Engine/Transmission (1998.5 - 2002) Pressure Drop Across Fuel Filter

[slong682000]

Been searching for an answer to this on the forums, but have not seen a simple answer. I have a 2000, a new DDRP installed, is running the stock filter assembly (with new filter, less than 500 miles) and has just had a Glowshift (I know, you get what you pay for) 30 PSI fuel pressure gauge installed.



The gauge is installed at the VP test port with a tapped banjo bolt, 36" of greasegun line, a snubber and mounted vertically. After the first sending unit would never measure more than 7 PSI on the gauge and a week of griping to their tech support, Glowshift finally sent me a replacement sending unit. Now, when I first start the truck, the Glowshift gauge generally hangs around 3 - 5 PSI and gradually moves (2-3 minutes) up to right around 17PSI. Measuring at the filter assembly test port, a mechanical gauge is reading right at 20 PSI. Due to time constraints and wife complaining about how much time I've been spending under the hood due to the screwy original Glowshift sender, I have not measured with the mechanical gauge at the same point that the sending unit is attached.



My question is, how much of a drop should you expect across a new filter? Is a 3PSI drop between the dirty side of the filter and the VP really something to worry about? I will be replacing the Glowshift gauge with something else in the near future, but until I get the time and money, want to make sure I'm not fixating on something that isn't an issue.

 

[CKelley1]

drop across a new filter is nill change the filter when the pressure under load drops to 5 psi

 

[ALoehr]

If you are going to use the grease gun hose as a remote mount option, be sure to bleed all the air out of it. loosen the fitting and run the pump until fuel squirts out continuous, then tighten the fitting with the pump still running to prevent any bleed-back. the air in the line will affect pressure readings since air compresses and fluids do not. I bought my FP gauge from Geno's Garage a few years ago and have had good luck with it. It is made by Westach. Another good addition would be the low FP warning light from BD that Geno's sells as well. Be sure to measure with the same gauge if you are doing prssure drop comparisons. 3 psi is well within the margain of error of some cheap gauges, not saying yours is, I am not familiar with that brand. CKelley is right, if you ever see less than 5psi @ WOT, change your filters, and no less than 10psi @ idle

 

[cerberusiam]

My question is, how much of a drop should you expect across a new filter? Is a 3PSI drop between the dirty side of the filter and the VP really something to worry about?

Since nobody answered the question and didn't bother to read you already had good pressure, I will. :-laf



No, a 3 psi drop across the filter is nothing to worry about. When you get a chance to test the VP port with the mecahnical gauge then you will know if there is actually that much or it is the difference in how thw gauges measure.



Not impressed with the accuracy or life expectancy of the glow shift senders either. Have gone thru 2 of them and it is still not a solid long term solution.

 

[slong682000]

Thanks, that is what I was looking for. I did expect to see some difference between the mechanical and electrical gauges, but was not expecting to see 3PSI drop across the filter especially with it being new.

 

[bcbigfoot]

I installed a Airdog100 but after checking the filter specs of the Airdog I decided to bring the stock filter back into the system, along with a big line kit from the filter to the VP44. The most psi drop was maybe 1 psi at WOT with the stock filter in the system.

 

[Joseph Donnelly]

With an accurate gauge, 16 psi is perfect and is what the stock pump delivered a idle. Over 20 psi is reportedly bad, and can blow the diaphragm in the injection pump.

 

[AH64ID]

Your question has been answered, but I was wondering is your sender above or below the VP? You want it below so any air bubbles will work out of the line.

 

[slong682000]

Right now it is mounted about level with the VP, but just received a mounting bracket for a Westach sender and will be moving it.