Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - View Single Post - Urba Centurion Update - (Kubota diesel, 100+ MPG in mixed driving

changzuki · 12-22-2014, 06:15 AM

- Dealing with the D850's reduced power and missing RPMs...
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Like the new injectors, apparently the "replacement" Zexel injection pump is less of an "exact replacement" and more of a "close approximate match". The current issue is the ~600 rpms that are now missing and thus limiting us to about 2400 on the tach along with reduced power for the hill climbs.
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If the governor is suspect, it's possible to watch it in action. Removing the "speed control plate" (and associated internal springs!) located directly in front of the injection pump will provide a window:
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Making sure your fuel shutoff is still hooked-up, it is possible to start the engine and watch the governor do its job. Although not recommended, if you're really careful, you can reach in physically move the governor forward to increase the rpms. Not only will you feel the governor weights gain strength to return the rack to idle, you will likely be swathed with a geyser of engine oil! Looking at Kubota's timing gear layout explains why they are so effective at slinging oil from the oil pan upward:
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After watching the governor through an OPEC champagne party, it was pretty easy to see what was limiting it and thus causing the fuel rack to stop short:
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Removing the acorn nut style cap screw allows access to the slotted adjustment screw and jam nut.

"Loosening" the adjustment screw will allow a more travel and allow the fuel rack to more fully open.

As long as your accelerator springs can overcome the governor weights, the previous rpm limit will be raised. NOTE** When abruptly accelerating from idle, this extended rack travel may result in a blast of "rolling coal" until the mechanical governor catches up to back off the fuel rack. The governor then regulates the opening of the rack at a more realistic rate and the exhaust should be mostly free of visible soot.
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**NOTE** There is a similar adjustment for the minimum governor travel to stop at and it's located at the lower rear of the injector pump and protrudes from the engine casting (much like the front adjustment does)...
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With adjustment made to obtain roughly 3400 rpm we are now ready to mop up from the Boston Tea Party and go for a road test!
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~CrazyJerry
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12-22-2014, 06:15 AM	#326 (permalink)
changzuki Changfa diesel + Suzuki Join Date: Jul 2012 Location: Northern, NY Posts: 527 Centurion - '74 FIAT X1/9 Centurion Full Race DNA Last 3: 143.5 mpg (US) Thanks: 160 Thanked 463 Times in 235 Posts	- Dealing with the D850's reduced power and missing RPMs... . Like the new injectors, apparently the "replacement" Zexel injection pump is less of an "exact replacement" and more of a "close approximate match". The current issue is the ~600 rpms that are now missing and thus limiting us to about 2400 on the tach along with reduced power for the hill climbs. . If the governor is suspect, it's possible to watch it in action. Removing the "speed control plate" (and associated internal springs!) located directly in front of the injection pump will provide a window: . . . . . . Making sure your fuel shutoff is still hooked-up, it is possible to start the engine and watch the governor do its job. Although not recommended, if you're really careful, you can reach in physically move the governor forward to increase the rpms. Not only will you feel the governor weights gain strength to return the rack to idle, you will likely be swathed with a geyser of engine oil! Looking at Kubota's timing gear layout explains why they are so effective at slinging oil from the oil pan upward: . . . . After watching the governor through an OPEC champagne party, it was pretty easy to see what was limiting it and thus causing the fuel rack to stop short: . . . Removing the acorn nut style cap screw allows access to the slotted adjustment screw and jam nut. "Loosening" the adjustment screw will allow a more travel and allow the fuel rack to more fully open. As long as your accelerator springs can overcome the governor weights, the previous rpm limit will be raised. NOTE When abruptly accelerating from idle, this extended rack travel may result in a blast of "rolling coal" until the mechanical governor catches up to back off the fuel rack. The governor then regulates the opening of the rack at a more realistic rate and the exhaust should be mostly free of visible soot. . NOTE** There is a similar adjustment for the minimum governor travel to stop at and it's located at the lower rear of the injector pump and protrudes from the engine casting (much like the front adjustment does)... . With adjustment made to obtain roughly 3400 rpm we are now ready to mop up from the Boston Tea Party and go for a road test! . . . ~CrazyJerry . Last edited by changzuki; 08-03-2018 at 11:51 PM..