Author Topic: Carb to tbi conversation  (Read 5785 times)

Offline st3vomettler

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Carb to tbi conversation
« on: August 01, 2018, 08:03:58 PM »
I’m converting my 77 c10 from carb to tbi. I took the wiring harness inside and out, intake, tbi and all sensors needed. I have a donor 90 c1500 that all the parts came off of. I’m getting spark but no fuel it will start with gas squirted in to tbi but pump and injectors won’t work. Need help please
77 c10 Silverado 350 nv3500 5spd

Online bd

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Re: Carb to tbi conversation
« Reply #1 on: August 01, 2018, 10:54:26 PM »
Check the ECM-I (ignition power) and ECM-B (battery power) fuses in the fuse box using an incandescent test light.  Make sure all of the ECM grounds are properly connected and 100% functional.  Measure the fuel pressure using a proper gauge.  Will it start if you connect a fused jumper wire between battery positive and the 4" red pigtail with a single black connector at the fuel pump relay?
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 #2 on: August 02, 2018, 06:08:48 AM »
I don’t have a test light but I did change the two fuses with new ones and there isn’t a 4” red wire coming out of my fuel pump relay pig tail but there is a smaller red wire and I jumped it to battery and still nothing and all grounds are bolted down.
77 c10 Silverado 350 nv3500 5spd

Online bd

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Re: Carb to tbi conversation
« Reply #3 on: August 02, 2018, 08:44:40 AM »
You need to determine whether there is power at the two ECM fuses - I recommend that you procure a test light.  Post a pic of the fuel pump relay
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 Irish_Alley

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Re: Carb to tbi conversation
« Reply #4 on: August 02, 2018, 03:21:18 PM »
this might help you

the red wire is the "C" plug
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 Irish_Alley

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Re: Carb to tbi conversation
« Reply #5 on: August 02, 2018, 03:24:24 PM »

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 #6 on: August 02, 2018, 05:55:46 PM »
I’m getting power to both fuses but no power to fuel pump
77 c10 Silverado 350 nv3500 5spd

Offline Irish_Alley

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Re: Carb to tbi conversation
« Reply #7 on: August 02, 2018, 06:08:19 PM »
are you getting power to the relay? what happens when you connect B+ to the red wire "C" on the relay.
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 Irish_Alley

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Re: Carb to tbi conversation
« Reply #8 on: August 02, 2018, 06:08:53 PM »
but x2 on this

You need to determine whether there is power at the two ECM fuses - I recommend that you procure a test light.  Post a pic of the fuel pump relay
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 #9 on: August 02, 2018, 06:17:17 PM »
The picture of the fuel relay won’t upload it’s to big but the wires are org, grn/wht, rd/blk, rd/wht and blk/wht
77 c10 Silverado 350 nv3500 5spd

Offline Irish_Alley

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Re: Carb to tbi conversation
« Reply #10 on: August 02, 2018, 06:49:39 PM »
this one?
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 #11 on: August 02, 2018, 07:11:09 PM »
I checked fire at fuel relay pig tail only got fire at orange wire and when I jumped orange wire to other wires nothing happened but the black wire sparked
77 c10 Silverado 350 nv3500 5spd

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Re: Carb to tbi conversation
« Reply #12 on: August 02, 2018, 07:39:52 PM »
The black/white wire is relay ground.  Orange is B+ powered through the ECM-B fuse.  Green/white is relay control from the ECM.  Do you know how to read a wiring diagram?  Do you have a voltmeter?
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 Irish_Alley

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Re: Carb to tbi conversation
« Reply #13 on: August 02, 2018, 07:51:20 PM »
dont jump wires unless you understand how they work. if you jumped orange to black you prob blew a fuse.

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 #14 on: August 02, 2018, 09:05:14 PM »
All furs are good and the fuseable links are getting power past them and yes I have voltmeter and no I don’t really now how to read them not my sting suit
77 c10 Silverado 350 nv3500 5spd