Not a Tahoe, but I need help with my '92 K1500 (TBI) please guys...

[ChrisAU]

'92 K1500 5.7L TBI

So yesterday I drive about 12 miles this afternoon on the way to get my rear ranch hand bumper (a long trip for this truck), and at the red light going to the freight terminal I notice a sort of reverse idle surge; it's not a rough idle, it just got low quickly and then bounced quickly back to normal a few times, takes no more than 2 seconds. Then I pull up to the gate and I notice it doing it again, then as I'm waiting for it to open it stalls. And it was a hard start, took 4-5 attempts. You can hear it turning over it just doesn't crank. Then it fires up, runs great. So we throw the bumper in the back of the truck and on the way home I notice the low surge so I start driving with two feet. We get back home and when I put the truck in reverse to park it immediately stalls again. And again, its a very hard start.

The truck has been stumbling a bit at start-up until it warms up. I just don't drive this truck enough at all to describe behavior differences.

Anybody got a clue?

New parts: plugs, wires, cap, rotor, distributor, spark control module, EGR valve, EGR valve solenoid, TPS, MAP sensor, O2 sensor, ignition control module, pick-up coil, IAC Valve, CTS, knock sensor (& pigtail), intake gaskets, and prob some more, all within the last 500 miles.

Discussion on GMT400 has me thinking I need a TB rebuild...I have a kit, just haven't gotten around to doing it. Fuel pressure is steady high, like 15-16 PSI. Could it be leaking FPR and/or injectors? I have steady fuel from both injectors, it just isn't anything close to a "mist" and the hard starting does feel like a flooded carb.

I ordered two new Delphi injectors this morning.

The kit I have is just like this:

I've never been in one of these TB's before, but is that all I need? Are there replacements for the actual pressure regulator available?

Please help!

 

[SunlitComet]

looks to be a complete kit. just take your time.

 

[retorq]

That Orange/Copper piece is your fuel pressure regulator, be careful not to tear it putting it back together. Do the Free TBI mods hwile it's out.

What does the pattern look like if it's not a mist??

 

[ChrisAU]

What does the pattern look like if it's not a mist??

It looks more like a shower than a mist.

 

[SunlitComet]

Then after your TBI rebuild you should see significant improvement.

 

[ChrisAU]

Then after your TBI rebuild you should see significant improvement.

I sure hope so!

 

[AtomicHoe094]

does it matter if the trucks hot or not really? the ignition control module will play crazy games once its hot. Check under it to see if you have enough of that special grease crap.

 

[ChrisAU]

Well the truck idles a little rough at cold crank, but the stalling and idle drop problem are once it is warm.

The ICM is new.

I watched some videos of bad injectors vs. good ones over at FSC, and now I have seen the light...my injectors are PISSING fuel. They look like a hose on a pulse setting.

 

[AtomicHoe094]

remember, just because its new, doesnt mean they always work. youll have to go through a few of them sometimes. parts are ****** now adays

 

[retorq]

Fuel pressure will effect the spray pattern ... who told you it was 15? When it's acting up and stalling have you verified the fuel pressure?? Putting new injectors into a TBI that needs a rebuild isn't going to help. Perhaps your O ring at the bottom is jacked up ...

 

[ChrisAU]

I am rebuilding the TB and replacing the injectors.

I had a good shop in my area hook up a fuel pressure gauge at the TB and I watched it hold steady at just over 15 psi even during stumbles. My injectors have no come shape at all its more like a pulsing water hose on both sides.

 

[SunlitComet]

you seem to have a most righteous pump and some bad sprinklers for sure.

 

[AtomicHoe094]

if this doesnt fix the problem (TBI rebuild) check into your temp senders..

 

[SunlitComet]

temp sensors don't fix crappy spray patterns.

 

[AtomicHoe094]

i said if it DOESNT fix the problem, look into temp senders.. they tell the pcm its -40 degrees out which means the injectors are going to DUMP gas, its not going to have a pretty pattern when it dumps gas.

 

[SunlitComet]

It will still have a good pattern but pulse width would be longer.

 

[ChrisAU]

Yeah I'm thinking the FPR diaphragm and/or the leaky injectors are causing the high pressure.

As for the temp senders, both are new AC Delco units. That had crossed my mind though, if I still have problems after this I am going to swap the AC Delco one on the manifold for a Delphi one.

 

[gpracer1]

I had a 93 with tbi, replaced with a Holley tbi. Replaced the carb on my boat with a holley tbi. All three of them shower, there is no misting. It takes too much fuel to feed a V8 through 2 injectors to have a fine spray.
As long as it is even all around and not pissing a stream it's probably ok, especially if the other one is the same. They run about 11-13 psi stock I think.

 

[AtomicHoe094]

i was thinking 15 lbs is too high from the beginning, but some years are different with each other.. mine dont spray a fine pattern either on my 454 or 350.....

 

[ChrisAU]

Well a leaky diaphragm and/or injectors can cause high pressure.

In a functioning system the pressure is limited by the FPR first and then the injectors, if they were free flowing there would be no point in having the FPR.