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Unread 02-07-2014, 06:06 PM   #1
RCYJ
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Premium gas issues?

Hello all,

I have an 87 yj 6 cyl with a Weber carb. I live in NY so it's cold. Haven't use the jeep for about 4 months because of brake issues but now it's fixed. During brake testing I used up the gas so I went to gas up and decided to use premium Sunoco 93. During the drive home engine won't idle? Did the 93 gas affect the carb. Had no issues before while testing brakes around the block a few times. Should I siphon the gas? Thanks for any help.

RC

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Unread 02-07-2014, 07:06 PM   #2
Mark05059
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probably the carb is gummed up from sitting... the 93 octane shouldn't have any adverse conditions...
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Unread 02-07-2014, 08:22 PM   #3
Michaelgoesrawr
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Don't waste your money on high octane stuff. Change your fuel filter and check to make sure your carb isn't gummed like said above.
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Unread 02-07-2014, 09:19 PM   #4
plym49
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Nothing will gum up in 4 months. You do not need premium gas. Premium gas burns SLOWER than regular. It has to, to prevent detonation in a high-compression engine.

Your Jeep six is not high compression! If anything, the premium is working against you in the bitter cold you describe.

Use the lowest octane gas available - 87 - in your Jeep. All premium does in your case is to separate you from your money.
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Unread 02-07-2014, 09:45 PM   #5
RCYJ
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Yeah, I thought maybe it will help start the jeep better since it was sitting for a while. I'll change that filter and maybe siphon it out. How can you tell if the carb is gummed out?
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Unread 02-07-2014, 09:58 PM   #6
imstillatwork
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Myth: premium has more power / burns hotter
NO!!!

'premium' is higher octane... the higher octane, the more pressure / heat the fuel can withstand before it ignites spontaneously... takes longer to burn, is more difficult to ignite!
High performance, high compressions engines need higher octane fuel so that the fuel ignite ONLY when it is 'told' to by the spark plugs. Low compression, low performance engines absolutely do not need, and cannot take advantage of high octane fuels. It might even run WORSE if the ignition system is not up to snuff.

A high compressions motor can pre-ignite the fuel if it is not high enough octane. You get 'ping' or 'knock' due to this. The fuel is igniting while the piston it still headed UP, because the fuel ignited too early due to high pressure /heat in the combustion chamber.

A high compression motor can make more power because the benefits of high compression overcome the negatives of hi octane.
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Unread 02-08-2014, 09:16 AM   #7
90DesertTanYJ
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If you have Chevron gas in your area you could try some of it to help with your fueling issues. If not available, look for Techroline additive at an auto parts.
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Unread 02-09-2014, 06:32 PM   #8
plym49
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Quote:
Originally Posted by RCYJ View Post
Yeah, I thought maybe it will help start the jeep better since it was sitting for a while. I'll change that filter and maybe siphon it out. How can you tell if the carb is gummed out?
If the engine runs but has a problem idling, your fuel filter is fine. Why? Because you require higher fuel flow running above idle. A plugged filter decreases flow - the engine idles but won't make power - exactly the opposite of what you are reporting.

The same thing goes for a gummed up carb. Idle is less affected, because less fuel is required. I doubt your carb is gummed. I also doubt your fuel filter is bad since the Jeep was running fine before storage. If the motor was not running during storage, how could the fuel filter get dirty?

These two general guidelines in the world of troubleshooting.

If you have told us all of the story, top it off with regular and drive it and it will be fine.

If there is more to the story, for example the motor would not idle when it was cold, or fully warmed up, then by all means fill in the details.
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Unread 02-09-2014, 08:17 PM   #9
RCYJ
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Quote:
Originally Posted by plym49 View Post
If the engine runs but has a problem idling, your fuel filter is fine. Why? Because you require higher fuel flow running above idle. A plugged filter decreases flow - the engine idles but won't make power - exactly the opposite of what you are reporting.

The same thing goes for a gummed up carb. Idle is less affected, because less fuel is required. I doubt your carb is gummed. I also doubt your fuel filter is bad since the Jeep was running fine before storage. If the motor was not running during storage, how could the fuel filter get dirty?

These two general guidelines in the world of troubleshooting.

If you have told us all of the story, top it off with regular and drive it and it will be fine.

If there is more to the story, for example the motor would not idle when it was cold, or fully warmed up, then by all means fill in the details.
Jeep was running and idling fine before putting the premium. The only issued were the brakes. I will siphon the gas and see what happens. Thanks.
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Unread 03-09-2014, 07:29 PM   #10
RCYJ
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So it's not the gas. The carb (weber) is not idling. Looks like the choke is not working causing the butterfly flaps to open up too much. Do anyone know how to adjust this?
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Unread 03-09-2014, 07:54 PM   #11
Mark05059
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the choke cap usually has 3 rivits holding the cap on. Drill those out and get some bolts/nuts to replace them with. You adjust the choke by turning the cap. If its opening too fast then the electrical part of it is working... but working too well..
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Unread 03-10-2014, 04:51 PM   #12
RCYJ
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Quote:
Originally Posted by Mark05059 View Post
the choke cap usually has 3 rivits holding the cap on. Drill those out and get some bolts/nuts to replace them with. You adjust the choke by turning the cap. If its opening too fast then the electrical part of it is working... but working too well..
Choke cap actually already had screws so I adjusted by turning to the left to close it more, but it didn't really help. The butterfly flaps still stays fully vertical,when engine is hot and letting go of the throttle which what causes the engine to stop. Maybe the electric choke has no power. I have to test it.
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Unread 03-10-2014, 05:53 PM   #13
roadyrob
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the choke is supposed to be off when the motor is hot. heres a thread on the weber carb, maybe it will help you.
http://www.jeepforum.com/forum/f8/we...ssion-1051137/
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Unread 03-10-2014, 05:58 PM   #14
jollyroger1
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I had the same issue a couple months ago,it was a vacuum leak.The adapter plates under the webber had loosened up
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Unread 03-10-2014, 06:38 PM   #15
captainauti
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Quote:
Originally Posted by plym49 View Post
If the engine runs but has a problem idling, your fuel filter is fine. Why? Because you require higher fuel flow running above idle. A plugged filter decreases flow - the engine idles but won't make power - exactly the opposite of what you are reporting.

The same thing goes for a gummed up carb. Idle is less affected, because less fuel is required. I doubt your carb is gummed. I also doubt your fuel filter is bad since the Jeep was running fine before storage. If the motor was not running during storage, how could the fuel filter get dirty?

These two general guidelines in the world of troubleshooting.

If you have told us all of the story, top it off with regular and drive it and it will be fine.

If there is more to the story, for example the motor would not idle when it was cold, or fully warmed up, then by all means fill in the details.
just a thought..... if the idle circuit is clogged, wouldnt that cause idle issues, reguardless of fuel demand?

OP, 4 month old fuel could be bad. if the ethanol fuel you had in your tank has separated, and/or sludged up, you could have clogged up the carb. get a rebuild kit and go to it. and when ever you lay anything up with fuel in it, use startron.
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