Fuel Injectors not working

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squarebodynewbie

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Looking for next steps...(never worked on vehicles but wanted to start a new hobby with my son)

Vehicle details - 87 Chevy, 4 wheel drive, 1/2 ton, 2 door, 305 V8 w/TBI

Truck cranks but doesn’t start because it’s not getting fuel - Fuel injectors are good, checked the electrical harness with a noid light and got no light (flashing or steady) when key was turned.

Replaced all the fuses - then checked the power to the fuse box. Also replaced the fuel pump relay.

ECM1 only getting power to the right side but not the left. ECMB not getting power at all.

Has a new distributor so not sure if that’s the issue. Just looking for a list items to run down and locate the problem.
 

gmbellew

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if start here if you don't have injector pulse from a noid light when cranking.

the injector harness won't flash a noid light with key just in the "on" position. you have to crank
 

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fast 99

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Should be power standing on one side of injector with key on.
 

fast 99

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true, but it won't flash the noid light. the ECM provides ground when they pulse.
Exactly, it's just an easy check if a noid light isn't available. No power there, problem not there.
 

Ricko1966

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Pull both fuses,check them for continuity. Key on check for power at all 4 contact points for those fuses at the fuse panel. You should have power at 2 points.
 

gmbellew

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Looking for next steps...(never worked on vehicles but wanted to start a new hobby with my son)

Vehicle details - 87 Chevy, 4 wheel drive, 1/2 ton, 2 door, 305 V8 w/TBI

Truck cranks but doesn’t start because it’s not getting fuel - Fuel injectors are good, checked the electrical harness with a noid light and got no light (flashing or steady) when key was turned.

Replaced all the fuses - then checked the power to the fuse box. Also replaced the fuel pump relay.

ECM1 only getting power to the right side but not the left. ECMB not getting power at all.

Has a new distributor so not sure if that’s the issue. Just looking for a list items to run down and locate the problem.
ECMB is the main power feed to the ECM and also feeds power to the fuel pump relay and also ties into the oil pressure switch as redundancy in case the fuel pump relay dies.

the ECMB wires are on the 440 circuit and are orange. they run in the main harness across the firewall and are prone to rub through on various brackets (MAP, cruise control, etc). it is constant hot. if ECMB isn't blown, but you don't have power on one side of ECMB, that may be a circuit to track down.

does the service engine light come on with key on? if not, your ECM may not have power at all.
 
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squarebodynewbie

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No service engine light with the key on

I have tone when the key is inserted.

When the key is turned to the on position I get the ‘Fasten Seatbelt’ light.

Then when I turn to crank I get the ‘Brake
 

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gmbellew

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No service engine light with the key on

I have tone when the key is inserted.

When the key is turned to the on position I get the ‘Fasten Seatbelt’ light.

Then when I turn to crank I get the ‘Brake
see if ECMB fuse is blown and or has power. did the light work before? there could be a chance that the bulb is out.

but this is the 440 circuit I described earlier.
 

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squarebodynewbie

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What resource did this come from and where could I find it? I have a Haynes but not as much detail as I would like.
 

gmbellew

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What resource did this come from and where could I find it? I have a Haynes but not as much detail as I would like.
it's in the Reference Library on this website. it is in the Drivability Manual, which is like the TBI Bible. there are also wiring manuals, service manuals, and repair manuals. all the GM manuals organized by year. download your year manuals and you will be set.
 

Ricko1966

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Exactly, it's just an easy check if a noid light isn't available. No power there, problem not there.
Who knows LEDs where to get them,different voltages types etc. I'll put it in context about 20 years ago one of our instructors told us to get xyz LEDs from radio shack twist the tails together,long side to short side and vise versa. Solder on 6 foot of 2 conducted wire and solder t pins on the other end. A homemade noid light that works on any injector and you can see from the drivers seat. I can't point people where or what to buy,Radio Shack is gone.
 

Ricko1966

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Look at this! They pre make them now. Mine is 2 leds tail to tail so you can't get polarity wrong, T pins for probes,and stick the light end under the wiper.
 

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