The Overflow Valve is on the banjo fitting on the return line at the forward end of the the IP. Inside is a spring and a bearing that holds pressure in the pump. When working properly it maintains a balance between the injection system and fuel flow returning to the fuel tank. As the spring wears the flow can lose that balance. If you notice a loss of performance that is a good place to look. In a pinch the spring can be stretched to give some temporary improvement in performance , but replacing the valve is an easy and cheap fix.
The Over Flow Valve is a check ball type setup and when the spring gets weak the its lowers the fuel pressure in the pump because it is letting fuel past to easy so to speak.
A simple temporary fix is to stretch the spring this will get you to a parts store
They are typically around 60 or so but probably 90 or 100 from dodge.
Should read 22 PSI at idle and 25-30 PSI at 2500 RPM
You can test the OFV by pinching off the return line. If the pressure goes up then the OFV is bad if it doesn't the LP is bad. You can pinch the return line with some vice grips on the rubber part of the line by the firewall
Symptoms of worn out OFV
Low RPM miss / instability
Engine dies at idle (especially when hot)
Fuel Filter cracking
So if i take that bolt out the spring is just loose and i can stretch it out and put it back in and see if thats the problem? when i says fuel filter cracking what that mean like literally it cracks? how would it do that?
You guys just made my day. Was getting ready to change my pump due to what was like dead pedal, but more of a power loss and seriously eratic idle, popped the banjo bolt out of another pump laying in the shop and is purrin. Thanks.