Bronco will not idle edlebrock 1406 issue

[mattyq17]

Bronco ran fine when parked a couple weeks ago, 8 gallons of gas in tank. Went out to start it on Wednesday and it fired right up, idling around 1200rpm. After a couple minutes I blipped the throttle to bring the rpms down to the normal 600 and it died. Would not restart. Added fuel to carb and it fired up but would not stay running unless I held idle above 1000. I noticed my fuel filter by the carb wasn't full (clear plastic filter so I can see the fuel) or half full like it normally is. Even when revving engine fuel seems to just be spitting into filter. Once I let off throttle it dies. I checked the oil and level is normal with no smell of gas so I don't think its the mechanical fuel pump. So any ideas on what to check next?

289, edelbrock 1406 carb, pertronix ignitor, pertronix coil, new plugs, cap, rotor.

Thanks
Matt

 

[Slowleak]

First thing to do is check for vacuum leaks. If it is sucking in air, it will run lean and die unless you open the throttle or close the choke, to give it fuel.

 

[jim3326]

Did you happen to put in a new tank? I put in a new 23 gal. and found out later the pickup tube didn't have any kind of sock on it, just a 3/8" tube at the bottom of the tank. I haven't figured out what was clogging it yet but it was choking the engine.

 

[SHX669]

I would check to see if someone siphoned out your 8 gallons of gas next i'd pull the fuel pickup tube from the tank and check the condition of the " sock/filter" . If it deteriorates it can plug the pickup tube.

 

[mattyq17]

Slowleak: I did a quick check for vacuum leaks yesterday by spraying carb cleaner around the carb and intake manifold and didn't notice any.

Jim3326: Stock tank

SHX669: I know no one siphoned off any gas as I live 20 miles out of town on a dirt road and no one comes out here. I did think about the fuel pick up tube and fuel lines. They are original as far as I know (66). New fuel lines are on my list of upgrades. I will try and find some time to check the lines this weekend and pull the sender to check the pick up tube(once I get the 8 gallons of gas out....)

 

[broncochevy]

You said 1405 carburetor I think it’s 1406 that has the electric choke, if you have an electric choke or a 1405 with an electric choke addition onto it, you might wanna double check that it’s set correctly. I know it was working fine when you parked it, but I had to set mine a few times to get it working correctly especially when the weather gets closer to freezing. Plus it’s is never as cold as it is when the block at its coldest.
And I would recommend checking the fuel pressure I’ve had fuel pumps go out that are not leaking fuel into the oil, or at least I didn’t think they did.

 

[mattyq17]

You said 1405 carburetor I think it’s 1406 that has the electric choke, if you have an electric choke or a 1405 with an electric choke addition onto it, you might wanna double check that it’s set correctly. I know it was working fine when you parked it, but I had to set mine a few times to get it working correctly especially when the weather gets closer to freezing. Plus it’s is never as cold as it is when the block at its coldest.
And I would recommend checking the fuel pressure I’ve had fuel pumps go out that are not leaking fuel into the oil, or at least I didn’t think they did.

Thanks Jimmy, you are correct 1406 electric choke, I will adjust that today and see what happens. Yes I will also check the fuel pressure as well.

 

[broncochevy]

Didn’t think of this before, but do u have power breaks? So swap them in it may be done already. If u do check your check valve and booster.

 

[West Tn Dawg]

I'm having somewhat of the same problem. After i run about 15 miles it starves for gas. Filter will be nearly empty. I thought it was vapor locking so i rerouted the fuel lines. Same issues. I installed a new filter and still doing the same thing. I thought my vented gas cap was not venting and pulling a vaccum. Ran with cap off and after about 15 miles, same thing. I don't think it is fuel pump, but I'm going to replace it next. If that doesn't work, I'm going to blow air back through the fuel line and see if the pickup tube is getting clogged.
Try your gas cap next, it's a free check.

 

[blubuckaroo]

Check the engine under load. (gas it)
if it doesn't die out under load, there's nothing wrong with the pump or filter.
Sometimes, the air bleeds for the idle ports get plugged with gas deposits. It usually takes a spray of ChemTool around the top of the air horn, with the engine running, to clear it.

 

[mattyq17]

Check the engine under load. (gas it)
if it doesn't die out under load, there's nothing wrong with the pump or filter.
Sometimes, the air bleeds for the idle ports get plugged with gas deposits. It usually takes a spray of ChemTool around the top of the air horn, with the engine running, to clear it.

Blu if I have the rpms at 1000 and hit the throttle on the carb it revs up no problem but once it drops down to normal idling rpms 600-700 dies instantly. What would cause the filter to not fill up? I have thought about blowing air back into the fuel line towards the tank.

I took the gas cap off no change.

 

[blubuckaroo]

Blu if I have the rpms at 1000 and hit the throttle on the carb it revs up no problem but once it drops down to normal idling rpms 600-700 dies instantly. What would cause the filter to not fill up? I have thought about blowing air back into the fuel line towards the tank.

I took the gas cap off no change.

Typically, an engine that's starving for fuel will struggle under load. But I suspect , from your description, you have either a leak allowing air into your fuel suction line, or you have a bad fuel pump.

Try this...
Disconnect the fuel suction hose from the fuel line at the pump and stick the hose end into a small can of gasoline. If it idles and runs fine, I'd suspect a leak in the fuel line between the tank and carb.
Do the car have dual tanks? Sometimes the selector valve is where the leak is.

If this test still doesn't isolate the problem, connect a vacuum gauge to the suction hose you've disconnected and crank the engine over. Most automotive vacuum gauges have a scale for furl pump vacuum.

 

[West Tn Dawg]

Typically, an engine that's starving for fuel will struggle under load. But I suspect , from your description, you have either a leak allowing air into your fuel suction line, or you have a bad fuel pump.

Try this...
Disconnect the fuel suction hose from the fuel pump and stick the hose end into a small can of gasoline. If it idles and runs fine, I'd suspect a leak in the fuel line between the tank and carb.
Do the car have dual tanks? Sometimes the selector valve is where the leak is.

If this test still doesn't isolate the problem, connect a vacuum gauge to the suction hose you've disconnected and crank the engine over. Most automotive vacuum gauges have a scale for furl pump vacuum.

In my case you are correct. Once I drive it for a while and it starts to miss the filter will be nearly empty, and it struggles(misses) a bunch when I try to excellerate.

 

[Justafordguy]

Sounds like the idle circuit of the carb is plugged up. Try to rev the engine with the air filter off and cover the air inlet on top carb with your hand while reving. This will sometimes suck the trash on through the passages and clear it up. If not you may need to take it apart and clean it out.

 

[mattyq17]

I didn't get a chance to mess with it this weekend, C-section on a pig Friday night, PBR on Saturday in Sacramento, (Pro Bull Riding not Pabst Blue Ribbon) and baseball all day yesterday.

I will try some of these things when I get home tonight and report back after.

Thank you all for the suggestions.

 

[blubuckaroo]

I agree with Justafordguy about the idle air bleed ports plugging up. It's happened to me on several occasions. I have a long tube made do direct carb cleaner from an aerosol can that makes it easy to flush em out. You just remove the mixture screws and blow it out. Make sure you count the turns on the adjustment screws before removing them though.

 

[mattyq17]

Took fuel line off fuel pump and blew air back towards the tank, no change.
Adjusted choke no change.
Removed idle mixture screws blew out holes, no change.
Gonna pull the top of the carb off and see if any debris is inside, also gonna pick up a vacuum gauge later this week and study up on how to use one.

Any other suggestions?

 

[Slowleak]

Bronco will not idle

I would back the idle mixture screws out and see if it gets better. You may be able to keep it running by feathering the throttle while you back out the screws. If it is running too lean at idle for some reason and stalling, this will make the mixture richer and it may idle. Turn each screw the same amount and keep track of the turns.

My old edelbrock never ran right unless the screws were backed out a lot more than the standard ~2 turns.

 

[blubuckaroo]

Took fuel line off fuel pump and blew air back towards the tank, no change.

Try putting air pressure on the gas tank with the lines still connected. If there's a leak in the suction line, it'll show up.

 

[pcf_mark]

I agree with Justafordguy about the idle air bleed ports plugging up. It's happened to me on several occasions. I have a long tube made do direct carb cleaner from an aerosol can that makes it easy to flush em out. You just remove the mixture screws and blow it out. Make sure you count the turns on the adjustment screws before removing them though.

OP is not packing a Holley..

Verify the choke and fast idle cam are fully disengaged. Get down in there close and check with the engine warm.