1992 Lumina z34 wont start.

[Rabbi]

picked up a 1992 z34 today for $400.

The guy says the car has a problem staying running, The car will start up then just die after a few seconds of running.

It will not start up at all now. The timing is not off for sure, Its turning over fine. It just wont fire up.

Where should i start?

Sounds like a fuel/electrical problem. What should we start with?

Havent pulled the code's yet, Will be doing that on sunday.

[Rabbi]

also the previous owner put some crappy ass ebay intake on it. What sensors are supposed to be on the intake box & intake pipe?

Theres only one on there as of right now, And its not even hooked up its just sort of sitting there....Maybe this has something to do with it?

Its been a VERY long time since i had a 3.4 so im back to being clueless, About all i remember about this engine is the good old timing belt swap procedure heh.

Going to be going to the junkyard in a few days, Going to pickup a ICM and a few other sensors.

[pocket-rocket]

It should still run without an air intake temp sensor, but will throw a code, and it will just run rough. Check for fuel and spark. Without either, it won't run.

[RedZMonte]

the '92 has only a AITS in the intake. No Maf or any other sensors.... I would 1st pull a plug and ground it to the car and see if you have spark when you crank it. If you have spark then i would put a fuel pressure guage on (under plastic "3.4 DOHC/Twin Dual Cam" cover). and see if you have fuel pressure. My guess is your not getting fuel. also if the fuel filter is plugd you may get pressure but not enough volume. So for the $5 i would do a filter. Do you hear the pump hum when you put the key to ACC on? does it just crank or does it try to start (crank and stumble but not start) or just crank?

I would definalty start by checking the easy thinkgs (Fuel/Spark) 1st. also check the codes foe show! guessing missfire codes....

S

[Rabbi]

Wont be able to get back to the car till monday or so.

But,


Fuel pump clicks on as usual.

The car cranks and sounds normal, Just no start. No skipping/backfiring etc.



Would a failing ICM cause the car to start up then die a few seconds later, Then not start for a while?

The guy said the car would run strong for a little while, Then just die and not start for awhile.

[pocket-rocket]

I would wait till you get it home to start pointing at the ICM. I mean, anything is possible, really. But before you can point at parts, you need to check them and rule them out before saying for certain, "Yes, it's such and such part."

[Juglenaut]

A outright fuel flow problem will not throw a usual code unless you force a fuel required component to fault like a map or idle air, Unless a code is already encountered or stored by someother means. Clear the ECM by disconnecting the battery for a few or have a scanner clear it, get the ECM out of "limp" mode. A fuel issue can in some cases throw a ICM code, however most likely a vac or air issue will fault a ICM. If low flow fuel is a issue the ECM may or maynot fault the o2 but it has to be at normal running temp before the ECM will pend one. Exhaust crossover and down tube will heat exceptionally fast and hotter then normal if the fuel is to low of flow, may even glow, the exhaust will smell very lean.

These OBD1 computers can run on two coils without a code for a short time, if extended will fault various codes. Ussually takes two occurrences to pend a code and three to fault.

[Rabbi]

ok i tested for both fuel & spark.

I tested for fuel at the fuel rail's valve thingbob (looks like a bycicle air valve)
fuel sprayed out pretty good, So i guess its getting fuel.


I Pulled two plugs out and both are getting spark.


There is no service engine soon light on, So i guess its not throwing a code.


Checked the timing belt and it looks like its in very good shape, Probobly has about 15 - 20K + miles on it from the condition it looks like its in.

Now its getting both fuel and spark, What should i be checking next?

I will run the codes tommarow hopefully if i can get back out to the car.

ALSO!

the engine looks like it may be from a newer vehicle, The top mount to pull the engine is scraped up so im assuming the engine has been pulled, or possibly the existing motor is from a newer car. Is there anyway to check to see what motor the car has come from? The engine is in REALLY good shape, It is probobly the cleaning engine bay i have seen that isnt a brand new vehicle. Im assuming the engine is from a newer Monte Carlo maybe. The engine also looks a little different from my 1991 lumina z34 that i used to own. I Dont remember the fuel injector cover on my old car saying "Duel Twin Cam V6" , Although it has been a good 4 years since i owned my old z34.


Guys im stuck at a stand still here, What should i be looking for next?

If its getting spark and fuel, It should be starting correct?

[Rabbi]

another update,

I Pulled the fuel injector cover and on the 3rd visible injector harness the wires seemed melted. Possibly the are being shorted out.


Would one fuel injector not operating because of a short, Would the entire fuel injector system stop operating?


Thanks

[pocket-rocket]

The injectors are fired in sets of 3 if I remember right, so the computer is like a 2 channel amp, alternating between the 2 channels to fire the injectors. If I am wrong, someone will chime in and correct me. But if I am right, and that 1 injector isn't firing because its wires are shorted, your going to have 3 dead injectors. I would try to repair it as best as you can and try to get it to fire again.

[Rabbi]

Update :

injector wire was not melted, Just covered in electrical tape. Thats fine.


Tested for fuel and its getting fuel to the rail.


First two plugs are NOT getting spark on the front bank.


its throwing no codes.

ICM or Coilpack?

[pocket-rocket]

Since it's two plugs on the front (which would be on different coil packs) start cheap and check your crank position sensor. Those are a butt load cheaper then an ICM. What you are looking for is on the back side of the engine, about center crank level. There is a 2 wire plug going into it. If memory serves me, they are Purple and Yellow, and they will be twisted together. The wire will run to the passenger side, under the oil pan and to the ICM. If you have an auto, it might be best to take the passenger side tire, brake hardware, hub with axle attached, and splash guards out to get to it. When you pull it out, if it has a crack or looks funny, replace it. It will probably be in there pretty good. If you replace it and it still doesn't work, make sure the wire going to the ICM is good.

The flow chart in the shop manual it basically asks if you have an SES light on, when key is on, and if your tach functions when you crank it, if yes, then go and check plugs 1 at a time for spark, if no spark then its an ICM. If spark on one, check pair of wires that did not spark, each wire should measure less then 30k ohms. If ok, switch coil assemblies. Does problem move?. If yes, faulty coil, if no, ICM.

I would think the thing would make an attempt to fire even on 2 cylinders if you had 2 bad coils. It might not run, but it would try to. Like I said though, CPS is cheaper then an ICM. Advance Auto is quoting me online $24 for the CPS and $100 for the ICM.

[Rabbi]

The flow chart in the shop manual it basically asks if you have an SES light on, when key is on, and if your tach functions when you crank it, if yes, then go and check plugs 1 at a time for spark, if no spark then its an ICM. If spark on one, check pair of wires that did not spark, each wire should measure less then 30k ohms. If ok, switch coil assemblies. Does problem move?. If yes, faulty coil, if no, ICM.

My Tach DOES function. When i crank it the tach will go up while cranking.

so recheck all plugs, and if none have spark my ICM is at fault?

[Rabbi]

thanks for all the help so far pocket-rocket, Its so nice having people like you who actually try to help instead of giving some idiotic answer like on a few of the other automotive forums i visit that i shall not name!

[pocket-rocket]

My Tach DOES function. When i crank it the tach will go up while cranking.

so recheck all plugs, and if none have spark my ICM is at fault?

I would say so. Since your tach does move, that means your CPS is sending a signal, and it sounds like you do have a bad ICM. Don't give me any credit until that puppy fires over, lol. Well, you know what? Since I have been posting on the net, the 60v6 crowd has the most level headed people that know what they are doing and talking about. I have gotten help, and in return, if I can offer up something that can help someone out. I think of it as my part of doing like that movie "Pay it Forward" or whatever it was called.