I bought a 1991 covertte from this guy for dirt nothing anyway i have changed the battery, steering column the car use to be hot wired so now i have wired a pushed in the car now a wire straight from the start to the button but now car injectors not pulsating.car sat for bout 3 years. went just bout all way through it. got spark,fuel to rail.cap and rotor...but my injectors have power just no pulse to run on its own.ive read alot and everyone says change this and that. ive also read that lots of that didnt need replacing. now i have the motor turning over just fine but it s not firing up..

 

See if they have +12 on one side of the connectors with the key on. They way they work is they have +12 always (with the key on) and the ECM grounds the other terminal to fire them. TPI is batch fire. All on one side and then all on the other.

If you have +12, then either you have a short somewhere (could be a bad injector), a distributor problem (it knows when to fire them based on the distributor trigger), or lots of other things like a bad ECM, blown fuses, bad ground, etc.

 

I worked on a 'barn find' type vette at a shop where I do some computer work. It sat for 7 years without running, it cranked but wouldn't start. We ohm'ed the injectors and found three that were questionable. We unplugged the questionable ones, cranked, and it fired right up. Then we started plugging the questionable injectors back in, when we hit the really bad one the motor stopped like we turned the key off. So the moral of the story is, I'd check the injectors by measuring their cold resistance with a multimeter. I believe 10 ohms is the minimum but could be wrong. Search the forum for better direction on measuring the injector resistance. And good luck!

 

@ jv9999...ok bro i changed the injectors so i know that they are all good....and i know i have spark so I'm stumped... i was thinking it could be the ecu well

 

if i spray start fluid it attempts to start but other than that it just turns over....

 

I had the same problem after doing some updating and mods on my 91. I pulled the steering wheel over the winter to have it recovered at my local upholstery shop.
I could not get it to start afterwards. I had fuel pressure, spark, new BoschIII injectors etc. No pulse to the injectors though.
Finally got out the "no start" flow chart from my FSM and there it was! The ECM was looking for a signal that showed the air bag was not deployed. I put the air bag fuse back in and she fired right up!

 

That is not true for L98s. All 8 injectors fire at the same time. See the article I wrote on this:

http://forums.corvetteforum.com/c4-t...-debunked.html

 

Could the injectors be not firing because the vats system was not bypassed correctly??....Just jumping over the ignition cylinder without a bypass would stop the computer from pulsing the injectors. Someone correct me if Im wrong..........WW

 

ok could some one please explain this vat system to me because i have the slightest ideal what everyone is talking about.. some say that it shuts the car down complete and that that the car would start then others say that the start and everything ees would be done as well?

 

http://www.lockmasters.com/ecommerce...%20Article.pdf
The best thing for you to do though would be to obtain a Field Service Manual for your year. You can find them on eBay, here is the parts for sale section or Amazon.

 

Thanks bud��

 

I feel the VATS is causing your problem. at min you need to install the right resister to get them to go. I am not a well versed on your year as others but I would get intouch with guys that deal in used parts (see4parts) is a great guy. and see if they have a key with a matching reader for your car. A complete colum with key and reading module would be idea. This is just my feelings testing can prove a lot but you are missing a lot of key parts to diag right

 

The injectors will not fire if the ECM does not see the correct signal from the VATS system. That will also set error code 46. Check for error codes:

http://corvettephotographs.com/c4vettes/codes.htm
http://forums.corvetteforum.com/1574918379-post18.html

What they mean:

http://forums.corvetteforum.com/1576116036-post35.html

 

? so the care didn't have a steering column when i got it. so i went and got one from a guy that sales corvette parts that came with keys and not that e everything is hooked up it turns everything on on the inside of the care but how do i get the ECM to ready the chip from the key. because i really think its the vat system as well.

 

It's the other way around. You need a key that has the right resistance. Or you can disable the VATs. Do some searching, lots of info on VATS out there.

 

If you want to get rid of vats, go to this site and read.....WW

http://www.vatssucks.com/
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If your car has a VATS system then you need a key that looks like this:



The resistor pellet in the key needs to match the resistor in the VATS module or it will not signal the ECM to enable the injectors.

You also need the wiring inside the column and the ignition cylinder to make this work.

 

there are a lot of people on ebay selling the vats module with the key code on it. get one of these get a key cut for the correct code and you should be good to go. Like I said before get intouch with the guy who sold you the colum and see if he has the module for that key and colum. The module just plugs in so not that big os a deal

 

can u send me the link

 

The ignition key lock cylinder has contacts built into it that make contact with the key pellet contained on the key.

When you insert the ignition key into the lock cylinder and turn the ignition On, the CCM reads the resistance value of the Key Pellet.

If it doesn't match what the CCM was programmed for the CCM will not enable the starter relay and the ECM won't pulse the injectors.

An indication the Key Pellet was read properly is the Security Light in the Dash Cluster goes On and then Off when you turn the ignition key to On.

If the Security Light stays on solid, the starter won't crank and the ECM will not pulse the injectors.

You have bypassed the starter relay and that's why the starter cranks the engine.

There is about a 4 minute time out period that must expire before trying to start the engine again.

In your case you need to find out by trial and error what the resistance value the CCM is programmed for. There are 15 choices. One of the resistance values #1 was not used in production vehicles so you have 13 to pick from since you know your current key doesn't work.

What you need to do is disconnect the two pin connector at the base of the steering column coming from the ignition key cylinder and place a resistor one at a time across the two pin connector leading back to the CCM. Turn the ignition On and see if the Security light goes off. If it doesn't wait 4 minutes and try the next resistor. Eventually the Security Light will go out and that's the resistor value you need. Have a new key cut with that resistance value and you're in business.

Or you can leave the resistor across the connector and drive it like that.


Here's a kit that has the 15 resistance values.
http://www.ebay.com/itm/Directed-652T-Resistors-Pack-General-Motors-GM-VATS-Override-Bypass-Kit-/291175559371?pt=US_Car_Keys_Transponders&hash=item43cb6a70cb&vxp=mtr