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95 Silverado 5.7 no fuel past throttle body

Discussion in 'GM Powertrain' started by mauricerichter, Feb 12, 2012.

  1. mauricerichter

    mauricerichter New Member

    Hello, my first time here. I'm 53, and been keeping my own vehicles running since I was a kid. Am I posting in the right area? Now I'm trying to keep one of my daughters truck running. I may not be providing the right info, but here goes!

    Current problem: she was driving about 45mph, it suddenly died. As I rescued her, this time it has spark at the plug wires. I could spritz a bit of starter fluid in the throttle body and it would fire. I brought it to my home for further work. It has fuel TO the throttle body. What do I check now? I suspect a computer problem. This truck has a type of reader plug but does not match the OBDII standard so my Autotap-on-laptop is not going to work.

    This next info may be completely unrelated: the private seller had been inside the steering column cover allegedly fixing a lock problem. But we have experienced a cranking-ok-but-no-spark intermittant about once a week which "cured itself" by the time I got there to rescue her. I Even a Chevy dealer mis-diagnosed it as an ignition switch, but I think I may have fixed that with an ignition module (inside distributor cap) but not sure because that has been less than a week between that last repair and this no-fuel-no-start.

    Any ideas where I need to start diagnosing? Or what does it take to remove this computer stuff to go back to the the style of engine I grew up with?! :) lol
  2. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts

    I am not a fan of converting the EFI back to carb (it really only takes removing the TB and putting on a carb, and a lower fuel pressure regulator, etc) but EFI when it isnt all hacked up is more efficent, and is also more reliable.
    Have you run an actual fuel pressure test? You will want to do that since you have to have a minimum of 10-13PSI. it does sound like you have a bad fuel pump which is common on those trucks.
  3. mauricerichter

    mauricerichter New Member

    Update on my problem. Rented fuel pressure tester guage form auto parts store and bought new fuel filter, checked fuel pressure, it was 12, I see various sources it should have been in the 60psi range +/-. Tested with old and new fuel filter. Return the rental guage, bought new fuel pump. Drop gas tank with daughter helping. Pull old pump/sending unit (broken float caused wrong gas tank level readings!) and old pump had screen fallen off. Remove broken flpat pieces and broken screen, install pump assembly, re-hang tank, add gas. Turn key and now can hear fuel pump start, run a minute, then shut off. (Did not re-test fuel pressure because that would be another double trip to town to rent&return guage.) Turn key to start... not cranking! Can see dash indicators/lights but not crank. Chase that problem, getting 12 volts to the small wire input terminal at the starter. Pull the starter, "bench test" at the truck with jumper cables - it will only hum. Drove to town again, auto parts store tested the starter and it showed "failed". Bought new starter, installed, test, it will crank over now, but not fire up. If I dribble a bit gas in the throttle body, it will run a few for that few seconds. Then it will sound like it is getting a tiny bit of with a sound like a cylinder here or there fires. So long way of asking: does the air need to be bled out of the fuel lines? I have not seen any references to do this. What do I check now? Thanks again for help!
  4. Josh

    Josh Member 100 Posts

    i wonder if there is a filter inside the TB. i too have a TBI engine. currently runs good but i keep up on peoples truck probs in case i have the same problem. when cranking does the injectors spray. im thinking this. you turn key to on. hear pump run. try to start and pump loses all power. like a relay of some sort that has popped. if you get into a bad spot. run an add a circuit to the fuse panel on a key on power feed with the proper fuse and a relay inline. that should get your pump running. ive had to do that to a k5 blazer i had. wasnt hard to do either. couple spools of white n black wire. add a circuit a relay and some wire strippers. if it has had ignition work in the column the guy could have messed something up inside. if you can see the wires maybe get a diagram to see what wire feeds what and find any related to fuel/ignition. just my .02 cents. hope you get her back on the road.

    ---------- Post added at 12:45 PM ---------- Previous post was at 12:43 PM ----------

    if theres air in the lines just crank it with your foot down a lil on the gas pedal. let it pump up pressure. wonder if the regulator is bad???
  5. mauricerichter

    mauricerichter New Member

    Josh, thanks for your post! I have never been inside the TB. I will do some research. I have not tried very much of the foot-down-cranking. I can have family crank while I listen for the pump. It seems the pump works good before cranking over. And I've already replaced the ignition switch! :)
  6. Josh

    Josh Member 100 Posts

    reason i mention the gas pedal is cause my 94 has a IAC that needs replaced so i have to use my foot a lil to get it to get enough air in to get it started. i think on the tbi,s there is a filter inside like a little screen possibly inside like a washing machine hose has. my neibor had an s10 that he had brought to me that had fuel problems. i went and got a new factory ac delco fuel pressure regulator. all was fine after that. fired right up first bump of the key. have someone crank it over and look in to see if you see fuel when key is turned on and then again when cranking. i believe that the tbi on the 305/350 engines do not squirt when key is on. i believe they only squirt when cranking. then run when engine running. hope you figure it out. best way to check for fuel on these is carefully remove the injector/s and crank. if fuel comes barrelin out of the hole you have fuel obviously. could be an injector not pulsing. never know till yah check. keep posting your findings and we can hopefully help you get her back on the road.
  7. dualdj1

    dualdj1 Rockstar 100 Posts

    Haven't been on here in a while, but I'm glad I stopped in. The best thing to do to check your fuel system, is #1 put a pressure tester on and check your line pressure. it should build up solid just turning the key on, if not cycle the key off and on a few times to build pressure. If you have anywhere 10-15lbs, you're in good shape there.

    Next, test your injector reference signal, as I have documented here:
    http://www.gmtruckclub.com/forum/sh...To-Test-TBI-Distributor-Signal-Injector-Pulse

    This should spray fuel. If you have fuel spray, then there is a problem getting reference from your distributor, often times it's just a bad connection, reseat the connector and wiggle it good to make sure it's making good contact.

    If you do NOT get spray, but hear an audible clicking, then your electronic side is working fine, and you do have a blockage somewhere.

    if no spray and no clicking, then you have a wiring or computer issue. Check your grounds, fuses, etc, or it's possibly a faulty computer.
  8. murdog94

    murdog94 Epic Member 5+ Years 5000 Posts


    What he said! LOL... the Vortec Motors (96-99) require 60PSI. the TBI motor (88-95) require the 10-15PSI. Let us know what you find out please. im interested to see what it is.

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