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  #1  
Old May 3rd, 2021, 10:31
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Emissions Fuel pressure test questions

Hey guys.
So I went and got my new 92 xj from Texas. drove her home.
Went for smog and passed everything except for the fuel pressure test.
I passed the Evap pressure test.
so.... My prior jeep never failed fuel pressure before (I've failed the evap prior)

From my understanding of the XJ fuel system, Tank pump has one gasket and 2 hoses. Rail has regulator and fill/return line. so my guess would be the tank gasket or gas cap?

where is common for it to leak pressure from?
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Old May 3rd, 2021, 10:32
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Emissions Fuel pressure test questions

Pic of the new project. She's decently clean. Still needs full paint correction and a few dents pulled... I'll start on this in a few months

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  #3  
Old May 3rd, 2021, 11:04
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Saudade Saudade is offline
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Re: Emissions Fuel pressure test questions

Fuel pressure test? How did they do that?
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Old May 3rd, 2021, 11:14
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Re: Emissions Fuel pressure test questions

I guess I should say Fuel Tank pressure test*they hook a tube to the gas cap/gas tank.
I'm assuming they are pulling a vacuum on the fuel tank/cap to see if it holds?
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Old May 3rd, 2021, 11:28
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Re: Emissions Fuel pressure test questions

Odd, here in CA that's part of the evap test. It's the Low Pressure Fuel Evaporative Test (LPFET). They put in a special gas cap with a hose connection and pressurize the tank. At the evap canister, they pinch off the hose that runs to the aircleaner (at least on my '88).

How much gas did you have in the tank?
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Old May 3rd, 2021, 11:30
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Emissions Fuel pressure test questions

Picture of test failure*

Interesting. Kk I'll check the evap canister

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Old May 3rd, 2021, 11:30
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Re: Emissions Fuel pressure test questions

I had 1/4 of a tank
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Old May 3rd, 2021, 11:50
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Re: Emissions Fuel pressure test questions

Just went and looked. the only hose that appears to connect to the charcoal canister was broken/disconnected.
Gonna replace that and try again with a full tank.
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Old May 3rd, 2021, 11:56
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Re: Emissions Fuel pressure test questions

Yep, broken hose would do it. I usually have about 1/2-3/4 tank when I test.
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Old May 3rd, 2021, 12:15
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Re: Emissions Fuel pressure test questions

I didn't have line that fit both sides. I used ID1/4"(6mm) The side connecting to the metal hose is much smaller than the charcoal canister side. so I used silicone to seal it up.
When it dries i'll take it for re-test
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Old May 3rd, 2021, 12:16
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Re: Emissions Fuel pressure test questions

also... I found out my new jeep has a oil catch can.... I'll post pics but woweee not OEM but nice!!
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Old May 3rd, 2021, 13:59
ljobbins ljobbins is offline
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Re: Emissions Fuel pressure test questions

The check valves/vents for tank could leak as well but that rare if they haven’t been messed with before.
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Old May 3rd, 2021, 14:46
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Re: Emissions Fuel pressure test questions

Quote:
Originally Posted by ljobbins View Post
The check valves/vents for tank could leak as well but that rare if they havenít been messed with before.
The fuel gauge on this jeep reads empty when full and full when empty, so it's possible someone wired up the sender unit wrong. (guessing someone has been in there)
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Old May 4th, 2021, 06:51
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Re: Emissions Fuel pressure test questions

It's a never ending journey of discovery with an old XJ.
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Old May 4th, 2021, 12:45
Ambar1 Ambar1 is offline
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Re: Emissions Fuel pressure test questions

Quote:
Originally Posted by Saudade View Post
It's a never ending journey of discovery with an old XJ.
Quoted for truth!
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