After buying my 1983 Sunrader, I fueled it for the first time and gas poured from the top of the tank. No flames and I made it home. First look showed that the flex fuel filler hose had pulled from the fitting on the optional Tranfer Flow 26 gallon tank which Greg has described. The Sunrader is nice for no water leaks but a pain to get to some areas because of the fiberglass construction, case in point...the filler hose. Sunrader rivited the outside fuel port into place, which was ok, just drill and remove and rerivit upon reinstallation. Most other manufacturers used screws. The idea was to take the metal port out , clamp a new hose to the metal filler port, reinsert and fasten to the side of the camper, slide the other end of the hose over the tank opening lip and clamp. Couldn't do it. If I had taken the rivits out and pulled the old hose and filler port out, there was no way to get it back in place (on mine anyway) on one side of the hose is the fiberglass wall for the propane storage compartment. I could have removed the metal propane box and cut the fberglass so I could guide the new hose back into place, and then repair the fiberglass. Or, on the other side of the hose is the fiberglass fender well. I just didn't want to destroy the integrity of the fiberglass with patches, so I opted for choice #3. I cut the old hose, which was still good, but had shrunk somewhat over the years and had pulled back from the tank. I inserted a piece of galvanized pipe which I had cut to fit and coated the inside with fuel tank sealer (I restore VW's so I had the sealer on-hand). I clamped the pipe between the two pieces of hose and it now fastened to the tank with no problems, except making that so-called flex hose bend enough to fit over the tank opening lip.
Back to the gas station and fueled up again (I had driven the camper around awhile to get the gas level down before working on the hose). Gas poured out again! I could see it coming over the edge of the tank at the top. There is only 1 inch from the tank top to the camper floor so I couldn't see what was going on up there. This time I had a fire extinquisher in my hand just in case. No flame and made it back home again. I drove it back and forth to work until I got rid of most of the gas. I measured the distance from the bottom of the tank to the pavement which was only7 inches. The tank depth measured 14 inches, and the distance from the frame to pavement was 10 inches, so I only needed to raise the camper 8 to 10 inches to clear the tank from underneath after dropping it.
I drove the front onto 10 inch high steel ramps. Placed the parking brake on, disconnected the ground wire on both batteries, loosened the lugs on the passenger side rear duals, chocked the front and back of the driver side duals, and proceeded to jack up the camper rear with a rated 2 ton hydralic floor jack (wally world type). I measured the distance of the tank to the ground until I got to 16 inches, then I placed another 2 ton jack (I own 3) underneath the axle and then placed one 5 ton saftey stand under the frame and another stand under the axle, all on the passenger side, the driver side rear wheels never left the ground. I then removed the passenger side dual wheels. I siphoned out 5 gallons of gas At the rear of the tank is a standard drain plug, I managed to carefully remove another half gallon of gas, in a flat drain pan and then pouring that into a gas container. If you smoke, DON'T! I had 3 fire extinquishers and a water hose at the ready. It would have been better probably to just let the rig idle in the driveway until it used it's remaining fuel.
Sunrader used the standard Toyota bulkheads to mount the tank, although I think one or both of them were moved to different points on the frame. At the rear of the tank, near the axle, three original Toyota bolts were used to hold the tank on (I had applied penetrating oil 3 days prior to all nuts and bolts that had to come off). At the front of the tank, Sunrader had screwed 3 lag bolts from the top down through the bulkhead welded nuts (see Greg's photo). The tank slides onto these bolts and are fastened with lockwashers and nuts from the bottom. The 26 gallon tank obtains it's volume by looking like an upside down letter "L" with the leg extending over the rear drive shaft. I had to remove that shaft by removing 4 nuts and bolts on either end and gently lowering and placing it to the side. I then loosened the nuts on the lag bolts and backed them off to close to the end of the bolts. I placed my 3rd hydralic floor jack under the rear of the tank and removed all 3 rear bolts. I slowly let the tank down until the front stopped at the nuts still in place. I then unfastened the fuel lines (remember or make a drawing of which goes where, if you have fuel injection, depressurize the fuel line first) I cut the plastic tie that holds the fuel sender wires to the frame and disconnected the fuel sender (Toyota connection). I removed the filler hose and small vent hose I took the 3 nuts off at the front and lowered the tank with one hand, it was surprisingly light. I lowered and removed the tank jack and slid the tank out.
My non-fuel injected model tank had 3 openings on top, all with the standard SAE size opening and 5 small bolt pattern. Fuel injection models will probably be different. The opening close to the rear contained the Toyota fuel sender unit with a neoprene gasket, next was an early emissions thing that consisted of a non-Toyota metal flange with a small cap on top of it with a pipe that a fuel line connected to with a cork gasket between the flange and tank, the front opening was the fuel pick-up flange where the gas lines connect with a neoprene gasket. Fuel injection models should have the fuel pick-up, fuel pump, and fuel sender down one hole. Tranfer Flow did not use a collar around any of the holes. On mine, the Toyota fuel sender flange turns down all around the edge so that when the 5 bolts were tightened, it warped the tank a little, sorta up and down all around the main hole. With a good (new) gasket in-place, this should not be a problem. As the gasket ages, it shrinks, collapses, etc and a leak can occur at fill-up. My sending unit gasket had deterioated a little, but the emissions cork gasket had blown out, ripped and pushed out and this is where my major leak had come from.
The front fuel pickup gasket was ok. Off to Toyota.
Discovered at Toyota that they couldn't identify the emissions thing on my tank and had no cork gaskets. They identified the other two gaskets. I ordered one sending unit gasket and two of the other gaskets, one to take the place of the cork thing. The gaskets arrived the next day. I tried to order a sending unit but Toyota no longer makes the one that fits the non-fuel injection models (I don't know about the fuel injection ones). I couldn't find either type of sending unit on the internet, I didn't check ebay. I also checked several junk yards for used ones. One yard had the unit, but I would have to buy the complete tank. I told him I may be back.
My sending unit wires had been pulled over to the side and due to the closeness of the tank to the floor, one of the wires (+) had frayed it's insulation about a half inch but the strands of wire had remained intact. I removed the plastic wire splices that Sunrader had used to lenghten the wires on the sending unit. I placed heat shrink tubing over the frayed wire and it's mate (the fray occured almost at the point of entry of the wires into the epoxy housing on top of the sender flange. I then glued the two wires to the flange with "Goop" sealant/glue so they would not bend at the tubing. Instead of using the plastic connectors again, I just soldered each wire connection and covered it with heat shrink. It looks better. The sending unit float leg is ajustable. I adjusted the full downward travel of the float until the bottom of the float and the edge of the flange was 14 inches, the depth of the tank. The Toyota sending unit measures 130 ohms at empty and 20 ohms on full, this is supposed to be set in stone. On my guage, it would not go to the full mark with 26 gallons in the tank. I also had some erratic movements of the guage, part from the fray and part from the loose wiper arm on the resistor (you can remove the cover). Over time, a combination of wear of both the arm and the wound wires over which it travels, contribute to failure of the accuracy of the guage. Do not try to bend the wiper arm, it is very fragile and you probably will cause it not to touch the wires at all. I used a pair of pliers and gently bent the frame just a smidge where the arm connects, this gave me more tension of the arm against the wire and very smooth ohm readings from 20 to 130. I reconnected the fuel sender to the truck and placed the ground cable back on the truck battery and turned on the ignition to read the fuel guage (fuel injection should have the fuel pump disconnected from power). I manually moved the float arm a little at a time, from one stop to the other, each movement required watching the guage again. It worked great except it still would not reach the full mark. I bent the metal stop tab for the float arm until the guage got to the F mark. I disconnected the connector and measured the resistance, it now reads 16 ohms at Full and 130 at Empty.
Reinstalled all of the flanges with their new gaskets (it would be wise to place a mark on each flange and the tank so that placement is the same). Stuck the tank under the truck and with one hand, raised the front end of the tank and slid it over the new lag bolts that I had previously installed, and started a new washer and nut on each bolt. I then connected the fuel lines and sender connection (remember where each fuel line goes, I had used a different color paint to code each line). I then raised the back of the tank with the floor jack and started the 3 bolts back there, adjusted the tank and tightened everything fore and aft. I left the drive shaft off for a while longer. Refitted the filler hoses.
Made sure the drain plug was tight and replaced the 5.5 gallons of gas. Checked the guage it read E. I had 2 other 6 gallon containers of gas that I use for my emergency home generator (Hurricaine Isabel left me without power for 9 days a couple of years ago.... well water pump, sump pump, refrig, etc,... never again). Poured in another 6 gallons, still read E, poured in another 6 gallons and still read E. Total of 17.5 gallons of gas it should read between 1/2 and 3/4. Disconnected the fuel sender and placed the multimeter back on it and it read 130 ohms. Said a lot of words and hit the side of the tank with the side of my fist, out of frustation. Watched in amazement as the meter started counting down to 50 ohms and then staying there. Reconnected the fuel guage and read between 1/2 and 3/4 full. I should have remembered the rule I learned as a technician years ago, "if you fix it and it still don't work, then fine-tune it with a BMFH". That is a hammer, nuff said.
I siphoned out all of the gas and the needle was on the E, added one gallon at a time while watching the guage. With 5.5 gallons it points to the E mark. So that is my reserve, 5.5 gallons left when it is on that mark and empty when it hits E. On the other end it is full when it is on the F mark.
Reconnected the drive shaft and wheels, and off to the gas station and put in almost 21 gallons, all the way to the top of the filler hose. Not one drop of gas leaked anywhere. The guage is at the F mark and has stayed there for the 100 miles I have put on it since then. I did see it move off a little when I stopped at a light, going up a hill, but at the top of the hill, back to the full mark. The design of the tank allows the guage to read Full a lot longer because of the extra volume that is packed up there.
If anyone finds a source for the sender units please let me know. I would love to have a spare, just in case.
Jerry
Sorry, I didn't pick up on this. My Sunrader did it twice, the same way. Shut it off and turned it back on, all OK. Seems the more I drive it, the less of these problems pop up. I think the problem is an external voltage regulator. After 20 years I probably need a new one. Jerry