97 Sahara - HORRIBLE gas mileage, check engine light, gurgling sound from gas tank - JeepForum.com

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post #1 of 7 Old 01-26-2011, 12:58 PM Thread Starter
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97 Sahara - HORRIBLE gas mileage, check engine light, gurgling sound from gas tank

1997 Jeep Wrangler Sahara 4L 6cyl

Check Engine light came on recently, brought it to tire kingdom, they said it came back with an evap error code (they didnt tell me the exact code, I should have asked).

I use 1/4 tank of gas just driving 10 minutes, the gas gauge suddenly goes to empty and the low gas light comes on (even with half a tank full). After driving for a few minutes, you can hear the gas gurgling/moving in the fuel tank while standing a few feet away.

Tire Kingdom quoted me $1100 for a new fuel pump, solenoid, and canister + labor.

I looked up the parts on autopartswarehouse.com and the total was under $200 LOL.

So I tried a local mechanic, he checked the fuel lines underneath and the fuel cap (brand new) and said it could just be a bad fuel cap causing there to be no pressure. Or it could be the surge valve? (maybe it was purge valve, didnt hear him clearly) I attached a picture.

Before I order parts, I wanted to see what the Jeep experts here on the forum had to say. Was tirekingdom or the mechanic correct on their diagnosis?

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post #2 of 7 Old 01-26-2011, 01:01 PM
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Stay far,far, far away from tire kingdom. As for the evap cannister, mine went to hell early last year, it's not unreasonable that it's time to replace it, and your symptoms could be from a blocked cannister, among other things. That's your purge solenoid, could be a factor, too. I changed mine out with the cannister.
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post #3 of 7 Old 01-26-2011, 02:22 PM
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you know the fuel pressure regulator is going bad when it takes you multiple attempts to start your jeep. that can be solved by turning the key on a couple times (but not the vehicle) to "prime" the lines; there a diaphram in the regulator that allows the fuel to drain back into the tank and out of the lines after you shut the jeep off. its goes bad after a while. i think my pump lasted for about a year and a half after this started happening (yours is a 97 like mine). though it had 160k on it. another symptom of a pump unit going bad is the tank not reading the right level. all of these things are not the actual pump going but that sending unit, but they are all contained in one fuel pump unit. you can get a bosch pump from amazon for 200 bucks. do not buy an airtex. IMO very poorly made.

poor gas mileage and engine light? whens the last time youve given it a tune up, changed the plugs distributor cap/rotor. when i first bought mine it did the same thing yours was. changed all that and it went away. i dont know how much the evap canister costs but id start there. i also bought my own code reader, if you do your own work helps out a lot and saves a lot in the end.

welcome to JF. fill in your profile as much as you can and it will help other members out when you ask questions.

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post #4 of 7 Old 02-01-2011, 08:33 PM Thread Starter
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Thanks for the tips! Luckily my Jeep has never had any problems starting so that's not a symptom. My '97 has 170k miles on it as well, but things have been replaced as needed over the years and it's been well taken care of. The gas gauge just plunges to empty every few minutes and the check engine light is still on. I replaced the vapor canister and purge solenoid today - no effect. So my next step is replace the fuel pump?
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post #5 of 7 Old 02-01-2011, 08:59 PM
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key trick.report codes here.

When was your last tune up?

The gas gauge is a chrysler thing every chrysler product of that vintage will drop to empty at random. When it starts doing it very regularly its time to replace the pump assembly.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #6 of 7 Old 02-18-2011, 12:19 PM Thread Starter
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Ok, update... I replaced the purge solenoid and canister, had advanceautoparts clear the evap codes for me... Gas mileage improved BIG TIME, the gas gauge never went out of control again, and the gurgling sound coming from the gas tank stopped.

Everything was fine for about a week... Then last night, the check engine light comes back on, I burn up over a 1/4 tank of gas driving about 10-20 min @ 45mph, and the gurgling sound coming from the gas tank is back.

I figured out how to get the error codes w/out a scanner (turn on, off, on, off, then finally on). The error codes are:

31 - Evap leak monitor pinched hose found (plug or pinch detected between purge solenoid and fuel tank)
42 - Fuel level sending unit volts too low or high (open or shorted circuit between PCM and fuel gauge sending unit)

Any ideas on how to isolate a plug or pinch between the solenoid and fuel tank?

And last, any ideas on how to determine if there is an open or shorted circuit between the PCM and gauge sending unit?

I think I might have to become a Jeep Forum Supporter, just because of how much money I might have saved from using this place instead of going to TireKingdom!
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post #7 of 7 Old 05-09-2012, 09:12 AM
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Did you ever find the fix to your error code 31? I have been doing just about the exact same thing you have. I bought a new purge solenoid, evap canister, and I have been replacing vac lines. One thing I did differently than you is I purchased the purge solenoid before I replaced the canister. My canister was letting out charcoal and I found some charcoal on the old and new purge solenoid. I am almost tempted to bypass the entire steel vapor line and buy 3/16 vapor/fuel line (about a dollar a foot) just to figure out if it is clogged with coal. I will be dropping the tank sometime this week to replace those vac lines and possibly replacing the fuel pressure regulator (haven't decided whether or not to replace the entire fuel pump assembly yet) because I am having to prime the line on a cold start. Any help will be much appreciated.
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