90 E-150 Fuel leak/stalls on front tank, runs fine on rear

Hello,

I bought my 1990 E-150 5.8L this year with about 132K on it; it's a conversion , and I'll start by saying I'm no mechanic but I can read a manual and follow most directions. :)

There are a couple of issues - I'll start with the most important - the fuel leak. Right now when I switch from rear to front it takes about 5-10 seconds and the engine starts sputtering - it will eventually die (whether on the highway at 60mph or sitting in the driveway). Before it dies, switching back to rear clears it up almost immediately. My mechanic (the one I won't go to anymore) replaced the oxy sensor (said it was bad) and sent me home saying the problem was not happening when it is. Any ideas?

HISTORY:Other than a transmission leak, it ran well for about 500 miles on the way home from the place of purchase and had decent mileage - 15/16 mpg with 2 people, 3 kayaks and gear. My mechanic fixed the transmission problem and a few other issues but I noticed after picking it up the exhaust was very rich and the mileage decreased considerably - 12mpg. (I mentioned it but of course he didn't notice it or do anything wrong)

Drove it for about another 500 miles - no problems. Next trip: after using both tanks on a trip (350 miles) we filled up and I smelled a lot of gas in the driver's seat area but didn't think anything of it as we were at the filling station. The next day, it still smelled considerably of gas (as though I spilled some near the driver's seat) but I didn't see anything leaking underneath, and with 8 people and kayaks on the way to a river, it died. Switched to the rear tank and it ran fine; the gas smell didn't completely disappear but diminished a lot. Have been running on the rear tank with a minor gas smell.
REPAIRS TO DATE:
Front & rear transmission seal, front bushing, oil sending unit, air tubes replaced 4/06
A/C recharged 4/06
Rotors turned, rear pads replaced 4/06
Thermostat replaced with racing thermostat 5/06
Alternator, oxygen sensor replaced 7/06
Thanks in advance for your advice!

Due to the fuel leak, the fuel lines are pumping air to the motor. When using the rear tank the pump is not pumping air to the motor. Find and fix the leak and your problem should go away.

Due to the fuel leak, the fuel lines are pumping air to the motor. When using the rear tank the pump is not pumping air to the motor. Find and fix the leak and your problem should go away. Great - thanks! Now another stupid question - any special tricks for easily finding fuel leaks (besides using a match :wink: )? I don't see anything dripping when the car's running (but it doesn't have to, I guess to get air in) but I sure smell it.

I took some pics - can anyone help ID these three things? Here's the flickr page with more info: http://www.flickr.com/photos/23621290@N00/ Thanks again!

#3 appears to have 4 lines running to tanks (2 to each) - is located in front of front (aux) tank on driver's side

http://static.flickr.com/98/243981116_35741d840b.jpg


#2 by driver's door - looks like a large rusty soup can

http://static.flickr.com/94/243981118_b3996fe4ab.jpg

#1

http://static.flickr.com/90/243981123_68449c8e17.jpg

If you can pay somebody at a gas station to put it on a lift it makes it easier.Use a flashlight and and look closely first with the truck shut off. Feel around the top of the tanks. Surely you will find a damp spot. Look at the hose on the filler neck they go bad sometimes. Start at the rear tank and follow the fuel line all the way to the motor. the same with the front tank.
Your no.2 looked like a vacuum canister. Pull the vacuum lines to the fuel pressure regulator and any switching valves to see if a diaphram is leaking.
I think for $5.00 or $10.00 to rent a lift and an hours time you will find the leak. Also check around the top of the motor.
This can cause a fire check it out immediately. Call a few stations until you find one.