Expert Fuel Pump Opinions Needed!

[211Racing]

Just got a 2002 Tioga 24D. Base is a Ford e350 Super Duty van. Will turn over strong, but starts for only an instant. With the help of Starting Fluid, will run for several instants. Zero pressure at the fuel rail. Tightened the gas cap. Replaced the Fuel Pump Relay. Replaced the Fuel Pump Fuse. Replaced the Fuel Pump Filter. Checked and cleaned the Inertia Switch (button is down). Thumped the bottom of the tank several dozen times. Absolutely zero effect. I am reluctantly moving ahead to draining the 40+ gallons of fuel and dropping the fuel tank to replace the Fuel Pump. Can you think of anything that I have missed before I commit to this job? Thank you for your help. (And ... I checked to see if I could access the Fuel Pump through the floor in the back of the RV. Lovely thought, but not possible).

[Gdetrailer]

Rigdon wrote:
If the unit had a serious thump very recently, it could be a fuel pump reset switch that sometimes triggers following a wreck or big drop.

OP is trying to bring back to life a rig that has been sitting still for a few yrs and not because it was in accident.. Has already tried resetting the inertial switch, replaced the fuel pump fuse and relay.

The "thump" the OP mentioned was from an attempt by the OP to bang on the bottom of fuel tank with a heavy object in an attempt to get the fuel pump to start.. No way that thump on the tank would ever be enough to trigger to inertial switch.

[Rigdon]

If the unit had a serious thump very recently, it could be a fuel pump reset switch that sometimes triggers following a wreck or big drop.

[Gdetrailer]

211Racing wrote:
Thank you to all. I do have a motorcycle jack and will see how to work it under the tank. Challenge is that the tank is 55 gallon and seems quite flexible when pushed on (thumped) from the bottom. It appears flush-mounted to the underside of the RV, so there's no peeking up there with a cell phone camera to get familiar with the layout/pump/lines. I have cleaned and/or replaced both of the frame to body grounds, but will look today if there is a specific ground on the tank.

Use a siphon pump and drain the tank to make life easier..



$12 or so, can get Harbor Freight and other stores, was able to empty a 30 gallon tank that was 3/4 full. Sold the truck and because everyone was low balling me (including the one that bought it) they only got a couple of gallons (left enough to get them to the nearest gas station) didn't get the 20 gallons of fuel I removed.

Once empty the tank will be much easier to deal with even if you used a motorcycle lift.. They typically do not give much slack in wiring or fuel lines to work with so having the tank as light as possible will be a bonus.

[Grit_dog]

So you’ve diagnosed that the pump is not running, presumably since you’ve replaced the fuse and relay. (Was the fuse blown? If not, why replaced?)
If the tank is 3/4 full as you say, Then the pump didn’t freeze up due to oxidation. It is and was submerged.
Before dropping tank, any rodent damage? Chewed wires a possibility?
Any chance of siphoning or pumping fuel out?

[dougrainer]

Your RV is 22 years old. Odds are the fuel tank was not very full for those years it was not used. The main thing that ruins Fuel pumps/Sending units is MOISTURE that rusts out the components in the fuel tank. What you need to do, is have the RV towed to a shop capable of dropping the fuel tank after draining and then cleaning out the interior of the tank to remove the rust and rust flakes that WILL be inside the tank. You need a new Fuel Pump/gauge sending unit. They will also need to flush out the fuel feed and return lines from the tank to the engine. Doug

[211Racing]

Thank you to all. I do have a motorcycle jack and will see how to work it under the tank. Challenge is that the tank is 55 gallon and seems quite flexible when pushed on (thumped) from the bottom. It appears flush-mounted to the underside of the RV, so there's no peeking up there with a cell phone camera to get familiar with the layout/pump/lines. I have cleaned and/or replaced both of the frame to body grounds, but will look today if there is a specific ground on the tank.

[Scottiemom]

We bought an 8-year old coach in 2012 that had sat for I think 2 years. We were able to drive it home and then had our mechanic go through it because we wanted to take it to Alaska. He changed all the belts, hoses, fluids and filters. Gave it back to us and said. . . "I didn't change the fuel filter/pump because I would have had to drop the gas tank and didn't think you'd want me to do that." Okay. Shakedown cruise went great. Second time out, lost the fuel pump. Fortunately were close to a truck repair place and they ordered the pump and filter and dropped the drivetrain and fixed her all up. The gas that had been in it, was not treated when she was made to sit, so that was the culprit. We had the tank drained and cleaned out while they had it out. Once done, put in all new fuel and all was good. She went to Alaska and back and now, 9 years later I am still using her.

Dale

[hondapro]

Have you checked for power and ground at the tank connector? I would test the circuit first before pulling the tank.

[jdc1]

If you know someone with a motorcycle jack, you will not have to drain the tank.

[theoldwizard1]

Crawl under near the tank. Have someone cycle the key from OFF to ON (not start). You should be able to hear the fuel pump run for about 10 seconds.

Sometime in the 1990s (?), most manufacturers (Ford for sure) started adding a fuel pump control module. These are usually near the tank. They are known to fail.