Foretravel Owners' Forum

We are still using our original mechanical lift pump on our Cummins mechanical C8.3-325 12-valve engine.

We think we could benefit by replacing the mechanical lift pump with a new separate electric fuel lift pump and if would be nice to have a permanent pressure gauge on the output to the injector pump.

We wonder if anyone has experience with changing the mechanical with an electric lift pump and with the following two products?

Research has come up with two similar products:

Airdog
PureFlow AirDog® ? Supplier and Manufacturer of Fuel Air Separator Systems and (http://www.pureflowairdog.com/)

Fass
Best Diesel Fuel Pumps | Fassride.com - The Diesel Performance Experts (http://www.fassride.com/)

Some experience with the Airdog here, have one on a 24 valve Cummins pickup.  Have had a couple issues with it so not overly impressed.  I'm curious why you would abandon the simplicity and reliability of the mechanical pump for an electric.

 Putting a pressure gauge behind the lift pump is a good idea, find out what kind of pressure the banjo bolt regulator is holding.  Might be time for a new one.

Just ordered a new lift pump (stock, Cummins) as it is seeping.  When fuel lines are replaced I will add a mechanical priming pump between filters and tank. 

I have the parts on order (headed my way) to replace my stock original "Overflow Valve" (banjo bolt regulator) with a Tork Tek adjustable pressure regulator (OFV020), PLUS the parts to add a permanent pressure gauge to the fuel line between the engine mounted fuel filter and the P7100 injection pump, PLUS a new (stock type) mechanical transfer pump.  I plan to do a little experimenting with the fuel system.  I will install the pressure gauge, get a good baseline fuel pressure, then change one thing at a time to see what happens.  I plan to change (in order) the frame mounted fuel filter, then the engine mounted fuel filter, then the overflow valve, and finally the lift pump.  After each change I will re-check the fuel pressure.  I am just curious to see if any of the changes make any noticeable difference in fuel pressure.

To the best of my knowledge, my engine is running fine at this time, but since I have zero experience with diesel powered motorhomes I have no basis for comparison.  I am not expecting any major improvement in performance - I just think it will be a interesting "science experiment".  Besides, all the new parts certainly can't hurt anything!

I will report on the outcome of this project, with lots of photos.

Look forward to hearing how this works out and will probably be doing something similar in the coming year as Our coach has the older more vulnerable fuel lines. Definitely like the idea of preventative maintenance!

I am very curious about the addition of the permanent fuel pressure gauge and where to install it.

I have a 3-in-1 Glowshift gauge on its way that measures boost, EGT, and any type of pressure that I am planning on using for fuel pressure but I'm not sure where to put the tee with the 1/8" NPT port into the fuel system.
Amazon.com: 3in1 Black Face Pyrometer, Digital Boost, and Pressure Gauge: (http://www.amazon.com/gp/product/B007EEJRYU/ref=oh_details_o00_s00_i00?ie=UTF8&psc=1)

So in the end, I'm very interested in how this works out for you.

I want to measure the input pressure just before the injection pump.  That way I am seeing the effect (positive or negative) of all the components of the fuel delivery circuit, including the (old, original) fuel hoses, both filters and the lift pump.  I decided to install the gauge at the banjo bolt where the supply line attaches to the pump.  I have read that a rigidly mounted pressure gauge will not live long on a diesel engine, due to vibration and the pounding from the mechanical lift pump.  I plan to mount the gauge remotely where it will be easily visible.  I picked a liquid filled gauge which is supposedly "temperature compensated" to avoid heat-induced error.  I decided on a 0-30 PSI gauge for better resolution of small pressure changes (the OFV020 overflow valve will be preset to open at approximately 30 PSIG).  Here is what I have ordered:

TORK TEK CUMMINS ADJUSTABLE OVERFLOW VALVE OFV020 - Tork Teknology (http://www.torkteknology.com/products/TORK-TEK-CUMMINS-ADJUSTABLE-OVERFLOW-VALVE-OFV020.html)

TORK TEK CUMMINS 14MM X 1.5 PRESSURE GAUGE SNUBBER CBS010 - Tork Teknology (http://www.torkteknology.com/products/TORK-TEK-CUMMINS-14MM--X-1.5-PRESSURE-GAUGE-SNUBBER-CBS010.html)

JEGS Performance Products 41057 JEGS Braided Stainless Steel Mechanical Gauge (http://www.jegs.com/i/JEGS-Performance-Products/555/41057/10002/-1)

Valley Instrument Grade A Back Mount 2 1/2in. Glycerin Filled Gauge — 0-30 (http://www.northerntool.com/shop/tools/product_413320_413320?cm_mmc=Housefile-_-SHIPPED-_-1206-_-CONF)

http://www.thoroughbreddiesel.com/stock-replacement/dodge-94-98-fuel-transfer-pump.htm (http://www.thoroughbreddiesel.com/stock-replacement/dodge-94-98-fuel-transfer-pump.htm)

I installed a low pressure fuel gauge on top of the frame mounted primary filter and a higher pressure on top of the discharge side of the engine mounted secondary filter. Since we have a different engine on our U300 the secondary filter is under higher pressure than the Cummins will be.

I also installed a pressure gauge on the discharge side of the generator secondary fuel filter (low pressure also). Makes it easy to troubleshoot the generator fuel system.

Attached below are also photos of the chassis mounted hand primer pump. You may have one of these but not the check valve. The O rings may need replacing and can allow air into the fuel system.

If you have a plastic see through water drain on the bottom of the primary fuel filter, replace the O ring if a leak is suspected.

The fuel lines on the early '90s U280/U300 may be good for the duration. Would not replace unless other members have had problems.

Easy to install a generator temperature gauge while working on the fuel system. See photo below.

If you encounter hard starting or loss of power, a suspect an air leak, you can take the return fuel line off, put a several foot replacement into a catch can with the end of the hose under the diesel, run the engine until air bubbles no longer are seen, turn off the engine overnight, start again in the morning. If any air bubbles are seen, air is leaking into the system. The same can be done for the diesel generator.

Pierce

Pierce: That is encouraging!  Have you replaced your original fuel lines?

No, they are fine. I can't remember the brand and number of the fuel hose that had bad formulation. Think it was on 96-97 models but others may have the exact years and models. There was a post that contained the info just a few days ago but I can't find it.

Pierce