First post, long time reader. I recently got my 1985 Corvette tuned up, from everything in the distributor to plugs, wires, new fuel pump and filter. This car had been stored so naturally changed the stuff that would need to be done. After being timed it was running like a champ, until yesterday. It started hesitating and almost starved out. I immediately put it in direct drive and floored it. It took off and got me home which luckily was about a mile away. I started it today and now it acts like it’s getting too much fuel. Is there something that I need to do to fix this or is it something that will work itself out? Maybe some debris in the injectors?

 

Did you change out the fuel pressure regulator? Coud be injectors, too. Heck, could be lots of things.

Check codes and do a fuel pressure check is probably the first thing to do.

 

Welcome to the Corvette Forum cindyncharles!!

Todays gasoline is diluted with Ethanol and this is done to help emissions they claim. Normally they use about 10% Ethanol in the Northern Virginia gasoline market. It is referred to as "Oxygenated Gasoline" and has a very short shelf life and it absorbs moisture in your fuel. The Ethanol also eats away at various components like the Fuel Pressure Regulator as it uses a rubberized diaphragm. If a Corvette is left for more than 30 days between running then you should be adding an additive to negate the effects of the Ethanol. I had fuel lines rust shut internally due to this wonderful Ethanol.

The Incident sounded like it happened after you were driving and the engine was in Closed Loop. It could be fuel related but I would take a look at a couple things, Fuel Pressure is one of the most important basic tests. If your Corvette is making the correct pressure and your fuel loop doesn't leak down too fast it might have been something else. The Fuel Pressure Regulator and it's Diaphragm are located under the rear of the plenum on the intake and is round with a vacuum hose attached to it. With the car off pull the hose off the FPR and smell inside it, if you smell raw gasoline then your diaphragm needs to be replaced. If the FPR Is bad it can make the mixture rich.

I would always check your MAF sensor (IF you have one). On my 1988 the MAF sensor is mounted on a tube that feeds the throttle body. Be sure that the hoses are tight and that no air can leak in anyplace around the MAF or that really screws up the drive-a-bility.

When your car was running it needs information from three primary systems/sensors. To get into Closed Loop you need a working Oxygen sensor, Mass Air Flow Sensor and Coolant Temperature Sensor. The Mass Air Flow is important as it measures the volume of air being ingested into the intake cycle of the engine. They make a cleaner spray that helps heavy crud build up on the MAF's Sensor Wire. The sensor wire is very tiny and if your engine is working properly you should see that little wire glow bright red as it is performing a "Burn Off" after shutdown. On my 1988 there are two relays that control the MAF function. One is for the Power and the second is used to perform the Burn Off function. Make sure all three are working and always replace all three together.

How old is the Oxygen sensor in the Corvette? The 1988 C4 Oxygen sensor is an unheated unit and they have a TWO year/ 50 K mile life. It is the best $25 you can spend as a new O2 will assure that your Corvette is getting the best economy and performance.

Did your Corvette generate any codes when you had the problem? Be sure the SES or Check engine light works, the bulb was removed on my Corvette.
Put some fresh gasoline in it.

Follow the vacuum lines and replace any that are leaking. The Exhaust Gas Re-circulation (EGR) valve is controlled using vacuum that is controlled by a vacuum solenoid up by the thermostat housing. The signal from the ECM is Pulse Width Modulation and then uses Vacuum to activate and control the EGR Valve. Having good vacuum is important. It also affects your Brakes and Cruise Control so it is important to be sure it is sealed.

Battery Connections and their cleanliness are important on a vehicle with an Electronic Fuel Injection System.

It is always possible that your Engine was burning some nasty old gasoline or something was flowing through. Nothing a Good Fuel Filter wouldn't solve.

Let us all know what happens when you start working on the Corvette! There are a lot of experts here that can help you with very specific problems on the 1985. That is a car I have not had to work on and I know there are several major differences. I hope that some of what I suggested might help you, Good Luck!

 

I would double check your tune up. There is a ground terminal that has to be transferred along with coil. Looking at were wiring connectors plug in there should be 5 spade terminals. The button should protrude out of hole in center of cap. Most likely ok but it happens. Crossed or not fully seated plug wires are very common errors. Plugs not fully tightened another. Vacuum leaks, if hoses are crumbling or stain your fingers when you handle them , replace with correct sizes. Fuel pressure regulator diaphragm vacuum port is something check for presence of gasoline.