HELP! My 625 AFB is going way lean at WOT - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
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post #1 of 8 (permalink) Old 04-23-2002, 03:58 PM Thread Starter
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HELP! My 625 AFB is going way lean at WOT

The Falcon was running better than ever and I drove it down to pick up some grub. When I left the parking lot of the restaurant and got into it the car nearly died and stumbled and continued to drive. It does it every time I try to get into the secondaries. I checked my Edelbrock A/F and it goes way lean as this happens.

Any ideas? The carb sat for a couple of years before being put on a few months ago. It ran about a thousand good strong miles before this happened.

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post #2 of 8 (permalink) Old 04-23-2002, 04:52 PM
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HELP! My 625 AFB is going way lean at WOT

So it happened all of the sudden? Did you do anything at all to the car right before this happened? What size rods, springs and jets are you using?

-Walt-

1964 Comet 289/C4 daily driver

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post #3 of 8 (permalink) Old 04-23-2002, 05:48 PM Thread Starter
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HELP! My 625 AFB is going way lean at WOT

I didn't do anything to the car just prior to this happening. It was running fine. I don't know what rods and jets are in the carb. I picked it up used.

But, it did run very well at about 13 to 1 A/F until this happened. I'm thinking a broken spring or a cloged jet or something. It had a new fuel filter on it though.

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post #4 of 8 (permalink) Old 04-23-2002, 08:01 PM
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HELP! My 625 AFB is going way lean at WOT

I would start by removing the rods/pistons/springs. This is a very 5 minute job. If one or both of them is gunked up/ not working it will run as you describe. It sounds as if you are getting air through four holes and gas through partially closed jets. This would be caused by the rods. They must raise to let the small diameter be in the fuel path. If it seems as if there is an obstruction/gunk on a rod, pull the top off. This will take a few more minutes, but is easy. Just remove the rods first and disconnect all of the linkage. Good Luck!
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post #5 of 8 (permalink) Old 04-23-2002, 11:38 PM Thread Starter
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HELP! My 625 AFB is going way lean at WOT

I checked the rods, they look great with nothing built up on them or the pistons or springs. Really nice action on them.

I've just got back from some more road testing. The car will accelerate fine if I use from part to mid throttle. As soon as I try to go to full throttle it stumbles. And if I leave it floored it will stumble and stumble and stumble. Never actually "catching up" with itself.

Any ideas on secondary circuit problems? Think it might be fuel pressure? It's got a good Mallory pump but it's getting kinda old.

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post #6 of 8 (permalink) Old 04-24-2002, 05:06 AM
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HELP! My 625 AFB is going way lean at WOT

Might want to pull off the top of the carb and spray carb cleaner in the secondary jet passages. Maybe something got lodged in the jet? Had that happen on my primaries once.

-Walt-

1964 Comet 289/C4 daily driver

There isn\'t an off position on the genius switch.
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post #7 of 8 (permalink) Old 04-25-2002, 12:48 AM
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HELP! My 625 AFB is going way lean at WOT

Once you get a motor to the stumble point you will generally have to back out of it for it to clean up and run.

Make sure you accelerator pump nozzles are both shooting strong jets of gas. It is common for these to get clogged up with trash.

If thats not it then it is most likely in the step up mode on your primary jets as in not enough jet or too much needle or the needles pull up too late and it leans out first.






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post #8 of 8 (permalink) Old 04-28-2002, 10:54 AM Thread Starter
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HELP! My 625 AFB is going way lean at WOT

Well, we pulled the top off the carb yesterday. It was all in very nice condition with very little "junk" at the bottoms of the bowls. No clogged jets or anything out of the ordinary.

I am going to put an old fuel pressure gauge on it today to see what she reads. Years ago when I put on the Mallory pump it read 8psi. But, that was years ago and maybe I have a pump developing a hole in the diaphragm.

I'll keep you guys posted.

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