Another dual tank thread,HELP...
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Another dual tank thread,HELP...
OK,I just purchased a 94 F150,4.9,2wd,Flareside,and I have the very common issue of fuel transfer between both tanks...Friday before last,the front pump failed(stopped pumping),at 3/4 full...Knowing that if I put more than 1/4 of a tank in the rear tank,I will over fill the front...Now,just sitting in my driveway for a week,the front tank is full and the rear tank is empty...I can hear the pump run in the rear,but it won't start...My questions here are,How does it transfer fuel without the truck running???...Siphoning I guess....The next question is,Reading some of the posts here,there is a pair of inline check valves that Ford offered as part of a recall to solve this problem...Does anyone have a part number for these valves???...I'm going to replace both fuel pump assemblies and I want to put these check valves in at the same time...Any help will be appreciated....Thanks,Bryce
Fleet Owner
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From: Easton,Ks
All you need to do is replace the front FDM and the back FDM might work OK.
The outside check valve are not needed. That was a cheap fix by Ford after they replace the bad Fuel Pressure Regulators in the 1993 trucks.
If the tank is full it might be easier to pull the bed off than dropping the tank.
The outside check valve are not needed. That was a cheap fix by Ford after they replace the bad Fuel Pressure Regulators in the 1993 trucks.
If the tank is full it might be easier to pull the bed off than dropping the tank.
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Yeah I'm going to pull the bed to them both,but I still would like to get the Ford part numbers,just in case.A local mechanic here in town remembers installing quite a few of the inline check valves,back in the day...I've called a few dealers around here and they tell me that my VIN is not one of the affected units covered under the recall...I even had a dealership's service advisor tell me that they wouldn't even work on a vehicle this old...I just laughed and hung up the phone...Isn't a recall in effect for a vehicle that has this issue,no matter what the age or mileage??...I recently had a headlamp switch and pigtail replaced,Under Recall,for a 91 ThunderBird SC,due to a known fire hazard issue....I don't want to pick a fight with them,I just want to fix it correctly...
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From: Easton,Ks
What it was is they had a bad run of FPR that let the pressure go to high on the 1993 trucks. It would blow out the HP check valve in the non running FDM. Then the driver would switch tanks and the other HP check valve would blow out.
Ford did not want to take the time and the cost of the FDM so they just replaced the FPR and put a check valve in each HP line leaving the FDM.
Note that putting the check valve on the HP will not stop the other tank from over filling if the shuttle valve is bad on the return side of one the FDM.
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Ford did not want to take the time and the cost of the FDM so they just replaced the FPR and put a check valve in each HP line leaving the FDM.
Note that putting the check valve on the HP will not stop the other tank from over filling if the shuttle valve is bad on the return side of one the FDM.
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From: Livonia, MI
I had the same thought you did last year. I called a few dealers (3 of them) and two of them couldn't even get the recall kit at all, and one could - but they wanted $249 for it!! I did find one on e-bay for $40. I attached a pic of it. If you really want one, I'll send you mine for the $40 I paid (I'll even pay postage!). However, SubFord is 100% correct - this kit is not for your vehicle. Now, I don't think the check valves would hurt if they were installed, but definitely do not use the pressure regulator. Again, I would listen to SubFord as he knows a lot more about this than I do. Let me know if you want it.
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Thank you SUBFORD and JOEGEDS for the advice and knowledge....This info is just what I needed...gonna change both FDM's this weekend and see what happens...My original thinking was to change both of the fuel pump and sender assemblies,but I'm just going to replace the FDM's...It appears that they are reading correctly as the front tank was 3/4 full and the rear was 1/4 full...now the front is full and the rear shows empty and it won't start on either tank,(remember the front tank has a bad pump),but it will try to run on WD40 sprayed into the THrottle Body...Again,Thanks to you both for your help...I'll update with the results when I'm done...
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OK,New pumps are in,now just need to drive it for a few days to see if it's gonna cross-feed...I'll keep y'all updated...
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Well,just to update...have driven many days since last post when I installed both pumps....Seems like all is well now...No more crossflow of fuel or siphoning,...Thanks to all who helped and gave me advice..I really appreciate it!!!
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TO Subford:All of your information on this dual Tank Transfer issue, and trouble shooting the problem to identify if it is in fact the FDM, was extremely helpful to me. Thank you! HOwever, please also tell Questioners, in at least the 1988 Superduty, like mine, there is also a breather valve on the front tank, this may be obvious to some, but the breather valve must be pulled out of the tank before beginning to drop the tank. The hose connection points on the valve will not put up with any undue strain. Since I had to drop my front tank as the bed was welded to the frame. The cost to replace the breather valve is $144.00. It is also recommended to replace the breather valve grommet.
I also found the Ford replacement front tank sending unit lead is not long enough to reach the original connection point on the pump terminal connection, nor does it have the correct wire connector. I had to cut off the factory connector, install my own and cover the NEW electrical connection with shrink wrap to protect the connection, similar to the factory method. Thanks again for all the GOOD information. KhFlatbed
I also found the Ford replacement front tank sending unit lead is not long enough to reach the original connection point on the pump terminal connection, nor does it have the correct wire connector. I had to cut off the factory connector, install my own and cover the NEW electrical connection with shrink wrap to protect the connection, similar to the factory method. Thanks again for all the GOOD information. KhFlatbed
Last edited by KHflatbed; May 24, 2014 at 03:47 PM. Reason: left some information out.
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From: Easton,Ks
TO Subford:All of your information on this dual Tank Transfer issue, and trouble shooting the problem to identify if it is in fact the FDM, was extremely helpful to me. Thank you! HOwever, please also tell Questioners, in at least the 1988 Superduty, like mine, there is also a breather valve on the front tank, this may be obvious to some, but the breather valve must be pulled out of the tank before beginning to drop the tank. The hose connection points on the valve will not put up with any undue strain. Since I had to drop my front tank as the bed was welded to the frame. The cost to replace the breather valve is $144.00. It is also recommended to replace the breather valve grommet.
I also found the Ford replacement front tank sending unit lead is not long enough to reach the original connection point on the pump terminal connection, nor does it have the correct wire connector. I had to cut off the factory connector, install my own and cover the NEW electrical connection with shrink wrap to protect the connection, similar to the factory method. Thanks again for all the GOOD information. KhFlatbed
I also found the Ford replacement front tank sending unit lead is not long enough to reach the original connection point on the pump terminal connection, nor does it have the correct wire connector. I had to cut off the factory connector, install my own and cover the NEW electrical connection with shrink wrap to protect the connection, similar to the factory method. Thanks again for all the GOOD information. KhFlatbed
Second if you have a 1988 the sender hanger does not have a pigtail, it only has a connector on top.
Also the valve on top of the tank is the rollover valve and I would think it to be kinda obvious you need to pull it out as you drop the tank and the vapor hose get a strain on them.
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