OK, a bit of out-of-the-box thinking here.
Our fuel systems on carburetted bikes are gravity fed. If the fuel shutoff valve is not religiously used each time, carbs are notorious for not completely shutting off fuel when the bowls fill up, causing cylinders to fill and hydro-lock on start up, bending con-rods, as well as some fuel leaking past rings into the crankcase to dilute the oil.
Fuel injection doesn't have this problem. Well, not very often! An injector needs an electrical signal from the DFI controller to open and pass any fuel at all. So, the shutoff valve can be left open indefinitely. On my '83 Voyager I never did shut it off in the eight years I had the bike. I went to reserve a few times on the road, but never shut it off, except to remove the tank for maintenance. I never had any leakage.
This is all leading up to that check valve in the fuel return line from the pressure regulator. What's it for? One mechanic opined that it acted like a"shutoff" valve to prevent any backflow when the bike sits. OK, I can accept that. But, otherwise, it doesn't affect engine performance when it is running.
I bought my '83 Voyager brand new and never had any issues with it. I started to remove the tank to do a valve adjustment after about 3k miles. When I removed that return line to the check valve fuel came "gushing" out. OK, it just ran out! Oops! Not good. I drained the tank to do my valve adjustment job. After I was done I took it back to the dealer and had them look at it. The bike ran fine. It leaked all over their floor, too, when they removed the return line! I warned 'em! They replaced it and the mechanic said that he cut it open and found that the small spring against the check ball has slipped past the ball a bit and jammed it open. He figured it was a fluke manufacturing issue of that check valve. The new one didn't let any fuel past. The engine didn't run any different after it was replaced.
So, what's the point? If that check valve is to act as a "shutoff" valve for the return line, why not eliminate that check valve completely and run that return line to a "T" in the fuel line just after the main On/Off/Res valve? Unlike a carb system, the fuel injection system doesn't have any points of concern for leakage when the bike just sits. Oh, it's possible that if you don't keep a good filter in front of the pump that a bit of debris COULD get stuck in an injector, jacking it open just a tiny bit, allowing fuel to seep past. But, not likely! Mine never did in eight years!
Just run that return line over to a "T" in that fuel feed line and be done with it. NO CHECK VALVE!
I recently bought my current '85 Voyager, with just 45k miles, and have been slowly going through it looking for non-functional parts. It runs like new, but so did my brand new '83 with a bad check valve! This thread made me curious about the check valve on my bike, so I went out last night and removed the return line. Drip, drip, drip, drip, drip! Almost a steady stream. I shot some low-pressure air up though it, but still, drip, drip, drip. So, when the weather warms a bit I will be putting my fuel lines where my mouth is and capping off that check valve. Will let you know how it goes.
