Fuel System Overview

[Lone Eagle]

Since I have a background in hydraulics I have been following the "air in fuel problem" with great interest. Even though I don't seem to have a problem with mine I would like to help. I am just going to ramble a bit with some observations. The only people that have a no start problem have a secondary filter. So it is safe to say that the add on filter installation is causing this. The very first thing that I thought from day one was the filter under the air box was too low to bleed the air out. Please don't start flamming me. This is just my opinion. Air will naturally migrate to the hightest point in the system. It does not want to flow along in a liquid. I think some have done a better job of bleeding the air than others and don't have a problem. I went up to my dealers today and had them print me a copy of the Fuel System Overview drawling. Item # 8 on the drawling is called a First Start Fuel Bleeder Valve. This valve is there to bleed the air from the lines between the filter and the pump. When we changed the lines we filled the system with air all the way to the pump inlet. If you look closely to where this valve is located you will notice this is the hightest point after the filter. I am pretty sure that are tanks are full of vapor all the time from the return fuel lines. I'll save some of the overview for later! Lone Eagle

[Idle_Chatter]

Great info, Lone Eagle! Where is this "first start valve physically located? In the engine valley? How is it getting bypassed by a megafilter tapped into the OEM ouput? Keep the info rolling!

[Lone Eagle]

Idle Chatter, Standing in front of the truck, it is just a few inches left of the alternator. It has a black cape on it. The last fuel line from the secondary filter went to a metal fitting down under the air intake line. That steel line goes to the pump. The bleed line is teed into it some way or other that I can't see. The drawing shows it also. Later! Lone Eagle ;)

[ 05-09-2003: Message edited by: Lone Eagle ]</p>

[Kennedy]

The port we use to measure filter restriction.

Lone Eagle,

It is not a bleeding issue when we see air coming from the EDU...

[ 05-10-2003: Message edited by: kennedy ]</p>

[jbplock]

Lone Eagle,
I was also looking at the overview page you were talking about and I saw the first-start bleeder valve but wasn't sure where it was. Thanks for clarifying this as I didn’t realize that this was the same port (duh) that I had been using to monitor restriction with my Kent Moore (GM) Pressure/Vacuum gauge. The first time I connected the gauge I had about 1000 miles on the megafilter installation. At the instant the quick connect couple was pushed on to the fitting, some fuel dribbled out. So I know there is no air between the MegaFilter and the pump. It will also hold pressure at his point for the period specified in the Helms when pumped up with the primer. smile.gif

[ 05-10-2003: Message edited by: jbplock ]</p>

[a bear]

It's also used by GM to check for restriction/leak down tests.

[Lone Eagle]

I understand that John. On new installations it would help to bleed the air here also. Later! Lone Eagle

[zip]

John- stop worrying about air-in-fuel problems and get to that dino run.
zip

[Kennedy]

Lone Eagle,

Bleeding at this port is pointless IMHO. Any air in the fuel should rise from the filter quite easily.

Additionally, I try to pump up the primer to a few psi with the engine running which should make sure that any air in there is pushed out.

zip,

Read my sig! I'll admit that I missed breakfast (7ish to me means a .5hr cushion) :D

[ 05-11-2003: Message edited by: kennedy ]</p>

[Lone Eagle]

John, When installing a secondary kit the whole system is full of air all the way to the pump. You can prime to you arm is sore and won't have a full line of fuel to the pump unless you have a hight point bleed. In no way am I infering that there is anything wrong with your kit. I had a choice where to put mine. There are some that say I have air and am just passing it because the Racor doesn't have a place to trap air. That is bull. If there was air in my system it would migrate to the top when shut down. Later! Lone Eagle