Author Topic: Carb to tbi conversation  (Read 5765 times)

Offline bd

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Re: Carb to tbi conversation
« Reply #15 on: August 02, 2018, 11:22:41 PM »
Disconnect the wiring harness plug from the fuel pump relay.  Connect your voltmeter to a verified ground and probe the green/white wire at the F/P connector.  Have an assistant key the ignition ON w/o attempting to crank the engine.  Does the meter measure 12 volts on the grn/wht wire for a few seconds and then drop to zero?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #16 on: August 03, 2018, 06:09:34 AM »
Just tried that and no power coming from grn/wht wire when key is turn on
77 c10 Silverado 350 nv3500 5spd

Offline bd

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Re: Carb to tbi conversation
« Reply #17 on: August 03, 2018, 09:47:39 AM »
The green/white wire connecting to the fuel pump relay that you verified has zero power when the ignition is first keyed ON is CKT 465 (fuel pump relay driver) from the ECM.  Purchase or borrow a scan tool and connect it to the ALDL interface that should be accessible under the dash (assuming you acquired it with the rest of the TBI harness).  The ALDL is the interface port for the ECM and is a huge advantage during diagnosis.  Determine whether there is any communication available with the ECM.

Pick up some CRC brand QD or equivalent electrical contact cleaner.  With the ignition switched OFF, clean the two harness plug connections to the ECM.  It may be a steep gradient under the circumstances, but you need to learn the basics of reading a wiring diagram.  You can find factory wiring diagrams and the emissions and drivability manuals in the Technical Forum.

Make absolutely certain that all ECM grounds to the engine and body are, in fact, connected and flawless, and that none were overlooked during installation.  Use your voltmeter or a test light to verify that 12-volt battery and ignition power is reaching the appropriate pins of the ECM while referencing the appropriate wiring diagram.  Power and ground are crucial to TBI function.  However, DO NOT randomly probe wires with an incandescent test light or you will run the risk of damaging the ECM.  Trace out the ECM/TBI harnesses to make sure that no wires were inadvertently chafed to ground or severed during installation.  If all of that fails to restore power to the fuel pump relay, see the attached image...
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #18 on: August 03, 2018, 11:19:04 AM »
Ok I will try that when I get off work I’ll carefully look over all connections and grounds making sure everything thing is right and I’ll let y’all now what I come up with
77 c10 Silverado 350 nv3500 5spd

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #19 on: August 04, 2018, 07:54:32 PM »
We’re my wiring harnesses that fasten to fuse box on fire wall has a bunch of black goo on it and I noticed that some of the male ends didn’t go in fuse block so I’m going to widen fire wall a little to allow more clearance
77 c10 Silverado 350 nv3500 5spd

Offline Irish_Alley

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Re: Carb to tbi conversation
« Reply #20 on: August 05, 2018, 02:37:25 AM »
the black goo is a good thing
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #21 on: August 05, 2018, 06:25:02 AM »
Ok just making sure I’ll update when I widen whole for fuse block
77 c10 Silverado 350 nv3500 5spd

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #22 on: August 05, 2018, 09:12:56 AM »
On the aldl how can I check to see if I’m getting power to it I don’t have a scan tool but I have test light and voltmeter and notice the neutral/ park wire got caught under valve cover and it had a four prong pigtail were my trans only has two prong sensor
77 c10 Silverado 350 nv3500 5spd

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #23 on: August 05, 2018, 05:15:35 PM »
I got fuel pump to kick on now but injectors still won’t fire
77 c10 Silverado 350 nv3500 5spd

Offline VileZambonie

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Re: Carb to tbi conversation
« Reply #24 on: August 05, 2018, 08:19:27 PM »
well how did you get it to kick on? Are you bypassing things or is the system functioning correctly and we're onto another problem?
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Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #25 on: August 05, 2018, 08:31:37 PM »
I watched a video on what wires need for tbi to work and he used prp/wht (c9) for tac on dizzy and the pink/blk (a6) for ecm power and once I did that fuel pump would kick on but injectors wouldn’t
77 c10 Silverado 350 nv3500 5spd

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #26 on: August 07, 2018, 07:10:28 PM »
Is there something that I’m missing because I still can not get it to run with power going to computer and fuel pump coming on it still will not run I checked to see if the injectors were pulsing but there not can some one please help I check over all connections and fuses and there all hooked up and I can’t find any more grounds and cleaned computer connections and fuse block still no power to injectors
77 c10 Silverado 350 nv3500 5spd

Offline VileZambonie

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Re: Carb to tbi conversation
« Reply #27 on: August 07, 2018, 08:26:21 PM »
I am not trying to sound harsh but this is not a job you should begin without the basic understanding of what the system needs to operate as well as having the tools and equipment to troubleshoot it. Thus far you have not been able to provide good answers to any of the questions that will lead you to the fix. So if you go back through this thread and read every post and clearly answer the questions, you will find your problem. It's difficult to assess what is going on and what exactly you are doing at this point. If the condition is crank no start:

Do you have spark, do you have injector pulse, do you have fuel pressure, is the distributor properly timed?
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74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10

Offline st3vomettler

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Re: Carb to tbi conversation
« Reply #28 on: August 07, 2018, 09:15:51 PM »
Yes I have spark and fuel pressure but no injector pulse it starts almost immediately when gas is poured in tbi and I understand I thought it would be easy to do but I was wrong. I have a 90 Silverado (that was my dads) with tbi and I thought that if I take Intake, wiring harness, computer, cab fuse block, fuel tank and all sensors and transfer it to my truck, hook all sensors and fuel pump it would run.
77 c10 Silverado 350 nv3500 5spd

Offline VileZambonie

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Re: Carb to tbi conversation
« Reply #29 on: August 08, 2018, 02:58:24 AM »
Did you get a test light yet?

Disconnect one of the injector harness connectors. Connect your test light to ground and probe the injector terminals with the key on. Do either of the terminals illuminate the test light?
,                           ___ 
                         /  _ _ _\_
              ⌠¯¯¯¯¯'   [☼===☼]
              `()_);-;()_)--o--)_)

74 GMC, 75 K5, 84 GMC, 85 K20, 86 k20, 79 K10