My Quadrajet is driving me crazy or crazier.:laugh: Any way it loads up at idle. First thing I did was had the float level checked. Carb shop said it was a little high and adjusted it according to their manual. Put it back on and it worked fine for a couple of days then back to the same problem. Checked fuel pressure. Running a GS pump had 8.5 lbs pressure. Put on a pressure regulator and set it a 5 lbs. Ran fine for a couple days. On the way home yesterday I decided to get on it a lttle. When I slowed down to make a turn it started loading up again. Ran it in the garage and checked the pressure again it was right wher it belonged 5 lbs. The first few times this happened I thought there might be a little dirt holding the needle valve open. Cleaned it out didn't see anything but when it was back together its the same thing runs fine then starts screwing up againo No: When I shut it off yesterday with the guage on the pressure dropped right away and it was loading up. So I'm assuming the float bowl was full and the needle valve should have been closed which I think should have held the pressure for a little while or at least dropped slowly. The carb is a rebuild from what I thought was a reliable shop In Auburn WA. Any ideas out there this thing is getting to me:blast: Thanks Bob H.
Make sure you are running on the idle circuit. Do the idle mixture needles have any effect when you turn them in?
Larry they have some effect but not a lot. Its just hard for me to believe it has something to do with adjustment because sometimes its fine and then its not. Doesn't seem like adjustments wouldn't keep changing but I'm willing to try anything at this point. Thanks for the reply. Bob H.
It's a common problem to have the throttle plates opened too much due to insufficient timing at idle. What happens is the idle transfer slot is exposed too much, which results in a hesitation or bog when going from a dead stop or low speed. Depending on how bad the problem is, the engine might be running on the mains instead of the idle system. If you crank the idle needles all the way in, does the engine still run? What is your timing at idle?
Hi! Larry it will die if the screws are turned all the way in. Besides its actually flooded if you let it idle till it dies. You can smell the fuel and have to treat it as a flooded engine to start by holding the throttle to the floor. I just put a new HEI in and haven't made the final setting for timing its at around 12 degrees right now thats without the vaccum advance of course. Keep Thinking:grin: Thanks Bob H.
Wierd one, Bob. I though about a bad well plug leak, but this would happen all the time, not intermittently. Only occasionally I've seen a plastic float that was damaged enough to hang up. One was a bent float hangar allowing the float to just barely touch the well wall. the other was a similar problem due to a scuffed float that swelled over time. I've also had an issue where the power piston would become stuck in the "up" position, allowing fuel to flow through the primary jets when it shouldn't have. Just some thoughts... Devon
How bad is it "loading up?" Just running rich, or flooding the carb? What kind of fuel filter are you using? I had frequent problems of flooding the carb when running a glass inline filter. The internal nut that held the filter element in place would back off from vibration, letting unfiltered fuel into the carb. Sooner or later, debris in the needle and seat, and flooding. Dave Hemker talked me into ditching the inline filter and putting the Motocraft filter in the carb. (The one Larry has mentioned here.) So far, so good.
The loading up varies a little not much. It will idle for a little while in nuetral but will eventually die. In gear it fades out faster. I thought about a little dirt in the needle valve but discounted the idea because of the inline filter. now you have me thinking otherwise. I will look for a little dirt. Thanks Bob H.
if it doesnt already have one put in a brass float set a 5/16 from top of gasket and check the choke pulloff for leakage. just take off the line and push in rod while in put finger over line and it should hold. definitely get rid of the glass filter, I had one once and literally watched the crap low through it. I usually install a metal fuel injection filter inline I can give you the number if you want, the one I use is threaded for 3/8 fuel nut on inlet and hose barb on other end gm filter:Smarty:
Thanks for the reply Walt. I would like the number of that FI filter I've lost faith in the off the shelf junk from AutoZone.:blast: Thanks again Bob H.
I'm now leaning toward stuck power piston. I've heard that this is supposed to be a common problem, but it's never happened to me. (Probably 'cause I have my carbs off and apart so often... ou: ) Power piston is easy to check. Put a small screwdriver down the vent on the carb, angled toward the front. You should be able to catch the top of the power piston, and push it down and have it pop back up against spring pressure. If it were debris in the needle and seat you'd be flooding and find the whole carb drenched with fuel after it died. Sounds like it's not that bad.
the filter number is wix 33093 or 3394 depending on which end you would like your hose nipple to be on, the filter is the same the flow direction is the difference. do check the power piston for hanging up earlier ones were brass and the piston and or bore may have carbon ,it takes very little, and the vaccume may not be strong enough to pull it back down every time polish the piston but do not sand it or wire wheel it as it will make it too small to function in the hole correctly. carb cleaner and air down the bore and I always spray it with a little wd or whatever and work it by hand a few times before reassembly good luck:3gears: :3gears:
A Couple Checks You Can Make Is To Shine A Flashlight Down The Primaries At Idle, If You See Gas Dripping Out Of The Main Discharge It Could Be One Of Two Things. Float Too High, Or Idle Speed Screw (drivers Side Screw On Linkage) As The Other Post Suggested. Another Check You Can Do Is To Pull A Vacumn Line Off At Idle, If The Idle Goes Up There Is Too Much Fuel At Idle. The Opposite Check Is To Slowly Close The Choke At Idle If The Idle Pick Up You Are Too Lean. Ideal Setting For The Idle Speed Screw Is To Have The Fuel Transfer Slot (vertical) Just Exposed By The Throttle Plate. If You Cannot Achieve This The Idle/transfer Circuits Need To Be Enlarged. Good Luck
Something to consider here is the possibility that the floats are absorbing fuel , getting heavy and floating on the fuel Older floats are notorious for this... Ray
I was going to suggest the same thing .Replace the floats with new ones.I know the Holley's do that and i was thinking the Quadrajets had a problem with that also.ou:
The problem with float fuel absorbtion is that usually the symptom is constant, not intermittent. I hope we hear some good news soon Bob! Devon
Thanks again for all the responses guys.:TU: I decided to give this project a little break. But will be back on it tomorrow. What little patience I had left was going fast.:af: Bob H.
