View Full Version : vehicle vapor locking
So my jeep is acting weird. I started smelling gas while driving on the hiway, i noticed my fuel was under 1/4. When i stoped at the off ramp the jeep hesitated to accelerat. when i finally pulled over and unscrewed the gas cap i had so much pressure in thee.
does anyone know what causes this?
soldier-of-the-apocalypse
08-05-2012, 17:24
It's a jeep
HoneyBadger
08-05-2012, 17:26
It's a jeep
[ROFL1]
You're SOOOO helpful! Could it be heat related?
Yep could be from the heat and/or you need a new gas cap. They are supposed to releive pressure and actually can go bad.
newracer
08-05-2012, 17:31
year and model?
92 cherokee. I was thinking it might be the gascap.
92 cherokee. I was thinking it might be the gascap.
You can start there. If it doesn't work you are not out too much. Is it a I-6 motor?
You better get that worked out!
rockhound
08-06-2012, 00:30
92 should be fuel injected
Very unlikely it would vapor lock, how about a fuel pump going bad instead
I have built driven wrecked and wheeled xjs for years, never saw a fuel injected xj vapor lock,
Vaopr locking usually is in the carbs of a non efi vehicle, you should not have pressure in your tank though, is your charcoal canister clogged?
There is a vapor collection system on the older xjs. It is supposed to collect excess vapors and is part of the vent system to the tank. Not sure of its origin or usefulness, whne they clog up the do not vent properly, if i recall mine was on the firewall on the drivers side
GilpinGuy
08-06-2012, 00:46
I had hesitation problems with my old XJ and it was the fuel filter - I think it was mounted on the frame on the drivers side. I've had several Jeeps though...
Start with gas cap, then fuel filter, then go on to more complex (and expensive) stuff.
blackford76
08-06-2012, 04:05
Just
Empty
Every
Pocket!!
SideShow Bob
08-06-2012, 04:57
Does this only happen when you are low on fuel (1/4 tank or less) ?
If so you could have rust particles in your tank, and when fuel is low they are concentrated and clog the filter/strainer on the end of the pick up tube in the tank. Even if it is one of the plastic tanks this is a possibility due to buying cut rate gas or using older gas stations that still have the old steel storage tanks.
wctriumph
08-06-2012, 08:27
Most likely cause is fuel tank venting, this is somewhat of an issue if used off road and not properly prepped. Some vehicles have vented gas caps that will eventually fail. Also, as was stated earlier, contaminants in the fuel system will cause hesitation so replace all of the fuel filters. If you are finding large amounts of debris in the fuel you will need to remove and clean out the fuel tank. While you are at it, install a new fuel pump too.
I had a similar problem on a Mazda and the gas cap went bad, go figure!
HoneyBadger
08-06-2012, 09:37
Just
Empty
Every
Pocket!!
Ya know, I've heard a lot of people whine about this, but I guess my Jeep experience was unique.
Sorry to take the thread OT...
in 2008 I bought a 95 Grand Cherokee Laredo with 161k miles on it for $2500. I left it stock and just used it to get around town and [occasionally] head up Mt Herman road or Rampart Range Road to drive some jeep trails. No rock crawling or anything crazy, but I did some offroading that scared the crap outta me.. Almost rolled a few times, at one point I got stuck with just 2 wheels making contact: my front left, and back right; there was about a 4 foot deep pit outside the driver's door, so I couldn't even get out to survey the situation. Ended up getting through it and finding an alternate route back through. I got stuck on a tree stump once because I wasn't paying attention and had to be lifted off by a REAL off-roader who laughed at me in my Laredo... My wife was driving it and got hit by a red-light runner, which totaled it in 2011. It had 188k on it then and still ran fine. During the 3 years I owned it I never took it into the shop for more than an oil change or tire rotation. When it was totaled, the insurance company gave us $2700 for it. I never had a complaint, and I wish I still had it.
....And now back to your regularly scheduled programming: Possible vapor locking problems for the OP.
rockhound
08-06-2012, 09:41
Ya know, I've heard a lot of people whine about this, but I guess my Jeep experience was unique.
Sorry to take the thread OT...
Ended up getting through it and finding an alternate route back through. I got stuck on a tree stump once because I wasn't paying attention and had to be jacked off by a REAL off-roader who laughed at me in my Laredo... My wife was driving it and got hit by a red-light runner, which totaled it in 2011. It had 188k on it then and still ran fine. During the 3 years I owned it I never took it into the shop for more than an oil change or tire rotation. When it was totaled, the insurance company gave us $2700 for it. I never had a complaint, and I wish I still had it.
.
SORRY, but how did this help get you unstuck?????????[ROFL1][ROFL1]
HoneyBadger
08-06-2012, 09:42
SORRY, but how did this help get you unstuck?????????[ROFL1][ROFL1]
Awwww shiiiiiiiit.... [Bang]
rockhound
08-06-2012, 09:45
i have trail rescued plenty of other jeepers and have been rescued by a few also,
this method never occurred to me
HoneyBadger
08-06-2012, 09:46
sort of NSFW for language...
nq61gZFBL-A
Awwww shiiiiiiiit.... [Bang]
hahahahaha!
Back to the OP.
1) Replace gas cap
2) Replace fuel filter (personally I would just do both of these at the same time unless you knew the filter has already been changed recently)
3) Check fuel pump discharge pressure and check proper operation of the back-pressure regulator. If the regulator is failing, you will have low fuel pressure and will cause the engine to fall on its face. If the fuel pump is failing then you will have the same effect.
Also I would run some fuel system cleaner for a couple weeks to clean the crap out of the injectors. When you run them at low pressures for a little while they tend to plug up more than normal. You might want to do this before you replace the fuel filter so that you don't crap up your new filter right away if there is a bunch of junk in the gas tank causing the problem in the first place.
Probably not directly related, but while you're at it check the CCV/PCV valve if so equipped. My old Bronco II drove me nuts with weird hesitation, bogging, etc. and it was simply a plugged up PCV valve.
Pacman89
08-06-2012, 12:38
Definitely check your fuel pressure @ injector rail. If pressure is ok, then you may have a faulty float on pump assembly and would need a new one. If the pressure is low check the pressure @ the fuel filter on pump side. If pressure is good replace the filter. How many miles & when was last tune up done? Is the check engine light on?There could be a problem with the ignition system as its OBD 1 & minor issues may not set off your Check ENG. light. There are virtually a number of issues that could cause a hesitation.
Did the gas cap fix work?
Fuel filter would be my second choice.
hghclsswhitetrsh
08-06-2012, 13:00
It's a jeep thing, I don't understand...
/troll session
blackford76
08-07-2012, 00:29
While you are checking fuel pressure, look at the injectors themselves. Specifically where the fuel rail hooks to them, and where they seat into the intake. The 'O' rings used to seal them were prone to failure. I would think that by now they have been replaced, but it won't hurt to look to see if any fuel is leaking past them.
Most likely a bad gas cap.
GilpinGuy
08-07-2012, 00:46
Man, the Jeep haters...
I had a '95 Grand (like HoneyBadger) that I traded in at 398K miles. Yeah, it was tired, but it ran fine. No major problems except the usual battery, water pump, etc. replacement stuff that comes with a seriously high mileage vehicle.
I've had 6 different Jeeps and have been very happy with all of them.
Frankly, I think that most sheeple just have lost touch with their vehicles and don't know how to maintain them properly. Proper maintenance = a properly running vehicle.
TANGENT: my VERY left wing boss at my old job once said at lunch after I mentioned that I changed the oil in my Wrangler "Oil change? Why would you change your oil? That's just stupid?" He had a Wrangler as well.
His opinion was that "changing oil" was a conspiracy by the oil companies so we use more oil. We never actually needed to change our oil. <sigh>
I challenged him of course, and his reply was "Well, my Jeep leaks so much oil, it's like I'm changing it all the time!" [Bang]
My '99 Wrangler has almost 200K miles and doesn't leak/burn a drop. Silly libs....
...I challenged him of course, and his reply was "Well, my Jeep leaks so much oil, it's like I'm changing it all the time!" [Bang]
Well, that was very green of him now wasn't it? [Shock]
Well i showed the jeep to Blackford and he figured out the problem in about 45 secconds. My exhaust had broke, then the malfunctions. Turns out the exhause was broke right by the tank. It was heating up the fuelpump and tank. Put a new exhaust on and the problem is fixed, took it on a long drive and no probs.
GilpinGuy
09-22-2012, 21:28
Well, you need new exhaust anyway so you'll fix two problems at once. Nice! [ROFL1]
[Beer]
GilpinGuy
09-22-2012, 21:34
By the way, I had to do yet another repair on my wife's Grand today. It pains me to say but I've had a change of heart. GRAND Cherokees are shite. I think I'll post a rant about this later on....
Man. I hate the grands. Its time i got a newer car haha.
GilpinGuy
09-22-2012, 23:04
Man. I hate the grands. Its time i got a newer car haha.
No way! That ride is bad ass "Mad Max" style bro! [Muaha] You Line X'ed the ENTIRE vehicle....bwahahahaha! That's awesome!
It is a fun jeep. Rides like a dream now. I need to go wheelin again.
http://i909.photobucket.com/albums/ac298/davidcordero/20120920_175047_zps0ac627fa.jpg
Is that your cute little new house in Castle Rock?
Yea but its in littleton lol.
blackford76
09-23-2012, 15:21
David, we gonna make the jack mounts or what?
David, we gonna make the jack mounts or what?
Yea. Maybe after our range trip next sunday.
blackford76
09-23-2012, 15:47
Yea. Maybe after our range trip next sunday.
Works for me.
I gather that you got the exhaust repaired.
Works for me.
I gather that you got the exhaust repaired.
Yea did it thursday. Thanks man.
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