I've been lurking here for years, and have allways found the info I needed by searching, but this time I'm stumped. I lost power on my truck, threw a code 0251 so I capped the leaking rail pressure relief valve (code didn't come back). But now with the plug in the banjo bolt I hear a whistle in the fuel system. It sounds like fluid going through a valve, similar to what hydraulic valves sound like. I pulled the plug out and the sound goes away, but the code comes back. Anybody have any idea what's making the sound?

 

Poor seal between the pipe plug and the banjo? - past the banjo threads.....its a poor fix IMO....Pipe threads/banjo threads were never meant for that kind of pressure.

 

I suppose that's possible, but many here have done it and reported no noise. It's temporary, just untill "floor it diesel" gets back to me for a new relief valve. I just want to make sure it's safe to drive untill then.

 

Hey hillbilly, you probably found all my post in your search regarding a whistle/squeel from the rail. Nobody had any ideas involving the fuel system for me so I ended up checked everything from belt/pullies to boost leak to throwout bearings with no luck. It sounds just like you describe, like an excavator hydraulic maxing out or high pressure fluid leaking past something. And with a stethoscope, i can hear is in the rail and fule lines, and especially from the relief valve so i also plugged it but mine still whistles. My problem is it does it with the valve capped or not, so i had just about given up on the releif valve idea until i read your post. I wonder if fuel is leaking around the pipe plug i put in so it can still leak past relief valve and make the whistling? If you find a fix please let me know, the floor it website is down so i havn't been able to order one of johns solid replacement valves...

 

FTE sells a pluged relieve valve for $67 shipped to lower 48. Mine poped so I will be ordering one from them soon. Give that a try, better than a plug threaded into the banjo.

 

I've been thinking about it and I doubt that it is coming from the plug itself. I believe the noise may be fuel coming around the banjo bolt threads themselves. With the plug in the bolt and a leaking valve, pressure will build above the valve and go around the course threads of the banjo bolt itself. The sealing of the banjo fitting is around the fitting itself and the threads were never designed to seal all that pressure. So I think maybe one of the machined relief valve delete plugs may get rid of the whistle. Or a new valve but they are pretty pricey. The pipe plug has fine threads that are tapered, the fuel pressure would have a hard time getting around it. The banjo bolt threads are much more course and would be an easier path for fuel. I wonder if you are hearing the same noise because fuel is escaping through the valve. Being somewhat restricted it could make the same noise. Then when you plug the banjo bolt you have the same problem I'm having. I'm not going to drive this thing until I get this resolved, I'm afraid all that pressure could erode the threads and the banjo bolt could blow out.

 

If fuel was pushed past the coarse threads on the banjo bolt, wouldn't you see it running down the outside, or would it still flow into the return line fitting??

I found a guy on ebay with solid stainless bolts that replace the banjo, but it would still have the problem of leaking fuel around the threads...

 

Anybody know if you can get a test fitting for the relief valve, like a banjo fitting with a line plumbed into it that you could run into a bucket to see if it was flowing fuel??

 

I don't believe it would leak to the outside, it would go past the shank of the bolt and into the banjo fitting and then drain. I think the bolt you saw would give you the same problem as the plug in the banjo bolt. I have a dummy relief valve ordered I'll let you know what happens. I think you are best off if you plug it right at the rail instead of on top of the valve. That's where the valve would stop the fuel if it were working correctly. The dummy valve looks like the original but has no passage for fuel to flow through it. So it should hold the pressure in the rail and not let it even get to the banjo bolt.

 

I put my relief valve cap off kit in yesterday, problem solved. No more whistle!

 

Did you get the one from floor it, for ~$70? I think i'm going to try that, mine still whistles away all day long...