Matt W

Hi, I just recently bought a Corvette and the test drive at the dealer was great. Half an hour later by the time we got home it was dying when we let off the gas. I've put distributor cap, plugs and wires and it started up and ran strong but then did the same thing after some time. Any suggestions on what to try next? I'd really appreciate it, thanks.

MelWff

Why didnt you go right back to the dealer? Anyway, did you do a fuel pressure test?

jdp6000

It could be any number of things. I need to know exactly what its doing. I know you say dying when you let off the gas but what happens when you give it gas? Is it sluggish? Does it fell like its bogging down? Or does it run perfect on acceleration?

My guess is its either the fuel pump or the hose in the tank from the pump.

Fill the tank to the top. See if the problem stops or gets less. If it stops the hose in the tank has deteriorated and the gas is leaking out back into the tank. This type of check is hit and miss, its not 100%.

Jim

Drawmain

Check your fuel filter, check fuel pressure. After that check the TPS on the drivers side TB, it should be set to .525 v with the throttle closed. Also check the CTS on the front of the engine. If that is not operating correctly the computer will not go into closed loop operation. These are good places to start. Let us know what you find.

Matt W

Have not checked the fuel pressure but that makes sense. Whenever I hit gas it's sluggish and bogs down like it's not getting enough fuel or maybe too much. Changed fuel filter tonight and same thing. Let me check those sensors and hose and I'll get back with you. Thanks a million

jdp6000

It definitely sounds like a fuel delivery issue. Its very common.

Don't mess with the sensors or throttle bodies. You will end up in a place of no return. Address the fuel issue for now. I think you will be fine. Bad sensors would have thrown a code...not always but eventually.

There is an off chance its a fuse. Not likely. With the air cleaner off you should see both injectors spraying a cone shaped pattern. If you are going to pull the cleaner watch for the one vaccum hose to the air cleaner door. Unplug it from underneath the air cleaner on the driver side. Then cap it off so you don't have a vaccum leak.

Here is how you know the fuel pump is working right. When you turn the key to on you should hear about a 2 second buzz from the tank followed by a strange noise from the injectors. The noise from the injectors is the prime pulse. If you don't here both on the first star of the day the pump or hose in the tank is bad.

Jim

wombvette

But it would be a good idea to check to see if anyone else has messed with them. Especially the balance. Look for the welded cap on the linkage to see if it has been removed and adjusted. If so all bets are off as to whether it will ever run right again without correctly re adjusting.

7T1vette

All this "guesswork" and the guy just bought the car? You should have immediately called the dealer and asked if he could check it out. If you are now beyond the "three day from sale" period, he probably won't give you the time of day. If it was a private sale, the PO would give you past info on engine problems, I'm sure.

Drawmain

The man has a point here. Was the car purchased from a dealer? If so, returning it to them to fix the problem at the onset would have been a wise move...

rdroe

I have purchased vintage cars from *dealers* before. The warranty ended when I crossed their driveway. Try it, but also get familiar with the techniques described above. I have just balanced out my 82 and it works really well. Just be methodical and go through all the sensors and systems. It's really a science.

TimAT

Crossfire intakes are pretty well known for sucking the gasket out from under the top too. Makes a great vacuum leak.

Matt W

Well I changed the MAP sensor and it took the check engine light off. still sluggish. Ends up being bad connection to right side injector. runs like a dream. Thank you all for the tips.

Drawmain

Awesome Glad you got it resolved