I'm pretty sure my gage reads in inches of mercury. 29.92in-hg (30) is generally considered a perfect vacuum (1 bar, -14.7 psig, 0 psia). As I recall my normal running vacuum with a clean filter is about 6 on the gage. The arbitrary green band runs between 0 and 10. Yellow is 10 to 15. And red is 15 to 30. The measure which is most important for the filter performance is the differential between suction and discharge. For this you would need 2 gages or a D/P gage. By using a D/P gage you eliminate measuring the lift of the fluid out of the tank and the line loss over the course of travel. The measure which is most important for the monitoring the fuel pump performance is the vacuum of the lift pump. A gage placed on the outlet of the Racor is best for determining this. Of course if you shut off the suction valve at the tank it doesn't matter. A gage on either side of the racor will eventually reach the shutoff suction pressure (vacuum) of the lift pump.
The best thing to do is trend the performance of your filter and lift pump. Nobody is going to give you a specific go/no-go value since every installation is different. But, if you know what a good baseline "new" value is for your pump and filter then you can recognize when those numbers are drifting or failing hard. You can also eliminate those components when troubleshooting if the values are still "good". https://youtu.be/H-GI38vE4hQ Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD On Mon, Jul 20, 2020, 08:53 Len Mitchell via CnC-List <[email protected]> wrote: > Tom, I think you have an issue with fuel lift. Either there is a hole in > the fuel pick up at the 15 gallon gallon level in your tank or the lift > pump for some reason isn’t able to pull fuel all the way from the bottom of > the tank. If you had crud and your filters were getting clogged a fuel > polisher would help that but there must be other issues. I would install a > 25$ vacuum gauge and see what the pump is pulling. I forget which engine > you have but if the fuel pick up line is good it’s maybe pump related. Mine > is a universal and the pump is pretty inexpensive, available and easy to > swap out. The electric lift pump on mine pulls 1 atmosphere of vacuum and > Josh’s yanmar pulls 3 or 4 if memory serves. The gauge I used is made for > an oil furnace filter so it’s pretty common. The other benefit to the gauge > is you can tell when your filter needs to be changed by an increase in > vacuum. Either way a fuel polish won’t hurt but it probably won’t help your > issue. > Len Mitchell > Crazy Legs > 1989 37+ > Midland On. > > > Sent from my mobile device. > _______________________________________________ > > Thanks everyone for supporting this list with your contributions. Each > and every one is greatly appreciated. If you want to support the list - > use PayPal to send contribution -- https://www.paypal.me/stumurray > >
_______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
