C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Firing problem

Old Feb 13, 2017 | 03:27 PM
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Default Firing problem

Hey guys I'm new here and I got a 90 it ran fine then the fuel pump winter out I replaced that and now it is not firing on 3 cylinders now I replaced injectors and no change I had it checked and can't find the problem does anybody have any advice I'm really thinking the computer is bad
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Old Feb 13, 2017 | 03:56 PM
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Originally Posted by Olschool
does anybody have any advice
Welcome to the group!

First, run-on sentences are tough to read and will make it hard for people to help you.

There is a lot that COULD be going on here.

We need more information.

You said that the car was running fine and then the pump when bad.
Did you only replace the pump at the time or did you change out several things at once. If you did change things, what did you change?

Any fault codes?

You say the car runs on three cylinders? Does it RUN, meaning, run on its own (but lopey)

Are all your sensors good? TPS, IAC and do you know you are getting adequate fuel pressure?
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Old Feb 13, 2017 | 04:00 PM
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It's not firing g on 3 cylinders and the fuel pressure is right the guy said but I have not had any sensors checked


UOTE=billschroeder5842;1594085730]Welcome to the group!

First, run-on sentences are tough to read and will make it hard for people to help you.

There is a lot that COULD be going on here.

We need more information.

You said that the car was running fine and then the pump when bad.
Did you only replace the pump at the time or did you change out several things at once. If you did change things, what did you change?

Any fault codes?

You say the car runs on three cylinders? Does it RUN, meaning, run on its own (but lopey)

Are all your sensors good? TPS, IAC and do you know you are getting adequate fuel pressure?[/QUOTE]
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Old Feb 13, 2017 | 04:27 PM
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Originally Posted by Olschool
It's not firing g on 3 cylinders and the fuel pressure is right the guy said but I have not had any sensors checked


UOTE=billschroeder5842;1594085730]Welcome to the group!

First, run-on sentences are tough to read and will make it hard for people to help you.

There is a lot that COULD be going on here.

We need more information.

You said that the car was running fine and then the pump when bad.
Did you only replace the pump at the time or did you change out several things at once. If you did change things, what did you change?

Any fault codes?

You say the car runs on three cylinders? Does it RUN, meaning, run on its own (but lopey)

Are all your sensors good? TPS, IAC and do you know you are getting adequate fuel pressure?
[/QUOTE]


You say it's not hitting on all Cylinders. Question to ask is it getting Spark down by the plugs? making it a Ignition problem.
What is the Fuel Pressure pressure, Just because the Fuel Pump is New Doesn't make it a Write off as Good.

If you put a Injector Pulse Light(NOID LIGHT) in the Injector harness does it have Pulse, if I am not mistaken the injectors Pulse as a group, So you my want to find a Noid Light. to see if a line is out.

Last edited by s carter; Feb 13, 2017 at 04:55 PM.
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Old Feb 13, 2017 | 04:28 PM
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I replaced the pump and injectors that was it its firing on 5 cylinders and I don't know about the codes
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Old Feb 13, 2017 | 04:31 PM
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Not sure what he said the pressure was but he said it was right but I know it has spark on all plug wires on the distributor so I figured it would be sparking at the plugs but I don't know
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Old Feb 13, 2017 | 06:03 PM
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Sure it was not on four and you just blew one of your injector fuses?
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Old Feb 13, 2017 | 06:13 PM
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Originally Posted by antfarmer2
Sure it was not on four and you just blew one of your injector fuses?
I'm not sure about anything on this car I know nothing about em where is that fuse at
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Old Feb 13, 2017 | 06:18 PM
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Originally Posted by Olschool
I'm not sure about anything on this car I know nothing about em where is that fuse at
Not sure on that car but some have two fuses one for each side might be a fifty cent easy fix.


https://www.google.com/search?q=1990...W_Fn8t14wGRhM:

Last edited by antfarmer2; Feb 13, 2017 at 06:23 PM.
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Old Feb 13, 2017 | 06:21 PM
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Originally Posted by antfarmer2
Not sure on that car but some have two fuses one for each side might be a fifty cent easy fix.
I wish
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Old Feb 13, 2017 | 06:25 PM
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Originally Posted by Olschool
I wish
https://www.google.com/search?q=1990...W_Fn8t14wGRhM:

Fingers crossed.
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Old Feb 13, 2017 | 06:29 PM
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Originally Posted by Olschool
I wish
AntFarmer2 makes a Point there may be 2 Inj. fuses, The Cheapy Shop manual I have is showing two fuses. 2 seconds with a Fuse puller and a EDM may save a pile of torn out Hair

Last edited by s carter; Feb 13, 2017 at 06:30 PM.
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Old Feb 13, 2017 | 06:32 PM
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I replaced the fuel pump relay and no fused r blown in the fuse noon the passenger side of dash is there more fuses?
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Old Feb 13, 2017 | 10:26 PM
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Olschool, first of all welcome to the Corvette Forum. I believe that soon you'll find it to be one of the most useful tools in your tool box.

Do you by chance have a service manual for your Corvette?


http://www.auto-repair-manuals.com/C...FYpXDQodxk0PrA

These are incredibly useful manuals, almost essential these days. You can find used ones on the Internet for a fraction of new and they will very quickly pay for themselves.

They are filled with troubleshooting steps for just about any system issue. Including most important of all how to pull any trouble codes, which will at least tell you where to start.

Good luck... GUSTO

Last edited by GUSTO14; Feb 13, 2017 at 10:29 PM.
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Old Feb 14, 2017 | 08:57 AM
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Does anyone know where the 2 fuses are for the injectors yal r talking about
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Old Feb 14, 2017 | 09:55 AM
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Originally Posted by Olschool
Does anyone know where the 2 fuses are for the injectors yal r talking about
Check the passenger side dash where the doors close, that is where the fuses for the injectors are located.

The 1990 is a batch fire system if any of the injectors on either side of the engine are firing it is not a computer problem. All 4 injectors on each side of the engine are controlled together so if one fires they will all fire. That would rule out the computer and point ti a wiring issue or injector issue. My thought is you have a ignition problem but it is only a guess.
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Old Feb 14, 2017 | 01:40 PM
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Originally Posted by Olschool
Does anyone know where the 2 fuses are for the injectors yal r talking about
I posted the link to the pic twice. Just click on it and open the pass side door.
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Old Feb 14, 2017 | 02:58 PM
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No fuses are blown so we back to having no idea
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Old Feb 14, 2017 | 03:56 PM
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Originally Posted by Olschool
No fuses are blown so we back to having no idea
Did you test for power or just look at them? I would borrow a noid light and test with that as well. Then ohm the injectors and report back.

Last edited by antfarmer2; Feb 14, 2017 at 04:01 PM.
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Old Feb 14, 2017 | 03:58 PM
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Just looked at them
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