Starts right up, but won't stay running.

Dachy · 02/16/08, 01:35 PM

I have a 302 with after market heads (RHS), RPM Performer Intake, and a Edelbrock 1405 600cfm carburetor.

When I turn the key it starts right up, runs for about 2 seconds then shuts off unless I rev it up. I have tried raising the idle speed but that does not seem to help at all.

I was told to check the idle mix, squirt some carb cleaner in the air bleeds to make sure they are clear and make sure the idle circuit is clear. Someone suggested it sounds like the idle circuit is plugged and it is running off the pump circuit when I hit the throttle.

This is all mostly Greek to me! Can someone explain this better? At first the truck wouldn't start up at all so my buddy rebuilt it real quick and it worked the first try. I would imagine the whole thing has been cleaned up real nice but maybe not? Any help is appreciated. Thanks.

- Charles

**broncnaz** · 02/16/08, 05:42 PM

I think you may have a vacuum leak. Either the a vacuum cap has been left off or is cracked and has a hole in it or you have a gasket leaking either under the carb or the intake manifold is leaking.

You idle bleeds are located in the throat of the carb you might try removing the idle mixture screws at the front of the carb and spray some carb cleaner through the passages and watch for it to spray out the holes in the throat(wear googles or face shield before you do this). If carb cleaner comes out and it still wont idle I'd check for vacuum leaks might want to try raising the idle speed until it will stay running with out you working the throttle then you can take the carb cleaner again and spray around the gasket areas. If the RPMs increase when you spray it in a certain area theres your leak.

Dachy · 02/16/08, 06:57 PM

is it very likely that this is a cam/timing chain issue? the motor sounds good to me when it's running but it has been suggested.

Pa PITT · 02/16/08, 07:53 PM

I'm sure I'll get slammed for this answer but I'd have some one else start it and I'd spray it with starting fluid every second or 2 to keep it running for 30 seconds or so ...So I could hear it ....Now maybe you could use berryman spray instead of either ...(Disclaimer here push it out of you house garage when your having carb problems I've of about 3 people burning their house down ,due to carb problems )

Itsa67 · 02/16/08, 10:04 PM

I'm going to vote for the vacuum leak problem. My 67 had a vacuum cap deteriorate to the point that it wouldn't keep running without constant throttle attention or bunches of choke applied...then one day I heard the tell tale whistle from up front and had it fixed in about 5 minutes. Do the spray test on gaskets + look at all vacuum hoses and caps for deterioration.

Madgyver · 02/17/08, 02:25 AM

While revving it up cover the airhorn with your other hand like you are starving it and as it starts to die let the air in to keep it running, do this a couple of times and it should clear the idle air bleeds if you still got the problem check the fuel pump....

**howiebilt** · 02/17/08, 07:09 AM

Just in case you don't have this , I included the link to Edelbrocks tuning manual so you can read it for hours and be just as confused as ever

http://www.edelbrock.com/automotive_...ers_manual.pdf

I would go over the IAM (idle air mixture)section

good luck and post up when you get it done

howiebilt

77broncoguy · 02/17/08, 07:44 AM

Mine does this on occasion when it's sat for a few days. Starts great then dies. I figured mine was a fuel delivery problem. I put a small inline check valve I got from work just after the tank. Since then I've had no problems. I guess the fuel line was draining back to the tank. It held enough fuel in the clear filters I have to start but would die until the pump filled the line again. I don't know if I found a cure or if its just coincidence. I thought I'd share since I haven't had the problem since.

Dachy · 02/17/08, 10:22 AM

thanks Howie and everyone else, I'll look into all those things. Just for clarification though, I was running it off a gas can hooked up directly to the carb so that rules out any fuel line problems...i'm going to hook it up to the fuel pump etc though either today or tomorrow.

**j.r.nice** · 02/17/08, 11:03 AM

Recheck your float levels, check your idle mixture. Run a vacuum gauge on it. Generally a vacuum leak will cause the engine to lean out and run faster. If it's loading up it will stall.

Dachy · 02/20/08, 01:01 PM

if this rain stops, and I can't get this thing to stay running, anyone in San Diego feel like coming over this weekend to help? I'm in the Tierrasanta area.

thanks,
Charles

73azbronco · 02/20/08, 01:16 PM

Sorry, I'm not getting the full picture. Did this problem happen after you did something to the motor or did it just start not idling correclty after it had been running right, then your friend rebuilt it real quick, which to me sounds bad? You said bad cam or timing chain, did you change those or again do you think they are going bad as time goes on? Can you give us the full timeline of how this went down, that will help decide mechanical, electrical or fuel...

I don't understand why your using a gas can as fuel source, why not fuel pump/fuel tank?

H8tulooze · 02/20/08, 01:43 PM

Do you have a Duraspark? If so I had the same problem, brand new Box was bad. I exchanged it and BAM! started right up.

**j.r.nice** · 02/20/08, 02:30 PM

Quote:

Originally Posted by Dachy

if this rain stops, and I can't get this thing to stay running, anyone in San Diego feel like coming over this weekend to help? I'm in the Tierrasanta area.

thanks,
Charles

darn, too far away......and it's snowing here

jpalmer · 02/20/08, 03:33 PM

Something else to look into is you might have sucked up some gunk from your gas can apparatus and that has clogged your fuel lines causing fuel only to get through when under throttle. That's something quick and easy to check.