i started my rex after a year of sitting, and tons of gas i saw under the car leaking out, its dripping right behind the motor and going leaking down over the front of the transmission. any ideas what it is, i cant see or get to where i "THINK" its coming from, it will leak with the car off with fuel pump running.
thanks for the help guys.

 

I haven't messed with the fuel rails in my car for a while, so I don't remember exactly how the fuel lines go, but I can pretty much guarantee it's one of the lines to/from/between the fuel rails. It could also be your pulsation dampener (do a search for more info), but that's near the front of the engine

Pull off the upper half of your intake manifold and jump the yellow 2-prong connector near the passenger-side shock tower and watch for leaks. You should probably replace all the lines while you're in there, anyway.

 

its behind the motor and leaks over where the tranny connects, i dunno how to get to it.

 

Have it towed to a mechanic if you don't even know how to remove the upper intake.

 

+1
The pulsation dampener seems to be the most likely culprit. However in your sig it says the engine has been rebuilt, who would rebuild an engine and retain the stock PD ?

 

replace all the rubber fuel lines.

 

Yeah man, get the upper intake manifold gasket ordered because you will be taking it off soon to get to the fuel rails. It might seem like a daunting task at first , but it really isn't that bad.

At that point you will be able to see if it is the FPR or just a hose. Either way, you will want some high pressure fuel hose handy to go ahead and replace them while you are in there.

Needless to say, massive fire hazard atm that has claimed more than one s4.

 

If it's any help, this is what you would be looking at on a S5. A few things, including the FPR on the top fuel rail are different, but this will give you an idea of the hoses we are talking about:

 

ok so i'm going to attempt this today, i rolled it out today and i turn the motor over for 2 seconds, and then off leave the fuel pump running and 1 min later gas is pooring over the top left of the tranny i mean TONS

 

any other help or pics would be very helpful, i've never taken a upper intake off before.

 

follow the factory service manual or go buy a haynes manual, both will give you the basics of how to remove the UIM. a camera comes in handy also for reference pictures. with the amount of fuel you are describing i can't believe it is the pulsation dampener, sounds like a cracked dry rotted fuel hose.


also on a side note, mazda never made a turboII in 1986, '87 was the first model year that the FC came in turbo.

 

You mention that the fuel is present towards the rear of the engine and not the front of the engine. Is this correct? If it is then chances are likely that the hose that connects the primary fuel rail w/the secondary rail is the culprit or the return hose to the fuel tank is problematic.

 

fuel will leak from many places ... cracked fuel line, bad clamps, bad pulse damper, bad injector o-rings ... the s4 fuel rails are different from the s5 rails, s4 rails are multi piece and have copper washers at each fitting that could be leaking

 

Since the S4 pulsation damper is located towards the front of the engine and the leak is occuring towards the rear of said engine, then doesn't that lessen the chance that the leak is coming from that particular item?

 

if i was physically there looking at it, i could probably narrow it down.. but since i am not i can't say...

if it was me, i would replace the hoses, the injector o-rings and the damper... but that's just me

 

I had almost the same issue with my S4 N/A, except it just wasn't leaking quite as much, but you could see fuel pooling on top of the engine and soaking one of the heater hoses. I pulled mine apart and as far as I could tell the crush washers and rubber hose looked okay, since there was nothing else in there that could be leaking I am replacing all of the rubber hoses you can't reach with the UIM on, and the crush washers. Just waiting for the washers to get here before I re-assemble.

 

I am guessing rubber line that connects to the return line to tank.

 

If it sat for a year you could have had a rodent nest up under the UIM and eat at the rubber hoses, possibly wiring as well.
You really need to pull the UIM and investigate.

 

this is a TII, the PD sits at the rear of the engine as well as the feed and return lines, the crossover hose from primary to secondary rail sits at the front. the PD is unlikely to leak that much as i haven't ever seen them give off more than a trickle in the worst cases.

we can guess all day but simply it has to come apart and pressurize the system to find the leak.

 

i had the same problem with my turbo 2 and it was the PD i would drive and u could follower a gas trail haha so going off how you are explaining it i bet its the PD

 

Have the lines replaced and get a fire extinguisher.

 

it was leaking under the FPR the hoses weren't

 

Problem seems to be fixed, but as someone might have mentioned above................the FUEL PUMP CHECK CONNECTOR has a purpose in life. Its purpose is for you to see if the fuel lines and injectors are leaking after working on that area of the engine and prior to reinstalling the upper intake manifold.

You do your repair job, and prior to reinstalling the upper intake, you jumper the fuel pump check connector and turn the key to just ON (not start). Fuel pump comes on and stays running which pressureizes the fuel rails and hoses and you check for leaks. Then reinstall the upper intake manifold. In other words you don't replace hoses/dampers/injector o'rings ***** nilly. You find the leaking item and just replace that items.

 

^^I agreed to that ... mostly

but the car is old so replacing some rubber lines here and there wouldn't hurt ...

Just make sure when you go buy some new rubber hose for fuel, remember you MUST BUY FUEL INJECTION HOSE! NOT FUEL HOSE! THEY ARE DIFFERENT !

2 weeks ago I went to an Autozone to get a few more ft of Fuel Injection Hose, the idiot there (maybe in his 40-50s) said he couldn't find it, and he said he has some Fuel hose, it's the same thing, and he has been working for AZ for 10 years and never had any customers come back and complaint ...

I was thinking like yeaaaa, sure, those poor suckers probably wonder why their car burst up in flames and everything just burn up and never thought it's the "FUEL HOSE" that blew up and killed their ride.

so I told him no, I'm not buying Fuel Hose.

I walked to the back with him, and I spot the roll of Fuel Injection hose just right behind the roll he was holding at ...

That explains why he has to work at Autozone for the past 10+ years and NEVER got a promotion ...

 

All his old customers cars burnt to the ground so they never had a reason to come back.

First time I ever had a problem with leaking fuel hoses was on a trip from Corpus Christi to Ft Worth. I had a faint smell of fuel all the way to Ft Worth. Pulled the upper manifold and jumpered the check connector. I had what seemed to be a pin ***** in the hose from the lower to upper fuel rail. It sprayed a fine mist when pressurized. Old hoses I reckon. Replace all while there. Just makes sense. That's when I found out fuel injection hose cost quite a bit more than standard non fuel injection hose.

Non fuel injection hose get??? what??? ten fifteen lbs/in and fuel injection hose around 70-80 psi.