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Rodbolts “understand” comment hit me in the belly, so Ive been reading wiring charts and trying to understand the operation of this engine. Unfortunately much of the info online while well meaning is anecdotal and based on situational experience not engineering principal or specific to this engines operational theory. As best I can see this system operates as a closed circut so to speak or a loop. With each sensor monitoring a speciific aspect of operational atmosphere which allows the ECU to direct adjustments in signal to the injectors. Very Reader’s Digest. Again, assuming Im understanding this correctly, the ECU adjusts timing to a higher reading in order to compensate for a faulty sensor? If thats correct, Im barking up the wrong tree by checking sensors. As my issue is stalling, the engine is being effected by a lack of fuel/air in fuel (which Im more inclined to believe as engine seems to be rich) or the energy to run the ECU or a faulty ECU? Which would mean testing the fuel supply, ignition components and ECU and grounds again forgoing the sensors at this juncture. Ill be doing another test, testing the wife for tolerance for me to purchase a new motor with a warranty! Lol That seems much less stressful!
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Last edited by Benwa Balls; 12-18-2018, 12:09 PM. Reason: Adjusted lack of fuel comment to include air in fuel -
you can have an IN RANGE failure that the ECU will react to and set no codes.
an example was an F@%) that 3 other dealers had looked at.
I hooked the laptop up and turned the key on and found the issue without ever cranking it.
Baro pressure indicated 19"Hg.
that is above 20,000 feet with an air temp of about -50*F.
why did the ECU set no codes? why did the ECU lean out the A/F mix so bad it would not run much above idle.
why is an outboard ECU programmed to run at 20,000 ft?
but it will try.
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Tested everything in the ignition and sensor system, everything checks out. Problem persists. After reviewing the way the fuel system is routed and runs (at least how I think it does) I pulled the injectors being they are new and made sure they were operational, they check out. Btw Im running on a 6gal aux tank with fresh fuel. Next I checked the hp pump pressure to ensure I was getting good flow, volts and amp draw, noticed the fuel pressure was up to about 45-47#. On a hunch I used vise grips and crimped the return line from the injector rail to the VST started motor it ran at 1100 rpm settled at 800 and idled fine, upping the throttle to 2000 rpm (in tank that comes about 6” over cav plate, not on hose) had no effect on performance, other than running at proper 2000rpm, i idled and held at 2000 without issue while return was clamped. (Smoking subsided also). Unclamped return, motor idled at 800 than faltered to a 500-700 and stumbled and sputtered. When it sputtered I clamped the return again and it resumed a good idle at 800. Unclamped and motor again stumbled. I let motor sit for one hour. Started and it went to 1100 rpm, settled to 800 for 20-30sec then stumbled to 509-600. While stumbling and almost stalling I clamped return and within 3-5 seconds it came up to a steady clean idle of 800 and did so for about a minute when I unclamped return line and it stumbled and stalled after 30-45 seconds. Im assuming I was bypassing or somehow negating the fuel regulator which would mean either I have a bad regulator or ??? I did replace regulator when this all started but that doesnt mean the part is good. Thoughts?Comment
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Checked all vacuum lines and they appear goose, however the one going to the regulator does not seem strong. It has vacuum but when I pull my finger away it doesnt seem to have a good grab of it. Ipive done some looking but cant find a spec of vacuum pressure. Anyone know how much oressure I shoukd be pulling? All filters including the thimble screen at fuel pressure regulator are new and I re-checked them for debris, they are clean.Comment
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what did the rail pressure do when you clamped that line?Comment
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Stayed at 45 +/- 5#Comment
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what is the spec for the rail pressure?
seems to me that if you keep any extra fuel from returning to the VST from the rail, the pressure would go highComment
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Manual sez 36.5Comment
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pull the vst,pull the regulator.
carefully extract the basket filter and clean it.
if it clogs it spikes pressure and make it run very rich.
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Ahead of you. Just pulled the vst filter, it was clean but I blew it with carb cleaner. Now it gets wierd... i hooked up the mityvac to the reg and gave 3kpi while running. Fuel pressure was at 35# it did not drop or rise. Out of curiosity I gave it 15kpi and niw the motor runs fine... maybe the diaphram in regulator was/is stuck?Comment
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Make sure you looked at the filter Rodbolt mentioned, not just the main pump pick up filter in the VSTOriginally posted by Benwa Balls View Post
I am a a loss as how pinching off that return line helped if the pressure was already too highComment
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I am with ya 99.
but there is a filter under the regulator.
and the OP has no clue as to why it has a regulator and what the vacuum does to it.
like I said you MUST have a complete understanding of the system and what each part does to the whole.
at idle 2 strokes don't generate a lot of intake vacuum like a 4 stroke.
so at idle there is maybe 10"Hg on the regulator,this causes the regulator to DECREASE fuel pressure.
at rapid acceleration intake vacuum disappears and it spikes the rail pressure about 5 psi.
coupled with asynchronus injector operation and extra fuel pressure at rapid acceleration it acts as an accelerator pump and keeps the mix from leaning out.
that and maintain pressure across the rail as the injector fire that is about it.
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I readily admit to not fully understanding the operating system. Unfortunately, there isnt a great deal of point by point technical data out there specifically for the ox66. That said, your explaination does make sense to me. I not only replaced the basket filter under the regulator as stated in OP but also pulled and checked it again as per your instruction. It was clean.Comment
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maybe stating part Numbers and parts break downs would help identify the parts you replacedComment
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