/A/W maint manual pg 8-22. Found heater resistance 5.6 ohm and the heat test after cleaning with acetone would heat up and read 6.8 vdc and drop almost instantly to 0.001vdc. Spec said heater resistance 100 ohm. Please verify this is scrap. BTW, the other engine is reading heater resistance 4.9 ohm. Are they both scrap?
Found carbon and oil fouling in bracket and joint. Cleaned with power tune, compressed air, then final wash with acetone.

Compressions all six at about 130 psi engine warm in five revolutions. +\- 8 psi

I could not get a 7/16" spark across a home made air gap. Cobbled together a chunk of 1/2" star board, two dry wall screws and high voltage copper cored wire from neon signs. It should have worked. Maybe star board is conductive at that high voltage. I'll try again, "I got an idea, watch this"

How about cold compression test? The symptoms seem to go away when warm, sometimes. Other times, I could be at operating temp and she will idle low missing and stall while mooring.

I took my plastic ignition grippers and pulled plug wires while she was running pretty good at idle, but still dwelling on a cylinder every while. #5 made minimal difference and the hesitation (or I should say jump) was not there.

[FabricGATOR]

Cooled off, retest

So I just restarted the motor after letting her cool off for about fif**** minutes.

Again, low idle, running poor, verge of stalling.

Got out my plastic ignition grippers and pulled one wire at a time. Wires 1, 3, 5, (starboard side) appeared to make little difference. Pull any wire on the port side, and she would drop RPM and stall.

Wait, let me check.

Just pulled all three wires on the starboard side and started it. Yep, she runs like when they are connected. At idle.

I think we're onto something. What next?

[rodbolt17]

the injection system is sequential, rules that out for bank to bank.
only thing I can think of that would take out a bank is poor stator charge coil voltage.
the OX 66 motors don't use a high and low speed,even though some manuals referenced it that way, they go bank to bank.
one coil feeds voltage for one bank the other coil the other bank.

flame test is a teat on a boar hog for the O2 sensor test.
I use running output voltage as per the tech bullitens.

[FabricGATOR]

Service bulliten

Rodbolt, thank you for your continued enlightment.

After my last post, I was contemPlating. Thinking I get different results cold run then after I run her up and then she runs different, better, your and others comments about now owning a spare pulsar coil, etc. what else changes. Battery voltage. I connected DMM to battery connections at the engine and monitored voltage before, during run, idle etc. for cryin out loud, don't tell me that I have a crap battery and it's causing this situation.

The flooded lead acid that I have in place was reading 12.6 before start, at idle high 12s and after a 2 minute run 1600 kicking then smooths out higher, then back to idle on the throttle lever, she idles at 6-700 relatively smooth except for the dwell #5 cylinder. Battery voltage 12.8. Should be sufficient, but maybe with a weak coil...

Reinstalled my Enersys *****ing thunder PCM1500 34r battery and tried again. No change in oPeration. Still running 246 cylinders at start. After a run at higher RPM CYC's 1+3 begin to pull and will idle 6-700 rpm.

Could you advise running specs and procedure to check the O2 sensor IAW service bulletin. I don't have access.
Thank you.