Engine Will NOT Start
 

OMG I am having a serious problem with my 1991 Corvette. I have been to the local auto parts place many times replacing parts thatI thought be the culprit ... but, to no avail.

The engine will turn over strong but will not start. I drove it home Friday night and Saturday morning, it wouldn't start. What has been replaced?: I bought a new coil for the distributor, because there was no spark. I checked the fuel injection plugs to see if there was power going to them ... there wasn't, so that pointed to the computer. Yes, I just installed the NEW computer and it will still not start. There is fuel going to the fuel rails. I have checked the Haynes Manual (haha) for any other possible solutions, but can't find any. The guys at the parts store are baffled also ... although, I am sure there boss is happy with me and my spendingof money there.

PLEASE HELP!![:@]

RE: Engine Will NOT Start
 

Welcome to the forums there, runna!

So the Fully Automatic Assault Wallet approach [sm=shootshoot.gif][sm=violent053.gif]hasn't worked thus far, huh? Don't feel bad - it never does. Spray the problem with a volley of new parts, and hope to hit the target...

OKAY...

To start... was there a spark after buyin' a new coil?

RE: Engine Will NOT Start
 

No, there wasn't. That got me mind boggled. The parts guy actually suggested checking the injectors with one of their 'borrowed' testers. I checked 4 of them and none gave any indication thatthey was working.

I guess the only good thing about buying the "volley of new parts" was that they are all lifetime warranted ... lol.

And thanks for the welcome!!

RE: Engine Will NOT Start
 

I'm suspecting the Distributor Ignition Module. If the ECM doesn't receive a pulse from the distributer, it will not energize the injectors, nor will there be a spark present.

I'm curious,.....Watch your tachometerwhile spinning the engine over and see if it's doing anything.


Heres a little info on the starting sequence.

Initial Crank Action:

If you then rotate the key to the start position (assuming the anti-theft system has not disabled the starter), the engine will rotate.

Once the oil pressure has reached 4 PSI, the oil pressure switch will close allowing the fuel pump to run. (Note that you should have a black oil pressure switch/sender. It is mounted behind the distributor on the driver’s side and if it is not black, it is suspect due to a run of bad units that stayed in the GM parts pipeline for some time).

The distributor will send a string of pulses to the ECM (Engine Control Module) in response to the engine being rotated by the starter. These pulses continue as long as the engine turns (both starting and running) and if they are not present, the engine will not run.

ECM Reaction:
If the ECM sees oil pressure greater than 4 PSI and the reference pulses from the distributor, it will energize the injector drivers which will begin pulsing the injectors on for 4 ms (milliseconds) periods. (In the L98, all injectors on one side of the engine fire at the same time followed by all injectors on the other side firing at the same time. On the LT-1, the injectors are fired individually at the appropriate time).

The ECM will also pull in the fuel pump relay in effect paralleling it electrically with the oil pressure switch. (If the fuel pump relay fails, you can still normally get the car to start and run unless you can’t make at least 4 PSI oil pressure. This is a “limp home mode” feature put in place to allow for a fuel pump relay failure).

The ECM also monitors the TPS (Throttle Position Sensor mounted on the throttle body assembly) and wants to see .54 volts at this time. If it sees appreciably more than 0.54 volts, it will assume the engine is flooded and the driver has pressed the accelerator to the floor to clear the flooded condition and restrict the fuel flow as a result. (.54 volts during start and at idle from the TPS is very important to both starting and run performance.)

Assuming the ignition module is good (meaning there is a spark of sufficient intensity to ignite the fuel), the engine will “catch”.

RE: Engine Will NOT Start
 

And buy a FSM from Helminc.com and chunk that Haynes manual, its useless.

RE: Engine Will NOT Start
 

not sure on the 91 but had the same exact problem on my 86 went through all the same things you did it turned out to be the plug that goes to the distributor right between the distributor and the firewall the heat got to it and and created high resistance in the plug I replaced the connector and no more problems. hope it helps

RE: Engine Will NOT Start
 

Ok ... took out the Ignition Control Module ... had it tested and it turned out ok. The casings covering the plugs on each side of the module literally fell apart after trying to take them off.

After asking around at work tonight, it came up that thepick upcoil on the distributor may have gone out. They said it would be easier to replace the whole distributor than to change out this coil. I am going to have to domore electrical testing on this part before sinking more money into non needed items. Will keep everyone updated for future use.

RE: Engine Will NOT Start
 

Good attitude on testing rather than more blind parts buying. It's a pain, but it's cheaper, and you get to know your motor too!

Ask ibelew! I bet he knows his '85 TPI inside and out now!!!
https://www.corvetteforums.com/m_37817/tm.htm

RE: Engine Will NOT Start
 

You hit the nail on the head with the stator (pickup) being bad. If you have no pulse or spark, more than likely the stator is bad. To test it, pull cap, rotor, then try and unplug 2 wire connector to to ignition module (this has to be done in the car to check for proper cranking voltage). Then use an a/c volt meter plugged into the 2 leads off stator and have someone turn engine over while measureing voltage. Careful not to get voltmeter leads tangled in rotor shaft while turning. You should have around .6 to .9 volts a/c while cranking. If no volts then stator is bad. If bad, then bump engine around till rotor is pointing at #1 cylinder and timing mark is pointing at 0 degrees before pulling distributor so you will have a reference point to reinstall it. After removing distributor, drive roll pin out of distributor drive gear, remove gear and washer, pull shaft out the top, then you can replace stator. Hint: Don't use a cheap Autozone brand, find a parts store that sells A/C Delco parts and use that. Install distributor back pointing at #1 again. You might have to work it a bit to get it to fall in oil pump drive.

RE: Engine Will NOT Start
 

UPDATE!! Ok, I did replace the distributor and finally got spark at the plugs ... but car still would not run. And now my fuel pump wasn't working anymore ... Hmmmmm. It took me a week now to finally take a look at the computer again ... even though it was brand new. I pulled it back out ... took it back to the parts place to have them double check to make sure it was the right one. Well, well, well ... they gave me the WRONG computer to put back in. I went ahead and traded out for the RIGHT one (plus they gave me the $83.37 difference ... [sm=bling.gif]) and it fired up perfectly!! I am sure, though, (or hope) that the wrong computer they gave me had to have burned up ... hee hee.

So what was the problem? The pick-up coil!! Thanks all!!