injector?????? tbi 4.3

outhouse · Oct 27, 2009

so before i go spend 80each on new injectors i was wondering. are they shot forshur when fuel drips out and not sprays? its an 88-92 tbi 4.3. i went thru and cleaned the whole tbi unit. it was pritty nasty.

uke:

Bill USN-1 · Oct 27, 2009

You can always try cleaning them.
run some inj cleaner or pull them and soak the tip in some cleaner.
You can manuall open the pintles by just quickly touching 12v and gnd to the connections on top while the tip is in the cleaner.
If you aren't sure how to pull the injectors I have the procedures posted on the binderplanet in the FI forum FAQ's.

crash2 · Oct 27, 2009

outhouse said:
so before i go spend 80each on new injectors i was wondering. are they shot forshur when fuel drips out and not sprays? its an 88-92 tbi 4.3. i went thru and cleaned the whole tbi unit. it was pritty nasty.uke:

TBI injectors spit more than they spray. They are not a fine mist by any means..

outhouse · Oct 27, 2009

crash said:
TBI injectors spit more than they spray. They are not a fine mist by any means..

well its 100% drip. as soon as it fires it runs for about 5 seconds and runs out of fuel.

iv already had the injectors out and kinda cleaned em just not soaked um.

crash2 · Oct 27, 2009

outhouse said:
well its 100% drip. as soon as it fires it runs for about 5 seconds and runs out of fuel.

iv already had the injectors out and kinda cleaned em just not soaked um.

I have yet to see a tbi injector get plugged or have the mechanical portion stick. Are they both doing it? If so you have a feed issue...

outhouse · Oct 27, 2009

crash said:
I have yet to see a tbi injector get plugged or have the mechanical portion stick. Are they both doing it? If so you have a feed issue...

yes they both do it equally. my pump is pumping and my regulator is turned up to 13.5 i belive. man you reply fast, Thanks:beer:

jimpaget · Oct 27, 2009

I run a Holley version of the 4.3 TBI. Several years ago I went through several injectors that seemed to be demonstrating the same behavior you describe. I eventually traced the problem down to bad, but partial connection in one of the wires.

It has now been several years since I replaced an injector, and in fact the ones that I am running were ones that I previously pulled out because the weren't "working".

Binder · Oct 27, 2009

outhouse said:
yes they both do it equally. my pump is pumping and my regulator is turned up to 13.5 i belive. man you reply fast, Thanks:beer:

So you've had a gage on it to varify the fuel pressure?

t1h5ta3 · Oct 28, 2009

yha, 13.5 psi isnt enough presure to get anything to mist.... latter /aftermarket tbi's use a smaller injecter @ higher presure to get closer to atomising...

crash2 · Oct 28, 2009

t1h5ta3 said:
yha, 13.5 psi isnt enough presure to get anything to mist.... latter /aftermarket tbi's use a smaller injecter @ higher presure to get closer to atomising...

Operating pressure should be between 12-14psi. For some reason I wanna say the big blocks only ran a high pressure tbi setup.

Bill USN-1 · Oct 28, 2009

crash said:
I have yet to see a tbi injector get plugged or have the mechanical portion stick. Are they both doing it? If so you have a feed issue...

I deal with them everyday and have seen several. Especially if they sit for a while without starting the engine.

To ensure there is no connection problems you can use a couple jumperwires and connect 12v and gnd to the inj as you have someone turn the key on.

But as EDIT: Rick said, you need to check the pressure with it running. When was the filter last changed?
Is the pump in tank or frame mounted?

You can check the spray pattern by pointing a timing light at the inj with the pickup on the coil wire instead of #1. You should note the inj's alternate fire not at the same time.

crash2 · Oct 28, 2009

Bill USN-1 said:
I deal with them everyday and have seen several. Especially if they sit for a while without starting the engine.

To ensure there is no connection problems you can use a couple jumperwires and connect 12v and gnd to the inj as you have someone turn the key on.

But as Mark said, you need to check the pressure with it running. When was the filter last changed?
Is the pump in tank or frame mounted?

Same here and I actually have only seen one I could easily fail/flow issue which is really rare on them.

As for sitcky when sitting like any injector I could see it.

I still think there is an issue on the pressure/feed side.

Bill USN-1 · Oct 28, 2009

crash said:
Operating pressure should be between 12-14psi. For some reason I wanna say the big blocks only ran a high pressure tbi setup.

CPI used a single TBI style inj at higher pressure to fead all 6 cyl's.

crash2 · Oct 28, 2009

Bill USN-1 said:
CPI used a single TBI style inj at higher pressure to fead all 6 cyl's.

True--but the poppets was the issues we saw with those. Not to mention the lovely hydrolocked motors with fuel we would see from time to time due to the feed lines cracking :haha:

outhouse · Oct 28, 2009

jimpaget said:
I run a Holley version of the 4.3 TBI. Several years ago I went through several injectors that seemed to be demonstrating the same behavior you describe. I eventually traced the problem down to bad, but partial connection in one of the wires.

It has now been several years since I replaced an injector, and in fact the ones that I am running were ones that I previously pulled out because the weren't "working".

thays whats on it is the holley version. and the wires have power. do you know how many volts they get at idol.

crash said:
Operating pressure should be between 12-14psi. For some reason I wanna say the big blocks only ran a high pressure tbi setup.

yup thats what my fantastic "book" says is 9 to 13.5 psi

outhouse · Oct 28, 2009

im dealing with a bran new howell harness so youd think every thing sould be getting the rite conecting. i know they screw up to. that would be my luck!

outhouse · Oct 28, 2009

Bill USN-1 said:
I deal with them everyday and have seen several. Especially if they sit for a while without starting the engine.

To ensure there is no connection problems you can use a couple jumperwires and connect 12v and gnd to the inj as you have someone turn the key on.

But as Mark said, you need to check the pressure with it running. When was the filter last changed?
Is the pump in tank or frame mounted?

You can check the spray pattern by pointing a timing light at the inj with the pickup on the coil wire instead of #1. You should note the inj's alternate fire not at the same time.

and yes the motor has sat for like 21/2 years without running, and redbeard who i got it from i belive didnt cover it. the filter is brand new and its a frame mounted pump.

Binder · Oct 28, 2009

So this is a new retrofit/ install? You need to go to the Binder Planet and read through the FAQs.

Bill USN-1 · Oct 28, 2009

thays whats on it is the holley version. and the wires have power. do you know how many volts they get at idol.

How old?
If this is the old style injectors with the round black plastic cap...you may want to just grab the inj pod off a GM throttle body and bolt it down.
The early holley inj's were very poor.
Even holley switched to delphi injectors.

Still need to check the actual fuel pressure and sheet 1 of the wiring diagrams I have posted list the key-on and engine running voltage checks for trouble shooting.

outhouse · Oct 28, 2009

the injectors are getting 12 volts like there soposto and the neg. is what feeds the pulse. i have 12 volts then when i hit the ing. it drops to 3 volts at the most. its not the tps i just repaced it. its getting plenty of fuel presure. the only thing i can think of now is the brain. and the check eng. light is on. it flashes once then is solid. cant find that code yet. any one now?