Fuel pressure spring

I changed both of the relief valves on the Filter housing and it made no difference. I bought a Spring kit and see that the one on mine is different. Mine has a 1/4 inch spring with a 5/8 nut on the outside. the new one has a 3/8 spring and a 1/4 inch allan head on the outside. I was thinking of going to a wrecker and picking up a newer style used pump and trying it.Will a 600- 625hp engine have a bigger pump than 475-550hp engine? or for that matter will a 475hp have the same pump as a 550hp.

If you remove the return line off the back of the filter housing and turn the FASS on, fuel should pour out right. I am sure it did before and it doesn't now. Thanks again every for you help and information.

 

Do they have a new spring for the old style? I thought is was just a upgrated spring kit. Would it be worth it to just pick up a used new style pump? new they are $300ish a person could have get a used one for around $150 from a wrecker I would think.

 

can the old styly 1/4 inch spring be shimmed or is it a bad idea?

 

I shimmed it with a piece of 1/4 inch plastic air line and it worked great for a while and then it lost pressure and now it does 80psi and under a load it is 65 ish.

 

It is a much weaker spring than the new style. I think I will have to buy a new style pump if I want to run high pressure or put an electric booster pump and regulator on it.