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GM TBI low voltage at the injectors

87 4x4 suburban won't start has spark, fuel pressure, injectors have been cleaned, truck will start if fuel is poured down the TBI and then dies. Pulled injector plugs to check voltage both plugs pulse from 0 to .02 volts. Checked all fuses all seem to be good. What am I missing?

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  • Anonymous Nov 22, 2008

    I have read many places that this problem is related to a spark problem. The injectors rely on a signal from the distributor to tell them when to fire. Apperantly we are losing that signal somewhere and its not teilling the injectors to fire; however, if i spray carb cleaner, the engine will start and run fine.

  • Rod2Pieces Mar 16, 2009

    Bought an 88 GMC Sierra SLE 4x4 that needed repair. Replaced fuel line and it started but ran with a stumble. Replaced the fuel pump and the injectors won't spray. (Will start fine when gas/starting fluid is sprayed in but still won't spray fuel from injectors. Fuel filter is clean. Fuel pressure is good, swapped TBI units and it worked for about 10 seconds then went back to the same scenario. Tested both units for flow w/ air pressure through lines (both good) also put a jump wire to bared injector wires: Left wire to positive - opens injector, half the time just drips slowly. Other times it just makes the fuel pump run. Right wire to positive - makes fuel pump run only. I am at wits end with this truck seeing as my Buick's transmission blew to pieces so I need a set of wheels. I've been reading a lot of stuff online and it all seems to come back to the Distributor? I'm used to working with carb engines so I'm not too keen with TBI setups/problems.

  • snoopannie Apr 20, 2009

    my 1994 chevy 1500 pickup does the exact same thing.i installed a new fuel filter and fuel pressure oil switch with no help.started as stalling at idle to not idling at all.if it is on cold running circuit it is oktill idle drops below 1000 rpm.somtimes it will work fine intermittantly.i have checked wiring for continuity to ecm had ignition module tested checked distributor shaft for wear side to side also pickup coil for ohms reading all test ok.i believe i am losing the ground side of the injector harness witch suggests a ecm.anyone with ideas would really help.

  • Anonymous Apr 29, 2009

    85 3/4 ton chevy had a 6.2 diesal now has a 91 350 tbi ran good when swaped out but its sitting for awhile. all new gas in truck and lines but wont start. if i pour gas in the tbi it will run for a bit.

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Yesterday i posted my problem of no idle or start on a 1994 1500 chevy pickup.what i found was power and ground was good at the injectors.but no power at cranking.you need to pull the four pin conector at the distributor .with a noid light conected to oneof the injector harness and a test light hooked to 12 volts prob the purple and white wire i believe ckt 436 when you probe it should light the noid light.if this is the case then the ignition module is bad.my module tested good 6 times at the local o"rilley auto parts house.also check power cranking at 5 amp fuse in fuse panel.

Posted on Apr 21, 2009

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Change fuel filter ?

Posted on Dec 23, 2008

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1 Answer

Injector not fireing


you have a TBI 8valve engine. just like my 91
the injector , not firing, so by guy method.
1: it dont click? (sonic ,stethoscope)
2: the noid dont flash. (use a noid lamp and win)
3: it dont squirte, watching it with eyes, cranking,

if the noid fails, that means ECU is bad or one of 3 inputs to ECU are dead.
if noid works, that means, the injector is cogged, it has 10 micron screens that are easy to clean. or there is no 35 PSI fuel pressure.

here is the page just for that.
  1. THE ECU IS PROGRAMMED to cut fuel if there is no spark preventing TV like crashes and burns. (and other fire reasons)
  2. the tests are all easy. no order but #1 is #1
  3. fuel pressure at spec.
  4. injector coil reads 1.0 OHMS.
  5. injector clean. (there is only one, so all hope is just here)
  6. noid lamp fails , so is CMP dead? or TPS TP pin stuck high or , ecu throwing code 41./42s errors, BINGO!

http://www.fixkick.com/INJECTORS/injectors.html

or no starts

http://www.fixkick.com/INJECTORS/injectors.html

May 06, 2014 | 1992 Geo Tracker

3 Answers

Geting fuel .spark.i spray gas in the throttel it run


you need to pull throttle body off and do an inspection and cleaning built up grime on it

Nov 09, 2013 | 1995 Isuzu Trooper

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1992 4.3 v6 tbi s10 starting problem. Won't squirt


Are the injectors getting power and a ground signal from the computer ?

Sep 06, 2013 | Cars & Trucks

1 Answer

I have a 1988 suburban 1500 4x4 5.7 liter v8. I replaced fuel pump and filter, will start and run for about 10 seconds then die and will not restart. Not getting fuel somehow. Injectors were also replaced....


Most likely it is the fuel pressure regulator..also check for spark here's some info for you.. The first thing to do is check for spark.

Disconnect #1 ignition wire at the spark plug.
Install a spark tester into the end of the spark plug boot.
Have an assistant crank the engine over and check for spark at the tester.
Repeat this process at each spark plug.
If any cylinder does not show spark, proceed to secondary component tests.
If ALL secondary components show no spark, test components individually.
If all cylinders test O.K., inspect for fouled spark plugs and clean or replace as necessary.

2010-08-21_174426_1.jpg

If spark checks out good, then you could have a fuel delivery problem. I would recommend to start by checking fuel pressure. Fuel injected cars are very fuel pressure sensitive. Fuel pressure is very important and must be within specifications! But if the pressure is low, it does not mean the pump is bad. A plugged fuel filter, a pinched line, and low voltage at the pump can contribute to low fuel pressure. All three must be check before replacing the pump! You can get a fuel pressure gage at a local auto parts store for cheap.

Fuel pressure testing is frequently overlooked but it is one of the common causes of poor performance. The test procedure must include testing that will insure normal
fuel pressure under all operating conditions.

Key Factors

1. Fuel demands are low at idle.

2. Wide open throttle at high engine revs uses the most fuel.

3. Port injection fuel pressure must be reduced when manifold vacuum is high. Vacuum pulls fuel out of the injector causing it to deliver too much fuel if the pressure remains high. Manifold vacuum is used to open the pressure regulator at a lower pressure when vacuum is high.2010-08-21_175858_1.gif

Mar 31, 2013 | Cars & Trucks

2 Answers

1989 K1500 was running fine and just quit. Not getting gas but I can hear the fuel pump start when I turn the key on. took fuel line off of TBI and seem to have plenty of gas flow but nothing comes out of...


you need to have the fuel pressure checked with a gage and volume as if its not at the spec the injectors won`t open to spray enough fuel.also you should check the injectors for proper voltages and ground as if these are not within specs then the injectors won`t work either

Oct 17, 2011 | 1989 Chevrolet K1500

2 Answers

My 1998 Chevy Blazer crank excessively when I try to start it. It always starts, and runs good when I get it started, but I would really like a smooth start. I have recently changed the fuel filter, spark...


leaky injector/s is flooding motor, mechanically clean or replace. And clean throttle body while you are at it with spray cleaner. Should be almost spotless where large throttle valve opens and closes.

Oct 21, 2010 | 1998 Chevrolet Blazer

1 Answer

89 suburban. No spray from injectors after replacing ESC


The fuel pump should be in the 20s. Also it could be losing presure slowly. Leave the fuel pump pressure gage on for at least 2 to 3 hours to see if it is losing pressure - It's a start

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89 GMC K2500 5.7L TBI not spraying fuel


have you checked the coolant temp sensor? it controls air-fuel mixture.

Jul 16, 2009 | 1989 GMC K2500

2 Answers

GM TBI low voltage at the injectors


sounds like a computer issue on the burb, but i would check the IAC(idle air control) valve and the TPS(throttle position sensor) first.
I would start with the IAC on the 93'.

May 29, 2009 | 1993 Chevrolet C1500

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