I have a 1990 Ford e250 w4.9L. The front fuel tank gets vapor lock (vacume in tank because tank is not venting as fuel is removed) Started when the rear tank forced fuel from the return line


Asked by Jul 16, 2014 at 12:12 PM about the 1990 Ford E-250

Question type: Maintenance & Repair

1990 ford e250 with front/rear tank.  Tank switching valve malfunctioned ( has been replaced ) and sent returned fuel from the rear tank into a full front tank forcing fuel out somewhere at the top of the front tank.  Now when using the front tank it has vapor lock (creates a vacume because no venting takes place as fuel is removed).  Where is the venting done on the tank when fuel is removed; at the vapor canister?  The tank works ok if the gas cap is off.  Any ideas?  dfcmike@iserv.net

3 Answers


There is a valve in the top of the tank that provides venting into the canister purge system, but as it only happens on the front tank check for a damaged hose or crushed line as you will have to drop the tank to get to the valve.


Your answer was helpful and the problem is the front tank. I believe the vent valve may have been damaged by the rear tank forcing the return line fuel into a full front tank which forced the excess gas out through the vent valve and probably destroyed it in the process. Could you please e-mail me a drawning of the location of this vent valve, mabe a name or part number from ford and the best way to replace it, if I can get one. Thanks Mike


F67z9b593ca I believe is the engineering number, your ford dealer can convert it to a Ford part number. there are 2 way to access it, one way is to drop the fuel tank, the other is to take out all of the bed hold down bolts and raise and block the bed enough to gain access to the front tank. Be careful with either way. I use the tank drop method with a floor transmission jack.

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