Fuel Leak - Dealer says something wrong with sending unit

[livelyjay]

- I've noticed an increase in fuel smell when driving, and when I'm done driving the smell lasts outside the car for a bit.
- The other day I moved the car and it was raining, and a rainbow spot showed up near where the driver's side rear tire would have been, indicating gas was indeed dripping.
- Took it into the dealership, testing and diagnostics came up with nothing.
- Dealer took out the back seat and said fuel is leaking from the sending unit, quoted me $550 for everything.

What the hell is the sending unit and why would it be leaking? I thought we just had a basket with fuel pump and strainer. How could it even leak? I was thinking maybe the O-ring went bad and they just want to charge me for everything.

Any thoughts?

 

[rally2003]

Do you know where the leak is at or is that what they just told you?

 

[livelyjay]

That's just what they told me. They said they saw no visual leak (no dripping), their smoke test was also negative for leaks. When he explained it to me, he said they took out the back seat, opened up the panel, and believes there's fuel weeping out on top of the tank or sending unit. They said it might also be a hole in the tank. I would be shocked if there's a problem with the tank, because the car only spent 1 winter in the salt. My silver MSP (I have two of them now) has seen 7 winters and has no issues.

 

[rally2003]

You would smell gas if it is coming from the tank and looked around the panel. Might be the injector seals on the IM?

 

[livelyjay]

I do smell gas, near the left rear tire, which is where the gas stain on the driveway was located. It's not a line though because all their tests and inspections came up negative.

My question is, what on/in/around the tank could be leaking and how do I diagnose it?

 

[bikingpro5]

this is a know issue with our cars as they get older, the plastic top of the fuel sending unit leaks. Its not a $550 problem to fix its much cheaper if you do the work yourself.

the top piece cracks and leaks fuel under pressure

full thread and pics on how to fix it here
http://www.mazdas247.com/forum/showthread.php?123718385-Has-Anyone-Had-Their-Fuel-Pump-Cover-Leak

its a common issue and a simple thing to fix

 

[livelyjay]

Mmmmmmm slimy mucky mess.

Thanks a billion for the link and heads up. I can totally do the work myself too, so suck it dealership. I'll just drive the car to work and deal with the smell until the gas tank is almost empty, then park it and wait for the parts and drive my silver MSP that isn't leaking. Weird how the car with 60k on it is leaking (2003) and the one with 130k on it (2003.5) isn't leaking and never has.

 

[Keno1542]

if you look in the fsm under the after fuel repair, it will tell you how to test for fuel leaks by shorting one of the diagonstic ports to ground.

 

[tyman108]

Its not a $550 problem to fix its much cheaper if you do the work yourself.

+1 had same problem my self super easy and a lot cheaper then the stealerships.

 

[Preferio]

In short, OP, go buy a fuel pump assembly, yank really hard upwards on the rear seat, use a Phillips screwdriver to remove the bajillion screws retaining the inspection cover, then disconnect the harness and fuel lines, remove the sending unit and reinstall in reverse order. Voila!

 

[rally2003]

Winning!

 

[livelyjay]

Well I have an update on this pain in the butt problem. I bought the replacement parts and waited till I had the time to work on the car. The 90 degree angle piece that's two pieces was indeed loose on the fuel pump assembly. I got 3 out of the 8 screws to come out. Stripped all the rest of the screws. Tried to tap and easy-out two more and the screw heads popped off. Bought the Craftsman screw-out that someone suggested and that just cut into the screw heads.

Last ditch effort I used two part epoxy and completely covered that outlet elbow. I let it dry for three days, then chiseled off the stuff that covered the hose section and the area around the electrical plug connection. Replaced the three screws with stainless hex bolts and put everything back together. I refilled the tank last night and drove it around a bit and didn't notice any fuel smell, but it was 0 degrees out with high winds, so I might not have been able to smell anything any ways. Once the weather warms and is less windy I'll drive it around a lot and see if there's any fuel smell. If not, then we have a way less invasive way to fix this problem.

 

[hornsfan10609]

Those screws are a major PITA, someone should have given you a heads up. They have to come out though, you really need to replace the sending unit and fix it correctly.

 

[livelyjay]

I did get a heads up, and there's nothing I could have done differently with the screws. I doused them with PBlaster two days before I even tried to remove them.

 

[hornsfan10609]

There are lots of tricks to removing phillips screws but I hate them for the most part. You can always use pliers to turn them or just grind the heads off.

 

[livelyjay]

Well yeah I can always drill off the heads, but then how do I affix the new fuel pump assembly? Drill out the screw entirely? I could see that possibly working but I don't have an 8mm tap. Guess I could buy a set and try it, since a $50 tap set is cheaper than a new gas tank and the labor to replace the entire thing and the tap set will probably get used sometime down the road.

 

[livelyjay]

Anyone know offhand what size those stupid screws are so I can buy the correct tap/die set? Are they 8x1 or 8x1.25?

 

[livelyjay]

Go figure, the epoxy trick didn't work. I'll attempt the drill out, re-tap of the screw holes and see how that works out. If that doesn't work or I end up drilling out the threads, I'll try using sheet metal screws or SAE bolts. If that doesn't work, I'll replace the tank. F U Mazda for making this such a hassle.

 

[hornsfan10609]

The gas likely ate the epoxy. I bet some self-tapping screws would do the trick once you drill the old ones out, if it comes down to it.

 

[livelyjay]

The gas likely ate the epoxy. I bet some self-tapping screws would do the trick once you drill the old ones out, if it comes down to it.

That's what I am guessing too. Wouldn't self tapping screws end up being too long? The OEM ones are only 8mm long. I wouldn't want to use a self tapping screw and have it go through the flange and into the tank.