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Amedee
Amedee, GMC Technician
Category: GM
Satisfied Customers: 25206
Experience:  ASE certified tech with advanced level specialist. Wisconsin certified emissions state inspector
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I have a 1993 s 10 pickup with a 2.5 4 cylinder that will

Customer Question

i have a 1993 s 10 pickup with a 2.5 4 cylinder that will start when i put fuel in the throttle body but wont stay running. i have replaced the ignition module and it did no good. when i check the blue wire on the injector for ground it has constant ground with the key opff but when the key is on the ground goes away. if i have the key on and ground the blue wire the injector pulses but weak fire from the plug wire.
JA: Thanks. Can you give me any more details about your issue?
Customer: we replaced the engine and someone hooked the plug that was supposed to go to the throttle body to the distributor and vice versa. I thought maybe we burned out the module so i changed it but it didnt help
JA: OK got it. Last thing — GM Mechanics generally expect a deposit of about $32 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: GM
Expert:  Amedee replied 1 year ago.

Hello and welcome! My name is ***** ***** I can assist you with your question. You need to start by checking fuel pressure and injetor pulse. It sounds like the engine is missing at least one of these preventing it from running. It has spark and compression and that is why it runs on starting fluid. Let me know!

Customer: replied 1 year ago.
Did you read my whole question? I said the injector pulses when I apply a ground to the blue injector plug wire with the key on. With the key off the wire has constant ground. The fuel pressure is adequate and has been checked.
Expert:  Amedee replied 1 year ago.

Sorry about that. Your right.. I did read the question incorrectly. I do apologies.

Expert:  Amedee replied 1 year ago.

Does the pink wire have power going to the injectors while cranking?

Customer: replied 1 year ago.
the pink wire has power with key in on position and while cranking
Expert:  Amedee replied 1 year ago.

Ok, good. Now we need to check injector pulse or the trigger signal on the other wire using a noid light while cranking.

Customer: replied 1 year ago.
I don't have any noir lights. Is there another way to check them and how much fuel pressure does it need
Expert:  Amedee replied 1 year ago.

You can use a test light but it is not easy. I would strongly recommend using a noid light. The fuel pressure specs are 9 to 13 psi

Customer: replied 1 year ago.
I'll get a mood light tomorrow
Expert:  Amedee replied 1 year ago.

Sounds good. Here is a link to a set I recommend

click here

Customer: replied 1 year ago.
just tried the noid light and no pulse. I have replaced the ignition module already
Expert:  Amedee replied 1 year ago.

The computer could be bad (or not powered up) or the crankshaft position sensor may possibly be bad as well.

Expert:  Amedee replied 1 year ago.

.

Customer: replied 1 year ago.
I just replaced the computer. Would a bad prom cause this. I used the prom out of the old computer
Expert:  Amedee replied 1 year ago.

YES, I do believe a bad prom can do this.