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
Gary, GMC Technician
Category: GM
Satisfied Customers: 10633
Experience:  15 years gm master tech/15 years ASE master tech
19513769
Type Your GM Question Here...
Gary is online now
A new question is answered every 9 seconds

I have a 87 chevy K20 pickup 350. I have replaced fuel pump,

Customer Question

I have a 87 chevy K20 pickup 350. I have replaced fuel pump, fuel pump relay, ecm. I can add 12volts to fuel pump test terminal at relay and pump comes on. I can ground the injectors and they will spray. I can dump gas into the intake and it will start and run a few seconds and die. the ses light will not come on when key is turned on, jumped a-b on the aldl connector no ses light, hooked up a code reader and with key on it still says turn key on or cable not connected. On one plug to computer there is two hot wires, on the other there is one hot wire. I have unbolted all the ground connections i can find under the hood cleaned and reconnected. So where is the computer ground? or what should I do next to make the truck run? it cranks fine 12.8 volts at battery
Submitted: 3 years ago.
Category: GM
Expert:  Gary replied 3 years ago.
is this a single tank truck?
Customer: replied 3 years ago.

No it is a dual tank truck, how ever I do have good fuel pressure at the TBI unit , all I have to do is crack the line a little and it sprays every where. I don't have a fuel pressure tester to see if it is at the 13 - 17 pounds pressure, but it sprays hard. It concerns me that it seems the computer is not operating. Because there is not check engine light when i turn the key on. And when I hook up my scout code scanner and turn key on it cant read codes it still says turn key on or cable not plugged in.

Expert:  Gary replied 3 years ago.
so at this point you do have the fuel pressure just no injector pulse spraying fuel in.do you have good spark at the wires where they connect to the spark plugs?
Customer: replied 3 years ago.

correct , and yes it does have good spark at the wires, If I dump a little gas in at the TBI unit it will start right up run a few seconds and die.

 

Expert:  Gary replied 3 years ago.
ok ecm and gage fuse are good?12 volts each side with the key on with the fuses in place?
Customer: replied 3 years ago.
yes, and at the computer one plug has two hot wires with key on , one plug has one hot wire with key on computer disconnected
Expert:  Gary replied 3 years ago.
ok with the computer connectors un plugged you need to check for 12 volts at C16(orange wire) and B1(orange wire) and A6(pink/black wire)

Attachments are only available to registered users.

Register Here
with the key on all 3 of those terminal on the connectors should have 12 volts.
Customer: replied 3 years ago.
ok no power at c16 and B1, I have power at A6
Expert:  Gary replied 3 years ago.
ok this truck either had a fusible link OR an ECM B fuse that powers BOTH those terminals with 12 volts.now get to the starter and off the big post on the starter there should be a few smaller red wires can you see if any of them are broken.pull lightly and see if any separate.now if they look good at the back on the firewall there should be a power junction block with some red wires going into it.see if there is 12 volts to and from that junction box.also can you see if in that area there possibly would be a small fuse holder.can you also check and see if there is a fuse in the fuse box called ECM B ?
Gary, GMC Technician
Category: GM
Satisfied Customers: 10633
Experience: 15 years gm master tech/15 years ASE master tech
Gary and 11 other GM Specialists are ready to help you
Customer: replied 3 years ago.
ok I do have a ECM B fuse, it has power, checked it with test light while still plugged in. wires at starter are good, 12 volts across junction block on fire wall, there is a fuse link wire leading off, I checked both sides of black plastic tube in wire has 12 volts, i probed the wires also at junction block just to make sure the connections aare good
Customer: replied 3 years ago.
hey your right if i wiggle the ecm B fuse and pust on it just right I can hear the pump come on and a relay cllick and I can start the truck, I have a bad junction box You are the man! Thanks!
Customer: replied 3 years ago.
So now I gotta figure how to fix that
Expert:  Gary replied 3 years ago.

is it the fuse in the fuse box?or junction block at the firewall?

Customer: replied 3 years ago.
The pins holding the fuse in were dirty and the bolt holding the inside block and outside block together was loose.
Expert:  Gary replied 3 years ago.
ok good job im glad its running now for you!! great job!
Customer: replied 3 years ago.

Thanks, XXXXX XXXXX has been kickin my butt for a week off an on. I never new just replacing a rusty leaking fuel tank could cause so many problems lol.

Expert:  Gary replied 3 years ago.
yes those side mount tanks were a tight fit

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 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
< Last | 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:

 
 
 
  • Gary

    GMC Technician

    Satisfied Customers:

    903
    15 years gm master tech/15 years ASE master tech
< Last | Next >
  • http://ww2.justanswer.com/uploads/ggrote1/2009-06-27_031011_me.jpg Gary's Avatar

    Gary

    GMC Technician

    Satisfied Customers:

    903
    15 years gm master tech/15 years ASE master tech
  • http://ww2.justanswer.com/uploads/CA/caprio23/2011-12-13_155550_20111213105344.64x64.jpg Anthony's Avatar

    Anthony

    ASE Certified Technician

    Satisfied Customers:

    476
    ASE Master Automobile Technician with over 20 years exp.
  • http://ww2.justanswer.com/uploads/Rocket2005/2009-09-13_133703_jack.jpg car tech's Avatar

    car tech

    ASE Certified Technician

    Satisfied Customers:

    448
    25 year master tech and shop owner
  • http://ww2.justanswer.com/uploads/2P/2paulm/2012-4-4_183431_justabswer.64x64.jpg Paul M ASE Master's Avatar

    Paul M ASE Master

    ASE Master Tech

    Satisfied Customers:

    187
    ASE Master Tech 20+ Years
  • http://ww2.justanswer.com/uploads/MU/muddyford/2012-6-13_1204_1.64x64.png Chris (aka- Moose)'s Avatar

    Chris (aka- Moose)

    GMC Technician

    Satisfied Customers:

    89
    16 years of experience
  • http://ww2.justanswer.com/uploads/AM/amedee/2013-10-24_23656_Amedee1.64x64.jpg Amedee's Avatar

    Amedee

    GMC Technician

    Satisfied Customers:

    360
    ASE Master Technician advanced level specialist
  • http://ww2.justanswer.com/uploads/DT/dt69nova/2012-6-15_234154_pic1.64x64.jpg Dave Nova's Avatar

    Dave Nova

    GMC Technician

    Satisfied Customers:

    2262
    ASE Master Certification. GM World Class Certification