More issues, no start & more.

[VetteMed]

Originally Posted by Tyler Townsley

Another tip is to run a wire from the starter out to the battery. Connect it to the starter in such a way that touching the other end to the positive terminal starts the car. I have done this with my 88 Ptype because it has a habit of doing the no-start because it cannot read the key correectly after sitting for a long period.

Tyler

Tyler, a question about this:

The VATS system incorporates a starter cutoff as well as a fuel cutoff -- so your fix would allow bypassing of the starter cutoff, but if I understand the system correctly, the engine should still not start, due to a lack of fuel delivery? Or is the '88 system only providing a starter cutoff?

Thanks,
Andrew

[Tyler Townsley]

I also bypassed the VATs in the code but found that for some reason it still would nostart. Using the start wire it will start and run.

Tyler

[Marc Haibeck]

If one does not want to repair the VATS system it’s easy to bypass it:
1. VATS disables the fuel injectors. The engine calibration chip can be modified to turn off the VATS control of the fuel injectors.
2. VATS inhibits the start relay. The start relay can be removed and a jumper can be inserted in the socket. The jumper goes between the 10 gage yellow wires.
3. With the above the car will start. The “Security” light will be on. Remove the lamp in the cluster.

[captcorvette]

Update on the no start and other issues. First let me thank everyone who has replied with suggestions and encouragements.

Spent some time looking in the manual and still did not see anything obvious that I might have missed. Next step was to take my '91 and parked it next to the z for comparison. Tried everything I could think of including removing the PCM and re-installing the piggyback chip from PCM's for less that was supposed to eliminate the VATs. No change---everything was exactly the same. Removed the driver's door panel and found the cannon plug had come off the door ajar switch. Replace that and the courtesy lights started working again when the drier's door is opened. Also the rear hatch switch on the driver's door started working again. PROGRESS---of a sort. Tired all three keys, double checked all door locks, waited over 20 minutes between all attempts with the key out of the switch. No change and still no start and the "security" light on solid.Repeated all the above but disconnected the battery during the 20 minute wait cycles. No change at all. All indicators were exactly the same.

Spent some time winding my butt and scratching my watch while backtracking the problem back to when I parked it on return from the inspection station and finding the cannot plug to the right front headlight had been severed and lost---most likely en-route back from the inspection. The cannot plug to the headlight on the z is two pin but has three wires. On the '91 the same headlight motor wire cannon plug is a two wire.

Removed the splices and tried to start the car. No start, went through a process of replacing the wires one at a time then connecting two at a time leaving one wire not connected and low and behold the third attempt the VATs started working as it should (even though the PCM's for less no vat's piggy pack chip is still installed) and works correctly with all three keys. However now the right headlight will come on but will not rotate. the left is fine. Still not clear of what should be and should not be when I am looking at the schematic. Like I said before I am not the brightest light in the box when it comes to sparky stuff. But cannot figure out where the 3rd wire should be spliced into. Hate splicing into anything but with the cannon plug being gone and all the plugs are two wire on the other cars and my spares, stock and donor car I am stuffed. Nothing like this is available anywhere I can find here in the middle east.

Side note the vacuum pump is still running all the time so there has to be a leak but I am not finding it. Guess the plenum has to come off----again. Have already gone through three sets of Jerry's gaskets and have usually been able to use them at least twice but that will tell you how many times the plenum has been off. Three time at various dealers, once when I sent the car to Kuwait for my guru friend to get his hands on it and the two times I have pulled it.

Plus side? Car is starting and is drivable. Headlights do come on and I can manually rotate the motor knob to have both lights at night.

Minus side? Car still has spells where it will run without missing with the key in the normal power position. Misfires, hesitates and has no torque with the full power switch on. If the full power switch has been turned on then off the car still continues to run badly and miss until the engine is shut off and restarted.

Even with all the above it is a real treat to drive.

[tpr60]

Thanks for the update. I have the same problem with the door electrical, but have not got to it yet. Still trying to pass Calif. smog.

About the vacuum pump running all the time, i have found if the pump does not put out enough pressure [i think it was over 14-16 lbs] the pump will not trip the internal start/stop switch. The pumps internal seals wear and not enough pressure builds up to trip the internal switch causing the pump to run all the time. My pump would turn off when engine vacuum would feed back to the pump and trip the pumps internal pressure switch. Check readings with a hand held pump. Beats removing the intake and looking for vacuum leaks you already repaired.

[captcorvette]

Thanks. I will put a gage on it to see the readings. Does anyone know if there is a replacement pump available? This one had gone trhough a front right accident and I rebuilt the pump but never checked to see if the psi was correct. A search though my normal supplier came up empty and discontinued item.

[tpr60]

Same pump is used on Ford/Dodge diesel trucks with cruise control, 1999 to about 2005. Mounted on the RF inner fender if you go to the wreckers, electrical plug is different so splice in the one from the donor truck.

[captcorvette]

Thanks for the great info.. We don't have a lot of diesel Ford or Dodge trucks over here but I will have a look. Might have to do my usual and give ebay a try. They are usually much faster than the local dealerships. Thanks again.
Wayne

[A26B]

Another optional source.....
http://jerrysgaskets.com/store2/root...e4e870d5eb584c

[captcorvette]

Jerry one of these days I will learn to check with you first and not shoot my mouth off until after doing a "Jerry check". Thanks for the heads up.
Wayne