How JustAnswer Works:

  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.

Ask Adin3 Your Own Question

Adin3
Adin3, Nissan Mechanic
Category: Nissan
Satisfied Customers: 3423
Experience:  Autozone Manager 3 years, mechanic 10 years
9051600
Type Your Nissan Question Here...
Adin3 is online now
A new question is answered every 9 seconds

Rough idle..tank..gas dry and 93 octane gas its still idling rough

Customer Question

Hello, I recently had a problem of rough idle at a 1/4 tank. I figured I had water in the gas. After fill up it went away till 1/2 tank and now after putting in gas dry and 93 octane gas its still idling rough. I replaced the spark plugs cause I figured they were fouled and replaced some bad vacume lines. The truck idles at 750 rpm where it always did but still runs rough.
Submitted: 6 years ago.
Category: Nissan
Expert:  Adin3 replied 6 years ago.

Hello and thank you for choosing Just Answer.

Just to clarify here for me, you had a rough idle at 1/4 tank but when you put in more gas the problem would go away?

Now you are having that problem no matter how much gas is in there?

Customer: replied 6 years ago.
it did go away and then when it reached 1/2 a tank it started back. No matter how much gas is in it now it does it all the time
Expert:  Adin3 replied 6 years ago.

Thank you.

This indicates that the fuel pump is going bad. The fact that the car runs fine when there is 1/2 tank, but not 1/4 tank indicates that the fuel pump is weak. The fuel pump sucks in fuel, if it's weak it need additional pressure to be able to suck the fuel and delivery it to the rails. With more gas in the tank there is more pressure exerted on the pump, allowing it to pump the gas with less efforts. You may consider doing a fuel pressure test on this car when the fuel is low, this is verify if the fuel pump is infact bad. You also may consider checking and replacing the fuel filter.

Adin3, Nissan Mechanic
Category: Nissan
Satisfied Customers: 3423
Experience: Autozone Manager 3 years, mechanic 10 years
Adin3 and other Nissan Specialists are ready to help you
Customer: replied 6 years ago.
I wasnt sure because trhis truck is carburated injected. So even though its idling at normal idle the fuel pump could be failing.. That always happens with a full tank of gas. I was a mechanic about 10 years ago and went into machining. So everything I checked just dead ended.
Expert:  Adin3 replied 6 years ago.

Yes even it the car is idling normal the fuel pump still may be going bad. The car requires the least amount of gas during idle operation. The fact that the problem was there while the tank was at 1/4 and not there at 1/2 indicates that the fuel pressure is having an issue. This is most likely due to a bad pump and is having trouble pumping gas, more gas in the tanks makes it easier for the pump to work.

Customer: replied 6 years ago.
Ok I will replace the fuel filter and test the pump. Thank you reply to this and I will accept
Expert:  Adin3 replied 6 years ago.
Thank you for accepting and using Just Answer!
Customer: replied 6 years ago.
Now it has cleared up the started back again! Whe I run at 1500rpm it seem to do ok. still the fuel pump?
Expert:  Adin3 replied 6 years ago.
It may not be the whole pump, there is a strainer attached to the pump that serves as a filter for the pump. You may also want to check for more vacuum leaks.
Customer: replied 6 years ago.
I have replaced the fuel pump and replaced strainer, fuel filter , Plugs, checked vacuum pressure, fuel regulator, No check engine light. I am truly stumped. I have talked to local mechanics and there not sure with out running up a huge bill for an old truck. someone said intake gasket could be bad, I check distributor for flash and its good, ran it in the dark to see if the wires were arching and there clean. what stumps me is it comes and goes but more goes than anything.
Expert:  Adin3 replied 6 years ago.

Well you can run a quick test on the intake gasket. Here is how you would perform that test.

  • Start the car
  • Spray carb. cleaner around the intake gasket
  • If the RPM's rise as you spray , the gasket is leaking. (The rpm's will spike)
Customer: replied 6 years ago.
nothing happened. any other suggestions. I have trie dthe idle air controle valve as well.

JustAnswer in the News:

 
 
 
Ask-a-doc Web sites: If you've got a quick question, you can try to get an answer from sites that say they have various specialists on hand to give quick answers... Justanswer.com.
JustAnswer.com...has seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like justanswer.com/legal
...leave nothing to chance.
Traffic on JustAnswer rose 14 percent...and had nearly 400,000 page views in 30 days...inquiries related to stress, high blood pressure, drinking and heart pain jumped 33 percent.
Tory Johnson, GMA Workplace Contributor, discusses work-from-home jobs, such as JustAnswer in which verified Experts answer people’s questions.
I will tell you that...the things you have to go through to be an Expert are quite rigorous.
 
 
 

What Customers are Saying:

 
 
 
  • I was in trouble with an electrical issue with my brand new Nissan. I frantically went online trying to find help and luckily I found your site. I reached a NISSAN tech named RIP. He was absolutely tremendous and helped me work through the issue. What a pro! cjaz Lexington, KY
< Last | Next >
  • I was in trouble with an electrical issue with my brand new Nissan. I frantically went online trying to find help and luckily I found your site. I reached a NISSAN tech named RIP. He was absolutely tremendous and helped me work through the issue. What a pro! cjaz Lexington, KY
  • I would (and have) recommend your site to others I was quite satisfied with the quality of the information received, the professional with whom I interacted, and the quick response time. Thanks, and be sure that I'll be back whenever I need a question answered in a hurry. Stephanie P Elm City, NC
  • used your service this weekend with "Trecers" help. thank you ,thank you, thank you. replaced an A/C fan motor. Local Auto Zone had part. $15.00 "tracer" fee and $40.00 for parts, I saved several hundreds of dollers at a shop. i will recommend you and use you in the future. David L. Richmond, TX
  • 9 dollars, 2 hours of my time, and I drove away. Your diagnosis was right on the mark. Thank you so much. Phil Marysville, CA
  • Lurch. Thank you very much. I had real doubts about this website but your promptness of response, quick followup and to the point answer with picture was incredible. Charles Walnut Creek, CA
  • As a single woman, I really appreciate an excellent and affordable opinion.
    Thank you Geordie, I will not hesitate to contact justanswer in the future!
    Sue Charleston, WV
  • Another great insight to what may be the problem. I will have my mechanic take a look at it tomorrow. Thanks again, Frank...you do indeed know your stuff. Jim Castleberry, FL
 
 
 

Meet The Experts:

 
 
 
  • Tim Mohr

    ASE MASTER TECH

    Satisfied Customers:

    446
    30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
< Last | Next >
  • http://ww2.justanswer.com/uploads/tsmodie/2009-6-10_144056_tim.jpg Tim Mohr's Avatar

    Tim Mohr

    ASE MASTER TECH

    Satisfied Customers:

    446
    30 YRS EXPERIENCE, FOREIGN AND DOMESTIC, GAS AND DEISEL
  • http://ww2.justanswer.com/uploads/CA/caprio23/2011-12-13_155550_20111213105344.64x64.jpg Anthony's Avatar

    Anthony

    ASE Certified Technician

    Satisfied Customers:

    306
    ASE Master Automobile Technician with over 18 years exp. in this field.
  • http://ww2.justanswer.com/uploads/FO/fordguy4u/2011-12-17_222940_HPIM1257.64x64.JPG Ron's Avatar

    Ron

    ASE Certified Technician

    Satisfied Customers:

    171
    34 years of automotive Repair
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris(aka-Moose)'s Avatar

    Chris(aka-Moose)

    Nissan Technician

    Satisfied Customers:

    165
    16 years of experience
  • http://ww2.justanswer.com/uploads/EU/eurotec/2012-6-11_13153_mpjaphoto.64x64.JPG Marty's Avatar

    Marty

    ASE Certified Technician

    Satisfied Customers:

    127
    ASE & Bosch master tech. 30 years experience.
  • http://ww2.justanswer.com/uploads/BA/baddad1/2013-8-30_131413_11848761610058140852271553042976n.64x64.jpg Mike V.'s Avatar

    Mike V.

    Nissan Technician

    Satisfied Customers:

    7443
    Nissan factory trained and Certified Subaru Technician.
  • http://ww2.justanswer.com/uploads/CR/crzydrvr00/2013-11-3_12123_246347.64x64.jpg Richard's Avatar

    Richard

    ASE Certified Technician

    Satisfied Customers:

    92
    Nissan Tech ASE certified technician