When is Dodge Cummins Diesel Fuel Pressure Important?

Testing the VP44 fuel injection pump

Undoubtedly you have heard from friends or internet forums that you need a fuel pressure gauge on your Cummins Turbo Diesel or else you run the risk of damaging your injection pump. This is true, but only if you own a 1998.5 (first year of the 24-valve engine) to 2002 truck. During these four years of production, a Bosch VP44 fuel injection pump was used on these engines. The VP44 is fuel cooled and needs to have more than 5psi to maintain proper cooling.

The VP44 is fuel cooled and needs to have
more than 5psi to maintain proper cooling.”

When the VP44 was added to the engine, the folks at Ram/Cummins also changed from a mechanical fuel transfer pump (tank-to-engine) to an electronic fuel transfer pump. After about 60,000 miles these electronic fuel transfer pumps were notorious for failure and/or would limp-along providing marginal fuel pressure. So, the truck might run okay, but lacking the 5psi of pressure and cool fuel, internally the VP44 would seize and you were faced with a $2,000 repair bill. Hence the need to monitor fuel pressure of these 1998.5-2002 trucks also due to these issues, an entire aftermarket has grown-up to provide owners with better fuel transfer pump solutions.

What happens if you own any other year Cummins Turbo Diesel and you have a fuel transfer pump failure? The truck will not start, so you will need to purchase a new lift pump. If your tank-to-engine fuel transfer pump fails, the truck will not start so you will need to purchase a new transfer pump. So every day we tell folks with 89′-98′ and 03′-current trucks, “You don’t need a fuel pressure gauge. Save your money”.

Often customers will want to buy a pressure gauge so they know when to change their fuel filter. The simple answer to this is change the filter every 15,000 miles as suggested by the owner’s manual. Consider the cost of a quality gauge kit which would be around $225 after purchasing a mount and various other installation components and shipping. In most cases, for the cost of a gauge kit you can buy a case of fuel filters and a spare fuel transfer pump.

Our Recommendations

We thought you would never ask.

For a permanent installation, we suggest either of these two gauges which make up the bulk of what we sell for 1998.5-2002 year model trucks:

ISS-17033 Fuel Pressure Gauge
ISSPRO R17033 Electronic Gauge


Auto Meter 2607900 Mechanical Gauge

Actual numbers: The ISSPRO outsells the Auto Meter 2 to 1.

For a Quick Diagnostic Check:

We suggest using:

Vulcan Performance Fuel Pressure Test Kit

Vulcan Performance Fuel Pressure Test Kit

This kit comes with the needed fittings to check pressure at the fuel filter head (‘98.5-‘99) or the Schrader test port (‘00-‘02) on your 1998.5-2002 Dodge Cummins Diesel truck.

Installation Hardware Required:

To complete your gauge installation, you will need these additional parts for stock/unmodified fuel systems:

Vulcan Universal Fuel Pressure Line

Vulcan Universal Fuel Pressure Line

This fuel line will allow you to tie in directly to the fuel filter head on ‘98.5-’99 trucks. On ’00-’02 model year trucks the line will attach to the Schrader valve located on the side of the VP44. On electronic gauges, the sending unit will connect directly to the other end. For mechanical gauges, the other end will be connected to the isolator supplied in our mechanical gauge kits.

RLT Fuel Pressure Snubber

RLT Snubber

A snubber dampens the fuel pressure spikes (hydraulic hammering) that is common on VP44 injection pumps. This can be installed on either end of your Vulcan Fuel Line depending on your configuration. Using a snubber will help with pressure spikes seen on the gauge as well as extending the life of your electronic sending unit.

Having trouble visualizing out how it all goes together?

For 1998.5-1999 Trucks

98.5-99 Dodge Cummins Diesel Fuel Filter Housing

When using the factory Schrader test port on 2000-2002 trucks (PN: FPADPT-KIT shown as substitute for factory fitting):

Fuel Pressure Adapter Kit

This is a picture of the opposite end when using an electronic gauge (RLT-SNUBBER is installed between VULCAN-FH and Electronic sending unit when installed on 2000-2002 trucks):

Set up for using an electronic gauge.

This is a picture of the opposite end when using a mechanical gauge:

Vulcan hose with Fuel Pressure Isolator

Mounting Options:

Regardless of the gauge, here are some mounting options:

AutoMeter A-Pillar Single Gauge Mount

Single Gauge A-Pillar mount

Mounts to driver side A-pillar.

Universal "Bullet Mount" Gauge Mount

Universal Gauge “Bullet” Mount

Can be mounted anywhere on dash.

In-Dash Gauge Face Plate

In-Dash Face Plate

Mounts in bezel storage compartment.

Universal “Doughnut” Gauge Mount

Intended for mounting under dash.

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