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WHICH GAS CAP FOR 1990 ?

MACH90XJ

NAXJA Forum User
Location
Oregon
I am looking up gas cap on parts websites and it seems to be multiple choice. We got vented, non vented, and 3 different emissions sizes. I really hate getting the wrong part from the guy behind the counter so I usually figure it out before I go buy. This many choices is much to much to ask of the parts counter guy.

Anyone got the specs for OEM cap ? search wont search for 3 letter words "gas cap".
 
Yeh, thats where I learned of the emission sizes. I not positive but I assume there refering to the diameter of the venting in the cap. You dont by chance have a part number you've purchased. Looks like 87' thru 99' cherokee and some yj's use the same cap.
 
I'll pass on little known gas cap info I came across today.

Emission Control type caps began in 1970 in California and 1971 nationwide. The fuel emission control system was designed to prevent evaporation of fuel into the atmosphere. The special fuel caps required are equipped with carefully designed and tested pressure and vacuum relief valves to maintain a specified amount of pressure or vacuum in the tank before relieving.

My FSM for 1990 states: Pressure-vacuum filler caps

SJ AND YJ relief pressure 1.1psi or vacuum 1.5hg.
ALL OTHER JEEPS 1.5psi or vacuum 1.8hg.

Ok so I know that, do you think manufactures put that on the label ? NOT. Getting closer !!!! :confused1:confused1
 
Here is my interpetation of what I read.

OEM is an emission cap not a pre-release cap. Will a pre-release cap work the same ? I dont know.

Part#'s that fit cherokee 84'-99' for sure, and a bazillion other cars.

OEM:
STANT- 10817
GATES-31748
NAPA-703-1231

OEM LOCKING:
STANT-10591
GATES-31778
NAPA-703-1603
 
Greets.., '89 and '90 are real close for swapping parts, hence my interest in this thread. Me, I'd hate to blow away someone in the dark with my .44 mag. wheel gun trying to siphon my XJ's fuel tank. Then I'd have to deal with the mess, and drag the body out in the woods for the bear. Just kidding. Really.., these economic times have an up-tick in gasoline thefts.., so.., just what locking caps do you guys use? My area stores, all two of them, are in real short supply of variety. Example: Napa has many brands of only SM grade oil, and one SN. Hmmm.., anyway I don't see a sticker label on the inside of the body's fill-flap-door hiding the cap.., that requires; "close cap at least 3 clicks".., i.e., in order to maintain tank pressure, (as another vehicle of mine does). My '89 FSM does say that in order to mess around with the fuel system, i.e., before discharging the Schrader release valve on the fuel rail, to open up the fuel tank cap.

I really didn't think too much about this fuel tank cap issue until you guys brought it to my attention, lol, thanks alot! So, how about one of you guys down there in the United States of parts galore look into locking caps for the rest of us far flung types.., 'eh? Thanks!
 
"Pressure-vacuum filler caps" is a term used in my 90'FSM, in the fuel tank section. I basically found there are "emission" caps, locking and regular and pre release caps locking and regular. Pre-release seems to have a button type pressure release for removing cap. If you look at your cap the outer edge is not sealing edge that is where it vents and the o-ring does the actual sealing. My current locking cap is a STANT that has the " 3 clicks" printed on it and not on my filler door.

The parts numbers I posted fit hundreds of vehicles spanning all makes foreign and domestic so it really should be a off the shelf item. The parts numbers are the emission type caps.
 
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