Virginia suddenly went from running great to barely running at all

[WoodenBirdOfPrey]

So when I bought this car it ran great.  Fired right up when cold, idled smooth, and all that.  (lasted about 2 hours then the flexplate started giving me trouble but that's a different story). 

Now the last few days she's started to run like crap, especially at idle when cold it shakes and sputters, feels like it's not firing on all cylinders and there's a definite lean condition because a jab at the throttle smooths out the idle for a second from the extra fuel it gets from the accelerator pump (if that's the correct term - most of my background is atvs/dirtbikes).  I popped off the air cleaner lid and looked down into it, there doesn't look like there's any fuel coming out of the venturi at idle and when I apply throttle a little bit runs out, but not atomized like it should be.  Initially I thought something is probably clogged up in the carb, but I really don't understand how I could have any dirt in the carb when the fuel is going through an inline filter before the fuel pump and then the 2 way filter after the fuel pump.

I don't know if it's related or relevant, but when the engine hasn't been fully warmed up yet, like if I only go 3 miles down the road to the store, when I shut it off it usually diesels for a couple seconds before giving up, twice it's blown the vacuum line off the manifold.

I really don't want to make the jump to the Motorcraft 2150 unless I really have to, I already need to fork out over $400 for tires, most of the fuel lines and brake lines are junk, it needs rotors and pads on the front, the valve cover gasket needs replaced, the windshield needs taken out and re-sealed, the rust on the floor needs tended to... and all i'm seeing is $$$$$$$ right now.  That doesn't jive with the rambler mentality.  I'm also not too thrilled about the idea of the motorcraft because of PA's visual emission inspection, and there's no way to hook up the pulse air system to the MC.  Yeah, I can try to dummy it up, but if the inspection station catches it then i'm up the creek without a paddle.

So before I dive into fumbling around with this carb, i was hoping I could get some sort of guidance about where I should start and what in particular I should look for, and what parts i'll need to get ahead of time.  The last thing i want is to get frustrated and just thrown the wrenches down, I have too many half finished projects around here because I got po'd and lost interest.  I'm already feeling like i'm one more breakdown away from pushing everything with an engine into a pile and burning it, the only darn vehicle i've owned in the last 5 years that's been halfway reliable is my 21 year old japanese dirt bike.  Somebody please remind me why i'm so hellbent on buying American when everything falls apart in my hands.

[ammachine390]

Are you sure all the vacuum lines are connected and/or not cracked and broken? It sounds like the idle tubes could be clogged, which is not that hard to fix, however, I am not sure if that would happen just instantly like in your situation.

[eagleman]

Sounds like its sucking air somewhere. Believe I would hook a vacumm gauge to it while its running and see what it sayes.A healthy running engine should read around twenty pounds of vacumm while idling.If it deisels when you shut it off its either idling to fast or you have a timming problem usually to far advanced,possibly could have jumped time.One way to check that is to run number one piston to tdc then take the dist cap off and see if the rotor is at the number one post.

[WoodenBirdOfPrey]

I'll start with the vacuum gauge, I have one I have plans to install eventually once i figure out where I'm putting additional gauges.  I have a feeling the needle is going to be jumping all over the place at idle.  It's very possible that there is another vacuum line off somewhere, but it's somewhere I can't see it very easily.

[WoodenBirdOfPrey]

And about the possibility of high idle causing dieseling - naturally it is idling higher than normal when it happens because the car isn't fully warmed up yet.  It's not abnormally high in my opinion.  Once the car warms up enough that the needle on the temp gauge is in the green zone the idle will drop down and it will shut off without a fuss.

[eagleman]

Well that should be about right then.My eagle will run on if I shut it off while its running on fast idle.Believe I would keep looking at the vacumn end however.

[WoodenBirdOfPrey]

Will do, i'll dig into it tomorrow after work.  Being that i know the dieseling has blown off a particular vac line twice, it's very possible that wasn't the only one.  And with there being so many of the darn things it wouldn't be hard to miss one.  I did find one line tonight behind the carb that was disconnected with a screw in it, and an open nipple on an actuator or valve on the passenger side of the carb.  Not sure what it's for.  Yay for bonus parts, seems like cars from the 80's had a lot of 'em.

[WoodenBirdOfPrey]

Looked all over the place for any vacuum lines that might have got disconnected or cracked.  I found a few that went nowhere and are capped, but I can't find anything badly cracked, loose, or disconnected.  Of course there are so many of them it wouldn't be hard to miss one.  I was going to put a vac gauge on it but I'm holding off on starting the engine because during my search, I found that the top transmission bolt started loosening up on it's own, it's backed out about half an inch.  Of course it would have to be the one that's nearly impossible to get, that thing was a pain even on the lift and the fact that it's loosened already is telling me we still didn't get it right.  So I gotta borrow some extensions and swivels and see if I can get it tightened good, and check the others while i'm at it.  The problems never end. *groans*

Oh... also found that the driver's side brake hose is leaking so I need to fix that before I can drive it.  Which sucks because I was at the local tire place today and ordered a set of 4 BFG All Terrains for the old girl, 215/75/15.  They weren't cheap but I was second guessing everything else they showed me so I went for the tire every other manufacturer tries to beat but seldom does.  The tires should be here Thursday but so far I haven't had much luck getting the brake lines locally, hopefully I can get a chance to call Napa and a few other places tomorrow.

[BenM]

Replace all 3 soft brake lines if you can while you're at it; if one is bad I bet they all are. There are a bunch of vacuum diagrams around here, it sounds like it's a good time to print one out and pick up a whole bunch of vacuum hose and just go through it all. Luckily it's cheap.

For the stiff tubing, you can get the stuff on the auction site as vinyl pneumatic tubing under industrial supply. 25' for about $10. It gets brittle and cracks with age.

[WoodenBirdOfPrey]

Well I temporarily installed a vacuum gauge today, I don't think that my issue is a vacuum leak.  At idle it's pretty consistently right around 15 - 17 which is similar to other vehicles i've owned that I installed a vac gauge on.  I guess it's a carb issue then.

[BenM]

Well I temporarily installed a vacuum gauge today, I don't think that my issue is a vacuum leak.  At idle it's pretty consistently right around 15 - 17 which is similar to other vehicles i've owned that I installed a vac gauge on.  I guess it's a carb issue then.

Actually, that sounds a little low. I usually get close to 20 with a stock cam, and I'm pretty sure others do. Have you tried plugging all the vacuum lines and checking?

[WoodenBirdOfPrey]

No, I haven't. I'm kind of worried that I'll never get them back on in the right places if I take them all off. I guess it won't be bad as long as I take a methodical approach to it and label them.

[AMCKen]

Vacuum at idle (20 inches, not pounds) depends on the ignition timing and idle speed. With a lot of initial advance you can close the plates more to keep the speed down and the vacuum will go 'up'. The vacuum line going to the passenger's side of the carb is for the choke pull-off. It opens the choke slightly after start-up. Getting that adjusted properly can help.
The dieseling probably means the carb may still on the fast idle cam and the throttle isn't closing when the key is turned off. That could also be a mis-adjusted base idle speed. Some people use the wrong screw to set up idle speed. It should be the one at the solenoid at the top-driver's side of the carb. There'll be two others there too - one for the fast idle and one for the off-solenoid idle. I generally don't use that one at all if the solenoid one is working properly.

[WoodenBirdOfPrey]

Thanks for the info.

My carb experience is limited to small engines so i'm not used to all these electric and vacuum operated controls.  If I could slap a Mikuni Flatslide carb on this thing I'd have it running smooth as butter in 5 minutes.  Ha!  I bet a bank of 4 flatslides off an old street bike would be enough to feed this thing plenty of fuel and air... that would be sweet.  But there's probably a reason people don't do that.  Mileage would suck.

If I reconnect the vacuum line to the choke pull-off, how would I go about adjusting that properly? 

Could there be a problem with the choke pull-off that the previous owner disconnected it?  Judging by the way almost everything under the hood is intact, it doesn't seem like he went around disconnecting stuff without good reason.

The dieseling only happens when the engine isn't warmed up all the way, so it would make sense to me that the choke isn't fully opened yet, and therefore it's still on the fast idle cam.  Once it's warmed up good (temp gauge in green zone) dieseling is not an issue.  So is it normal for these things to diesel if shut off when at high idle?

[BenM]

Make sure the pull-off is holding vacuum, it has a rubber diaphragm inside. It should pull the choke open about 1/4" (I'm not sure offhand what the TSM says) when vacuum is applied. It's job is just to crack the choke when the engine catches.

AMCKen is right about the using the Sol-Vac to set idle. It should idle lower with the base idle screw, the EaglePedia has a writeup on how to properly set up the idle on an Eagle.

The vacuum system isn't as complicated as it seems, it's separated pretty well into parts. The most branches come off the "Ported Vacuum" port halfway up the side of the carb on the passenger's side. If you just view each system, like the EGR or Spark Advance individually it makes the whole mess easier.