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

The Way We Were

I HATE TO DO THIS - FUEL TRANSFER PUMPS REVISITED

In two previous Issues of the TDR we’ve followed the editor’s difficulties with his 24-valve engine (self-inflicted VP-44 fuel injection pump failure—Issue 30, page 36; marginal fuel transfer pump performance—Issue 32, page 39). In this issue we continue the saga with the replacement of the fuel transfer pump.

Hindsight is 20/20. With the marginal performance of the fuel transfer pump I should not have installed the performance module and then drag raced the truck. The Bosch VP44 fuel injection pump needs fuel for lubrication and for cooling. With its acknowledged marginal performance, would the VP44 fuel injection pump fail? “As you increase the power output of the engine from its intended design, the hot-rodder has to look at upgrading other components.” This hot-rodder should have looked closely at this fuel transfer pump’s performance, as I knew it wasn’t up to par. The VP-44 bit the dust, leaving me stranded at the drag strip.

Fuel Transfer Pump Failure

After the installation of a Westach fuel pressure gauge, the fuel transfer pump on my truck would only give a reading of 3 psi. Having earned the degree of “shadetree mechanic,” I first looked at my workmanship with the gauge for the cause of the problem. As a test bed for products sold at Geno’s Garage, the truck is equipped with two fuel pressure gauges—one reading fuel pressure prior to the fuel filter, the other reading fuel pressure after the fuel filter. Yes, they both showed 3 psi. I swapped the sensor leads and even tried a replacement sensor to see if the problem was with my workmanship. The reading was still 3 psi.

Convinced that the transfer pump was the problem, I ordered a fuel transfer pump from Cummins. Likely this could have been covered under the engine’s warranty, but I did not have time to spare. The latest Cummins part number is 3990082 (the part numbers have been changing with much frequency). The cost, $160. The 3990082 kit includes a wiring pigtail to allow the pump to be used in all 24 valve applications. I also ordered four fuel line, banjo bolt gaskets, part number 3963983 at approximately $1.00 each.

Before examining the illustrations of the transfer pump, let’s refer to the Dodge Service Manual for their pump removal instructions. When I read Step (3): remove starter motor, I knew two things. One – I don’t have a service bay with a hydraulic lift allowing access to the starter motor and transfer pump from underneath. Two – I would not be doing the job as outlined in the Service Manual.

Sounds like an opportunity to rewrite the manual. Can this job be accomplished from above? You bet, and it is not as difficult as one might imagine. Follow the pictorial for tips on how to do it.

Step (1): This step is not pictured, but it involves the common sense recommendation of disconnecting and pushing the oil dipstick tube and other related cables and wires out of the way of my access- from-above service location.

Step (2): Remove the fuel supply line from the transfer pump. From the bench-picture you can see the two, blue quick-connects that you push in to release the fuel supply line.

Pinch the blue disconnect and the fuel line will come loose.

The fuel line to the transfer pump and the fuel line
that goes to the fuel tank are pictured here.

Step (3): Disconnect the transfer pump’s wiring harness.

Step (4): Disconnect the supply-to-filter assembly fuel line from the transfer pump. A 17 mm “stubby” wrench works wonders for the removal of the banjo bolt holding the fuel line to the transfer pump.

Step (5): Loosen the three 15mm nuts that hold the transfer pump to the bracket. Remove the 10mm bolt that positions the fuel line to the bracket. Remove the 15mm nuts that you previously loosened and remove the transfer pump.

The three 15mm nuts that hold the fuel transfer pump in place (1-3)
and 10 mm bolt holding the fuel line (4). Arrow 5 points to a fuel line
that you have to remove with a 17 mm stubby wrench.

Step (6): Remove the supply-from-tank fuel line from the old transfer pump and reinstall loosely on to the new transfer pump.

Step (7): Reinstall the new transfer pump. Reconnect wiring harness and the fuel lines—the torque specification for the banjo bolts is 18 ft-lbs. Reconnect the supply line from the tank by pushing the line into the quick connect fittings. Listen for the fittings to click.

Step (8): Purge air from the fuel system (easier said than done). This can be a long and arduous experience. Turn the key to start the engine (that is, briefly turn the engine over). Let the key come back to run. Leave the key in the run position and listen for the fuel pump to operate. It should run for 25 seconds. Repeat this procedure at least four times before trying to start the engine. Continue until the air is purged from the system. It is normal for the engine to sputter and cough.

Step (9): Engine cranks? You’re finished.