View Single Post
DeFreest DeFreest is offline
Registerd 930 user nut
DeFreest's Avatar
Join Date: Apr 2012
Location: NH
Posts: 256
If you had a serious vacuum leak I would think your idle AFR would show it as well, but maybe not. Try squirting starter fluid or brake cleaner around all the intake injector blocks. Perhaps your wrench over-torqued them and cracked a couple to where they're sucking air.

Couple other thoughts: I wonder if the metering arm is moving freely. Almost sounds like it's not, since you go instantly lean when pressing on the gas. If the arm doesn't pull down in response to air flow then you wouldn't be getting the fuel needed. Don't know why this would be affected by a top end rebuild, though, but you never know. Pull off the air cleaner and push down on the metering plate to see if it moves freely. And/or, start the car up and push down on the mixture adjusting screw to where it contacts the metering arm and push further to see if your car will stumble from being overly rich.

One other thought: There is a frequency valve back behind the fuel distributor that's part of the Lambda system. If perchance your wrench had unplugged the wiring to it, you will see a very lean condition that cannot be corrected with any amount of adjustment. Do a listening check: Turn the key but don't start the engine. Force the pumps to run by pulling the green connector behind and on the left side of the fuel head (it connects to the metering arm via a micro switch). Pulling the plug will make the pumps come on as well as the frequency valve. You should be able to hear the valve's obnoxious buzzing. And while doing this test, go up front and pull each fuel pump relay one at a time and listen for the affected pump to stop running....just to confirm that both pumps are operating.

That's a start, anyway. More help to come I'm sure.
Mark: The metering plate moves freely like a ballance beam scale and once there is pressure on the system when the pumps are running there is a slight pressure or stiffness to the metering plate. I think thats normal? Anyway it feels the same as when it ran well before rebuild. I will check the intake blocks for cracks / vacuume leaks. I know they are new and hope there not cracked from overtightening. I will check the frequency valve. I don't remember any noise comming from that area. The only noise I could hear was the pumps.
I did check the pumps and both are running. If there was only one pump running wouldn't the system pressure be low? I want'ed to spray something on the intake blocks but worry about a fire. Is there a way to hook up a vacuume guage to the engine and see if the vacuume is correct? If there is what should the reading be?
The mixture screw on the fuel dist.will change the engine speed and seems to work as it should. One note though with reguards to your first line about the idle being affected by a vacuume leak, the idle screw seems like its close to being bottomed out like 1/4 of a turn from being bottomed out to get the idle to 950 warm. Isn't that an air bleed screw? That may point to a vacume leak as It wasn't like that before. I wonder just how much of a vacuume leak it take to get an engine to run lean like this? Seems like it needs to be quite a large leak to have an effect like this but not sure. The reason I say this is avery one of the old intake block were cracked and the engine ran good. By the way I did check the AAR and it works as it should. Compleatly closed after about 3 or 4 min and no leaks there.

Jwasbury: I will check the firing order but I think it runs to good at idle ( like before rebuild) to be out of wack but will check anyway just to scratch it from the list. Ing. timing is supposed to be 26deg at 4000 rpm. The starting point is 2deg at idle. I know this from the before rebuild settings. It's close like plus or minus 2 deg as it sits now.
Keep the ideas comming and I will check them one at a time. I'll keep you posted.
Old 04-06-2013, 07:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)