Engine/Transmission (1994 - 1998) Lift pump on a 12 valve??

[Cooker]

I'll take that as being meant in a constructive manner.



Ah yes, I thought I was quite aware the it was 90*- obviously. :-laf



How restrictive it would be in it's natural state on the other hand, I needed some insight toward.

What I was getting at is the 90 is a molded bend and is not just a hose folded to make the turn. The space is too tight to take a straight hose and make it work without affecting the flow, as I tried this first before spending the few bucks on the new part from Cummins. You could possibly make a stright hose work smoothly by severly trimming the barbed fittings on both the LP and fuel heater but then I think you might be opening up a potential arear for leaks by doing so.



What could have happened is that if your LP was replaced some of the fittings on the newer LPs are longer than the original and this could cause your bend to not be as smooth. In order to make a smoother transition I had to trim one barb off the LP fitting.



Also the new hose was longer on one side than the original. I also trimmed a little off the hose to make it smoother.



If I would have installed the hose and the new LP fittings in their original state the hose would still have kinked in the middle despite it being a premolded 90.

 

[biggy238]

Thank you Cooker.



Joe, Have you got any other info on by-passing and or cleaning the fuel heater and screen?



I've been laid up from surgery so i'm working off memory. I'm gonna try and look at the hose today, and maybe get a replacement this week.

 

[Joe G.]

The heater and pre-filter are in the same assembly. The screen is the pre-filter. The fuel heater is the black hockey puck looking thing above the pre-filter screen. You need two tools, a 17mm socket and a 10mm allen wrench. Unplug the wireing harness from the fuel heater. Use the 17mm socket to remove the pre-filter part of the assembly. Use the 10mm allen wrench to remove the screw that holds the fuel heater in the assembly. Put the fuel heater, screw, and one of the gaskets on your work bench. Put the pre-filter back on. The screw is really an adapter with the same threads on both ends so the pre-filter will fit just fine without the fuel heater.



If the fuel heater is bad it is not repairable. What happens is that the heating element burns up. Probably because of a stuck fuel heater relay or a failed fuel temp sensor. When it burns up it heats up one of the pins in the electrical socket for the wireing harness. This causes a fuel leak around that pin. You can't see it by looking at it. Below are four pictures of the fuel heater from my truck so you can see what can happen. I have drilled out the aluminum rivets so you can see the damage. The first picture is the screw that holds the fuel heater in place.

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This is part of the fuel heater/pre-filter assembly. In this picture the rivits have been drilled out.

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This shows the cover and heater element removed from the fuel heater. The arrow indicates the burned connector.

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The arrow indicates the leak caused by the burned contact inside the fuel heater. When the engine is running this is an air leak. When it is stopped fuel will seep out here.

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Easy to test. Just take the fuel heater out. Start the truck. It will run a little ratty at first because of air in the system caused by opening up the fuel heater and pre-filter assembly. If the fuel heater was bad it will smooth up and run fine. take it for a drive and see how it runs.

 

[JohnG]

Joe, you've got to be one of the most helpful guys around. Just wanted to throw that at ya and say thanks. .



Well Fri I got my truck back and it runs terriffic w/ the #6 plate and the 3000GSK REALLY did the trick RPM wise. (I'll start another thread and give more details). Back to my fuel pres prob. . I told them to replace the overflow valve and they said the old one looked 'poor', BUT I think removing the isolator was the real key! (As I said before, even tho' the new pres guage read as low as 2 psi, the truck ran fine), I called Hewitt and talked to Bruce, (Very nice fellow), and he told me that if the little piston in the isolator gets, somehow, slid toward the end toward the guage, that's exactly what it will do. So, since this shop had never installed an isolator before, I think that's is what happened. Also they DID use the 'special' banjo bolt that I purchased, but put it in the top of the fuel filter. I informed them that it should be at the pump, so as not to occupy the bleed hole of the filter. . (They had never thought of that). . so they will change it later. (Not a big deal to me, but seems I may be teaching them a few things also, just because of all my reading here). When I spoke to Bruce at Hewitt, he assured me that all their pres guages have small orifices built in, to prevent needle bounce. . NOT. . the fuel pres needle bounces so bad I can't even see it, so I will be informing him of that Mon. , (Could be that because they actually made this guage, custom for me, from a 50 psi boost guage, that the orifice just isn't small enough for fuel pres use). but also I'll be installing a needle valve when we move the banjo bolt to the correct location. The guages look terrific and the tip I read here about using 2 of the little green booties on the bulbs worked perf. . They look very close in color and brightness to the orig dash guages, AND they're backlit nicely. . Thanks guys. . John G

 

[biggy238]

Sweet.

Joe was the first person to answer any of my questions when I joined the TDR. He's awesome.



The hose on my heat-pump connection is folded. It will be a few days before I can replace it. I hope the ultimately fizes my fuel pressure issue.



Thanks guys.