This article originally published in Issue 56 of the Turbo Diesel Register.

The Way We Were

It has been duly noted that the TDR has reprinted material from previous magazines. Deciding when this practice is appropriate and timely is a difficult task--darned if you do, darned if you don’t. From time to time we will crank up the “way-back machine” and repeat material that is relevant for present consideration. For this issue I went back to several old TDR magazines to revisit the topic of fuel transfer pumps.

I HATE TO DO THIS - FUEL TRANSFER PUMPS REVISITED
(or The Final Answer - Perfect Transfer Pump Article)

As the deadline for Issue 56 was fast approaching, I called TDR writer Jim Anderson. Jim is the point guy for miscellaneous e-mail and phone inquiries that come into the TDR. I asked, “Hey Jim, what’s on the minds of those that you are corresponding with?” His response, “It seems that problems with the Third Generation trucks vary. There is not a common complaint that needs to be addressed.” This is good news for the Third Generation crowd.

Jim continued, “However, with the used truck purchase of ’98.5-'02 vehicles the education about fuel transfer pumps is an endless task.” I responded, “Ouch, I know what you mean. Perhaps I should emulate the country music singer David Allen Coe’s efforts to write the perfect country music song by writing the perfect transfer pump article.” Jim responded, “Keep it simple, try the catch phrase from the Millionaire show ‘Is that your final answer?’”

Thus, I present the final-answer, perfect transfer pump article. While the article focuses on the '98.5-'02 owners, this collection of TDR oldies also has tips for '94-'98 12-valve owners and '03-'07 HPCR owners. The information was pulled from our Issue 32, 48, and 50 magazines. Updates have been added to reflect the latest part number information.

Then, to add a final crescendo to the article, I’ll share with you a story that will be of interest to 300,000+ owners of '03 and '04.5 HPCR owners.

Below is an outline of the topics that will be covered.
• ’98.5-’02 trucks, correct fuel pressure
• ‘94-’98 12-valve, fuel transfer pump replacement
• ‘98.5-’02 24-valve, fuel transfer pump replacement
• Fuel pressure gauges and opinions
• ‘98.5-’02 24-valve, fuel transfer pump relocation kit
• ‘98.5-’02 24-valve, what to do
• ‘03-’04.5 HPCR, what to do
• ‘05 to current HPCR, what to do

Here we go…

In May of 2001 there was a great deal of concern about fuel transfer pump delivery pressures. The problem first surfaced as a result of a production batch of inadequate transfer pumps and the resulting product recall. Hand-in-hand with the recall was the increasing number of warranty claims. (When the article was written the early '98.5 engines were 2.5 years old.) The problems were aggravated by those that hot-rod their trucks as well as purchase fuel system accessories that add restriction to the system. The bottom line is that the 24-valve’s Bosch VP44 electronic fuel delivery pump needs to see at least 5-6psi of pressure from the fuel transfer pump. Less than 5-6psi (more is better) and there is a danger of “overheating” the VP44 pump for it uses fuel to cool and lubricate its internal parts.

In the photo, note that the Editor’s truck (a '99 model) is outfitted
with two gauges—one is a mechanical, liquid-filled gauge
and the other is a Westach electrical gauge with a pressure
sending-unit mounted to the filter head assembly.

In order to install a gauge, the ’98 and ’99 24-valve engines have a filter head with easily accessible 1/8 NPT fittings. On the 2000 and up trucks the service design team at Cummins was mindful of the need to test the fuel transfer pump’s delivery pressure. Thus, your truck is equipped with a “banjo adapter with a Schrader valve assembly.” Say what? For clarification let’s look at a photo and a description.

On the inside, the part with the rifled opening attaches the fuel line to the fuel pump. On the outside, the Schrader valve (think A/C valve or, better yet, a tire valve) has a press-for-pressure needle. Here is the catch, you can take the pressure needle out of the Schrader valve.

In order to install a gauge, the ’98 and ’99 24-valve engines have a filter head with easily accessible 1/8 NPT fittings. On the 2000 and up trucks the service design team at Cummins was mindful of the need to test the fuel transfer pump’s delivery pressure. Thus, your truck is equipped with a “banjo adapter with a Schrader valve assembly.” Say what? For clarification let’s look at a photo and a description.

The readings that I am seeing on the gauge:

13-14 psi at idle
12 psi @ 2000 rpm – no load
11 psi @ 3000 rpm – no load
10 psi @ 3500 rpm – no load
10 psi @ various rpm – 10 psi boost
8 psi @ various rpm – 20 psi boost
3 psi @ various rpm – 30 psi boost*

*From the readings at idle and at various rpm with a load (and a resulting boost reading that is at stock truck/20 psi or below levels), the gauge checks out okay. As I push the performance envelope with my hot-rodded engine (i.e. the 30 psi boost reading), the fuel pump is marginal.

Does the fuel pump meet the stock specifications? Yes. Is it ideal for my truck’s hot-rodded performance? Good question. In discussions with other hot-rod owners I find that the old adage, “I am my own warranty station” once again proves correct. As you increase the output power of the engine from its design, the hotrodder has to look at upgrading other components. Discussions with other owners have uncovered various solutions to the low pressure at high performance blues: drilled out banjo bolts for better fuel flow, bigger fuel lines, different fuel pumps, different pump locations. The saga will continue.