only runs wide open

so my jeep has been running great. yesterday was beautiful here in ne iowa so off I went for a cruise. after putting over 100 mi in and about thirty mi to go, im on the highway at 55 or 60 all at once it acts like I shut it off but it still idles just fine with the clutch in and the only way to get acceleration is to completely floor it! if I blip the throttle it gives a deafening backfire. remember all this is at highway speed.

I just put an all new ignition system in a couple months ago and haven't had a lick of trouble with that. so I don't think its ignition, im guessing carburetor.
its a 304 with a motorcraft 2100
has anyone experienced this?

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Have you done anything to the carburetor?

Test the carburetor power valve by running the idle mixture screws all the way in and see if it still idles. If it idles, the power valve diaphragm has a hole in it and must be replaced.

 

are these symptoms what you would expect from a blown power valve?
I haven't done anything to the carburetor and it happened so suddenly

 

I think I only have one mixture screw on the front

 

Only if you have a 1V carburetor. Check the picture in the TSM. You are lucky - the '74 manual is online www.oljeep.com

 

there is an idle screw and one air screw that I can find. are those symptoms of blown power valve

 

I ran the screw in and it still ran but like crap

 

There are two mixture screws at the base of the carburetor. These are not on the linkage, but at the base of the carburetor, facing forward.

This is the bottom of a Mustang carburetor, but it's basically the same as the Jeep 304 carburetor



Yellow = mixture screws. Red = power valve cover.

 

correct. found the other screw after removing carburetor.
replaced the power valve and accelerator pump with no difference.
any other ideas.

symptoms again are idles fine as always, almost no throttle response just a sucking noise from carburetor until wide open then raps up quickly.

 

Did you carb clean/blow out all the fuel delivery passages?

Sounds like some crud blocking part throttle circuits

 

no not yet. the rebuild kit is an order part and I was trying to avoid totally tearing it down.
mid throttle is the float right. so maby needle is stick but wouldn't that screw up wide open also?

 

Is it flooding?

 

Did you check the timing?

 

You need to download the online manual and print out the carburetion section for the two barrel and read it through. It will tell you all about each circuit and then you will be able to better use any info we could give you.

I just printed mine out to do my 1 barrel as I typed this.

Cheers!

 

I did try to download the manual but all I got was the pics? whatever. just got done cleaning the carburetor and that didn't change anything. I started checking timing and disconected the vac advance and wala! so I look under the distributor cap and the wires going to the magnetic plate that moves as the ignition is advanced looked like they had been pinched between the distributor and the cap, messing up the timing. don't know how this manifested all at once like it did, it seems like it would have been like that since the cal was installed.
thanks for the input everyone