03 Protege leaking from fuel tank seal

[matt701]

I have an 03 protege lx that has developed a gas leak. I found the access panel under the rear seat and found the source of the leak is on the top tank cap where the pump goes in. Does anyone know if there's bolts that come out, or does the whole top cap spin off after I remove all of the hoses and wires? I see tiny bolts on the outside of the cap, but they are so rusted I couldn't get a tool into them. I'm not even sure if they had a head or are flat I guess. The gas is coming up into the middle of the cap, so I'm assuming I just need to replace the gasket. The rest of the tank is in pretty good shape, I don't want to spend a lot of money if I can just replace the cap or gasket. Thanks for any advice!!
Matt
Syracuse, NY

[matt701]

I thought of one more detail. When I turn the key on, it starts leaking but only a little. When I start it, it really starts coming out and thats on 1/4 tank of gas.

[goldstar]

Welcome to CP.

The fuel pump unit cover is attached to the tank with bolts which must be removed in order to take it off. It doesn't just spin off. According to the FSM, the torque setting is 14-23 in/lbs (1.5-2.6 N-m)so go easy when reinstalling. Most likely it's the gasket under the cover that's leaking (which should be replaced everytime after pump removal anyway).

Good luck with the job.

Happy Motoring!

[matt701]

Goldstar, Thanks for the reply and welcome! Are those the smaller bolts on the outermost lip? I think there's about 6-8 of them if so. The heads of those are rusted. Do you think the mazda dealership would be able to grind them out and install new parts? I'm trying to avoid a whole new tank cost if at all possible.

[matt701]

Also, you wouldn't happen to know if thats a torx or allen head on the bolts do you or what size I need?

[goldstar]

Sorry, I took the information from the FSM, not the actual assembly, and the diagram was unclear as to the type of fastener used. They are the small fasteners around the outside of the mounting plate. I'm sure the dealer could help you out on the removal.

Happy Motoring!

[matt701]

Thanks again, I really appreciate it!

[smokstac]

One of my Proteges had allen heads and the other had Philips heads on the screws holding the fuel pump housing in place.

Oh, and grinding anything near the gas tank is a big NO-NO.

Is it physically leaking liquid when the key is turned on or do you just smell gas?

[matt701]

They do look like allen heads. I won't be grinding anything. As soon as I turn the key on, a small puddle forms right in the middle of the cap and then it seems to stop. Once i start the car, it seems to increase the flow but I cannot tell where its coming from. It looks like it's coming from under the metal plate thats sitting over the rubber gasket, but I can't tell where. I didn't know if the outlet hose from the pump had its own gasket somewhere.

[goldstar]

Diagram of fuel pump unit showing components and disassembly/assembly order. Components marked R should be replaced before re-assembly.

[smokstac]

I still can't imagine how fuel is getting on top of the metal housing aside from one of the rubber hoses to/from the engine not being tight enough or having a small leak. The fuel pump is beneath the cap and pumps upward through the cap, to the hose, and the other hose returns fuel from the engine to the tank.

Maybe there's a small crack in the housing from where someone pulled on the cap before and slightly broke the fitting.

[matt701]

Thats whats confusing also. I would assume driving around and hitting bumps would put gas past the rubber seal if that were defective. I'm not driving or moving the car with 1/4 tank of gas and it leaks as soon as I turn the key on or just start it. The first sign I see is from around the metal plate, gas comes from under there and then moves inward around the hoses and electrical connector for the pump. It then drips forward of the tank and drips to the ground, so it looks like it's leaking from the seam if you only looked under it.

[smokstac]

The only thing that makes any sense is that the tank is really full and your sending unit is saying it's on 1/4 tank. I can't think of any logical reason why it should do this. What happens if you take the fuel cap off and try to run the pump?

[smokstac]

Although I guess it's possible the collar between the fuel pump and the housing could have separated allowing pressure to build up on the bottom of the housing. That sounds reasonable. I did notice this before on a few Protege fuel pump/housing units at the JY...some had more clearance than others between the top of the actual pump and the housing where it attaches to the fuel tank. IIRC there's a small rubber hose that connects the outflow from the pump to the housing and if that has split you might get the symptoms described.

[matt701]

No, the guage is right. Wife smelled gas end of last tank and still filled it. I've been driving back and forth to work to empty the tank so someone can work on it, been about 300 miles and it's around 1/4. The leak wasn't any worse when she brought it home full than it is now at 1/4 tank. I will try pulling the cap tonight to see what happens. It seems to leak worse in the heat we've been having, so I wonder if it's not venting out the cap like it's suppose to or if the pump is just running all the time and there's a split in the line somewhere in the tank cap. I'm going to see if I can get the bolts out this weekend using vise pliers. They are small and only put on with 14lbs of torque, seems like they would come out pretty easy, even rusted. If I can't get the cap out I'm dropping it by Mazda on Monday. The exhaust pipe runs right under the center of the tank where the cap is leaking, so I don't want to drive it too much more. It's neat though that Mazda put an access panel under the seat so you don't have to drop the tank. This is my first Mazda, I traded straight out for my near mint 95 firebird on craigslist. Only been 2k miles in it so far and it's really fun to drive.