car runs crazy

Your going to want to check the simplest things first...Loose vaccum hoses can create a fast idle. I would then inspect a plug....Look under the rotor cap....for corrosion on terminals..Check for full voltage @ the battery should charge to 13+..Low voltage will cause weak spark. It is probably just one simple item..We may go to the fuel system next..What ignition do you use?

Hey daxter,

Idle problems. Here's my mental checklist:

1. Not enough fuel, carb's idle circuit is bad, old fuel gummed up in the fuel bowl. Since it runs at higher rpm, I don't suspect the float & needle assembly.

2. Too much air, vacuum leak, PCV valve stuck open

3. Ignition retarded or weak, timing chain slipped, distributor advance is in bad order, voltage to coil is low due to excessive resistance in circuit. Dougo had a low voltage to his coil that we fixed last month.

4. EGR operating at idle, should be closed at idle

#4 is easy to check, so lets do that first.

Remove the air filter assembly from atop the carburetor. Pull the vacuum hose off the EGR valve diaphragm & plug the hose. It's the big round diaphragm device behind the carburetor, you can see it with the air filter assembly removed. Its attached to a plate that is sandwiched between the intake manifold & the carburetor.

Start the motor & let me know what happens.

your friend on the PIBB, George

Cool Im going to try everything on both lists. Ill get back to you and psot my results. Such a bummer, ran great for 10 years. Well I think youre both right and its something simple. I will check things out soon as possible and report. Oh if youre both right you can split the 2,000,000 reward. Thanks a lot.

daxter,

Keep posting your Pantera problems here and give us all a crack at future rewards!

Michael

My bet's on George collecting the reward money.

would a vaccum leak, and make us both right?

quote:

Originally posted by lastpushbutton:
would a vaccum leak, and make us both right?

Sure!

But sounds like the problem is ignition related to me.

Kevin

Ignition or EGR get my votes. Back firing is ignition or lean mixture.

I've never seen a vacuum leak large enough to snuff a motor, make them idle fast, yes, make them idle rough, yes, snuff the motor, no. But there's always a first time for everything!

Don't worry Bill, you can have the reward, so long as the first round of buttery nipples are on you. Deal?

Nothing keeps a mechanic purring like lubrication!

George

Hello again, I spent last night (first night I wasnt tired from work) going over a few things. First I plugged off the EGR and started the engine. Same thing, runs a little ruff and dies out if I take my foot off the gas. Ignition I bought from Hall 10 years ago. Its the electronic Ford. So I checked the cap and rotor and they look pretty good. I then checked the plug wires and they were good too. Plus were good. I checked all the hoses and there were good. I even spent the time taking off the engine cover to inspect any wires and water hoses since I was there. My wife (who is a genius) reminded me that over the last few months the car became harder to start. It use to just crank over and fire right up and purr. Voltage was good.
Well I was thinking about rebuilding the carb. Its a Holley 650? Sounds about right. I had it off 8 or 9 years ago. Yes it still backfires some right now and that scares me. Is it possible its something in the carb?
I was thinking to take it to a shop (so wife cant yell at me while Im trying to fix it). I am in Mission Viejo and wonder if anyone has worked on one down here. I almost trust my reg mech but I know he has never touched one. Anyone know of a place? Or should I try rebuilding the carb first? Couldnt hurt to rebuild it could it?
Cant wait to hear any sugestions since my wife is about to kill me if I dont fix it. Ok I know but shes all of 4-11 95 pounds and cant even drive it. But she loves the car and says anything in the garage should run good. Shes right.

Dax,
Can you move the EGR? You might want to check if it moves. If it's stuck open you can get a rough idle.
What shape is the fuel system? Do you have a in-line fuel filter? Have you ever checked the fuel tank for junk? OR the fuel sock on the end of your fuel sender? This is if you still have a stock system. You might want to also check fuel pump for proper volume..... Just some thoughts..

Yes I removed the EGR and shook it to make sure it was moving. Fuel system, inline was ok and no, I have never checked to see how much junk is in the tank.It was always running really rich, so rich your eyes would burn from the exhaust sometimes. I am going to take off the carb tomorrow and clean it anyway. You know all those flamming backfires out of the carb kinda turned it BLACK just a little.

Before I forget, wanted to thank all you guys for all the help.

The thing you remove from the valve cover & shake is the PCV valve.

The EGR valve is a plate sandwiched between the carb & intake manifold that has a diaphragm actuator attached to the back. An engine will die if the EGR valve is open at idle. It should be closed at idle. If the valve is stuck in one position, partially open even just a crack, that would be a problem.

your frind with all the acronyms on the DTBB, George

OK tomorrow Im going to try and find the EGR and see if it moves or not.

The EGR plate had holes in it that matched the throttle bores of the Autolite 4300D spread bore carburetor, since you have a Holley carburetor, your EGR has most likely been removed.

There is a slim chance you could still have an EGR plate, because Holley did manufacture 650 cfm & 750 cfm replacements for the Autolite 4300D carb back in the 1970s. The 650 cfm Holley replacement was a list #0-6708 and the 750 cfm Holley replacement was a list #0-6709.

George

Hey I finally had some time and bought a edelbrock 4506 carb. Put it on and it started up pretty quickly. It even idles and doesnt stumble. Its does spew out a fair amount of white-ish smoke. I tried to adjust the carb acording to the book. It brought the white smoke way down. At first I thought it was a head gasket but it wasnt bad before and it never overheated. Just needs some adjustments. Was even talking the wife into a rebuild but she thinks it will cost a years pay. Yeah she doesnt know too much about cars. I wonder how much a rebuild is anyway? Im in South OC and still dont know a good place to take it if I do it. Thanks to everyone with all the help. Oh Im going to change the plugs and the wires since I know they have been in the car for 5 years.

Glad you got running. Where is South OC, Orange County?

South Orange County, Mission Viejo. Yeah maybe I should look into a rebuild but I dont know a good shop down here. Maybe one of you knows a good honest (cough) place. Soon as I have more time Im going to try and dial in the new carb and see what I can do,. Figure I will replace the plugs and the wires too. Plugs are about 5 years old and the wires are over 10. yeah I know but it always ran good until a few months ago.