I have a 389 peterbilt with a paccar, The fuel is being pulled from the drivers side tank filling up the passenger side. A couple days ago I unlatched the drivers side fuel cap while I was on my 10hr break. The tanks leveled out and started back working. Now its doing it again. How can I fix this?
Tanks not equalizing
Discussion in 'Peterbilt Forum' started by krazzyboi_44, Jan 23, 2026 at 11:09 AM.
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Sounds like a venting problem. Check any vents. Some fuel caps are vented so it may be a bad cap. Switch the fuel caps if you can and see what happens.
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Find vent tube on top. Run small stick or metal clothes hanger to clear blockage. Dirt dobbers have blocked them tubes too
TurkeyCreekJackJohnson, OldeSkool, '88K100 and 1 other person Thank this. -
Or splitter valve on return.
Oxbow Thanks this. -
The vent is frequently the culprit as many hang between tank and frame and get packed with ice during inclimate weather
Dumping fuel conditioner in tanks can free up the splitter valve, or just park in heated shop overnight to defrost everythingOldeSkool Thanks this. -
I had that happen on a Junkliner Classic XL I owned in the late 90's.
A plugged vent hose was the culprit.Oxbow Thanks this.
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