1993 Chevrolet S-10 one injector not firing

CHADJREED

MEMBER
1993 CHEVROLET S-10
4.3L
6 CYL
RWD
AUTOMATIC
130,000 MILES

I am putting a 1993 chevy TBI 4.3 "Z" motor in my old jeep. I had a harness made from painless and I recently started it up for the first time the motor sat for three years once it was pulled from a good working truck in the back of my shop all covered up. I recently put it in my jeep and it started quickly but ran like total garbage. I noticed that one of the injectors was not firing. So I took an old wire harness and took off one of the injector plugs and hooked a nine volt battery to it and it worked like a champ. Great pattern and all. So then I thought the ignition control module was bad so I replaced it still ran poorly and didn't fire on one of the injectors. I then thought that perhaps the harness was wrong so I pulled the ECM plug back out and the injectors where on a16 and a9 like they should be. The only items I have left to replace is the ECM, MAP, TPS, temperature sensor. However before I put anymore money in to this do you have any other suggestions. I also cleaned the engine ground and hooked it straight to the negative terminal. I AM LOST PLEASE HELP!
Thank you in advance too.

7 Replies

RIVERMIKERAT

MECHANIC
6,110 POSTS

Use a test light to see if the affected injector is receiving its pulse.

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Thursday, October 15th, 2015 AT 3:53 AM

CHADJREED

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4 POSTS

I tried the noid light and no pulse. I also checked the wires to the computer and they both were good

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Friday, October 16th, 2015 AT 9:27 AM

RIVERMIKERAT

MECHANIC
6,110 POSTS

If you've got access to a known-good injector, plug it into that connector and put it in a bottle or jar to see if it sprays. Spray carb cleaner or brake parts cleaner into the fuel inlet of the injector as you have the engine firing. Push the straw from the can of cleaner as deep into the inlet as you can as you spray it into the injector.

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Friday, October 16th, 2015 AT 10:07 AM

CHADJREED

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4 POSTS

I checked the injector that is not firing during the first post with a nine volt battery and it worked like a champ.

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Friday, October 16th, 2015 AT 10:25 AM

RIVERMIKERAT

MECHANIC
6,110 POSTS

Ok. With the engine running, check the injector voltage at several places between the ECM and the injector. Make sure it's seeing at least 9 Volts at the injector on the injector side of the plug, not the wire side. Also make sure there's about 20 Ohms of resistance across the unplugged injector. Between 11 and 24 to be exact.