Fuel Gauge is acting wonky
- Thread starter Giant Asian
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- 100 series fuel fuel gauge
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Wanted to circle back and close the loop on my "wonky" acting fuel gauge.
I ordered a new sending unit and went ahead and also ordered a new fuel pump to replace while I was in there. Replacing the sender corrected the problem. Replacing the OEM pump with the Denso Kit seemed to improve my throttle response/driveability. It could be my imagination but throttle response from 0-50% throttle position is smoother, faster, (more-better). The fuel strainer filter was not plugged on the old pump, but its possible it had lost some of its ability to provide low pressure response pressure. I never checked it before replacing. It worked but at 195k, 14 years and with back seats out and pump assembly out of the tank it made sense to me to replace everything at one time.
Bench testing the sending unit revealed some sporadic volt measurements way out of spec as the level was moved to high & low. I'm not sure if it was maybe the potentiometer was wearing out or a ground issue.
Removal tips for others:
FSM says to disconnect the electrical connector under the left side passenger door. Its a pita to get apart- be careful and patient.
Back seat: the single seat can remain in the truck, the double needs to come out. Remove head rests, fold forward, remove mounting hardware slide off from the mounts and wrestle that heavy biatch out from the truck and set aside. Remove the door sill kick plates and 3rd row seat access tread plate on driver & passenger side
Fuel pump assy: as you can see from the photos, the top of the FP assy. is covered in road grime. Before disconnecting or pulling anything apart fully clean the area with light water based degreaser and a old tooth brush. ( you dont want crud falling into your tank). Carefully remove the yellow plastic locking clips, work one side at a time and partially walk it off the tabs, then pull it off being gentle and mindful to not let it fall off and down between the tank and skid. Disconnect and remove vapor sensor, fuel pump connector, fuel return and fuel out lines. I plugged the fittings with 5/16 vinyl vacuum caps and wrapped the hose ends in small bags to keep debris out and fumes under control. To remove the FP assy, you want an extension and a long handled wretched, or better a T-handle like shown. Screws are slotted but dont attempt to use a screw driver. The bolts required a fair amount of effort to unseat and you'd strip them with a screwdriver. Carefully remove and place screws in a magnetic tray as not to let them fall down between the tank and tank skid to never be seen again. Have a plastic coffee tin lid or a piece of plastic sheet- or saran wrap to place over the open tank to keep vapors contained- some magnets to hold down the temporary cover helps.
On your work bench with FP assy. before you: If replacing pump, remove the FP- slide out of the holder, remove rubber seat, remove hose clamps, remove strainer filter, disconnect electrical connector. Fuel sender: make note of where the ground is attached to the top of the pump assy. ( take a picture- it will help during reassembly). Remove two small screws holding Fuel level sender ( having JIS #2 type phillips screw driver helps because these screws are really tight and will strip easily), remove and replace in reverse order.
Note: fuel strainer should be replaced when new pump is installed: you can order as a full kit with strainer, fuel hose, hose clamps from Denso 950-0107. Disregard the other extra parts in the box. Tank Gasket: this must be replaced every time: single use 77169-33020. Dont cheap out and think its ok to reuse- its not worth leaking vapor or fuel down the road. When reinstalling the FP assy on to the tank, I used some blue locktite ( medium 242) to help minimize corrosion- these must also be torqued to spec: 31 INCH pounds. Best to slow tighten this down in criss-cross pattern in multiple passes to seat the new seal evenly. Then placed a dab of synth. grease on top of each screw after torqued to cut down on corrosion.
Some pics:
I ordered a new sending unit and went ahead and also ordered a new fuel pump to replace while I was in there. Replacing the sender corrected the problem. Replacing the OEM pump with the Denso Kit seemed to improve my throttle response/driveability. It could be my imagination but throttle response from 0-50% throttle position is smoother, faster, (more-better). The fuel strainer filter was not plugged on the old pump, but its possible it had lost some of its ability to provide low pressure response pressure. I never checked it before replacing. It worked but at 195k, 14 years and with back seats out and pump assembly out of the tank it made sense to me to replace everything at one time.
Bench testing the sending unit revealed some sporadic volt measurements way out of spec as the level was moved to high & low. I'm not sure if it was maybe the potentiometer was wearing out or a ground issue.
Removal tips for others:
FSM says to disconnect the electrical connector under the left side passenger door. Its a pita to get apart- be careful and patient.
Back seat: the single seat can remain in the truck, the double needs to come out. Remove head rests, fold forward, remove mounting hardware slide off from the mounts and wrestle that heavy biatch out from the truck and set aside. Remove the door sill kick plates and 3rd row seat access tread plate on driver & passenger side
Fuel pump assy: as you can see from the photos, the top of the FP assy. is covered in road grime. Before disconnecting or pulling anything apart fully clean the area with light water based degreaser and a old tooth brush. ( you dont want crud falling into your tank). Carefully remove the yellow plastic locking clips, work one side at a time and partially walk it off the tabs, then pull it off being gentle and mindful to not let it fall off and down between the tank and skid. Disconnect and remove vapor sensor, fuel pump connector, fuel return and fuel out lines. I plugged the fittings with 5/16 vinyl vacuum caps and wrapped the hose ends in small bags to keep debris out and fumes under control. To remove the FP assy, you want an extension and a long handled wretched, or better a T-handle like shown. Screws are slotted but dont attempt to use a screw driver. The bolts required a fair amount of effort to unseat and you'd strip them with a screwdriver. Carefully remove and place screws in a magnetic tray as not to let them fall down between the tank and tank skid to never be seen again. Have a plastic coffee tin lid or a piece of plastic sheet- or saran wrap to place over the open tank to keep vapors contained- some magnets to hold down the temporary cover helps.
On your work bench with FP assy. before you: If replacing pump, remove the FP- slide out of the holder, remove rubber seat, remove hose clamps, remove strainer filter, disconnect electrical connector. Fuel sender: make note of where the ground is attached to the top of the pump assy. ( take a picture- it will help during reassembly). Remove two small screws holding Fuel level sender ( having JIS #2 type phillips screw driver helps because these screws are really tight and will strip easily), remove and replace in reverse order.
Note: fuel strainer should be replaced when new pump is installed: you can order as a full kit with strainer, fuel hose, hose clamps from Denso 950-0107. Disregard the other extra parts in the box. Tank Gasket: this must be replaced every time: single use 77169-33020. Dont cheap out and think its ok to reuse- its not worth leaking vapor or fuel down the road. When reinstalling the FP assy on to the tank, I used some blue locktite ( medium 242) to help minimize corrosion- these must also be torqued to spec: 31 INCH pounds. Best to slow tighten this down in criss-cross pattern in multiple passes to seat the new seal evenly. Then placed a dab of synth. grease on top of each screw after torqued to cut down on corrosion.
Some pics: