will not run
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
will not run
Hello everybody. I own a 1984 4 plus 3 Corvette. A couple of weeks ago I ported the manifold. Car ran great. Today it ran AWFUL. I can start the car and when it is at operating temperature and 900/1000 rpm it is pulling 20 inches of vacuum. When I start to go it stalls out. It can idle for ever but once I start driving it wants to stall and usually does. The TPS is at 0.5 volts at idle. Any ideas. I am thinking fuel pump but I put one in about 800 miles ago. Regulators? I have a shop manual. Thank you
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
Start by pulling the codes
http://www.corvettephotographs.com/c4vettes/codes.htm
Check the fuel pressure
http://www.corvettephotographs.com/c4vettes/codes.htm
Check the fuel pressure
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
Does the light come on when you 1st turn the key on?
Does the bulb work?
You say you have the shop manual .The correct test procedures are documented there
Does the bulb work?
You say you have the shop manual .The correct test procedures are documented there
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
thank you
Burning Brakes
Joined: Sep 2004
Posts: 1,123
Likes: 19
From: Arkansas
I had an 84 and the cat converter clogged up. The car would idle fine but barely moved, it was really smothered down.
Look to see if it glows red after the car runs for a few minutes. This will not set a code.
Shawn
Look to see if it glows red after the car runs for a few minutes. This will not set a code.
Shawn
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
2027 Corvette vs The World: Every Model vs Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
car won't run
So I located the diagnostics in the shop manual. It said to apply 12 volts to terminal G on the ALDI. So I did that. and the pump did not run. But when I apply 12 volts to the pump connector the pump runs. The fuse is good. I seperated the connector at the relay under the hood and put a test lamp to the leads. I get a completed circuit but no pump running.
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
So I decided to see if the car would run. I poured gas into the TBIs and the car ran and the TBIs pulsed.
Could the poor performance be the IACs reacting to the porting.
But then why didn't the pump run when I used the OBD1 connector port to power the pump
Could the poor performance be the IACs reacting to the porting.
But then why didn't the pump run when I used the OBD1 connector port to power the pump
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
You may have a fault/ break in the wiring from the fuse to the tank
If the fuse is confirmed good , put a DVM between each of the fuse terminals and the tank connector and see if you get continuity.
If not you know where your problem lies
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
The ALDL terminal uses the same wiring back to the pump , all it does it let you run the pump with the key off.
You may have a fault/ break in the wiring from the fuse to the tank
If the fuse is confirmed good , put a DVM between each of the fuse terminals and the tank connector and see if you get continuity.
If not you know where your problem lies
You may have a fault/ break in the wiring from the fuse to the tank
If the fuse is confirmed good , put a DVM between each of the fuse terminals and the tank connector and see if you get continuity.
If not you know where your problem lies
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
Circuit 120 runs from ALDL terminal G to the pump. The fuse is that fuse the fuse box or inline. What is between the fuse and the pump. Fuse able link. Sorry I just don't yet understand electronic short hand.
thank you
thank you
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 12
Drifting
Joined: Jun 2013
Posts: 1,590
Likes: 60
From: ft myers FL/Munising MI
Hello everybody. I own a 1984 4 plus 3 Corvette. A couple of weeks ago I ported the manifold. Car ran great. Today it ran AWFUL. I can start the car and when it is at operating temperature and 900/1000 rpm it is pulling 20 inches of vacuum. When I start to go it stalls out. It can idle for ever but once I start driving it wants to stall and usually does. The TPS is at 0.5 volts at idle. Any ideas. I am thinking fuel pump but I put one in about 800 miles ago. Regulators? I have a shop manual. Thank you
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,451
Likes: 48
you didn't indicate what the fuel pressure was or if it stayed up...I had a similar problem....went through the same trouble shooting guide...I also had recently installed a new pump...if pressure is an issue...look where it says to pinch off the pressure and return lines at your tank...I had a loose connection between pump and pulsator...started/ idle ok...wouldn't go....that part will tell you whether it's the pump or regulator...if your pressure stays up, ignore my 2 cents....