Did you figure this issue out yet? What year is your Hino?Hello
Have a hino 185 and has slow acceleration when in gear and driving (under load). Also air pulses back out of the air filter, happens every 5/6seconds. When i acceleration fully and let of the throttle quickly the engine shudders like its not get correct air flow. Truck is not smoking. Does not sound like a fuel problem more an air issue. Any suggestions would be greatly appreciated!