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 Gary Your Own Question
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15407
Experience:  15 years GM master tech
Type Your Chevy Question Here...
Gary is online now
A new question is answered every 9 seconds

I have a 1993 Chevy 3500 extended cab 6.5 turbo diesel truck.

Customer Question

I have a 1993 Chevy 3500 extended cab 6.5 turbo diesel truck. I am having a fuel problem.
The tank is clean the fuel pick up in the tank was changed out @ six mounths ago. It has a
new lift pump and a new filter. The lift pump seems to be coming on but not as often as it should. When I open the water seporator drain valve to purge the fuel filter housing. The fluid will not come out of the hose and the engine will go air bound. Also now the filter housing will not stay full of fuel. The level starts to drop in the filter housing and eventually the engine starts to get air bound. The engine cranks real good and when the filter is topped off it starts ouick and idles great. The mechanical fuel injection pump was rebuilt @ 50,000.0
miles ago when the engine was replaced with a new one. The truck runs and handles great
just need to get this fuel problem solved. Would appricate any suggestions on the problem.
The oil pressure sensor also has been changed out @ 6 months ago.
Submitted: 6 years ago.
Category: Chevy
Expert:  Gary replied 6 years ago.
so if you open the bleeder on the top front of the engine(brass petcock) and crank it fuel will come out?then close the petcock and it should start up and run.will it do that?
Customer: replied 6 years ago.

I have not tried opening the brass Filter drain valve and cranking the engine. When I open the needle valve to purge the filter housing the engine gets air bound. If the engine went air bound I just fill it from the top of the filter housing by removing the air bleeder cap completely and fill it with a bottle with a nozzle on it as not to run my starter down so much. It seems as though the lift pump is not comming on as it should. What component sends a signal to the lift pump to pressure up the fuel system. there is a water in fuel sensor in the bottom of the fuel filter housing. Is there a fuel pressure sensor in line anywhere.

Expert:  Gary replied 6 years ago.
the computer
try to bleed the air from the brass petcock that is how you remove air from the fuel system.then see if it runs
Customer: replied 6 years ago.

What does the computer pick up the fuel pressure signal from in fuel system to see the correct pressure.

Expert:  Gary replied 6 years ago.
the lift pump lifts the fuel up to the fuel filter and to the injection pump once the air is bled out threw the front brass petcock there is supposed to be fuel in that line.if you bleed it threw the brass petcock and get the air all out and it still will bleed down the fuel in that line then there more than likely is a problem where that line is getting air in it and it can not hold the fuel in that line.kinda like if you try to drink a drink threw a straw that has a hole halfway down the straw your gonna suck some air and when its off the fuel that is supposed to be kept in that fuel line will be empty.try bleeding it threw the brass petcock and see if it will run.then if that line and fuel filter line are still getting filled with air we are going to have to trace back that fuel line from the injection pump all the way back to the fuel tank and find the leak
Gary, Chevy Technician
Category: Chevy
Satisfied Customers: 15407
Experience: 15 years GM master tech
Gary and 4 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.

Your answer is making alot of sense to me and I guess I will have to back check my lines to see where it could possibly be sucking air from between the filter and the fuel tank suction pickup. To me the problem seems to be in that area. I am out of town now and cannot work on my truck at the moment. When I get back in town I will check the system. Thank you for your information I will get back to you when I check for and find the air leak. Tim




Expert:  Gary replied 6 years ago.
ok let me know

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... seen a spike since October in legal questions from readers about layoffs, unemployment and severance.
Web sites like
...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 having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
< Previous | Next >
  • I was having a terrible problem with the wheel bearings on my 98 Chevy Cavalier and I suspect that using this website saved me plenty of time and money. Todd L Rochester NY
  • Wonderful service, prompt, efficient, and accurate. Couldn't have asked for more. I cannot thank you enough for your help. Mary C. Freshfield, Liverpool, UK
  • This expert is wonderful. They truly know what they are talking about, and they actually care about you. They really helped put my nerves at ease. Thank you so much!!!! Alex Los Angeles, CA
  • Thank you for all your help. It is nice to know that this service is here for people like myself, who need answers fast and are not sure who to consult. GP Hesperia, CA
  • I couldn't be more satisfied! This is the site I will always come to when I need a second opinion. Justin Kernersville, NC
  • Just let me say that this encounter has been entirely professional and most helpful. I liked that I could ask additional questions and get answered in a very short turn around. Esther Woodstock, NY
  • Thank you so much for taking your time and knowledge to support my concerns. Not only did you answer my questions, you even took it a step further with replying with more pertinent information I needed to know. Robin Elkton, Maryland

Meet The Experts:

  • GM Tech (Cam)

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
< Last | Next >
  • GM Tech (Cam)'s Avatar

    GM Tech (Cam)

    Chevy Technician

    Satisfied Customers:

    GM Grand Master Technician 2007. 14 years experience.
  • Tim's Auto Repair's Avatar

    Tim's Auto Repair


    Satisfied Customers:

    Have owned a repair shop for 25 yrs.
  • Gary's Avatar


    Chevy Technician

    Satisfied Customers:

    15 years GM master tech
  • Dave Nova's Avatar

    Dave Nova

    Chevrolet Technician

    Satisfied Customers:

    ASE Master Certification. GM World Class Certification
  • John's Avatar


    Master A.S.E Automotive technician

    Satisfied Customers:

    A.S.E MasterTechnician A1-A8 w/L1,38 years experience General Motors Master Technician
  • Don 'Mo Lurch''s Avatar

    Don 'Mo Lurch'

    Auto Mech / Electronics

    Satisfied Customers:

    Chevrolet Cert., Heavy Line Mech, Race Shop Owner, Mobile Electronics.
  • Ron Z.'s Avatar

    Ron Z.

    - Chevy Tech -

    Satisfied Customers:

    18+yrs experience. State Inspector and Chevy Diagnostics