74 Bronco dies when I slow down, want idle

• Aug 14, 2012

• #2

R

RNichols

New member

Joined

Mar 15, 2011

Messages

74

Reaction score

0

Location

Alabama

I had my bronco running good,and it was running before it quit, I slow down to make a turn and it died. It crank back up and will continue to crank at half throttle, but dies at idle. It sounds like its missfiring, sputtering like, but it excelarates smooth from half throttle on. What do I need to check? 302,auto,stock

 

Last edited by a moderator: Aug 14, 2012

• Aug 14, 2012

• #3

B

Bully Bob

TOP GUN

Moderator

Joined

May 23, 2004

Messages

3,844

Reaction score

12

Location

Boulder City, Nevada (Las Vegas area)

Hi RN..,

A couple possibilities come to mind.

One being the idle curcuit inside the carb. has some crud in it.

Another would be an obvious vacuum leak.

A weak fuel pump. (fuel dribbles out bottom of pump)

Least likely may be a flooding issue. (sticky needle & seat &/or float.)

 

• Aug 14, 2012

• #4

OP

OP

R

RNichols

New member

Joined

Mar 15, 2011

Messages

74

Reaction score

0

Location

Alabama

thanks for the reply, the filter was replaced a year ago,I did take it off and could see through the screen in side. The vacuum hose has been replaced, and since it would'nt idle I wasnt able to check for a leak by myself. The carb was rebuilt a year ago, but it could have developed a problem inside. new fuel pump & it dosnt leak.

 

• Aug 14, 2012

• #5

B

Bully Bob

TOP GUN

Moderator

Joined

May 23, 2004

Messages

3,844

Reaction score

12

Location

Boulder City, Nevada (Las Vegas area)

YEP.., runn'n good in all conditions except idle.., it's not likely elect. soooo., it's an air leak or fuel starvation at idle.

Do fill-in your sig. page.... it helps us find clues.. >< <'>

 

Last edited by a moderator: Aug 15, 2012

• Aug 15, 2012

• #6

Rons beast

Active member

Joined

Dec 13, 2007

Messages

1,537

Reaction score

13

Location

Florida..in my mind , sitting on the beach

Hey R,

As Bully said, most likely there is some restriction in the idle and off idle circuits. This is actually not uncommon after a carb rebuild, if the gaskets are squeezed just a little too much then after time a small sliver of gasket material will break off and slip into a jet or orafice...and we are talking really small, like the tip of a toothpick. That is all it takes to get these kind of problems.

On rare occations I have witnessed the obstruction clearing on a highspeed run, or a few seconds of WOT. Admitedly it is rare, but if you want to try it, get on the highway and pick a gear that will run the engine rpm at 3000-3500rpm. Only for maybe a mile or so, and be careful and aware of other traffic.

If it doesn't help, "open carb surgery" is needed.

Good Luck

 

• Aug 15, 2012

• #7

C

cjcargo

New member

Joined

Feb 28, 2012

Messages

9

Reaction score

0

Location

Baltimore, Maryland

Idle set too low? Does it idle in your driveway, while in park?

 

• Aug 16, 2012

• #8

OP

OP

R

RNichols

New member

Joined

Mar 15, 2011

Messages

74

Reaction score

0

Location

Alabama

cjcargo said:

Idle set too low? Does it idle in your driveway, while in park?

Click to expand...

 

• Aug 16, 2012

• #9

OP

OP

R

RNichols

New member

Joined

Mar 15, 2011

Messages

74

Reaction score

0

Location

Alabama

No, it want idle. It will run at a slite excelleration, but it lopes. If I excellerate hard and let off it back fires.

 

• Aug 16, 2012

• #10

Rons beast

Active member

Joined

Dec 13, 2007

Messages

1,537

Reaction score

13

Location

Florida..in my mind , sitting on the beach

RNichols said:

No, it want idle. It will run at a slite excelleration, but it lopes. If I excellerate hard and let off it back fires.

Click to expand...

That's an indication of a lean condition, very possibly a vacuum leak.

Or as stated before circuits clogged in the carb.

 

Last edited by a moderator: Aug 16, 2012

• Aug 16, 2012

• #11

B

Bully Bob

TOP GUN

Moderator

Joined

May 23, 2004

Messages

3,844

Reaction score

12

Location

Boulder City, Nevada (Las Vegas area)

Ahhh..,

Now that also sounds like timing..! Use your timing light... if the dizzy is tight in place but timing is off, it could be a bad timing chain.

 

• Aug 19, 2012

• #12

bigbluebronc

New member

Joined

Nov 9, 2005

Messages

394

Reaction score

4

Location

ca

RNichols said:

I had my bronco running good,and it was running before it quit, I slow down to make a turn and it died. It crank back up and will continue to crank at half throttle, but dies at idle. It sounds like its missfiring, sputtering like, but it excelarates smooth from half throttle on. What do I need to check? 302,auto,stock

Click to expand...

all these darn old broncos are fuel sensetive clean out your tank blow out your carb change the fuel filters clean out your pump and it will run all day

 

• Aug 20, 2012

• #13

rustyoldbronco

New member

Joined

Aug 16, 2012

Messages

17

Reaction score

0

Location

Afton,Wyoming

I was having a simular problem after my stock carb was rebuilt.It kept stalling in turns etc.I got fed up and went to that new Holley Truck avenger.I was never a Holley guy.Ive used 2100's and Quadrajets.That holley has run really smooth.I went real small though,I think its a 425cfm.Donn

 

• Sep 4, 2012

• #14

OP

OP

R

RNichols

New member

Joined

Mar 15, 2011

Messages

74

Reaction score

0

Location

Alabama

It needed a carburator rebuild, back on the road. Thanks

 

• Sep 4, 2012

• #15

Rons beast

Active member

Joined

Dec 13, 2007

Messages

1,537

Reaction score

13

Location

Florida..in my mind , sitting on the beach

And thanks to you for keeping us updated.