4.3 tbi problems

[Gaylord]

ANyone want to drink beer and eat pizza for FREE. I am lost I have a 91 TBI 4.3 in my 3b that is running like ****. I't won't start unless you dump gass down the throught then when it does start it runs rather rough and rich. Once it warms up it will starve for fuel. Has new fuel system and most of the engine sensors have been replaced.
somone told me it could be the distibuter as it send a signal to the injectors based off the RPM's. Is this true? I could stab a new dist. in from the junk yard if you all think it's a wise part to through at this problem. ??

 

[crash2]

Where are you located?

 

[Brian H]

ANyone want to drink beer and eat pizza for FREE. I am lost I have a 91 TBI 4.3 in my 3b that is running like ****. I't won't start unless you dump gass down the throught then when it does start it runs rather rough and rich. Once it warms up it will starve for fuel. Has new fuel system and most of the engine sensors have been replaced.
somone told me it could be the distibuter as it send a signal to the injectors based off the RPM's. Is this true? I could stab a new dist. in from the junk yard if you all think it's a wise part to through at this problem. ??

If you add boobies to your offer Crash is your man !

 

[Gaylord]

Port Orchard.

Might get the lady to show you her tittys if we let her drink with us. She did win best box on the beach in Vantage a few years ago.

 

[Gaylord]

Man, wifes boobys not good enough? There BIG !

 

[KarlVP]

What's the fuel PSI at the injector?

 

[GaryTJ]

since it will run when adding fuel, the spark is ok. forget the dist.

Make sure the fuel lines are not on backwards going into the injector body.

next would be to make sure of all powers and grounds to the ecm. Use a voltmeter not a testlight. powers should be within 1/2 a volt of battery voltage. It is very common for you to loose the ground for the computer that attached at the thermostat housing.

 

[Gaylord]

since it will run when adding fuel, the spark is ok. forget the dist.

Make sure the fuel lines are not on backwards going into the injector body.

next would be to make sure of all powers and grounds to the ecm. Use a voltmeter not a testlight. powers should be within 1/2 a volt of battery voltage. It is very common for you to loose the ground for the computer that attached at the thermostat housing.

Gary I will check that stuff, thanks. However Injectors are not priming wich is controlled by the distibutor and my tach signal is all f-ed up so I beleive that very well may be the problem.

 

[crash2]

since it will run when adding fuel, the spark is ok. forget the dist.

Make sure the fuel lines are not on backwards going into the injector body.

next would be to make sure of all powers and grounds to the ecm. Use a voltmeter not a testlight. powers should be within 1/2 a volt of battery voltage. It is very common for you to loose the ground for the computer that attached at the thermostat housing.

Actually gary not really. You can loose the reference from the ignition module to the ECM which controls injector pulse.

If the rig is not priming I would look at what gary said---ecm feeds/grounds because you should get a 2 second run of the fuel pump when you turn the key on and the pump should run once the ECM gets a refence from the dist...

 

[Gaylord]

Well how do I know wich wires should be hot and wich should be grounded?

Getting to the computer and checking that stuff should be easy enough I just have no idea wich wire does wich thing.

Also I do not have a oil pressure safety so when the key is on the pump is on. I was going to fix that later, becuase it could cuase a problem when layin on your lid.

I might add this jeep ran perfectly till it was rolled. It has never ran right since. All sensors have been changed, fuel pump., pick up and lines. I beleive that the distributor is so close to the firewall that in the roll this could have been affected.

 

[zig80toy]

x2 on the checking grounds.
sounds like maybe a ground came loose, wire got pinched, etc... when you rolled.

 

[Gaylord]

If distributer does not work I think I pull the entire wire harnes out and check it that way. My father wired this Jeep 10+ years ago.

 

[wazz]

Well how do I know wich wires should be hot and wich should be grounded?

Getting to the computer and checking that stuff should be easy enough I just have no idea wich wire does wich thing.

your lucky day, I got board waiting for my parts to show up so click :beer:

 

[Gaylord]

Thanks!!!!!!!!!!!!!!!!!!!!!!!!!:clappy: :beer:

Although this Jeep has a homemade wire harness . I beleive these color codes will work at the computer plug.

 

[Gaylord]

Wazz, so are the wires marked with 0 voltage supposed to be grounds?

 

[wazz]

Wazz, so are the wires marked with 0 voltage supposed to be grounds?

You computer grounds are C2, C3, D2, D3 :;

at a 2nd look, actualy it looks like D2 and D3 are grounds being outputed by the computer to the sensors originated from C2 and C3 so if a ground broke off some wheres thems the ones to check.:redneck:

 

[crash2]

at a 2nd look, actualy it looks like D2 and D3 are grounds being outputed by the computer to the sensors originated from C2 and C3 so if a ground broke off some wheres thems the ones to check.:redneck:

if thats the case then you would more than likely have a code for that particular sensor.

 

[wazz]

I would wanna check real quick and see if both injectors are spraying fuel, the symptom sounds to me like 1 injector might not be working. Thats the cool'ness I like about TBI you can watch what the injectors up to and get a look see of what its doing.

 

[crash2]

I would wanna check real quick and see if both injectors are spraying fuel, the symptom sounds to me like 1 injector might not be working. Thats the cool'ness I like about TBI you can watch what the injectors up to and get a look see of what its doing.

bUT are they working "right"

Had a 454 once that kicked my butt--ended up being a bad injector but looking/Ohm it was perfect--just flowed a tad less than spec...

And for the record I have only had like 3 bad tbi injectors in 18 years..

 

[wazz]

Yes I agree it is rare i think ive only seen 1 actual TBI injector on a chevy go bad. IM sure you have patched up and replaced pleanty of them 4 wire harnesses though, I found quite often the wires under the air cleaner spacer failing. Just sucks they dont give an easy way to check the PSI without like using the motorvac machine leads.