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Starts right up, but won't stay running.

Dachy

Full Member
Joined
Jun 30, 2004
Messages
262
Loc.
San Diego, CA.
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

Bronco Guru
Joined
May 22, 2003
Messages
24,341
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.
 
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Dachy

Dachy

Full Member
Joined
Jun 30, 2004
Messages
262
Loc.
San Diego, CA.
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

Contributor
Bronco Guru
Joined
Jul 15, 2005
Messages
11,252
Loc.
Stephenville TEXAS
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

Sr. Member
Joined
Jan 26, 2006
Messages
446
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

Bronco Madman
Joined
Jul 30, 2001
Messages
14,678
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....
 
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77broncoguy

Sr. Member
Joined
Nov 12, 2004
Messages
500
Loc.
Grand Rapids, MI
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.
 
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Dachy

Dachy

Full Member
Joined
Jun 30, 2004
Messages
262
Loc.
San Diego, CA.
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

Bronco Guru
Joined
Feb 8, 2004
Messages
1,615
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.
 
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Dachy

Dachy

Full Member
Joined
Jun 30, 2004
Messages
262
Loc.
San Diego, CA.
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

Contributor
Bronco Guru
Joined
Nov 11, 2007
Messages
7,796
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

Full Member
Joined
Feb 27, 2007
Messages
201
Loc.
Corona, CA
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

Bronco Guru
Joined
Feb 8, 2004
Messages
1,615
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:D
 

jpalmer

Sr. Member
Joined
Feb 15, 2008
Messages
436
Loc.
Boise, ID
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.
 

j.r.nice

Bronco Guru
Joined
Feb 8, 2004
Messages
1,615
I just re-read your initial post. What someone was telling you is that something is clogging your idle system. It's not getting any gas at idle and the only time it does is when you step on the pedal and the accelerator pump shoots a stream of fuel into the carb. Holleys are very susceptible to dirty or clogged idle air bleeds. I dont know about Edelbrocks. Air bleeds are inside the air horn. You need to remove the air cleaner and look down inthe carb. They are small holes about the size if a pin. Using carb cleaner with the small red tube attached. Squirt some cleaner down the holes. See if that helps. If not something may be in the idle passages inside the carb body. Try pulling the idle screws out and squirting some cleaner in them. Dont use compressed air on any of it while it's together on the engine. This will only help if it's the carb.

Ignition is another matter. My 77 would never idle when it was cold. After I replaced the entire ignition with an MSD it purred like a kitten.

Take a peek courtesy of Edelbrock: (go to figure 2)
http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf
 
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Dachy

Dachy

Full Member
Joined
Jun 30, 2004
Messages
262
Loc.
San Diego, CA.
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?

Alright well I bought this truck with a rebuilt motor about a year ago. It had been sitting for 10 years. I changed the oil, threw on a fuel filter, changed the plugs/wires and it started but wouldn't idle. A year later (now) we tried to get it running but it wouldn't even start up until we rebuilt the carburetor.

My friend who rebuilt the carburetor tried turning the idle all the way up but it still won't stay running. So he suspects that it is the timing chain, and says while I am at it I might as well replace the cam as well but I am trying to avoid that thinking it is most likely the carburetor.

As for using a gas can, we were doing that because the gas tank wasn't set up. I'm setting it up to run off the tank as soon as the rain stops and I'll also do as you guys suggested.

Oh, and I have a new stock points distributor on there.

- Charles
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
The fact that it does start then dies points more towards the fuel system than anything else. I wouldnt tear into the engine and start changing out parts because someone thinks thats the cause If it was the timing chain then it would still start but lack power. You might want to recheck your points setting but I doubt if thats the cause of your problem.
 

mr incredible

Bronco Guru
Joined
Feb 25, 2007
Messages
2,217
sounds like an ignition system problem ,, starting circuit is on when cranking ,due to the starter solinoid sending power to the module or coil . then switches off at the on position of the key ,, make sure you have fire with the key in the on position ...
with the idle screw screwed all the way up ,, it should run on the secondary cuircuit , illiminateing the idle side .. if it does not , then it is ignition ...
 

j.r.nice

Bronco Guru
Joined
Feb 8, 2004
Messages
1,615
with the idle screw screwed all the way up ,, it should run on the secondary cuircuit , illiminateing the idle side .. if it does not , then it is ignition ...

I am not sure if you are saying what it looks like.

If the idle screws are turned all the way in, it will not supply fuel to the idle circuit. The engine will die. The carb will not automatically shift the load to another circuit. By cracking the throttle plate it will open the primary side ....not the secondary. It will also cause the squirters to pump fuel.

Additionally, once the key is off "start" the engine keeps running for 2 seconds (according to first post). So it has power in the "run" position.
 
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