Another TBI Need Help Thread... - Pirate4x4.Com : 4x4 and Off-Road Forum

hardline04 · 10-23-2007, 07:44 PM

I am in the process of converting an '85 4.3 carb motor to TBI. Have a harness off a 350 and TB off a 4.3, I have everything swapped over and hooked up. I cannot get my injectors to fire. I have the schematics on the wiring and have check all grounds and have power going to both hot injector wires, but they don't fire. The coil is working I can get it to run off ether but injectors aren't working. I don't think its injectors being bad since both are not working but I don't know. Fuel pump is good and working.

Hawkes · 10-24-2007, 07:28 AM

Engine ground hooked up?

BEANE · 10-24-2007, 07:53 AM

read this it might help
http://www.pirate4x4.com/forum/showt...ght=tbi+wiring

hardline04 · 10-24-2007, 09:41 AM

Quote:

Originally Posted by Hawkes

Engine ground hooked up?

Yes grounds are all there. Got the injectors to fire but it wont crank, can crank it with ether and it will stay running and has throttle response but wont start without ether.

vaz71 · 10-24-2007, 06:31 PM

Don't know what all you have swapped in this process, but is the fuel pump putting out the pressure the injectors require to pop off properly? I only ask this because i was taught you can't run an engine off ether alone, it has to have a little gas (or diesel) to run. Sounds like a fuel pressure problem.

vaz71 · 10-24-2007, 06:43 PM

To correct myself before i get busted, diesel injectors rely on pressure alone to fire, yours are opened by electricity but if the fuel pump is from the carburetor the gas is dripping out instead of spraying a mist which is crucial in a TBI to get the right air/fuel mix through the maifold to all the cylinders.

KWTMECH · 10-24-2007, 06:45 PM

What distributor did you use? The distributor signals the injectors to pulse

Urban Wheeler · 10-24-2007, 07:02 PM

Quote:

Originally Posted by KWTMECH

What distributor did you use? The distributor signals the injectors to pulse

+1.

There is also a wire that goes to the starter to tell the ecm that the engine is cranking.

Bill usn-1 · 10-24-2007, 08:44 PM

The C8 crank signal wire is not required to start the engine.
It is used to adjust the parameters during cranking.

Start by ensuring you have 12V to the injectors and the ECM while you are cranking.

It sounds like you tried to wire the injection system straight to the stock wiring and are not using relays to power the system.
The old 12V wire going to the coil should only be used to energize the relays...meaning more then one relay.....

If you haven't been to the link in my sig yet then start there in the injection forum and the FAQ's.

Tim84K10 · 10-24-2007, 10:59 PM

Check the oil pressure switch.

Bill usn-1 · 10-25-2007, 07:14 AM

Also make sure you review the parts required FAQ.
You need the ecm to match the engine.
Both removeable chips in the ECM are different between the 6 and the 8's.

Meph · 10-25-2007, 07:28 PM

Quote:

Originally Posted by hardline04

I am in the process of converting an '85 4.3 carb motor to TBI. Have a harness off a 350 and TB off a 4.3, I have everything swapped over and hooked up. I cannot get my injectors to fire. I have the schematics on the wiring and have check all grounds and have power going to both hot injector wires, but they don't fire. The coil is working I can get it to run off ether but injectors aren't working. I don't think its injectors being bad since both are not working but I don't know. Fuel pump is good and working.

What is the ECM service number? Is it from the 4.3 or the 350?

If you have no luck with this, take a look at our aftermarket wire harness:

http://www.affordable-fuel-injection...ng-harness.htm

It is a lot easier to install than a factory harness, and includes all of the relays that you need. You may also want to get a custom chip as well. We specialize in building custom wire harness and chips for engine transplants such as yours.

pcorssmit · 10-26-2007, 03:26 PM

Quote:

Originally Posted by hardline04

Yes grounds are all there. Got the injectors to fire but it wont crank, can crank it with ether and it will stay running and has throttle response but wont start without ether.

Check to make sure the computer is getting power while cranking. I suspect you hooked it to one of the power leads that is not energized while cranking, but is while the key is in the on position.

Pete

10-23-2007, 07:44 PM	#1 (permalink)
hardline04 Registered User Join Date: Oct 2005 Member # 55362 Location: Jonesboro, AR Posts: 773	Another TBI Need Help Thread... I am in the process of converting an '85 4.3 carb motor to TBI. Have a harness off a 350 and TB off a 4.3, I have everything swapped over and hooked up. I cannot get my injectors to fire. I have the schematics on the wiring and have check all grounds and have power going to both hot injector wires, but they don't fire. The coil is working I can get it to run off ether but injectors aren't working. I don't think its injectors being bad since both are not working but I don't know. Fuel pump is good and working. __________________ East Coast Buildup: [url]http://www.pirate4x4.com/forum/showthread.php?t=597717[/url] Acts 20:24

10-24-2007, 07:28 AM	#2 (permalink)
Hawkes Registered User Join Date: Apr 2005 Member # 45512 Location: Nova Scotia Posts: 194	Engine ground hooked up? __________________ '70 Jeepster, 4.3, SM465, toy axles, spring over, etc

10-24-2007, 08:44 PM	#9 (permalink)
Bill usn-1 Registered User Join Date: Jun 2003 Member # 20423 Location: Finally back in the US-Wdby Is, WA Posts: 1,066	The C8 crank signal wire is not required to start the engine. It is used to adjust the parameters during cranking. Start by ensuring you have 12V to the injectors and the ECM while you are cranking. It sounds like you tried to wire the injection system straight to the stock wiring and are not using relays to power the system. The old 12V wire going to the coil should only be used to energize the relays...meaning more then one relay..... If you haven't been to the link in my sig yet then start there in the injection forum and the FAQ's. __________________ Bill USN-1 EFI Moderator at http://www.binderplanet.com

10-25-2007, 07:14 AM	#11 (permalink)
Bill usn-1 Registered User Join Date: Jun 2003 Member # 20423 Location: Finally back in the US-Wdby Is, WA Posts: 1,066	Also make sure you review the parts required FAQ. You need the ecm to match the engine. Both removeable chips in the ECM are different between the 6 and the 8's. __________________ Bill USN-1 EFI Moderator at http://www.binderplanet.com

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10-24-2007, 07:53 AM	#3 (permalink)
BEANE Registered User Join Date: Jul 2005 Member # 51119 Location: CHAPEL HILL ,TN Posts: 83	read this it might help http://www.pirate4x4.com/forum/showt...ght=tbi+wiring

10-24-2007, 06:31 PM	#5 (permalink)
vaz71 Registered User Join Date: Sep 2007 Member # 99784 Location: BFE,Virginia Posts: 24	Don't know what all you have swapped in this process, but is the fuel pump putting out the pressure the injectors require to pop off properly? I only ask this because i was taught you can't run an engine off ether alone, it has to have a little gas (or diesel) to run. Sounds like a fuel pressure problem.

10-24-2007, 06:43 PM	#6 (permalink)
vaz71 Registered User Join Date: Sep 2007 Member # 99784 Location: BFE,Virginia Posts: 24	To correct myself before i get busted, diesel injectors rely on pressure alone to fire, yours are opened by electricity but if the fuel pump is from the carburetor the gas is dripping out instead of spraying a mist which is crucial in a TBI to get the right air/fuel mix through the maifold to all the cylinders.

10-24-2007, 06:45 PM	#7 (permalink)
KWTMECH Registered User Join Date: Sep 2002 Member # 13786 Location: moved 7 miles to colfax, ca. Posts: 4,224	What distributor did you use? The distributor signals the injectors to pulse

10-24-2007, 10:59 PM	#10 (permalink)
Tim84K10 Banned Join Date: Nov 2003 Member # 24704 Location: Illinois Posts: 4,430	Check the oil pressure switch.