I am currently experiencing fuel pressure drops when letting off of the throttle, however when under normal throttle my PSI is running between 15 and 20 PSI. I have the Fuel Boss that has a check valve on the return line and a month ago I cleaned this out and installed a new ISSPRO mechanical gauge with a snubber as I was having similar issues. My fuel pressure was good for a length of time, fluctuated from 18 to 20. Right now it will be at 19 under normal throttle, but when idling it drops all the way down to 8 and my engine begins to stumble as it is starving for fuel. Obviously an issue. My question is, can the return line banjo with the check valve on the VP44 fail and cause this issue of fuel pressure dropping as its allowing fuel to pass through freely? I haven't read of any failures due to the banjo bolt, but just curious. Thanks.

I don’t think it’s a high fail item but it’s always possible for it to fail. Even if it were failing I’m not sure it’d cause the issues you’re experiencing. Sounds like whatever regulates the pressure is the problem. 

12 minutes ago, notlimah said:

I don’t think it’s a high fail item but it’s always possible for it to fail. Even if it were failing I’m not sure it’d cause the issues you’re experiencing. Sounds like whatever regulates the pressure is the problem. 

I think you are correct, it is the check valve on the return line that caused the issue last go round. A very small piece of debris was caught on the face of the valve keeping it from closing entirely and allowing the fuel to free flow if you will. Thanks, I have not heard of one failure of the banjo, but I read on blue chip diesel that is something to check.

Below is the check valve, one end unscrews and you can adjust pressure by increasing the spring tension with small stack able washers.

Edited June 26, 20186 yr by Red Rambler

Did you use any tape or thread sealant on those? Possibly any other leaks in the system? 

1 minute ago, notlimah said:

Did you use any tape or thread sealant on those? Possibly any other leaks in the system? 

No thread sealant or tape as it’s AN on both ends. I park my truck nose up hill most days and it starts fine. I have never had any starting issues. When I put my new gauge in I used threat sealant in between my filter canister and injection pump. I am going to open the check valve again and look for debris tonight. 

I just had this happen with my fuel boss. Add the fleetguard strainer pre fuel boss, GDP and genos both have them. Debris keeping the check valve from closing. Service the valve again. 

 

https://www.genosgarage.com/product/ff5079/fuel-system-accessories-replacement-parts

25 minutes ago, CTcummins24V said:

I just had this happen with my fuel boss. Add the fleetguard strainer pre fuel boss, GDP and genos both have them. Debris keeping the check valve from closing. Service the valve again. 

 

https://www.genosgarage.com/product/ff5079/fuel-system-accessories-replacement-parts

Thanks much, I am going to try to find one locally for the time being like you got from Geno's, and will order a Earl's plumbing push lock one like below. I have one on my old Chevy truck and the media inside of it replaceable. I'm glad you have confirmed this issue happened to you as well. I think I may have somehow gotten trash in my tank as this is the 2nd time in little over a month. I have been going to the same fill station for a while now.....

 

EDIT: I see that what you posted is a strainer and not a filter, that is probably a better idea and would catch a lot of debris. I think I will follow your lead on that, maybe I can find it locally. Thanks!

 

 

Edited June 26, 20186 yr by Red Rambler

I got home and was able to take the check valve apart and sure enough, debris was the culprit. My only suggestion for the fuel boss would be to purchase the pre pump strainer as a required upgrade. It works flawlessly other than that. Thanks @notlimah and @CTcummins24V for the help. 

Glad you got it figured out!

i second the return check valve, when installing my fuel boss a small piece of nylon tape got caught in it and it wouldnt build pressure.  once cleaned... pow 21psi!   the banjo return on the vp44 can wear as the spring gets old but it takes a lot of miles to wear one out, basically it wont hold 14psi anymore and open easier. they are not cheap either.

On 6/26/2018 at 5:28 PM, Red Rambler said:

I got home and was able to take the check valve apart and sure enough, debris was the culprit. My only suggestion for the fuel boss would be to purchase the pre pump strainer as a required upgrade. It works flawlessly other than that. Thanks @notlimah and @CTcummins24V for the help. 

Just found this post and I have a question.  I have a fuel boss also. Would I put the strainer before the "T" going to the fuel filter and fuel boss or after the "T" going just to the FBoss?

Thanks,

Alan

57 minutes ago, my99ram said:

Just found this post and I have a question.  I have a fuel boss also. Would I put the strainer before the "T" going to the fuel filter and fuel boss or after the "T" going just to the FBoss?

Thanks,

Alan

The strainer is pre pump (fuel boss). Make sure it’s a strainer and not a filter. The filter will cut down on flow, however the strainer will still allow free flow, but will catch the larger debris. To answer your question it’s before the T that runs up to your stock lift pump, if you have the block mounted lift pump. In the below picture, put your strainer after your hard line, obviously, but before the yellow T. 

 

Edited September 20, 20186 yr by Red Rambler

Thank you very much for the quick answer.  That location was the one that I was leaning toward.

1 minute ago, my99ram said:

Thank you very much for the quick answer.  That location was the one that I was leaning toward.

You bet, it’s a very accessible location, you will cut the rubber hose and then make a second cut to remove a short section about 1.5” long. Enough to allow diesel to drain down your arm and into your armpit  however that will hopefully be your last go at having to mess with the check valve.