AMC Eagle Den Forum

The Mighty 258 => Fuel Systems. => Topic started by: maddog on February 06, 2013, 04:08:52 AM

Title: running rich
Post by: maddog on February 06, 2013, 04:08:52 AM
i have noticed that Eagle Eyes is running a bit rich and haven't been able to cure it. any suggestions?
Title: Re: running rich
Post by: carnuck on February 08, 2013, 01:42:43 AM
What have you done so far? Choke open all the way after 5 mins running? (may need adjusting leaner)

Fuel line coming into BBD tight? (stupid design rotates downwards from gravity, loosens the brass fitting which is also the seat for the needle and seat, which raises the float level) Don't crush the brass when re-tightening.

Vacuum leaks?

Make sure the carb body doesn't have loose screws (ALL mine have before I got them) Up to approx 17 mpg now just by tightening and adjusting the carb. (non-computerized BBD)
Title: Re: running rich
Post by: maddog on February 08, 2013, 03:37:38 AM
i have completely rebuilt the carb so no leaks there. and once she warms up actually does a bit better than when she's cold. i did find a loose hose and for the life of me i can't figure out where it goes (it comes off the air cleaner).
Title: Re: running rich
Post by: Eagleearl on February 08, 2013, 06:06:22 AM
Is this the original computerized carb? Is the computer still hooked up and adjusting the carb? Have you removed some of the vacuum hoses?
Title: Re: running rich
Post by: carnuck on February 08, 2013, 04:19:06 PM
Does the air cleaner have 2 vacuum motors on the inlet pipe? One of those is for close off of air to keep fumes inside. When they go bad, or come unhooked (like mine did) it closes the air coming in and makes for VERY rich mixture! (I went through a WHOLE tank of fuel in 50 miles!)
Title: Re: running rich
Post by: maddog on February 08, 2013, 09:19:54 PM
no she only has the single. and the carb is not computerized as the car is a 1980.
Title: Re: running rich
Post by: ammachine390 on February 08, 2013, 11:51:03 PM
Check these vacuum diagrams to see if you can figure out which line fell off
http://www.amceaglenest.com/~iowaeagl/guide/index.php?title=Diagram_Section#I-6_Eagle_Engine_Vacuum_Systems

I'm guessing the one that came off is for the heat riser vacuum motor. The line should go from the vacuum motor, a sensor on the bottom of the air cleaner, 1 hose in, then 1 hose out, and onto the driver's side back of the carb.

Vacuum leak would cause running lean, what's it doing that makes you think its running rich?

What is the difference between running cold and hot?

Finally, if all else checks out, you could try adjusting the main air/fuel ratio adjuster, which is the main metering rods. They are located underneath the little cover plate on top of the carb that is secured with 3 little screws. There is a gap between the top piece and the vacuum piston that should be measured, and adjusted to spec. If you just want to mess with it a bit, mark the position of the adjusting screw on the top, so you know where it was before you adjust it, then turn it counterclockwise to lean the mixture.
Title: Re: running rich
Post by: maddog on February 09, 2013, 02:37:09 AM
i know for a fact that the heat riser hose is on there as i just replaced it a couple of weeks ago. now what makes me think she's running rich is the plugs when i checked them as they had a lot of whitish yellow build up on them. when she's cold you can smell how rich she is running, but when she's hot she runs a lot better and you can't really smell the exhaust.
Title: Re: running rich
Post by: eagle87 on February 09, 2013, 01:05:58 PM
what is your ignition timing set at, and also how old are the plugs and type?
Title: Re: running rich
Post by: maddog on February 09, 2013, 08:32:46 PM
funny you should mention the timing as i was just thinking that today, as for what it is set your guess is as good as mine. the plugs are E3's and they are about two years old  (the wires are about the same age)but they are guaranteed for six years or three hundred thousand miles and i haven't put anywhere near that many on them.
Title: Re: running rich
Post by: eagle87 on February 09, 2013, 09:22:04 PM
i would start with the timing, need to get yourself a timing light, also would change the plugs if they appear worn or the timing is off, i highly recommend the bosch +4 or fusions which i run in all my eagles and jeeps, made a huge difference.
Title: Re: running rich
Post by: maddog on February 10, 2013, 02:39:08 AM
i already have a timing light so checking the timing wont be to hard.
Title: Re: running rich
Post by: eagle87 on February 10, 2013, 02:23:27 PM
that will be a good place to start
Title: Re: running rich
Post by: greymarooneightytwo on March 22, 2013, 07:03:04 PM
... vacuum advance for the distributor maybe?