5.7 tbi - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cfan10 · 07-27-2017, 08:25 PM

Bought a '91 suburban without engine/transmission or wiring harness for $200 body is excellent...I have a '90 suburban cracked frame going to switch everything from the '90 to the '91
I haven't actually driven it since not really sure early 2016...fuel pump I thought went out but a friend hooked the relay to the battery and it started and drove fine but obviously would drain the battery. I did replace the relay and oil pressure switch but without it being hooked to the battery with the hot wire it won't start.
I'm a total novice at wiring, any help on what is out of place would be greatly appreciated!

'90 gmc suburban 5.7 tbi/700r4 miles on engine 45k
Having issues uploading photos

cfan10 · 07-27-2017, 08:28 PM

Photos

cfan10 · 07-27-2017, 08:38 PM

More photos

daddyjeep · 07-28-2017, 12:24 PM

A relay is essentially a switch. If you can only get it to run by applying direct power to the "switched" terminal then whatever is telling the switch to open is where I would look. There are 4 wires on a relay... 12v power in from battery, 12v out to fuel pump, ground, and switch wire. Figure out which wire is your switch and trace it back and see if a problem shows itself. I am not familiar with the wiring for the TBI engine to give you any better advice.

cfan10 · 07-31-2017, 06:52 PM

Now, I know why the wires were wrapped in duct tape, electrical and loom...to hide this mess!

cfan10 · 08-03-2017, 09:39 PM

Fixed the engine harness today, found this when tracing the wires to the tank. Could this cause it to not start? Thanks!

07-27-2017, 08:25 PM	#1
cfan10 Registered User Join Date: May 2011 Location: Texas Posts: 968	5.7 tbi Bought a '91 suburban without engine/transmission or wiring harness for $200 body is excellent...I have a '90 suburban cracked frame going to switch everything from the '90 to the '91 I haven't actually driven it since not really sure early 2016...fuel pump I thought went out but a friend hooked the relay to the battery and it started and drove fine but obviously would drain the battery. I did replace the relay and oil pressure switch but without it being hooked to the battery with the hot wire it won't start. I'm a total novice at wiring, any help on what is out of place would be greatly appreciated! '90 gmc suburban 5.7 tbi/700r4 miles on engine 45k Having issues uploading photos __________________ Rest In Peace:Mikhail {Mickey Rooney} Alpha 2/5/13 Omega 7/22/14 10:28AM I love you tremendously and outragiously Superpuppi Thai Ridgeback...The most intelligent dog known to me. Don't mess with my truck, my momma or my money...not necessarily in that order. © Stand for something or fall for anything. [LIST][*]'98 Bourbon St. Brawl ©2010

07-27-2017, 08:28 PM	#2
cfan10 Registered User Join Date: May 2011 Location: Texas Posts: 968	Re: 5.7 tbi Photos Attached Images __________________ Rest In Peace:Mikhail {Mickey Rooney} Alpha 2/5/13 Omega 7/22/14 10:28AM I love you tremendously and outragiously Superpuppi Thai Ridgeback...The most intelligent dog known to me. Don't mess with my truck, my momma or my money...not necessarily in that order. © Stand for something or fall for anything. [LIST][*]'98 Bourbon St. Brawl ©2010

07-27-2017, 08:38 PM	#3
cfan10 Registered User Join Date: May 2011 Location: Texas Posts: 968	Re: 5.7 tbi More photos Attached Images __________________ Rest In Peace:Mikhail {Mickey Rooney} Alpha 2/5/13 Omega 7/22/14 10:28AM I love you tremendously and outragiously Superpuppi Thai Ridgeback...The most intelligent dog known to me. Don't mess with my truck, my momma or my money...not necessarily in that order. © Stand for something or fall for anything. [LIST][*]'98 Bourbon St. Brawl ©2010

07-28-2017, 12:24 PM	#4
daddyjeep Registered User Join Date: Nov 2015 Location: Smethport, PA Posts: 1,213	Re: 5.7 tbi A relay is essentially a switch. If you can only get it to run by applying direct power to the "switched" terminal then whatever is telling the switch to open is where I would look. There are 4 wires on a relay... 12v power in from battery, 12v out to fuel pump, ground, and switch wire. Figure out which wire is your switch and trace it back and see if a problem shows itself. I am not familiar with the wiring for the TBI engine to give you any better advice. __________________ 85 K30 crew cab dually - Project http://67-72chevytrucks.com/vboard/s...d.php?t=694939 87 Wrangler Rock Crawler - Reason for the project http://www.wranglerforum.com/f330/da...ld-122601.html 04 1500 crew cab http://67-72chevytrucks.com/vboard/s...d.php?t=786514

07-31-2017, 06:52 PM	#5
cfan10 Registered User Join Date: May 2011 Location: Texas Posts: 968	Re: 5.7 tbi Now, I know why the wires were wrapped in duct tape, electrical and loom...to hide this mess! Attached Images __________________ Rest In Peace:Mikhail {Mickey Rooney} Alpha 2/5/13 Omega 7/22/14 10:28AM I love you tremendously and outragiously Superpuppi Thai Ridgeback...The most intelligent dog known to me. Don't mess with my truck, my momma or my money...not necessarily in that order. © Stand for something or fall for anything. [LIST][*]'98 Bourbon St. Brawl ©2010

08-03-2017, 09:39 PM	#6
cfan10 Registered User Join Date: May 2011 Location: Texas Posts: 968	Re: 5.7 tbi Fixed the engine harness today, found this when tracing the wires to the tank. Could this cause it to not start? Thanks! Attached Images __________________ Rest In Peace:Mikhail {Mickey Rooney} Alpha 2/5/13 Omega 7/22/14 10:28AM I love you tremendously and outragiously Superpuppi Thai Ridgeback...The most intelligent dog known to me. Don't mess with my truck, my momma or my money...not necessarily in that order. © Stand for something or fall for anything. [LIST][*]'98 Bourbon St. Brawl ©2010



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