Attention: TDR Forum Junkies 
A little background first. I am the third owner of the truck and bought it from a friend who was fanatical about the truck and is a fix things before they break kinda guy. Truck had about 160,000 on the clock and was bone stock when I got it. I've added the mods in the sig and have done my best to carry the maintenance forward at the same high level. Fast forward... ...
After I installed the gauges, specifically the fuel pressure gauge, I noticed that my fuel pressure as around 15lbs at idle and would only come up to 21-22lbs under load going down the road. Being an electric gauge, I was unsure how much of that was fuel system related, how much was the snubber, how much was the gauge itself. But slowly I noticed the truck seemed to lose its jump. It still starts on first crank (with just a tap of the pedal), doesn't smoke, gets consistent fuel mileage in the 18. 5 to 20. 5 range (temp. and load dependent). I am anal about fuel filters and change it out every 6 months, so I could rule that out right away.
So I busted out Joe G. 's fuel system how to (thanks many times over) and decided to educate (or at least try) myself and figure out if something was amiss. I read though as many posts as my eyes would allow before the blood started to leave my head. Being unsure and not wanting the truck to be down longer than one day, I ordered a GENUINE CUMMINS (seems that anything for the motor, you are best served going with original stuff) lift pump from Geno's along with the short elbow hose that goes to the fuel heater and I figured I might as well change out the screen in the heater. I ordered an overflow valve as well, but took a chance on one of the units from Tork Teknology. Their product seemed to be legit and their testing seemed pretty thorough, so I ordered up OFV020. Its for stock fueling, but is compatible with varying fuels, just in case.
All that stuff arrived during the week and today was the day to tackle it. I dropped the starter out of the way just to give myself a fighting chance at seeing what I was doing and to prevent dumping fuel all over my new(ish)starter. The bowl of the heater comes off pretty easy (17mm I think) and the 8mm allen wrench made short work of the heater element itself. Both of these items could have contributing factors to my problem. The strainer had a decent amount of rust? and other dirt and debris and the fuel heater connector was burned and brittle. So I ditched the heater all together (per Joe G. 's write up) and associated wiring. The elbow shaped fuel hose also got ditched and had multiple cracks in the outer casing, no fuel leaks, but air may have been getting in? While there and with good visibility I could see that the other two rubber fuel lines, which can be problematic, must have been placed by the previous owner because they looked newer and have double worm style hose clamps versus factory style spring clamps.
Now for the fuel pump. I struggled with this for some reason. I removed the fuel filter and still couldn't get my line wrench (14mm or 9/16ths) on the fuel fitting and feel good about it. So I had to loosen the line at the filter head (which added a few steps), then remove the fuel pump/line as a unit from the block. Then on the bench remove the fuel line from the lift pump. This actually worked really well because that sucker was tight and there was no way I could have gotten it loose without stripping or tearing the fuel line if I had done it on the truck. It was so tight in fact that I ended up loosening the larger fitting that screws into the pump body, then had to remove the fuel line from that. Also transferred over the brass elbow fitting from the old pump to the new. Cleaned everything, new gaskets, new rubber fuel hose, re-install everything. I installed the new overflow valve too, which was straight forward. Ironic thing was that pump I took off was not a Cummins part (must have been replaced at some point in the past) but was made in the USA. New pump was a Cummins part, but was made in China, go figure?
Next I primed the system. Then jumped in and it fired almost immediately, ran rough for a second or two then smoothed out. Best of all, fuel pressure was now 21lbs +/- at idle and 40lbs +/- going down the highway at 70mph. Tork Tek said the over flow valve (adjustable) is present to provide between 17 and 22 lbs of fuel at idle, so they hit that mark very nicely. Fuel pressure gauge is much steadier and the truck feels like a whole different truck. It gets out much better, doesn't have a flat spot just off idle that it did before. Amazing difference.
So in review for the 12v crowd, here's what I came away with:
*Get Joe G. 's fuel system how-to and keep it somewhere safe.
*The fuel heater should be chucked as far as possible, worthless.
*The fuel strainer should be part of the maintenance ritual as should inspecting the rubber fuel lines.
*The lift pump is a PITA job for a first timer, remove the starter and the fuel filter to avoid headaches and allow more access for large hands.
* Careful with the metal fuel line going from the pump to the filter head, space is minimal and it might be easier to remove the line and pump as a unit.
*On Board fuel pressure guage is an invaluable diagnostic tool, even for the 12V. Not sure I would have even done all this without the fuel gauge giving me cause for concern????
Thanks to TDR and all the members.
After I installed the gauges, specifically the fuel pressure gauge, I noticed that my fuel pressure as around 15lbs at idle and would only come up to 21-22lbs under load going down the road. Being an electric gauge, I was unsure how much of that was fuel system related, how much was the snubber, how much was the gauge itself. But slowly I noticed the truck seemed to lose its jump. It still starts on first crank (with just a tap of the pedal), doesn't smoke, gets consistent fuel mileage in the 18. 5 to 20. 5 range (temp. and load dependent). I am anal about fuel filters and change it out every 6 months, so I could rule that out right away.
So I busted out Joe G. 's fuel system how to (thanks many times over) and decided to educate (or at least try) myself and figure out if something was amiss. I read though as many posts as my eyes would allow before the blood started to leave my head. Being unsure and not wanting the truck to be down longer than one day, I ordered a GENUINE CUMMINS (seems that anything for the motor, you are best served going with original stuff) lift pump from Geno's along with the short elbow hose that goes to the fuel heater and I figured I might as well change out the screen in the heater. I ordered an overflow valve as well, but took a chance on one of the units from Tork Teknology. Their product seemed to be legit and their testing seemed pretty thorough, so I ordered up OFV020. Its for stock fueling, but is compatible with varying fuels, just in case.
All that stuff arrived during the week and today was the day to tackle it. I dropped the starter out of the way just to give myself a fighting chance at seeing what I was doing and to prevent dumping fuel all over my new(ish)starter. The bowl of the heater comes off pretty easy (17mm I think) and the 8mm allen wrench made short work of the heater element itself. Both of these items could have contributing factors to my problem. The strainer had a decent amount of rust? and other dirt and debris and the fuel heater connector was burned and brittle. So I ditched the heater all together (per Joe G. 's write up) and associated wiring. The elbow shaped fuel hose also got ditched and had multiple cracks in the outer casing, no fuel leaks, but air may have been getting in? While there and with good visibility I could see that the other two rubber fuel lines, which can be problematic, must have been placed by the previous owner because they looked newer and have double worm style hose clamps versus factory style spring clamps.
Now for the fuel pump. I struggled with this for some reason. I removed the fuel filter and still couldn't get my line wrench (14mm or 9/16ths) on the fuel fitting and feel good about it. So I had to loosen the line at the filter head (which added a few steps), then remove the fuel pump/line as a unit from the block. Then on the bench remove the fuel line from the lift pump. This actually worked really well because that sucker was tight and there was no way I could have gotten it loose without stripping or tearing the fuel line if I had done it on the truck. It was so tight in fact that I ended up loosening the larger fitting that screws into the pump body, then had to remove the fuel line from that. Also transferred over the brass elbow fitting from the old pump to the new. Cleaned everything, new gaskets, new rubber fuel hose, re-install everything. I installed the new overflow valve too, which was straight forward. Ironic thing was that pump I took off was not a Cummins part (must have been replaced at some point in the past) but was made in the USA. New pump was a Cummins part, but was made in China, go figure?
Next I primed the system. Then jumped in and it fired almost immediately, ran rough for a second or two then smoothed out. Best of all, fuel pressure was now 21lbs +/- at idle and 40lbs +/- going down the highway at 70mph. Tork Tek said the over flow valve (adjustable) is present to provide between 17 and 22 lbs of fuel at idle, so they hit that mark very nicely. Fuel pressure gauge is much steadier and the truck feels like a whole different truck. It gets out much better, doesn't have a flat spot just off idle that it did before. Amazing difference.
So in review for the 12v crowd, here's what I came away with:
*Get Joe G. 's fuel system how-to and keep it somewhere safe.
*The fuel heater should be chucked as far as possible, worthless.
*The fuel strainer should be part of the maintenance ritual as should inspecting the rubber fuel lines.
*The lift pump is a PITA job for a first timer, remove the starter and the fuel filter to avoid headaches and allow more access for large hands.
* Careful with the metal fuel line going from the pump to the filter head, space is minimal and it might be easier to remove the line and pump as a unit.
*On Board fuel pressure guage is an invaluable diagnostic tool, even for the 12V. Not sure I would have even done all this without the fuel gauge giving me cause for concern????
Thanks to TDR and all the members.
