Engine/Transmission (1994 - 1998) fuel line overhaul

[Vaughn MacKenzie]

My issue with the 12v fuel system is you have a pumping machine in that lift pump sucking through a small fuel line a long distance from the tank. That puts major vacuum on the line, meaning any spot that's slightly compromised is going to suck in air. Not a great recipe when you have many spots in the fuel system that can have problems: the in-tank pickup assembly (hoses have been known to crack), fittings on the top of the fuel module, plastic hoses going to hard lines (can crack, rub through or pinch down like mine did). Next when you get up by the engine the hard line going to the prefilter has a O-ring that dries and fails, and cannot be found from Dodge or Cummins (at least I wasn't able to). Then you got the L-hose that dries & cracks held by weak spring clamps, and then the prefilter section with crapola heater and large O-rings that multiply the chances for leakage. Here is a little writeup I did redoing my fuel system: http://www.nwbombers.com/forum/index.php?showtopic=15869&hl=fuel



I went to the extent of modifying the pickup assembly,and running -8AN hose all the way to the prefilter. I have found one benefit of the -8AN line is my fuel pressure stays strong running filtered WVO, whereas it drops noticeably on my '98 with its stock fuel line because of the elevated viscosity of the veggie oil.



My plan is to pitch the prefilter setup completely, so that once you get to the engine bay the first thing the fuel meets is the lift pump. The prefilter screen on the fuel pickup assy in the tank is plenty fine, no need for a prefilter. I am going to install a 2000+ fuel filter assembly (my measurements says it will fit).







Vaughn

 

[CToney]

Modifying fuel system

TS find something that is bulletproof and not astronomically expensive to do. I've had the regular fuel system troubles. I got rid of the fuel heater and replaced it with an inline filter like is on our tractors (probably fleetguard). My biggest problem was my lift pump, the piston was scored real bad. But I changed the overflow valve and the fuel lines running to the frame. I would like to replace all the way to the tank but don't know how to get the fitting to hook up to the tank. There are probably lots of trucks ou there with leaks causing their owners all sorts of trouble and money. Air and diesel don't mix, well not until the cylinder anyways. Low power and hard starting are no fun. The FASS works, they also send out good hose with their kits.



TTFN

CR Toney

 

[JAmos]

On my 95 I changed the fuel line from the tank to the fuel heater, and it made a noticeable difference in smoothing out upper rpms and felt a little more power.



I think I just broke the connector/coupler off the metal line that comes out of the tank and slid on the 3/8 hose and double clamped it.



Jordan

 

[KennyM]

They sell a 3/8 and 5/16 barbed to quick disconnect fitting at any auto parts store. This will provide a good seal at the tank module.

 

[Joe G.]

Fuel flow questions

Does anyone know what the fuel flow GPH is for a stock fuel system at 3K RPM or so? It's mechanical so GPH increases as RPM rises.



Does anyone know what the GPH consumption is for a modified P7100 injection pump at WOT with a heavy load?