Pre Filter or Post filter Fuel Pressure??

[JR2]

Okay I have my new SPA press gauge installed and tomorrow I am going to install my my new SS fuel lines and move the liftpump to the rear of the truck. My question is do I want to measure my fuel pressure pre filter or post filter??



I will add that eventually I will be measuring it in both pre and post, but for now I only have the time to set it up in one place.

 

[EMDDIESEL]

If you are only going to monitor ONE location, i would want to monitor Post filter, this way you know what fuel pressure your injection pump is really getting. You can also tell when your fuel filter is getting clogged by rembering what the pressure is with a new filter, and then watch it decline.

 

[JR2]

EMD - After I posted this last night I went and read about a million post about fuel pressure and I decided that what you say is correct. The post filter is best for now. I am trying to get the time together to figure out how to run dual press senders on one half of an SPA. I plan on running a little switch that will let me choose which sensor I want to look at. That is probaby a fall project so for now I will go post and be happy.

 

[dresslered]

What EMDDIESEL says is absolutely correct. There is no reason to run pre-fuel filter unless you can't remember the original post-filter pressures with a clean filter.

 

[Ninearrow]

About a year ago, I installed a Holley liquid filled guage screwed directly into the top of the canister, post filter. It allowed me to read the pressure post filter, but only with the hood up. My son had to operate the throttle while I watched the guage. This was all done in the garage while setting still, of course.



After reading all the posts about fuel pressure, I ordered and installed the Westach setup from Geno's. Am very satisfied with it.





I moved the old Holley guage to pre filter position. Now I can monitor both sides while setting still. You might want to consider such a setup. The Holley guage was only $18.

 

[Bigsaint]

JR2, I have mine set up just as you are about to do and agree 110% with the above advice, go post filter and when time permits you could always add a pre-filter gauge if you want. If nothing else, it's a good reason to buy another gauge. When you set up your SS lines and elbows, just equip the line running to the inlet of the OEM fuel filter with a pressure port. Plug it with a 1/8 NPT plug and when you are ready to add a gauge all you have to do is remove the plug and replace same with the sender line or screw in one of the small, 1 1/2 FP gauges that are sold at Jegs or Summit. Piece O cake. Personally, I justified the expense of another gauge pre-filter as I wanted to know exactly what psi's I have the Mallory set to run on and in case the SPA sender does go toes up.



Scott W.

 

[Bigsaint]

Forgot to add, you might want to check out this link, if you haven't already seen same.



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=20268



Scott W.