Fuel Lift Pump?

[jsmiracle]

I bought an Aux. Fuel Filter system, installed it, and then measured the vacuum at the test port. It read about 5.0"Hg. I was reading somewhere that a fuel pressure mismatch may actuate at about that pressure mismatch.

For those who have measured their fuel pressure at the test port, what is the typical fuel pressure? Do I need a lift pump? I value your thoughts on this topic....

Jim M.:confused:

[jbplock]

Vacuum at the Schrader valve test port is typically 2 inHg with a fresh filter. A secondary filter will increase vacuum .. how much depends on the filter and location. Before adding a lift pump my post OEM mega filter increased vacuum approx 1 inHg.

Your 5inHg reading sounds a bit on the high side.. Did you also change the OEM filter when installing the AUX filter? If not try installing a new one and recheck vacuum... A lift pump offers some benefits but many people run AUX filters without them...

Which type of AUX filter did you install?

:)

[Kennedy]

I think the Dmax just runs better with a little help pushing fuel. It keeps the filters full of fuel, not air, and seems to aid in responsiveness.

At 5"hg I am looking to change my filter(s) I have also recently completed my pump/filter combo.

[jsmiracle]

Which type of AUX filter did you install?

I installed the Aux fuel filter from Lube Specialist. It is a 2-micron Baldwin filter. The engine seems to be running fine, but I didn't want to significantly increase the load on the injection pump(?) and cause it to fail prematurely.

I did not change the OEM filter. It is the new design Racor filter. It has about 4k miles on it. I installed the new Aux fuel filter Post-OEM and plan to change it once a year (about 15k miles; 20% towing) I plan to change the OEM filter at every engine oil change (6 months or 7500 miles). Right now, the engine has just over 16k mi. on it.

BTW, thanks everyone who replied. I think I will add the lift pump in the next months.

P.S. The typical vacuum of 2"Hg.....It that with the old style OEM fuel filter? Is it the same or higher with the new double pleated design?

Jim M.

[Kennedy]

I typically see 2-3" hg with my dual filter setup and new filters on level ground with a full tank. One key though is that air in the filter(s) seems to make quite a difference. I also engineered my setup for maximum flow without restriction in that it has big hose and free flowing fittings along with a HUGE media surface area.

At this point, I would suggest that you change the OE filter and top off your tank so that you have a fresh filter baseline.

[LanduytG]

You need to change the OEM filter. With the dual pleated Pff5544 and the Baldwin you can expect to see 3" of Hg. Also very important when taking readings is make sure you are on flat ground and have the tank full. Tank would not have to be full but if it is then you are starting at the same point every time.

Greg

Greg

[jsmiracle]

I changed the primary (OEM location) fuel filter (PFF) today. The PFF is a Baldwin BF7827. The post or Aux. Fuel Filter (AFF) is a Baldwin BF1223. I read the fuel pressure (FP) before (5.25" Hg vac) and after (3.75" Hg vac). I guess this will be my baseline for future FP readings.

Is there a vacuum value for FP above which is consider too much for the injector pump or just change at recommended 3-4" Hg increase in vacuum?

Thanks in advance,
Jim M.

[LanduytG]

That seems high compared to what I get. Did you have a full tank of fuel? Also did you make sure the gauge was at zero before starting?

Greg

[jsmiracle]

I zeroed the guage by depressing the valve core until it read zero. The truck was also level. The fuel tank; however, was only about 1/2 full. I plan to fill it tomorrow and take readings before and after it is filled.

I did not dislodge the plug on the back of the facing of the pressure gauge. Should I ? I was happy to see an almost 2"Hg drop with the new dual-pleat BF7827 filter installed. It was about 4500 mi. old. Like I said earlier, the truck seems to run fine. My concern was adding the extra stress on the injection pump.

I was planning to add the lift pump to negate the headloss I introduced by adding the extra 2-micron fuel filter.

P.S. The install was very straight-forward and the parts are high quality. Thanks.

Jim M.

[LanduytG]

Having half a tank will make some difference. I always pull the plug on the back of the gauge. Not sure if it really needs to be or not. But if you do everything the same every time that is when you get meaningful readings.

greg

[Kennedy]

The plug on the back of the gauge should be pulled (carefully so as not to tear) IF you cannot get the gauge to near zero by depressing the center stem (check valve) to equalize.

The Duramax sure seems to run a whole lot better with a good lift supply and full filters...

[JoeyD]

The plug on the back of the gauge should be pulled (carefully so as not to tear) IF you cannot get the gauge to near zero by depressing the center stem (check valve) to equalize.

The Duramax sure seems to run a whole lot better with a good lift supply and full filters...

The set up thats in the monthly letter from the diesel page?

[Kennedy]

http://www.thedieselpage.com/reviews/jkfuelpressure.htm