Pickup Tube Help

Jon Walker

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Location
Cedar City, Utah
My truck runs perfect on a full tank of fuel. After I run through about 4 gallons of fuel I occasionally begin to get air in the fuel line. At half a tank I can drive 30 seconds at fuel throttle and then air gets in the line and it looses throttle until more fuel gets into the line. At 1/4 tank it isn't drive able.

I pulled the tank from the truck and removed the 90 degree pickup elbow. Is there supposed to be a way to remove an actual tube that goes into the tank? It looks like the nut the elbow was attached to is welded into the tank. How can I remove the pickup tube from the tank?

I read the TM's and can't find anything about removing the tube from the tank. aua
 

DiverDarrell

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This is the first I have heard of this issue, any way to rig a bypass to ensure it's the pickup and not the fuel filter housing that's known to cause air fuel issues?
 

Jon Walker

Member
31
1
6
Location
Cedar City, Utah
Truck runs perfect pulling fuel from a jerry can. I will replace the air filter, I have a spare. Checked the pickup tube after draining the tank. Looked down it with a flashlight and saw no signs of damage or corrosion.
 

Suprman

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I have heard of pinholes in a pickup tube. If you disconnect the hose from the pickup and hook up a secondary fuel source and that's fine then chances are there's an issue with your tank. You could always just replace the tank.
 

coachgeo

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I have heard of pinholes in a pickup tube. If you disconnect the hose from the pickup and hook up a secondary fuel source and that's fine then chances are there's an issue with your tank. You could always just replace the tank.
Yup what superman says. Pinhole. BUT... try this. Take off your fuel cap when your at a point that the truck is not running right. LEAVE IT OFF and drive to see if your problem seems to go away. If it does then it is an issue with your Tank's venting. The air is not able to replaced used up fuel space via clogged/blocked/bent vent thus creating a vacuum in the tank. With this vacuum the IP and/or fuel pump will have a hard time overcoming this. This added vacuum will also suck air in thru any weak spots in the fuel system. With out the added vacuum these weak sports typicaly the fuel system's built in air bleed set up can deal with just fine.
 
Last edited:

Jon Walker

Member
31
1
6
Location
Cedar City, Utah
Yup what superman says. Pinhole. BUT... try this. Take off your fuel cap when your at a point that the truck is not running right. LEAVE IT OFF and drive to see if your problem seems to go away. If it does then it is an issue with your Tank's venting. The air is not able to replaced used up fuel space via clogged/blocked/bent vent thus creating a vacuum in the tank. With this vacuum the IP and/or fuel pump will have a hard time overcoming this. This added vacuum will also suck air in thru any weak spots in the fuel system. With out the added vacuum these weak sports typicaly the fuel system's built in air bleed set up can deal with just fine.

My truck did have a clogged vent tube. It has been fixed. There was no sealing compound on the pickup tube elbow, I added some and put it back together. I left the tank 20 gallons low. I am going to drive it around and see if I notice any difference. If it isn't fixed I think I am going to try a new tank.
 

Jon Walker

Member
31
1
6
Location
Cedar City, Utah
The entire vent line was replaced with a brand new line. Hooked an air compressor to the old vent line and blew air through it. No air came out the other side. Old vent tube removed, new tubing put in its place.
 

Jon Walker

Member
31
1
6
Location
Cedar City, Utah
Problem has been fixed! My dad (heavy diesel mechanic) was able to get the pickup tube removed. The tube was fine. :( We put a small fuel pump on the pickup tube to send extra fuel and keep pressure in the lines. While I didn't fix what is causing the problem I did removed all the symptons of the problem. I no longer lose throttle when I don't have a full tank so I can finally start driving it farther than 10 minutes from my house.
 

coachgeo

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Sounds like air leak further up. The pump your Pop installed is pushing fuel past the air leak. You might find that the area that once was sucking air in..... might now... have diesel fuel pushed out of it. Could make it easier to find the leak and fix. Watch for weeping spots on your fuel lines; esp. at connections.
 
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