Erics40 » Well, the great gas tank experiment is over. I ran the car to empty and got 474 miles, validating the owners maunal. I have been getting about 30 mpg so this mileage proves the 16 gallons in the tank and a smidge under 30 mpg. Yes I did have a 1 gallon can in the trunk.
So now the head scratcher. The float must bottom out in mid-tank with 6 gallons left. My next foray will be to autopsy the sender/float to see if it can be extended or fooled. If not, it’s back to to old days of mototcycle or guageless VW: calculate the tank using the odometer and ignore the guage. For the moment I’m going to use 425 miles as the fillup time.
oldacura » I recently bought a 2001 V40. I’ve been looking for a service manual. Is there a “best” manual (Haynes or HP Books)?
Also, I have filled the tank twice. The owner’s manual shows the tank should hold 16 gallons. The second time I filled it after the low fuel light came on (about 300 miles). I was able to get just over 11 gallons in. This figures to be about 27 mpg but it seems like the tank is only about 12 gallons. Is there something wrong with my tank?
Erics40 » I had yesterday off and just couldn’t leave well enough alone. I pulled the fuel pump and sender assembly and bent the arm. At the mount end, I bent the wire straighter making the float rise and extend. It probably moved out a half inch and up a half inch.
Then I bent the lower kink to make the float droop. I put the pump/sender on a flat table and the float was about 1 inch above the surface. I bent the lower kink to drop the float to about a half inch below the table. At this point I twisted the arm at the float so the wire going into the float was the low point and the float points up at 10-15 degrees. With me?
I put it back in and hoped. I drove to work today (40 miles) and here’s where the numbers lie: I have 280 miles on the odometer, the Miles to Empty reads 160 and the guage is at 1/3 full. It looks about right!! I am looking forward to the light and empty to see where the bottom is, but it’s close enough now I will be able to live with it.
Erics40 » Here’s the final result. I have adjusted the resistance to read 104 ohms when the pump/sender unit and the float are both on the table. This pops the fuel light on at 14.5 gallons, leaving the reserve amount to 1.5 gallons.
The float arm has to be bent ‘shorter’ (closer to the sender body) so the float at the top uses as much of the resistor as possible. On mine, the float at the bottom of the rubber sleeve (top of the tank) measures about 5 ohms.
This may be too much for casual fiddlers and parts changers but I’m posting just to show that it can be done. As a side ‘benefit’ I can pull the pump, adjust the float and reinstall everything in about 10 minutes. It’s that easy. Be brave.
billofdurham » You have succeeded where others have failed, or even failed to go.
My friendly Volvo tech has been given a copy of your modifications. He told me that no-one where he works had come up with a solution for this common S/V40 problem. They would only advise trying a new sender unit which invariably read the same as the old one.
Erics40 » Just a brief update on the fuel tank issue for those still in doubt. I performed the above sender modification some months ago and have used countless tanks since. When the light comes on, I have about two gallons remaining in the tank. When the “Range to Zero” indicator reads “0” (no miles left) there is less than a gallon, time for a fill. It takes 15.2 gallons at that point and I’ve gone 440 miles on the tank.
I am well pleased with the range because I get about a week between fillups.
RDEJR » Sorry for reviving an old thread, but here is my reasoning for the fuel gauge reading lower than it should.
Electric In-Tank fuel pumps use the fuel to cool the pump motor. If you have less an 1/4 tank in there, there is not enough fuel to reach up and tough the motor to keep it cool. By setting the sender so it makes the gauge read low, you will likely fill the tank while there is still some amount of fuel in the tank to keep the pump cool.
Pumps that fail early in my experience have always been with people who constantly run their vehicles low on fuel.
My .02
Service Manuals & Fuel Capacity
Last Updated on May 6, 2024
