Go Back   Ford Truck Enthusiasts Forums > Performance, Engines & Troubleshooting > Ford Inline Six, 200, 250, 4.9L / 300
Sign in using an external account
Register Forgot Password?


Welcome to Ford-Trucks Forums!
Welcome to Ford-Trucks.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the Ford-Trucks Forums community today!





 
Reply
 
LinkBack Thread Tools Search this Thread
  #1 (permalink)  
Old 07-06-2014, 04:11 PM
lvin4jc's Avatar
lvin4jc lvin4jc is offline
Posting Guru
 
Join Date: Jul 2006
Location: Rapid City, SoDak
Posts: 1,155
lvin4jc is gaining momentum as a positive member of FTE.lvin4jc is gaining momentum as a positive member of FTE.
Thumbs down 300 running super rich, mpg's dropped by 4 ???

My '82 Bronco was occasionally going into "bogs" when driving. It would just get loud, lose gobs of power and just generally run poorly every once in a while (also backfired on deceleration a lot during these episodes). Then, for no reason it would come out of the bog and run fine. I also had a large vacuum leak inside the carb. So a couple of weeks ago I rebuilt it.

After that it ran much better, had no vacuum leak and the truck overall was more responsive. Life was good for about a week. Then the bogs started happening again and I could tell it was running a little rich. Well the running rich problem has gotten worse, a lot worse. In fact my eyes are burning while I drive this thing around. It drives ok, isn't putting out all the ponies it should be but the biggest sign of a problem is the drop from 14mpg's to 9mpg.

Now, the only problem I have with the carburetor that I know of is that the fuel/air screw on my Carter YFA doesn't do anything. The engine reads almost 25 lbs of vacuum as it sits, but adjusting that screw doesn't do anything (not vacuum, idle speed, nothing) until it bottoms out in the hole from being tightened or falls out from being loosened.

I did notice while spraying some carb cleaner around looking for vacuum leaks that the distributor responds to spray indicating a leak.

One more hint, over the last couple of weeks the gas tank has become extremely hard to fill up. Even on one click and with the nozzle pulled out so far it's barely hanging in there it goes about $5 before clicking off even when the tank is empty.

So... where should I start with this thing?

Thanks!
__________________
1982 Bronco 300/6 4WD 4spd
2004 Expedition Eddie Bauer 5.4 - Wife's

Gone - 1990 F250 XLT Lariat RC LB 4x4 302/M5R2 - 1951 F1 w/226 - 1962 F100 w/223 - 1989 F350 XLT Lariat CC LB 4x4 460/ZF-5 - 2004 Explorer Limited AWD 4.6l
Reply With Quote
  #2 (permalink)  
Old 07-06-2014, 05:34 PM
cstephens cstephens is offline
Junior User
 
Join Date: Sep 2013
Location: Hot Springs, AR
Posts: 97
cstephens is starting off with a positive reputation.
@GimpyHSHS https://www.linkedin.com/pub/christopher-stephens/86/759/16 @GimpyHSHS
Quote:
Originally Posted by lvin4jc View Post
My '82 Bronco was occasionally going into "bogs" when driving. It would just get loud, lose gobs of power and just generally run poorly every once in a while (also backfired on deceleration a lot during these episodes). Then, for no reason it would come out of the bog and run fine. I also had a large vacuum leak inside the carb. So a couple of weeks ago I rebuilt it.

After that it ran much better, had no vacuum leak and the truck overall was more responsive. Life was good for about a week. Then the bogs started happening again and I could tell it was running a little rich. Well the running rich problem has gotten worse, a lot worse. In fact my eyes are burning while I drive this thing around. It drives ok, isn't putting out all the ponies it should be but the biggest sign of a problem is the drop from 14mpg's to 9mpg.

Now, the only problem I have with the carburetor that I know of is that the fuel/air screw on my Carter YFA doesn't do anything. The engine reads almost 25 lbs of vacuum as it sits, but adjusting that screw doesn't do anything (not vacuum, idle speed, nothing) until it bottoms out in the hole from being tightened or falls out from being loosened.

I did notice while spraying some carb cleaner around looking for vacuum leaks that the distributor responds to spray indicating a leak.

One more hint, over the last couple of weeks the gas tank has become extremely hard to fill up. Even on one click and with the nozzle pulled out so far it's barely hanging in there it goes about $5 before clicking off even when the tank is empty.

So... where should I start with this thing?

Thanks!
When ya rebuilt the carb, did you make sure the float level and drop were accurate? My float was GONE when I bought the truck, rebuilt the carb, didnt do the float adjustment right, and the idle air mix did nothing because I was still spilling gas into the engine. My engine RPM would fall off when it would flood then rev back up all of a sudden, causing more fuel to come in, then would flood again, and so on so forth.

Is the vac leak actually around the spark advance? Check your vac hoses for cracks. Also, it may seem crazy, some say I am, and this is prolly not gonna be recommended by ANYBODY else, but if you are desperate enough, buy some vac caps, cap off everything but the dizzy and the PCV, and put new hoses on those. As has been said to me by others on here "the engine can run with NO vac lines plugged to ANYTHING, so long as theyre capped off right".

Then grab some carb cleaner and see if ya missed anything.

Keep us up to date with developments.
Reply With Quote
  #3 (permalink)  
Old 07-06-2014, 11:02 PM
lvin4jc's Avatar
lvin4jc lvin4jc is offline
Posting Guru
 
Join Date: Jul 2006
Location: Rapid City, SoDak
Posts: 1,155
lvin4jc is gaining momentum as a positive member of FTE.lvin4jc is gaining momentum as a positive member of FTE.
Quote:
Originally Posted by cstephens View Post
When ya rebuilt the carb, did you make sure the float level and drop were accurate? My float was GONE when I bought the truck, rebuilt the carb, didnt do the float adjustment right, and the idle air mix did nothing because I was still spilling gas into the engine. My engine RPM would fall off when it would flood then rev back up all of a sudden, causing more fuel to come in, then would flood again, and so on so forth.
I set the float according to the rebuild kit instructions, it was pretty close. The metering rod was waaay off from where the instructions said it should be. I don't know my carb terminology but the kit said that the metering rod should bottom out when the (don't know the name of it) other rod that it's attached to bottomed out, so they should hit at the same time. I probably had to put 4 full turns on the metering rod to get it to do that. But again, it ran great for the first week after I rebuilt it. I dunno, I just did what the kit said to do.

I like your idea because it's the easiest way to find the problem by adding one more thing back until there's a problem. The only thing is I have 23-24 on my vacuum gauge right now, isn't that about as good as it's going to get?
__________________
1982 Bronco 300/6 4WD 4spd
2004 Expedition Eddie Bauer 5.4 - Wife's

Gone - 1990 F250 XLT Lariat RC LB 4x4 302/M5R2 - 1951 F1 w/226 - 1962 F100 w/223 - 1989 F350 XLT Lariat CC LB 4x4 460/ZF-5 - 2004 Explorer Limited AWD 4.6l
Reply With Quote
  #4 (permalink)  
Old 07-06-2014, 11:15 PM
Tedster9's Avatar
Tedster9 Tedster9 is offline
Posting Guru
 
Join Date: Apr 2002
Location: Waterloo
Posts: 1,452
Tedster9 has a very good reputation on FTE.Tedster9 has a very good reputation on FTE.Tedster9 has a very good reputation on FTE.Tedster9 has a very good reputation on FTE.
Something isn't set right in the carb. Just guessing, but it's not running on the idle circuit, (when it should be) and that's why the idle mixture screw doesn't have a positive action.

Make sure your timing is set correctly and use your vacuum gauge to adjust carb after you get the throttle plate adjusted right or whatever it is. Over 20 inches of vacuum is "good" but "too good" - maybe related to the carb being horked, dunno. Should be 19 to 21, say. Tuning with a vacuum gauge is real precise and the idea is to lean out the carb as far as possible (but no more) making adjustments to idle and mixture. As idle speed increases with mixture the throttle stop is backed down, etc. The idle mixture needle will have a definite sweet spot on a well tuned engine. Make sure your linkage is set correctly and throttle plate has proper gap at idle, and is perfectly vertical at full throttle.

http://classicinlines.com/vacuum.asp

Sent from my iPhone using IB AutoGroup
__________________
Keep 'er between the ditches.

1964 F-100 292 V8
2009 XLT Ranger 4.0 V6
Reply With Quote
  #5 (permalink)  
Old 07-06-2014, 11:29 PM
cstephens cstephens is offline
Junior User
 
Join Date: Sep 2013
Location: Hot Springs, AR
Posts: 97
cstephens is starting off with a positive reputation.
@GimpyHSHS https://www.linkedin.com/pub/christopher-stephens/86/759/16 @GimpyHSHS
Hmm true. I didnt see that part about engine vac. Got ahead of myself. Well, Im going to be honest. Carbs aren't anything I know anything about. I just know what problems I had, and were similar at some points.

What do you have your idle speed screw set at? Theres a spec for it. When you hold the gas pedal at an even height, i.e. steady RPM, does the bog happen, or does it smooth out? If it doesnt, when ya take off the dizzy vac line, then cap it at the intake tree, does it smooth out?

Idk all of what the problem could be. Im not the greatest, and Im young, so not too much experience, just a little classroom learning. But I have learned (thanks guys) that a lot of problems can be fixed simply by eliminating the impossible. Whatever remains, however improbable, must be the truth. (Sherlock)

Also read this thread, I had the same conundrum with my air/fuel mix:
http://www.ford-trucks.com/forums/13...se-help-2.html
Reply With Quote
  #6 (permalink)  
Old 07-07-2014, 08:38 AM
hillcountryflt's Avatar
hillcountryflt hillcountryflt is offline
Senior User
 
Join Date: Mar 2014
Posts: 318
hillcountryflt is starting off with a positive reputation.
Get back to the pressure reference on the gas tank. Not being able to fill it properly. I am surmising you think there is pressure keeping it from filling, not an obstruction.
For grins, does it make any difference when you run the engine without a gas cap?
How many lines are coming from the gas tank - one for fuel, a vent line and do you have another going to some sort of canister in the engine compartment.
I am with cstephens, start by simplifying the environment.
__________________
Central Texas.
My F100 work in progress:
http://1drv.ms/1m9ESSk
2013 Ford Escape SEL;
2011 Mustang;
2010 H-D Electra Glide Ultra Limited.
Reply With Quote
  #7 (permalink)  
Old 07-07-2014, 11:19 AM
1986F150six 1986F150six is offline
Posting Guru
 
Join Date: Jul 2009
Location: Sheffield, AL
Posts: 2,404
1986F150six has a great reputation on FTE.1986F150six has a great reputation on FTE.1986F150six has a great reputation on FTE.1986F150six has a great reputation on FTE.1986F150six has a great reputation on FTE.
Is the idle speed higher than normal?
Reply With Quote
  #8 (permalink)  
Old 07-07-2014, 12:50 PM
lvin4jc's Avatar
lvin4jc lvin4jc is offline
Posting Guru
 
Join Date: Jul 2006
Location: Rapid City, SoDak
Posts: 1,155
lvin4jc is gaining momentum as a positive member of FTE.lvin4jc is gaining momentum as a positive member of FTE.
Timing was just set after I rebuilt the carb, it's dead on at 10.

I will check the throttle plate and the gas cap off. You are right, i'm wondering if there is pressure in the tank that's affecting life under the hood.

The "bog" is far less predictable than I must have explained it. The only thing I can say is that it usually, but not always, happens when the engine is cold. It goes in to what I think is a mega rich condition. So it goes from ridiculously rich to stupid rich for a bit, sometimes for a couple hundred yards, sometimes for 2 miles before it comes out of the bog. Nothing I can do seems to affect it.

I guess I should have said, my plan was to buy a new carb. I started this thread because I thought maybe there was another explanation that would save me putting on a shiny new carb only to find out that it wasn't the problem.
__________________
1982 Bronco 300/6 4WD 4spd
2004 Expedition Eddie Bauer 5.4 - Wife's

Gone - 1990 F250 XLT Lariat RC LB 4x4 302/M5R2 - 1951 F1 w/226 - 1962 F100 w/223 - 1989 F350 XLT Lariat CC LB 4x4 460/ZF-5 - 2004 Explorer Limited AWD 4.6l
Reply With Quote
  #9 (permalink)  
Old 07-08-2014, 04:07 PM
cstephens cstephens is offline
Junior User
 
Join Date: Sep 2013
Location: Hot Springs, AR
Posts: 97
cstephens is starting off with a positive reputation.
@GimpyHSHS https://www.linkedin.com/pub/christopher-stephens/86/759/16 @GimpyHSHS
Quote:
Originally Posted by lvin4jc View Post
Timing was just set after I rebuilt the carb, it's dead on at 10.

I will check the throttle plate and the gas cap off. You are right, i'm wondering if there is pressure in the tank that's affecting life under the hood.

The "bog" is far less predictable than I must have explained it. The only thing I can say is that it usually, but not always, happens when the engine is cold. It goes in to what I think is a mega rich condition. So it goes from ridiculously rich to stupid rich for a bit, sometimes for a couple hundred yards, sometimes for 2 miles before it comes out of the bog. Nothing I can do seems to affect it.

I guess I should have said, my plan was to buy a new carb. I started this thread because I thought maybe there was another explanation that would save me putting on a shiny new carb only to find out that it wasn't the problem.
Might try hooking the vac gauge and driving it. You should drop waaaay down when you clip the throttle, if you dont pop back up, that may tell ya something. Try just watching the vac gauge while driving, if it bogs, see what the gauge is doing. The motion of the needle tells a story in itself.

Might take the vac gauge and watch it when ya spray the carb cleaner on the dizzy. If there is a vac leak or something fishy at all, and the throttle plate stays closed while the engine revs, the needle should go up, Im thinking. Again, motion of the needle is important.

Does it fluctuate? Stay steady?
Reply With Quote
Old 07-08-2014, 04:07 PM
Reply

Go Back   Ford Truck Enthusiasts Forums > Performance, Engines & Troubleshooting > Ford Inline Six, 200, 250, 4.9L / 300

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
`82 300 I6 runs pig rich after smog removal (SOLVED, or maybe not)) Bugzturbo 1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks 28 06-28-2014 02:32 AM
randomly stalling help luthoro 1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks 5 12-24-2012 11:17 PM
Low Vacuum/Carb Problem Carter YF jbwolfe Ford Inline Six, 200, 250, 4.9L / 300 13 12-01-2012 10:57 PM
'89 F150 5.0 AOD surging, irregular idle DWB Small Block V8 (221, 260, 289, 5.0/302, 5.8/351W) 8 11-01-2012 01:58 PM
1990 f150 4.9 300-6 cyl laggy zstangkrewson Ford Inline Six, 200, 250, 4.9L / 300 81 09-26-2012 07:26 PM



All times are GMT -5. The time now is 01:30 PM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup