[AlexFolino]

4.3L z engine.
new distributor with pickup coil, new wires, plugs, cap, rotor, MAP sensor. Engine is properly timed. For some reason this engine will still not run. I can get it to partially start and run for roughly a fraction of a second and thats it. 4 mechanics i had even come to my house are stumped. Its getting gas. Each cylinder is getting spark. The coil is good. Compression in every cylinder. However i noticed it seems like theres some gas in the oil when i pulled the dip stick? The engine once in a blue moon will start however but has a very rough idle.
Can anybody diagnose or lead me in the right direction? thanks!

 

[67CAMAROSS]

is it vortec or tbi? if it is vortec with the injectors and regulater under the upper intake they may be bad just had one in the shop getting gas in the oil so i changed the regulater and injector assy. and up a new nut kit in it{hoses that hooks up to the regulater]

 

[SixtyAte]

If you have the injector setup 67 was talking about, you need to change it out. Its called the "Spider Injector System" and due to being under the intake with all the heat, they leak bad. Its common to have them fail about 60,000 mile range. I would yank the intake and replace the setup...


Kev

 

[AlexFolino]

The injectors are already new as well. New gaskets everywhere for the TBI. Any ideas to why it isnt starting still?

 

[VI009DZ]

Make sure your timing is good; try screwing with it in both directions. Kind of sounds like its off enough so it'll quickly fire on whats left in the cylinder, but won't run after that.

 

[AlexFolino]

Exactly, i think we might be a few teeth off in the distributor. Ill give it a shot.

 

[jaguareats]

put a timing light on it if timed right. check fuel pressure alot of times with that spider injection the pressure regulator goes bad and dumps fuel also check a new plug it will smell like gas.

 

[AlexFolino]

Did all of this. Still same problem. Im losing my mind over this now.

 

[Mark C]

What year 4.3? The computer controls the timing on the 4.3L if its an early 90's or later, there is no adjustment of timing, the distributor goes in straight up and you have to get the distributor installed correctly in order for the car to run correctly. Theres a specific procedure for installing the distributor in that motor.

 

[dnult]

Theres a specific procedure for installing the distributor in that motor.

I know some of those 90 something model truck engines required a diagnostic tool to set the timing.

 

[kustomwerker]

firing order is 165432clockwise i believe...set timing with brown pigtail wire disconnected at 4 degrees...(pigtail conn is by ecm...1 wire black conn on brown wire...)sounds like the dist is 180 out to me...newer obd2 dists are set with rotor at tdc and dist body is located by a pin in the intake through a groove in the body of the dist...what yr is the truck???

 

[ZZ_430]

What year 4.3? Theres a specific procedure for installing the distributor in that motor.

Exactly. We need more info on what you have.

 

[novaderrik]

the "Z" engine is the TBI, and the "W" is the Vortec, correct?
he says he's got the Z engine, which makes it not too much different than any carbureted engine.

 

[AlexFolino]

1991. I tried literally almost every combo for distributor position. Anything else?

 

[novaderrik]

think of it as just an engine, and forget about the electronics..
find TDC on the #1 cylinder, right after the intake valve closes.
that's the compression stroke. put the distributor in with the rotor pointing at the #1 terminal. i always mark the base of the distributor with a shaprie right where the terminal on the cap goes, that way i don't have to guess.
make sure the wires are in the right order, and fire that sucker up. if it doesn't run, then you've got other problems besides just the timing.

 

[AlexFolino]

Tried that Novaderrik last night... I do have issues mentally and physically at this point lol.. Anybody know what fuel pressure the truck is supposed to have? Some guys are telling me i might be flooding the engine with too much fuel although i can see it spraying correctly but at this point what else is there?

 

[kustomwerker]

9 to 12 lbs for tbi

 

[AlexFolino]

Its getting the proper fuel pressure. I just wish i can find out why its not starting.

 

[kustomwerker]

drop the y pipe and see if it`ll run...might be a plugged cat

 

[AlexFolino]

I did that as well.