Locking gas caps: shocking facts revealed.

Pretty interesting stuff JD, who would have thought. Though, instead of a cabinet lock, why not one of those electronic billet fuel doors?

Kate

14 to | 21 mpg with only those two changes. Amazing. | | The Beater must be smogged in a couple of months, so I installed a non-locking | cap on that as well. It actually runs much better now! My mileage has also | increased from 29 to 33 mpg at last check. I would have never thought that | such a small change would have such a profound impact on both performance and | fuel mileage. | | Food for thought. At $2.25/gal for regular around here, this deserves a LOT | of thought. I've never installed a locking cap on Charlene, and after | learning of this, I may instead put in a cabinet lock on the fuel door | instead, if I feel it absolutely necessary to secure it. | | -JD |

I gave up on the paranoia of locking gas caps a loOOONG time ago !

First of all, modern cars have siphon traps in them, so you can't get a hose far enough down the filler neck to get it wet anyway, Second who siphons gas anymore?

Even if they DID siphon some out. IMO it would have to happen quite often to make the aggravation of having to use a key worth while.

Now, I realize that they also keep extra "addatives" out of your tank, and if you live in a problem area, or have a lot of enemies that *might* be a valid reason to own one. Other than that, I think they're a waste!

if you're that paranoid buy a car with a fuel door release inside !

my .02

The reason I gave up on locking gas caps years ago is that (while repoing cars) the keys are nearly universal. Most of the time if you take any locking gas cap key, put it in the slot and jiggle it, it WILL unlock.

Oh, and while I'm at it, did you know that glove boxes on Mustangs are the same way? On my year model anyway. Put any ol key that fits the hole, and Viola!

Kate

| > HC was way up there, at least 100 ppm beyond nominal. CO and NoX numbers | > supported a fuel system problem as well. Everything else (visual and | physical | > check of all engine and fuel system components) was fine. | >

| > How could this be? This is a nearly-new, 1000 mile old rebuilt 5.0 | directly | > from Ford that was installed by Ford's own techs, and it runs great except | > that it is a bit cold-blooded in the morning. | >

| > After finding a 'Gold Seal' shop, we finally get answers. (Gold Seal here | in | > CA is the best of the best: they are licensed to do checks and service | both, | > not just smog checks, and they are heavily regulated and watched closely.) | >

| > The answers: | > ------------ | >

| > 1. The shop who smogged it first were dumbasses and thieves. They did not | > operationally check various engine control components, and missed a very | > important clue in this mystery. All they did was run it up on the dyno | and | > sniff the pipes, nothing more. | >

| > 2. The Gold Seal shop found one leaking injector, something the engine | tech at | > the Dealership missed when installing the new engine. (You would | think...) | >

| > 3. He also tested the Stant locking gas caps and found that neither worked | > properly. In his own words, "I've never seen a locking aftermarket gas | cap | > that will pass a vacuum/pressure/seal check, and most shops don't bother | to | > check them." Apparently, the first shop did not, helping the vehicle fail | the | > test. | >

| > 4. The reason according to shop #2 for this is that they want you to come | back | > for another $60 retest after someone else does the repairs. Often, they | will | > offer a $10 discount as well. Sneaky yet profitable. | >

| > Shop #2 retested free after ONLY changing out the fuel caps with Stant | > non-locking units. It passed, though barely. After replacing injector | #2, it | > passed again just fine. | >

| > His advice: Use a non-locking cap when you get a smog check. Be aware | that | > some fuel systems behave badly when aftermarket locking caps are used, and | > poor fuel mileage and excessive emissions will be the result. | >

| > Her engine runs like a fine swiss watch now. Her fuel mileage went from | 14 to | > 21 mpg with only those two changes. Amazing. | >

| > The Beater must be smogged in a couple of months, so I installed a | non-locking | > cap on that as well. It actually runs much better now! My mileage has | also | > increased from 29 to 33 mpg at last check. I would have never thought | that | > such a small change would have such a profound impact on both performance | and | > fuel mileage. | >

| > Food for thought. At $2.25/gal for regular around here, this deserves a | LOT | > of thought. I've never installed a locking cap on Charlene, and after | > learning of this, I may instead put in a cabinet lock on the fuel door | > instead, if I feel it absolutely necessary to secure it. | >

| > -JD | >

| |

That's an option I hadn't thought of. She stays locked up in the garage now, but if things change, that's one way to go. I've had cars sugared in the past; a locking cap stopped the last vandal. They instead cut both front brake lines. Nice people!

-JD

I've noticed this, Chief. Even now that fuel is $2+/gal., you don't hear about gas thieves. Personally, I think the really stupid ones were killed off by chemical pneumonia back in the 70's during the so-called 'fuel shortage.'

Charlene stays in a locked garage, so she isn't a target. The beater however, stays out and gets parked in seedy areas, and I'm more concerned about vandals than anything else. I may just install a $5.00 cabinet lock on the fuel door this afternoon and fergetabouddit.

-JD

Wow, you mean you stick a key in your glove box, and a stringed instrument pops out ???

or did you mean Voila :D (ducks and hides in the back of the garage for a while )

You're right though... glovebox locks are usually a cheap lock with only a few tumblers, so it's common for a zillion keys to actually work on them.

Explain this one to me. How can a leaky cap affect fuel mileage and emissions ? The only emissions you'll have is the evaporation of the fuel out the leaky cap. It won't affect your engine itself. Same for poor fuel mileage.. that might be due to the leaky cap, having fuel evaporate out the cap. Unless the car is not driven much at all and a LOT of fuel evaporates, I can't see why there's such a huge difference in mpg....???

The other day I had fueled up and as soon as I drove out the gas station the fuel gauge didn't move at all.. I shut the engine down, started it up and it did move. While driving the following days after that the gauge would sometimes drop to 0, stay there for a while, then go back to reading the fuel level. After about two days the service engine light came on. This is when I checked the fuel cap.. it seemed closed normally, I opened it and closed it again. SErvice engine light went out, and the fuel gauge worked normal since. The stock cap wasn't locking correctly. Weird that it also affected the fuel gauge, but that also helped me find the problem. I was about to read the codes which would have indicated the fuel system anyways.

Remove NO-SPAM from email address when replying

Damn... and no bodies? Who are you pissing off anyway? K.

No silly... little purple flowers!

| > Kate | >

| >

| > | > HC was way up there, at least 100 ppm beyond nominal. CO and NoX | > numbers | > | > supported a fuel system problem as well. Everything else (visual and | > | physical | > | > check of all engine and fuel system components) was fine. | > | >

| > | > How could this be? This is a nearly-new, 1000 mile old rebuilt 5.0 | > | directly | > | > from Ford that was installed by Ford's own techs, and it runs great | > except | > | > that it is a bit cold-blooded in the morning. | > | >

| > | > After finding a 'Gold Seal' shop, we finally get answers. (Gold Seal | > here | > | in | > | > CA is the best of the best: they are licensed to do checks and service | > | both, | > | > not just smog checks, and they are heavily regulated and watched | > closely.) | > | >

| > | > The answers: | > | > ------------ | > | >

| > | > 1. The shop who smogged it first were dumbasses and thieves. They did | > not | > | > operationally check various engine control components, and missed a | very | > | > important clue in this mystery. All they did was run it up on the | dyno | > | and | > | > sniff the pipes, nothing more. | > | >

| > | > 2. The Gold Seal shop found one leaking injector, something the engine | > | tech at | > | > the Dealership missed when installing the new engine. (You would | > | think...) | > | >

| > | > 3. He also tested the Stant locking gas caps and found that neither | > worked | > | > properly. In his own words, "I've never seen a locking aftermarket | gas | > | cap | > | > that will pass a vacuum/pressure/seal check, and most shops don't | bother | > | to | > | > check them." Apparently, the first shop did not, helping the vehicle | > fail | > | the | > | > test. | > | >

| > | > 4. The reason according to shop #2 for this is that they want you to | > come | > | back | > | > for another $60 retest after someone else does the repairs. Often, | they | > | will | > | > offer a $10 discount as well. Sneaky yet profitable. | > | >

| > | > Shop #2 retested free after ONLY changing out the fuel caps with Stant | > | > non-locking units. It passed, though barely. After replacing | injector | > | #2, it | > | > passed again just fine. | > | >

| > | > His advice: Use a non-locking cap when you get a smog check. Be aware | > | that | > | > some fuel systems behave badly when aftermarket locking caps are used, | > and | > | > poor fuel mileage and excessive emissions will be the result. | > | >

| > | > Her engine runs like a fine swiss watch now. Her fuel mileage went | from | > | 14 to | > | > 21 mpg with only those two changes. Amazing. | > | >

| > | > The Beater must be smogged in a couple of months, so I installed a | > | non-locking | > | > cap on that as well. It actually runs much better now! My mileage | has | > | also | > | > increased from 29 to 33 mpg at last check. I would have never thought | > | that | > | > such a small change would have such a profound impact on both | > performance | > | and | > | > fuel mileage. | > | >

| > | > Food for thought. At $2.25/gal for regular around here, this deserves | a | > | LOT | > | > of thought. I've never installed a locking cap on Charlene, and after | > | > learning of this, I may instead put in a cabinet lock on the fuel door | > | > instead, if I feel it absolutely necessary to secure it. | > | >

| > | > -JD | > | >

| > | | > | | >

| >

| |

"Rein" wrote

I've had the same problem on my old Hyundai and my Dodge. Gas cap not sealing correctly can screw with the 'puter. Sealed system and all.

That, and it will make a helluva conversation piece. That, and having "The Club" installed on the steering wheel.. maybe get a couple of ADT signs for the back windows ROFLMAO!!!

luv ya....

K.

I'm not even goign to tell you how many keys I need to be able to get into most any Ford car.

Umm...

*big proud grin*

my guess would be....none......?

K.

| > Oh, and while I'm at it, did you know that glove boxes on Mustangs are the | > same way? | > On my year model anyway. Put any ol key that fits the hole, and Viola! | >

| > Kate | >

| | I'm not even goign to tell you how many keys I need to be able | to get into most any Ford car. | | -- | YOU are the real piece of work in this post. I think you are | a couple of drumsticks short of a picnic there bud. - SVTKate

I'm not an expert --I can only parrot what the tech told me. Apparently with newer fuel injection systems, fuel tank integrity is very important for proper functioning of the fuel delivery system, hence the MIL that is set whenever the fuel cap is not functioning properly. From what I understood, a poorly functioning cap will cause the engine to run rich, and often rich enough to fail a smog check.

The first thing this guy does before a smog inspection is check the fuel cap(s). If they're of the locking variety, he flat-out tells the customer they will FAIL before he even begins the dyno test, as none he has ever tested will hold pressure or vacuum levels to OEM specs, and that the engine will run too rich with them installed, and that a dyno run is a waste of time. Some customers bring their non-locking OEM cap with them and install it prior to the inspection so that it will all pass.

As for the increase in fuel mileage, I am equally mystified, however I do know that pressure/vacuum leaks anywhere in the system will cause big problems with fuel pressure and flow, and anything that deviates from OEM specs with respect to fuel tank integrity will affect the entire fuel delivery system. I also know for a FACT that fuel mileage is greatly affected by using a non-OEM fuel cap, shocking as it may seem. If I hadn't checked her fuel mileage before and after, I would not have believed it could make such a huge difference.

I've re-installed the OEM fuel cap on The Beater. It runs smoother, but as for big mileage increases, I don't know yet: I only use about $20.00 in fuel per month, so it may be a while before I know for sure.

Perhaps Jim Warman can enlighten us on this subject? He's the tech guru around here. I am only passing on curiosities and pithy observations.

-JD

ROFL! I tend to piss stupid people off whenever I point out the gap between their ears. No, no bodies, but I did get even. Very, very even, which is almost as good.

-JD

I'm reasonably certain, as in 99% certain, that the gas cap integrity check is entirely concerned with controlled evaporative emissions. I may be ignorant, but I'm not aware of any injection design which pressurizes the entire fuel tank in order to maintain fuel pressure.

Keeping in mind that gasoline is a blend of many different components varying in volatility, it's quite possible that fuel quality will decline as the more volatile components of the gas evaporate. When you drive the car, the poorer fuel may result in reduced performance.

They check the caps even on non-fuel injected cars.

Dana

hell JD, that's even better!

I've not seen any difference running the locking cap vs the original factory cap on the mustang.

Since fuel injection works by the fuel pump pumping more fuel than the engine needs and the engine taking what it needs and sending the rest back to the tank. The cap shouldn't mean a damn thing as far as the engine is concerned. I don't see how there would be any kind of metering error, and even if there were, the O2 sensors would detect the condition and it would compensated for.

Then WHY IS IT that if you nad a cap with a bad seal or you don't get it screwed on tight you get a CEL ? Kate

| > I've re-installed the OEM fuel cap on The Beater. It runs smoother, but as | > for big mileage increases, I don't know yet: I only use about $20.00 in fuel | > per month, so it may be a while before I know for sure. | | I've not seen any difference running the locking cap vs the original | factory cap on the mustang. | | Since fuel injection works by the fuel pump pumping more fuel than the | engine needs and the engine taking what it needs and sending the rest | back to the tank. The cap shouldn't mean a damn thing as far as the | engine is concerned. I don't see how there would be any kind of metering | error, and even if there were, the O2 sensors would detect the condition | and it would compensated for. | |