Fuel leak from rear of car

twinbopilot

twinbopilot

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'98 has a strong smell of gas. Noticed a small puddle of gas under the fuel tank on the passender side rear. Slow drip coming from tank bottom but likely the source is somewhere higher and the fuel is just running down the tank. Car is 1/4 full.

My search yielded few results, but one thread mentioned a "purge valve solenoid". Could this be my problem?

Any suggestions on how to best troubleshoot and repair?
 
if you have made it a habit to fill your car past the gas pumps automatic cut off, then you probably have flooded your EVAP system and the hoses are dripping.

if that isn't a possibility, then you probably have a leak in the crossover hose that goes from the back of the tank on one side OVER the driveshaft to the back of the other side of the tank.
 
twinbopilot said:
'98 has a strong smell of gas. Noticed a small puddle of gas under the fuel tank on the passender side rear. Slow drip coming from tank bottom but likely the source is somewhere higher and the fuel is just running down the tank. Car is 1/4 full.

My search yielded few results, but one thread mentioned a "purge valve solenoid". Could this be my problem?

Any suggestions on how to best troubleshoot and repair?
Click to expand...


I found my leak to be the thin rubber gasket that the fuel pump sets on. It wasn't in it's groove. I replaced the gasket with one from a 93 tank and now I have no leak anymore. Being on the pass side, I'm going to have to say it's one of the 2 hoses that slide onto the pump or the seal itself for the pump.
 
Will I have to drop my tank to troubleshoot these things? :(

Anyone have any photos, or a diagram?

And no, I have not over-filled the car. I'm lucky if I can afford half a tank most of the time!
 
If you put 8 to 10 gallons in and make a left hand turn, do you smell gas? If so, try to run it down and only have about 2 to 4 gallons in and make that same turn and I bet you won't smell gas.
 
Its actually dripping while it sits on a nose-high incline in my driveway with about 4 gallons or less in the tank.
 
twinbopilot said:
Its actually dripping while it sits on a nose-high incline in my driveway with about 4 gallons or less in the tank.
Click to expand...

Odd one but with the cross over tube being so high up at the back of the tank, I wouldn't think that's it but do check it. I'm thinking it's one of the two tubes going into the pump. They just slide in with some cheap plastic clips that hold them in. One is white and the other is black. It could also be a dry rotted hose that goes into the tank from the filler neck. When you get the pass side dropped down, you'll find it fairly simple. If not, shake the hell out of it and it should show you where it's coming from.
 
twinbopilot said:
Thanks Nolimit94!
Click to expand...


No problem but also check the crossover tube as XLRVIII suggested. Any of those hoses could be dry rotted or simply just not clamped down anymore and loose. That one is a rubber hose with screw clamps and there are two more on the pass side with screw clamps on the back top side of the tank (pass side) that also have screw on clamps and then two hoses just slide into the pump with ease. In order for you to get the tank down far enough, remove the clamp from only one side of the crossover tube and the rear of the exhaust has to come down. Not a fun job but once you do it, the next time (if needed) is easy because you will know everything involved.
 
Matter of fact, before you go taking the tank or exhaust down, check the big hose coming from the filler neck. You should be able to see both clamps on that hose and if any were to dry rot, that would be the one. You will see another clamp on the smaller hose connected to the filler neck but you won't be able to see the end that attaches to the tank until it's dropped down. I really think it might be one of the two since it's on that side and it's on an incline with the front upwards. Must be kinda steep. If it's the big hose leaking, you're in luck. No tank drop needed. Take that hose off and go buy another one just like it.
 
Whatever it turns out to be, I'll post some photos of it here for future reference.
 
If it were the return line to the tank as nolimit94 described it would be a GUSHER of gasoline spraying out the passenger side of the car.

Since the care is sitting with a nose up attitude the sympton would not indicated the fuel pump Oring either as that is in the very front part of the tank.

This is going to be EITHER

the crossover tube on the rear of the tank that is just forward of the rear end housing..
OR the fuel filler neck and return that also go into the back of the tank.
 
Thanks Tommy - Looking forward to a Houston trip!

Here is a picture - not very good though. You can see the fuel on the bottom of the tank and then the puddle. It looks like almost the whole tank is wet from front to rear. Hard to say where its coming from yet...we shall see soon enough!
4176569575_6f7ee42e24_b.png


More info - the car was sitting overnight when this took place.
 
^oh crap

that very well may be the return fuel line, fuel pump oring seal that's alot of leakage and it being up in the front, almost totally rules out the crossover hose

Now I think NoLimit94 is probably correct

you can probably pull this off by only jacking up and supporting with stands <--for damned sure) the passenger side of the car.

I got my whole tank out from under my car only lifting the passenger side because I didn't/couldn't beg/borrow or steal enough stands at the dragstrip to safely get the whole car up.

ANYWAYS.

get the passenger side up high
take out both front tank bolts and ONLY the passenger side rear bolt and that should let it fall far enough down and to the side to get at the fuel lines at the front corner of the tank
You've probably got one of those nylon hairclips not correctly holding the hose OR a bad oring inside that connection.

Once you get the tank dropped down you can have someone cycle the key and pinpoint where it's coming from.

trust me when I say this.. sheild your F'n EyeS when they turn the key on!
Make sure your not staring into a fountain before you open your eyes

beware of static discharge at all times, dont blow yourself up bro..
becareful

Gas is one thing
Fumes are about 100% more hazardous
Pressurized fuel is about 100% more hazardous than fumes because it can rapidly expand into a very large fume cloud.
 
Turned out to be a hole in the bottom of the tank! Used a little tank putty and she's good to go...
 
Funny thing is I DID drop the tank - it was bone dry on top. Thats when I looked again at the bottom and saw a tiny seam maybe 1/4" long on the tank bottom. I had just assumed the fuel was coming from the top. At least now I know how to drop a tank on a Mark VIII! :D

PS - Did someone mention these tanks being made of plastic? Mine was made of metal. Gen 1 vs Gen 2 maybe???
 
Well that explains it. Thanks for all your help Tommy and NoLimit94!

PS - Dropping the tank was no big deal - took maybe 10 minutes.
 
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