1G Slight gas leak on most recent refill

[XC92]

I tried to refill my '92 Talon TSi AWD's tank a few days ago and several odd and worrying things happened.

First, the pump clicked off at what seemed like too low a gallon count. The tank holds just under 16 gallons and the fuel low light had been on for at least 5-10 miles by then, and it stopped after just over 10 gallons. Should have been at least 13-14.

Then, I saw that a small amount of gas had leaked onto the back of the tire and on the ground, maybe a couple of ounces, but had stopped leaking after the pump shut off, so I didn't see the actual leaking, just the aftermath.

Is this potentially dangerous, especially while driving, and is the most likely cause a bad fill tube, or perhaps the mechanism that prevents siphoning jamming? This has never happened before, to the best of my recollection.

There don't appear to be any leaks in any of the gas lines or hoses, but I haven't done a thorough check yet. Too damn cold here. But I was going to drop the tank to clean and coat the interior and derust and paint the exterior this spring, and replace some of the hoses and fittings and strainer. Better do that sooner than later?

 

[1990TSIAWDTALON]

Check the rubber coupler on the gas tube coming from the cap to the tank. That rubber piece gets hard and "could" be where it is coming from. That doesn't explain the pump kicking off, but my 1g leaked there so you should investigate that in any case.
I hope that helps!

 

[XC92]

Thanks. I'll check that. When I drop the tank I'll probably replace all the rubber hoses and other parts there, as routine preventative maintenance. Same with everything on the engine bay side, fuel and air lines, probably coolant too. It's way past time for most of these anyway.

And I wonder if modern pumps have sensors that shut them off if any change in pressure plus or minus is detected, to prevent not just overfill but also leaks, which would explain the shutoff?

So I just did a little research and apparently the way pumps know when to shut off is that there's a small hole near the tip of the refill nozzle, and when fuel covers it, as would be the case with a full tank, it tells the pump to shut off. However, fuel can also cover it if there's some sort of backflow before the tank is full, such as with certain leaks.

So this is probably what happened, and the leak is likely near or just below where the nozzle ends. I'll try to reproduce it next time I refill, and this time pay close attention to the refill hose in the wheel well.

 

[Mello]

When I drop the tank I'll probably replace all the rubber hoses

Heads up - not all rubber hoses are rated for gasoline.

 

[pauleyman]

Heads up - not all rubber hoses are rated for gasoline.

Excellent point. Do not be tempted to use a radiator hose to fix this. Auto parts store carry generic straights and bends in gasoline rated hose. The rubber fill hose for a 1g awd has long since been discontinued.

 

[XC92]

What, a piece of cheap garden hose wouldn't work?

Obviously I'd use proper hoses and fittings, etc., for all this. OEM if still available and not too expensive, decent alternative if not.

 

[pauleyman]

The fill hose is metal except where it connects to the tank. I had to replace it once and the hose was not availale to I used two pieces of straight and a metal elbow. There are 90 degree elbows available if this is your issue.
Check here.

https://www.dsmtuners.com/threads/resolved-1g-fuel-filler-hose-rubber-elbow.318092/

 

[XC92]

Thanks. I'll improvise as necessary, but only to spec. I wonder if Amayama has some items that aren't available in the US through dealers, or if there are decent aftermarket or performance versions available here?

 

[ErikTande]

I'm 99% sure it's the hose from the filler neck to the tank. Mine started leaking one day in the exact same manner. Luckily it's pretty easy to see and get to from under the car. Take it off and take it to napa and see if they have anything close.

 

[Paul@RTM]

We carry this hose.

 

[Mech Addict]

I got a new fill hose (elbow) at NAPA , but it was a little loose. I bought a fancy Mishimoto t-bolt clamp for a little extra oomph. Amayama and MegaZip are NLA. If RTM has one they found that works, you should get one from them.

I doubt that's your leak, though. There is a air vent that is rubber and reconnects way up high on the bigger diameter fill pipe. I would start looking there.

Also, in my car the "low" fuel light comes on with 4 gallons left. Refueling when the light comes on for me is right around 12 gals to full.

 

[XC92]

I'm 99% sure it's the hose from the filler neck to the tank. Mine started leaking one day in the exact same manner. Luckily it's pretty easy to see and get to from under the car. Take it off and take it to napa and see if they have anything close.

I'll 100% check it, for sure. Probably time to replace it whether or not it's to blame. Rubber dry rots and there's a lot of surface area there to rot.

We carry this hose.

Thanks. Good to know. There's a couple of other items I was planning on buying from you guys so I'll add it to my list.

I got a new fill hose (elbow) at NAPA , but it was a little loose. I bought a fancy Mishimoto t-bolt clamp for a little extra oomph. Amayama and MegaZip are NLA. If RTM has one they found that works, you should get one from them.

I doubt that's your leak, though. There is a air vent that is rubber and reconnects way up high on the bigger diameter fill pipe. I would start looking there.

Also, in my car the "low" fuel light comes on with 4 gallons left. Refueling when the light comes on for me is right around 12 gals to full.

Yet another part to check and probably replace. Perhaps the gas flowed so fast into the tank that it pushed fuel into the vent hose, which blocked the shutoff hole in the pump nozzle?

I also wonder if this could have anything to do with an idle surge issue I've been having, where at idle rpm fluctuates between around 1200-1500, each cycle taking several seconds, like clockwork. MPG has been horrible.

I also wonder if not completely draining my tank after the car sat for 5 or so years with the engine rarely being run had anything to do with any of this. I probably left a gallon or two in there before topping it off with fresh gas and adding some dry gas or Techron for added measure.

 

[Dericsh]

Hey I think @TK's9d2TSi had a fuel fill problem a while back maybe something similar?

 

[ist dwa]

Fair warning, when servicing anything on an OEM dsm tank by now be ready to purchase a new JM fab drop in because it can go real south real quick. Broken studs for the drop in unit, leaking at the split in the tank, dry rotted hoses, bad inlet and out let metal hoses, bad gasket for sender...... rust, rust and more rust!

 

[waltah]

Fair warning, when servicing anything on an OEM dsm tank by now be ready to purchase a new JM fab drop in because it can go real south real quick.

I'd go a little farther: If you plan on keeping and driving your car for a while, buy at least those hoses and have them on hand. They do rot, they flex as the car is driven (full gas tank is heavy), there are no unimportant gasoline leaks and it may not be possible to get a proper hose quickly when it does fail.

I also wonder if this could have anything to do with an idle surge issue I've been having, where at idle rpm fluctuates between around 1200-1500, each cycle taking several seconds, like clockwork. MPG has been horrible.

Idle of 1200-1500 RPM is wrong. Things that could cause that include an air leak in the intake area, the Basic Idle Speed Setting misadjusted, the throttle stop screw misadjusted, and the closed throttle position switch failed or set incorrectly.

'Horrible MPG' (15 MPG or less?) is probably something else -- a leaking injector would be one possibility -- but I'd work on the idle first because that's clearly wrong and fairly straightforward to troubleshoot. The more symptoms you can get rid of, the cleaner picture you'll have to look for the next thing.

I wouldn't give yourself a hard time over not following some fantastical perfect restart-after-five-years procedure to avoid all troubles. That does not exist. The main thing with older cars and current ethanol blend gasolines is probably 'drain it when you stop driving it' if you can but looking at things from the other end of the telescope -- you bought the car, the prior owner said "it's been off the road for a while" the best you can do is clean it up and start driving, realizing that water+oxygen has been at work for a while and you will have troubles.

Then, I saw that a small amount of gas had leaked onto the back of the tire and on the ground, maybe a couple of ounces, but had stopped leaking after the pump shut off, so I didn't see the actual leaking, just the aftermath.

A leak there that stops when you stop filling is likely in the rubber hose at the top of the small vent line. A leak in the fill hose is down next to the tank and the symptom is you finish filling, smell gas, look under the car, and the back of the tank is going drip-drip-drip on the ground.

It's also possible for the two metal pipes to rust through but usually the hoses go first.

 

[92AWDHX40]

I found a hose at napa year's ago , still hold up, I por 15 the entire pipe year's ago to its holding up great.

 

[AWD-Tony]

Hey I think @TK's9d2TSi had a fuel fill problem a while back maybe something similar?

I replaced the filler neck and both hoses. Didn’t have a leak but when I went to fill up, the gas pump kept stopping. I cleaned the check valve since it was right there (idk if that had anything to do with it tbh). Haven’t had a problem since.

 

[XC92]

So I took another look by the gas tank area. The metal filler pipe is a bit rusty but otherwise seems ok, along with the middle vapor hose pipe. When I service the whole thing soon I'll remove them and everything else, remove the rust, clean them up and paint them with something durable, as I've done with everything else so far.

I even bought a Milwaukee M12 right angle die grinder with all sorts of abrasive wheels so I don't have to use a low-speed driver or drill as I've done in the past. And yes, I'll be careful since it's gas.

I'm also going to replace all the hoses. RTM sells a Gates elbow hose that can replace the no longer available OEM lower filler hose, so I'll get that. As for the various vapor and return hoses, what kind of fuel hose do I need? I think that some are 14mm ID while others are 8mm. Does that cover it or are there 6mm too? And what kind/brand is recommended? Anything that RockAuto sells as fuel hose ok?

And what about the high pressure hose from the pump to the hard line, replace that as well, and get the OEM, or an aftermarket replacement?

I'll also replace the upper filler gasket and fuel pump gasket, and pump strainer. I've already got new lock nuts that attach the tank to the body, and a new crush gasket for the drain bolt. Anything else I should replace? What about the cap or at least its rubber o-ring? They seem to be OOS.

Oh, and after I clean and derust the tank, what if anything should I coat the inside with? I assume that anything's suitable for the exterior surfaces.

 

[luv2rallye]

I have a 2g but the metal filler neck tube is what typically rusts at the bend and starts off with pin hole leaks. Don't scrap off the rust on it or the pin holes will get bigger. I'm replacing mine right now again (2nd time in 23 yrs failed exactly the same way).

 

[XC92]

I'll check, thanks.

Yeah, saw those. When I take it all apart I'll check for rust that's gotten beyond the surface stage. But, so far on my car I've not come across rust this bad, on anything. It was garaged for many of the years I owned it and I've generally not driven it much in rust-promoting conditions. Plus the plastic shield there covers it up pretty well.

 

[Mech Addict]

Some of those other hoses are metric and don’t play well with common fractional-sized fuel hose, as preposterous as that sounds. I think the 14 mm makes 1/2 hose very tight, but 5/8 is loose. I believe I searched Amazon and found actual 9/16 hose and it was a nice snug fit. I don’t remember the other ones being as much a problem. I do remember protracted fighting with 1/2, lubing it with a little gas, and still pita. I got one part on enough, but removed it because of concerns it might split over time.
The threaded pressure hose with fittings I believe is nla, so if yours looks weathered or rusty fitting, not sure what to do. Mine was “ok”, though I would have gladly replaced it if I could have bought a replacement reasonably.

 

[Mech Addict]

I have a 2g but the metal filler neck tube is what typically rusts at the bend and starts off with pin hole leaks. Don't scrap off the rust on it or the pin holes will get bigger. I'm replacing mine right now again (2nd time in 23 yrs failed exactly the same way).

Might be a 1g-2g difference here in terms of rust-potential, because my tank was all rusty on the inside (and a bit on the outside) but the filler spigot was totally sound.
Also, be careful with the fuel gauge sender when you remove the pump hanger, because those also are nla.

 

[XC92]

I'm actually a bit confused as to what kind of hose to get, in terms of type and size, especially the ID. The DSM parts catalog appears to indicate 14mm for the vapor s hoses that go back to the filler pipe, but what about the 2 short hoses that go to the hard lines that go to the engine bay, the vapor and return hoses, what ID are they?

And what about the high pressure hose, if it's no longer made, are there aftermarket ones available? If I'm taking it all apart I might as well replace it all, to the extent possible. At this point I'm not looking to replace the actual hard lines under the car or any hoses or lines downstream of them, unless I see some bad ones that need replacement.

Btw, did you clean and coat the inside of your tank when you had it out? And what kinds of precautions did you take so it wouldn't explode? After draining all the gas from the drain plug, is it ok to dump lots of water in there to dilute any remaining gas and drive out any fumes, or is that bad or ineffective?

 

[Mech Addict]

Yes I did clean and coat the tank interior. Thought I had that in my build thread, but just checked to find I don’t. My advise for tank safety is to drain or siphon all the free liquid you can, remove the tank from under the car, and let it sit outside somewhere for several days to evap all the volatile vapors. Perhaps not the most environmentally sensitive way, but safer. Then use some water-based cleaners to clean etc. I used the Eastwood kit. It generates a lot of waste acid and solvent batches, but seems effective. Haven’t looked in my tank since doing it, but no more symptoms related to tank crud.

 

[XC92]

Unfortunately my situation doesn't allow for letting an empty tank sit outside for days to let the gas fully evaporate. It would either get stolen or reported to the police as a potential explosive hazard (and rightly so as I work on my cars on the street). But, given how volatile gas is, isn't it reasonable to expect it all to evaporate within hours on a relatively warm and dry day?

I actually bought the Delphi tank cleaning kit a while back. Is that any good? It's only to clean it, not coat it. I'll probably put a chain or nuts and bolts in there to slosh around to dislodge the rust and gunk. I might also put in some Evaporust and do some manual brushing to agitate the crap off. I want it to be as pristine as possible before coating, so I'll never have to do this again.

But, what to coat it with?

Also, I think I've found a good source for the 14mm fuel hose that goes in-between the 2 metal tubes on the vapor line that feeds back into the filler tube. It's 5/16" which is just a hair narrower than 14mm.

But I'm still unclear as to the ID of the fuel and vapor return hoses that connect the top of the tank to the lines that come from the engine bay. Any idea? The FSM & catalog aren't clear.