Am totally at wits end. 89 C4 was having hard starting problems. With a tune up ( wires plugs etc ) I replaced one injector by recommendation of shop. Within weeks was hard to start, even had to have it towed. Checked some tech bulletins: Recommended replace all injectors due to Ethanol effect on fuel system. Did this and had induction cleaning. Now the Nightmare begins. Cranks over as if not getting fuel and if battery holds out it will eventually crank but pops or backfires on initial start. After start it seems fine, but shut it down and wait 5 min and 2nd episode begins. Some one suggests regulator. Trying to sell but don't desire to pass headaches on.

 

Engines require spark and spark at the right time, fuel and air and in the correct ratio and cylinder compression in order to start and continue to run. You need to find out what is missing which is causing your hard starts. Replacing parts ***** nilly is THE dumbest way to fix a problem. You need to make some measurements to find the cause of your problem. Use a timing light during cranking to see if you have spark and spark at the right time. Pull a plug wire and bring a grounded wire close to the boot during a short crank, you should have a snappy at least 1/2" spark. In total darkness during cranking, look for sparks along each plug wire. Measure the resistance of each plug wire, factory wires are about 5000 ohms per foot. Weak spark will cause hard starting. Measure fuel pressure, it should be 35-42 psi and it should hold up when the ign is off or you may have leaky injectors or defective check valve in the pressure regulator. Use a noid light to see if the injectors are being pulsed during cranking. Use some starting fluid to see if the engine will start and if so, you have a fuel delivery problem. Pull the air hose from the air filter, your filter might be clogged. Unplug the MAF and if you get a start, you may have a defective MAF. Measure cylinder compression.

 

While I do appreciate your response let me say, " not a nilly ***** " Those things were done as routine. It was during an induction clean, replacing egr valve that all hell broke loose. Injectors were replaced by tech buliten recommendation. Motor only has 50,000 miles so I believe compression good, but anything could happen. When it cranks runs like a " Scolded dog " Am leaning more to possible regulator. Guess time to purchase a gauge and get busy.

 

It would be interesting to note that when your EGR valve was replaced, your problems started. I would get a dentist's mirror and a flashlight and determine that when the shop put your intake back together, that the intake runner gaskets didn't slip. It sounds like the bank of runners get too much air. And since it takes forever to start, I would think it was on the top left side since the O2 sensor reads the left bank, the left runners feed the right side of the engine. Since your fuel mixture seems ok after start, I would think it was a left runner gasket.

 

There may be another GM Multec Fuel Injector failing or has failed.
In past experience,
GM Multec fuel injectors in a "V" Banked engine layout seldom fail in Single alone.
Typically there are at least another 2 or 3 bad also.
Alcohol in the gasoline is the culprit.
Eats up the Bobbit coil winding insulation internal over time.
Mileage of use no longer matters.
What matters is if there was 100 % pure gasoline running through your C4 Corvette since day 1 it was built.
Very likely not.
Unless you special ordered gasoline fuel by the tanker truck full 5,000 gallons at a time & stored it away yourself,
Or purchased special unleaded high octane 96 + motor octane fuel.
I would say near "0" C4 owners did this.

Maybe just a few 1990- 1995 C4 ZR-1 & 1987- 1991 C4 Corvette Callaway owners did that.
Only group of C4 owners obsessive enough to do so.

Brian R.