hey 92 - Ford Forums

351w · 10-16-2003, 22:02

do you have an possible solutions for a vehicle that runs fine during warm or dry weather but when it's around 50 degrees and raining or foggy about 5 min after initial startup in the morning will start to run really rich and stall at stops.
then if you shut it off or let it stall out for a min or 2 restart and run fine.
it acts to me like something draws moisture and then after it dries off will run fine.
it just starts loading up at idle rpm till it floods out. (eye watering rich)

no emmissions system, naturally aspirated, ford duraspark ignition and distributor.

'92BigBronco · 10-17-2003, 11:49

If I had to guess I would say your choke is sticking or isn't adjusted right. That's the only thing I can think of that would cause it to run like that when it's cold out yet still run fine when it's warm.

When you first start it up when it's cold outside, the choke closes (if it's electric choke) and richens the mixture up to keep it running until the vehicle warms up. Once the truck warms up, the choke butterfly should open again and if it doesn't....it'll stall out the same way you're describing.

351w · 10-17-2003, 18:44

yes it is an electric choke but i dont think the problem is that simple.
i have never had a problem with the choke sticking and what you didnt consider is when i said it only does it when its raining or foggy.
even if it is dry out it can be 20 degrees and i will have no problem at all.
the problem seems to be related to the humidity level more so than the cooler temps.
at this point my next step is to unhook my ram air intake and let the engine breath the heated air from the engine compartment to see if anything is different.
any other suggestions come to mind ?

'92BigBronco · 10-17-2003, 19:25

It wouldn't happen to be a Q-Jet would it?

If it's flooding out as bad as you describe, I can't see it being anything else other than the choke not opening back up. It's the only thing on a carbureted engine that can cause it to flood out like that when it's cold but still run fine when it's warmer. Just because you never had a problem with it before doesn't mean that's not the problem now.

Reason I asked about the Q-Jet is because they're kind of notorious for loading up bad at idle when not adjusted properly. Be sure your idle mixture screws are adjusted correctly.

Since it is electric choke, the humidity could very well be responsible for CAUSING the choke to not work properly. Be sure there's no bare wires or bad connections. A little moisture can cause an intermittent short and cause a lot of problems.

Next time you have the problem, leave the key on to maintain power to the choke and pull your air cleaner off and take a look.

351w · 10-17-2003, 19:37

ewww no,
it not a Q-jet they are for chebby's.
it is a Holley street avenger and i would bet money its not the choke because the sucker gets hot enough to burn ya after it has power for a while.
i also had the same problem when i had the edelbrock carbie on there.
you might have a point with the idle mixture cause now that i thinks about it if it was running a little rich normally the engine would suck it up but with the high moisture content in the air and an already rich mix.
hmmm.
i might have to break out the tach and vaccuum guage over the weekend and lean out the idle mix a smidge.
unfortunatly i dont have one of those handy dandy fuel ratio monitors to show me if i am lean or rich and i got no puter to change anything either.

'92BigBronco · 10-17-2003, 19:48

I've never used an exhaust gas analyzer to tune a carb although I bet it would make it easier. I've always just turned each mixture screw out a ways then turned it back in until the idle gets rough. Then just back it out until it smooths out and you're close to where you should be.

351w · 10-17-2003, 19:54

yea i always use the vaccuum guage and a tach and watch how the 2 respond to the adjustment.
now for the next question what would be a normal compression for my 351w when i do a compression test.
i did a half arse test without blocking open the throttle and without taking out the plugs.
and she cranks over with 195 psi compression.

'92BigBronco · 10-17-2003, 20:04

I've never found a book that will give an actual number on compression for some reason. They usually say that the lowest cylinder must be 75-80% of the highest cylinder. I guess they're going on the assumption that at least one cylinder will be close to spec. You're .030 over so that will lower your spec a bit. I can tell you how much if you really want to know.....

89F150 · 12-14-2003, 01:10

Hey 92 havn't seen you around in awhile. Hows it been going?
Well anyhow, just wondering if you knew what hypereutectic meant?