Where does air in the fuel come from - Diesel Forum - TheDieselStop.com
7.3L IDI Diesels FAQ Frequently asked questions in the Powerstrokes 7.3L IDI Diesels forum.

 
LinkBack Thread Tools Display Modes
post #1 of 11 (permalink) Old 08-07-2011, 03:14 PM Thread Starter
Senior Member
 
Join Date: Jun 2011
Location: Troy, MO
Posts: 168
My Photos: (0)
Feedback Score: 0 reviews
Where does air in the fuel come from

How does air get into the fuel system? I thinking someware between the fuel tank and filter. After the filter if there was a leak wouldnt fuel leak out not air in?

Thanks,

1990 F250 Extended Cab 7.3 Non Turbo 280,000
erik49051 is offline  
Sponsored Links
Advertisement
 
post #2 of 11 (permalink) Old 08-07-2011, 03:24 PM
Senior Member
 
chuckster57's Avatar
 
Join Date: Apr 2008
Location: Central Valley, Ca.
Posts: 17,604
My Photos: (7)
Feedback Score: 1 reviews
There are a number of places air can get into the fuel system on the IDI. Most often air is allowed into the system after you shut down. The return system has "O" rings and the plastic caps can get distorted over time. When you shut the engine off, if there is any breach in the itegrity of the return system, fuel will "drain back" into the tank and the void will be filled with air. Air can GET IN WHERE FUEL CAN'T get out. Another spot for this is the supply line from the filter header to the back of the IP. Fuel will drain onto the valley pan and you might not see it, and once again the void is filled with air.

While your running, air can be sucked into the fuel system from a failed "O" ring on the tank connection or the selector valve. In rare cases the flex line from the frame to the inlet side of the lift pump can get cracked.

1994 F-350 7.3 IDI Turbo, crew cab, E4OD,4:10 L/S, LB, Dually
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

ATS Turbo upgrades: 3" DP with 3" exhaust Magnaflow XL muffler:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

2012 Copper Canyon 273 FWRET w/2 slides, Air Lift 5000 bags
Pillar pod: Autometer C2 Series gauges: pyro,trans, boost, water, oil pressure
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Hypermax Cowl induction, K&N air filter, flex-a-lite 26K trans cooler with fan,Tekonsha prodigy
Train Horns:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


PM please not visitor message
chuckster57 is offline  
post #3 of 11 (permalink) Old 08-07-2011, 03:39 PM Thread Starter
Senior Member
 
Join Date: Jun 2011
Location: Troy, MO
Posts: 168
My Photos: (0)
Feedback Score: 0 reviews
I have a rough idle, if a leak is comming from "While your running, air can be sucked into the fuel system from a failed "O" ring on the tank connection or the selector valve", would this be visible in a clear line running from the return rail up to the filter head?

Thanks

1990 F250 Extended Cab 7.3 Non Turbo 280,000
erik49051 is offline  
Sponsored Links
Advertisement
 
post #4 of 11 (permalink) Old 08-07-2011, 03:43 PM
Senior Member
 
chuckster57's Avatar
 
Join Date: Apr 2008
Location: Central Valley, Ca.
Posts: 17,604
My Photos: (7)
Feedback Score: 1 reviews
Quote:
Originally Posted by erik49051 View Post
I have a rough idle, if a leak is comming from "While your running, air can be sucked into the fuel system from a failed "O" ring on the tank connection or the selector valve", would this be visible in a clear line running from the return rail up to the filter head?

Thanks
The clear line test will positivley identify air in the system. If you make a loop, then yeah you can tell which direction it's coming from. I don't have the specifics handy but I know it's been posted a few times under "clear line test".

1994 F-350 7.3 IDI Turbo, crew cab, E4OD,4:10 L/S, LB, Dually
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

ATS Turbo upgrades: 3" DP with 3" exhaust Magnaflow XL muffler:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

2012 Copper Canyon 273 FWRET w/2 slides, Air Lift 5000 bags
Pillar pod: Autometer C2 Series gauges: pyro,trans, boost, water, oil pressure
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Hypermax Cowl induction, K&N air filter, flex-a-lite 26K trans cooler with fan,Tekonsha prodigy
Train Horns:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


PM please not visitor message
chuckster57 is offline  
post #5 of 11 (permalink) Old 08-07-2011, 03:51 PM Thread Starter
Senior Member
 
Join Date: Jun 2011
Location: Troy, MO
Posts: 168
My Photos: (0)
Feedback Score: 0 reviews
great, I read though the post for clear line test but wasn't clear wether it would indicate where the air is comming from.

Thanks for the help!

1990 F250 Extended Cab 7.3 Non Turbo 280,000
erik49051 is offline  
post #6 of 11 (permalink) Old 09-02-2011, 10:51 PM
Junior Member
 
Join Date: Sep 2011
Location: O H I O
Posts: 1
My Photos: (0)
Feedback Score: 0 reviews
hey guys I have a 93 7.3 idi 4x4 truck with an auto trans. 152k I just bought this truck and i like it, it has enough power for what i want it to do!

the prob.. the truck runs great! but every morning i have to purg air out of the srader valve on top of the fuel filter. after it cracks for about 5 to 10 sec's it will push fuel out.
then i crank it on the floor it starts and has a rough idle or a short min. i know that the air is making the prob but where is it coming from!!
tmracing is offline  
post #7 of 11 (permalink) Old 01-22-2012, 12:29 PM
Senior Member
 
drinkypoo's Avatar
 
Join Date: Mar 2009
Location: Kelseyville, CA
Posts: 6,680
My Photos: (25)
Feedback Score: 0 reviews
http://www.thedieselstop.com/forums/...coming-292428/
Ford diesel 6.9 7.3 IDI (from thread http://www.thedieselstop.com/forums/...arting-283547/)

1992 F250 XLT 4x4 Super Cab 7.3 IDI E40D 3.55 ATS 088 4"R.C 360k
1982 MBZ 300SD W126 California model w/Sunroof, no EGR
1997 Audi A8 Quattro 225k Warm/Cold packages
drinkypoo is offline  
post #8 of 11 (permalink) Old 10-18-2012, 10:38 AM
Junior Member
 
Join Date: Oct 2012
Posts: 3
My Photos: (0)
Feedback Score: 0 reviews
fuel drain back problem

I need help.
I have a 1989 Ford 1 ton with a 7.3 liter diesel, 180,000 miles runs perfect. Now the problem, for some reason when the truck has been shut off for 10 or more hours the fuel has drained back to the tank. Iíve changed all lines between injectors with a new kit, new fuel pump and it still seems to be getting air back into the system to let it drain.

Forgot to add that it has 2 tanks so could the selector valve be my problem?
Thanks for your help.
SteveBdogs is offline  
post #9 of 11 (permalink) Old 11-13-2012, 06:35 PM
Member
 
Join Date: Mar 2009
Posts: 53
My Photos: (0)
Feedback Score: 0 reviews
If the truck runs fine otherwise it's likely bleeding in through the filter head. Try removing bleed line on filter head and plug fitting. No need to plug hose. The next morning remove plug and replace hose. If it starts and runs ok installing a cheap vacuum check valve in the hose shouldl eliminate the problem.
leyrret is offline  
post #10 of 11 (permalink) Old 11-14-2012, 07:52 AM
Junior Member
 
Join Date: Oct 2012
Posts: 3
My Photos: (0)
Feedback Score: 0 reviews
Fuel draining back to tank

Found the problem, it was the continuous vent with check valve located on the filter head. Starts right up with no problems and it runs great.
Thanks for your help.
Steve
SteveBdogs is offline  
post #11 of 11 (permalink) Old 03-03-2013, 04:51 PM
Junior Member
 
Join Date: Mar 2013
Posts: 2
My Photos: (0)
Feedback Score: 0 reviews
I have found a couple times on different trucks that when the was shut off and the next time you when to start up and engine ran like it had got air into the system, I have found that the air bleed off on top of filter housing was the culprit. Put a good metal cap with an o-ring on valve and problem solved(use to get them from tire store or a good bicycle)
mjacks is offline  
Sponsored Links
Advertisement
 
Reply

  Diesel Forum - TheDieselStop.com > Ford Diesels > 7.3L IDI Diesels (Not Power Strokes) > 7.3L IDI Diesels FAQ

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Diesel Forum - TheDieselStop.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome