Please look at my video and let me know. I bought the car not running, it sat for 10 years. I emptied the tank and cleaned it.
Any ideas of what is going on with this hesitation. New injectors. Cap rotor wires. Fuel filter. fuel pressure regulator. Fuel pump and added check valve to the line. New EGR valve. Checked for vac leaks. Cleaned all grounds. Cleaned the throttle body. Cleaned fusible links terminal. New battery. No changes runs poor still

Youtube link

 

Hello there Larry,

My name is Chris and I have a 1988 Corvette that sat for a while and the strangest thing happened. I was able to get it to run but not very well either. The problem in my car was that the fuel supply line had ethanol/gas in it and it collected water at the low spot and then corroded shut internally. There was no sign of it until I measured the flow coming directly out of the fuel pump with a short hose and then I did the test at the fuel filter. It became obvious that a little fuel was getting through the blockage but not enough for the L98 to run normally on. I ended up replacing the supply lines and the return lines to be safe. It doesn't take too long to get rust on the inside of those steel fuel lines they used with the 10% ethanol they put in gasoline.

You mentioned replacing the EGR valve, did you replace or verify the operation of the EGR Vacuum solenoid? The solenoid on my car went bad and then the EGR system became plugged with carbon. After cleaning the carbon out I was surprised that the EGR was still not functioning properly. It seems that the EGR Vacuum solenoid was bad and not controlling the vacuum needed for the EGR to function properly. Be careful checking this solenoid out as the ECM uses PWM to control the solenoid. A bad EGR system can cause a car to run poorly.

After ten years of sitting you NEED to replace the 02 sensors as well. If those are the old ones you should try replacing them as they are not supposed to last that long. You can verify if they are working by checking the voltages coming out of them but I was taught to replace them every 2 years of constant usage. When an 02 sensor gets old they tend to lag a bit and are not as fast responding like the computer needs them to be.

If you can check your Coolant temperature sensor and see what it sees for the temperature. If the CTS is bad it might try to convince the car that it is very cold or very hot and that affects the running performance. Usually this affects the starting of the car the most.

Another item could be your Catalytic converters as they like to plug up when not being used all the time. I parked a car for two months while on a boat trip and when I got back to my car it would not rev properly. I had to replace the catalytic converter to make it go fast enough to drive 400 miles home.

Last but certainly not the least is your MAF sensor which could not be measuring the volume of air going into the engine properly. The critical sensors for Closed Loop operation are the MAF sensor, the 02 and the coolant temperature switch and with that information the ECM calculates the proper air/fuel ratio. Old MAF sensors frequently go bad if not used as they have a wire about 1/10th the diameter of a millimeter that can get corroded or dirty and may be unable to burn off the junk on the wire when the relays tell it to.

Also just for fun check your engine to be sure the engine is grounded properly. Put a multi-meter on the battery directly and then do the same but put the ground wire on the engine this time, the numbers should be the same or very close. The engine being grounded is critical to make this engine work with its Electronic Fuel Injection. There are several ground straps on these engines and they are all important.

I am betting it is either your MAF or the 02 sensors lagging. That alone will drive your engine crazy. Do you have any kind of scanner or OBD1 code reader? Those are very helpful at times like this. Are there any codes being displayed? If not I would go straight to the 02 sensors as my first guess, the MAF is my second.

When does the car start acting weird? Is it when the engine is in open loop or after the transition to closed loop? This is helpful because it would help us zero in on the problem. How many miles are on the Corvette? Was it working normally when they parked it or was it parked because it was not running right? The more we know the better we can help you.

I look forward to hearing the answers to the above questions.

 

Getting closer. I marked the current position of the distributor and adjusted the timing and it helped a lot. The problem is I cannot find the timing marker, it seems to be missing. Did it fall off or the previous owner do something. I know it should be at about the 2pm position above the dampener and it is not there. I am just not winning here, when I went to shut it down the key will not come out now. Is this pic not the right spot. I am getting frustrated.

 

My car didn't have a timing tab when i got it ('86L) so i bought a chrome one from PEP boys. I don't know where it went but someone had been into mine before i got it. Yours does sound like the timing is off. Does it crank over easy and start up ok? Have you had the distributor out? Any trouble codes?

 

I adjusted the distributor to a point where it revs much better now but without the pointer I do not know what the timing is. I had to turn it quite a bit, either it was WAY off or something else is still wrong with my motor. With how it runs in the video, I hope it was just way off and I have it close now. I never took out the distributor and do not really want to unless rebuilding it will help. I need to get the new ignition key replaced so I can do more testing. I will post a revised video if it runs better.

 

vacuum leak