Bronco Idling high

[gslack]

I have a 69 eb with a 302, i have recently had an electric fuel pump installed and it has a 8mm fuel line and when i let the car feed gas into the carb it seems to idle around 900-1200 rpm right off the bat, but when i go through a few shifts and drive awhile when i put it in neutral at a stop light its always around 1300-1500 rpm. i am wondering if the fuel pump is not supplying the carb with enough gas and its forcing the engine to work harder to put out power. i have all vaccum leaks and what not sealed up on the engine and it runs solid. though i am wondering if i need a bigger fuel line, help? or maybe to have it tuned to supply more fuel?

 

[broncnaz]

Sounds more like you need to clean your throttle shafts/linkage they are probably just sticking. If to much fuel was flowing into the carb your idle would drop and it would start missing.
Another possibility is that you have a vacuum leak maybe you knocked a vacuum hose off or cracked it while installing the new setup. Or it just happened to develop a vacuum leak at the same time you swapped pumps.

 

[redtail]

Sounds like your choke is stuck

 

[gslack]

yeah i already thought of all that though, i opened up the engine compartment and jiggled the linkings a bit and its still being odd, in the morning when i start it up for the first 2 seconds it idles at 800 rpm like it should then it goes to around 1200.

 

[Viperwolf1]

It does sound like a choke adjustment. You should have someone that is familiar with carbs take a look at it.

 

[DirtDonk]

And on older carbs, sometimes just jiggling the linkage is not enough if it's gummed up.
Easiest way to clear that up is a quick dousing with Chemtool and then a few shots of WD-40 to lube it up.
Or a reasonable facsimile thereof...

Like Viper said though, if it's not simply gummed up, your adjustment is off too. It should not start out at 800. That's near a normal hot-idle once the choke is open. When cold and the choke is on, the idle should be in the 1400 rpm range.

Next time the engine has cooled off, pop the air filter off and manipulate the throttle linkage and watch the choke plate and mechanism. As soon as you pull the throttle back, it should spring closed and the stepped fast-idle cam should rotate up/down so that the fast-idle screw (cleverly hidden down under there) contacts one of it's higher "steps" and holds the throttle open slightly.

This is all sometimes hard to see down there beside the choke housing, but you can go back and forth until you see just what's moving and when.
As you manually rotate the choke plate open with one hand, and open the throttle slightly with your other, the fast-idle cam should rotate with it and eventually break contact with the fast-idle screw. When that happens, your throttle lever should only be in contact with your normal, or "curb" idle screw.

Clean and lube all the little pivoty-thingies down there and see what happens.

Good luck.

Paul

 

[gslack]

And on older carbs, sometimes just jiggling the linkage is not enough if it's gummed up.
Easiest way to clear that up is a quick dousing with Chemtool and then a few shots of WD-40 to lube it up.
Or a reasonable facsimile thereof...

Like Viper said though, if it's not simply gummed up, your adjustment is off too. It should not start out at 800. That's near a normal hot-idle once the choke is open. When cold and the choke is on, the idle should be in the 1400 rpm range.

Next time the engine has cooled off, pop the air filter off and manipulate the throttle linkage and watch the choke plate and mechanism. As soon as you pull the throttle back, it should spring closed and the stepped fast-idle cam should rotate up/down so that the fast-idle screw (cleverly hidden down under there) contacts one of it's higher "steps" and holds the throttle open slightly.

This is all sometimes hard to see down there beside the choke housing, but you can go back and forth until you see just what's moving and when.
As you manually rotate the choke plate open with one hand, and open the throttle slightly with your other, the fast-idle cam should rotate with it and eventually break contact with the fast-idle screw. When that happens, your throttle lever should only be in contact with your normal, or "curb" idle screw.

Clean and lube all the little pivoty-thingies down there and see what happens.

Good luck.

Paul

yeah i took off the air cleaner and pulled the choke and the plate and all the mechanisms are fine, i checked the linkages and theyre fine too, nothing blocking them and theyre not gummed up or anything. I just got a new carb about 3000 miles ago. and actually what you say makes sense, because i am in colorado and it has not been above 10 degrees lately, but i have noticed the warmer it is the lower it idles.

succesful diagnose.

solution: summer, hurry up.

 

[broncnaz]

succesful diagnose.

solution: summer, hurry up.

Thats not success thats just putting up with a issue. It doesnt matter how cold it is outside at some point the engine and the choke will come up to temp and the choke should operate normally. Might try adjusting the choke so its leaner. It might just be set to rich and is not fully opening due to the cooler weather. Also check to ensure its fully open when the engine is warmed up fully. There's a differance betwen ensuring everything moves and the parts actually moving when at temp.

 

[gslack]

well it wouldnt make sense that it is rich because the carb was just tuned. it only gets to around 170 degrees though unless im driving high speed on the freeway cus of how cold it is here.

 

[Adarcy]

I had a dashpot that wouldn't let my come down once. It kept sticking. You could try removing it. Just a thought.

 

[broncnaz]

well it wouldnt make sense that it is rich because the carb was just tuned. it only gets to around 170 degrees though unless im driving high speed on the freeway cus of how cold it is here.

Just because it was tuned doesnt mean it was tuned correctly. Overall tuning could be spot on but the choke its self is out of wack slightly. Along those lines tuning changes over time as well thats one of the drawbacks about carbs. My whole point is that idle speed doesnt change just because its cold outside. If it did then the responses to your issue would have been thats normal. Its not normal and something is just out of wack.

 

[DirtDonk]

well it wouldnt make sense that it is rich because the carb was just tuned.

And what az was actually referring to in his original post gslack, was the rotational adjustment of the choke spring. There are "rich" and "lean" settings on the dial. Richer closes the choke plate with more spring pressure and takes longer to open. Leaner closes it with less pressure and takes less time to fully open.

Paul

 

[ol gray mare]

Make sure the "heater wire" is hooked up on the choke. I knocked mine off the other day changing the air filter element, and it caused similar symptoms.

 

[DirtDonk]

Good call, but his '69 would not have come stock with an electric choke unfortunately.
Unless it's been changed? How's about it gslack? Is there a male spade connector on that black plastic cover by any chance?
Stock carb?

Paul