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subzali
07-05-2007, 06:41 PM
I have this problem that's only been happening maybe since last fall; I don't really remember it happening last summer at all. If I'm going along and come up to a stoplight (happens most of the time coming off the highway, but will happen between stoplights in town too) and push in the clutch, the engine will idle down all the way until it dies. This will also happen if I'm going down a long hill and put the tranny in neutral and coast. It does not appear to be dependent on whether I have the brakes engaged or not, though sometimes it seems as if having the brakes engaged makes it worse. Once the engine quits I can tap the gas a couple times and it will start right back up and idle fine. Except once the other day when it quit again while I was sitting at the stoplight. That time it was sputtering and would not idle at all, I had to keep it revved up to keep the engine running.

I can't think of anything that I changed before I started noticing this, but any suggestions at this point would be welcome. I tried 87 octane instead of 85 just for grins and that didn't change anything.

DaveInDenver
07-05-2007, 08:28 PM
Which truck is this?

subzali
07-05-2007, 09:11 PM
the Cruiser, sorry. :o

treerootCO
07-06-2007, 10:06 AM
not enough vacuum at idle, idle jet screwed all the way in, miss adjusted fast idle/slow idle, choke getting sucked shut/miss adjusted...

If I had to guess, your idle circuit is plugged. Swing by tonight and we can fix it.

subzali
07-06-2007, 03:30 PM
Sorry Mike truck is at my parent's house, but thanks for the tip I'll see if I can fix it. I was kinda thinking the same thing about the idle circuit, is it fairly easy to fix? I just have a Haynes at the moment and don't know how detailed it is.

treerootCO
07-06-2007, 03:45 PM
stuck PCV or EGR will also cause this. FSM has detailed instructions on how to check both. If you know what hose to suck on you can rule both out pretty quick. The carb adjustment is less likely an issue but it is also in the FSM

MDH33
07-06-2007, 03:59 PM
Everything Mike said... :)

Also, is this mainly happening when the engine is warmed up? Could be vapor lock due to the high temps. Does your 40 have the carb cooling fan in place?

subzali
07-06-2007, 05:00 PM
I thought about vapor lock, and no I don't have a carb cooling fan (when did it start on 40s?), but it starts right back up with no problems after it quits once. However it does seem to happen usually only when the engine is warm, but not necessarily...

treerootCO
07-06-2007, 07:17 PM
There are a few carb cooling fans laying in the yard if you want to put one in. Why is your truck in Sedalia? :p:

subzali
07-06-2007, 07:29 PM
cause it's not running right :p:

besides I got the red truck running again, so since gas is so expensive I'm driving that :thumb:

I might have to take you up on your offer for the carb cooling fan...

subzali
07-06-2007, 08:43 PM
Well I'm starting to think it's the brake booster (again - that's the 3rd one, I'm getting sick of this :rant:) unless it is carb related. The only way I can figure it to be carb related is if something got jammed in a passage somewhere - which is possible since I had the carb off for a few weeks while I was doing the head work this spring.

I've checked the PCV before but I should just get a new one anyway...

don't know how to check the EGR, guess I could look at that at some point.

60wag
07-06-2007, 10:00 PM
Just cap off the booster vac hose to see if the idle is fixed. I bet its a clogged idle circuit or a vac leak. Plug a vac gauage into the manifold to rule that out. A stuck egr valve would do it too.

nakman
07-06-2007, 11:58 PM
Carb fan is really for only after you shut the truck off. Intentionally. :doh: :)

wouldn't help you in this case, afaik.

MDH33
07-07-2007, 10:18 AM
Carb fan is really for only after you shut the truck off. Intentionally. :doh: :)

wouldn't help you in this case, afaik.

Right.

My 40 is doing the same thing as Matt's except it will stay running if i give it a tiny bit of choke. I'm going to pull my carb today and see what's up.

treerootCO
07-07-2007, 11:31 AM
Check for vacuum leaks first. PVC or stuck ERG first. Call me if you want me to walk you through that. To baseline it, do what Bruce mentioned above about the brake booster but also block off the EGR and PVC hose completely. None of them are needed and can be capped for testing purposes. The idle circuit is only engaged when the throttle plate is completely closed. There is an extremely small hole just below the throttle plate if you look. The needle that adjusts your air fuel at idle points directly at it and in fact pokes through it when the needle is fully seated.

MDH33
07-07-2007, 11:43 AM
I just checked my PCV and it is stuck. Good call.:thumb:

treerootCO
07-07-2007, 12:00 PM
stuck open or closed? Open you run lean and burn up the valves, stuck closed you'll build pressure in the crankcase and might start causing leaks.

MDH33
07-07-2007, 12:24 PM
stuck open or closed? Open you run lean and burn up the valves, stuck closed you'll build pressure in the crankcase and might start causing leaks.

The ball bearing inside wasn't moving, I soaked it, and it seems to be free again. My guess is that it was stuck open because it would only run with choke.

treerootCO
07-07-2007, 02:44 PM
good catch, want to come see my dad's burnt valve because if that? Today we are putting a new head on.

subzali
07-13-2007, 05:04 PM
I plugged the brake booster, EGR and got a new PCV and I still got it to die. If I'm on the throttle in 4th gear at about 50 mph for a little while and push the clutch in so the engine drops to idle pretty fast that's pretty much a guaranteed way to do it. I've only really been able to get the engine to do it when it's warm. There seems to be a smell associated with it, my guess would be unburnt fuel/rich smelling, but it doesn't smell like straight gasoline. I checked my carb and the gas is real high on the sight glass right after it dies FWIW.

MDH33
07-13-2007, 05:32 PM
I checked my carb and the gas is real high on the sight glass right after it dies FWIW.

Same with mine. Carb comes off tonight and rebuild begins. :)

subzali
07-23-2007, 07:44 AM
The problem has somewhat been solved by reconnecting (well, duct taping really) one of my vacuum hoses back on my BVSV, the one I broke off. Didn't have too much trouble with it yesterday, except after I got home I would start it up and move it a few feet here and there and with that idling around it would die. I suppose I have a vacuum leak somewhere I can't find. I'm going to get some starting fluid (or any other suggestions on something really flammable?) and start searching around. I don't know how to find out about an internal vacuum leak, which I would really like to not have - any methods besides the starting fluid to find vacuum leaks?

treerootCO
07-23-2007, 09:48 AM
water works well for finding vacuum leaks, just use a fine spray.

MDH33
07-23-2007, 10:36 AM
Still no dice for me either. Full carb rebuild and all new vacuum lines (there are few because it's desmogged) and I still can't get it to idle. I checked the idle solenoid and it seems to work (clicks with ignition).

Mike, where might an internal vacuum leak originate? my rig was running great until a few weeks ago and the problem started with no indications.

treerootCO
07-23-2007, 12:03 PM
burnt valve, hung valve.....but....there are lots of other things we can look at first. I work the late shift today; however, I'll make time to swing by soon and help out. Same goes for Subzali. I will be working South all next week so I can swing by Sadalia and help out.

MDH33
07-23-2007, 03:01 PM
Thanks Mike. Is there a way to tell if I have a valve issue without running a compression test?

Rzeppa
07-23-2007, 08:42 PM
Is there a way to tell if I have a valve issue without running a compression test?There's no quicker or easier way that I am aware of.

BTW, I was corrected/instructed by Jim Chenoweth during one of our phone conversations over the years that the idle circuit ALWAYS provides fuel while the engine is running, not just at idle. Thus, idle mixture affects mixture across the entire operating range, not just idle. The effect diminishes as the power valves begin to operate, obviously.

subzali
07-27-2007, 01:13 PM
Update: cannot find vacuum leaks anywhere, sprayed around all over the place. Thought it might be from one half of my BVSV being broken, so I plugged both vacuum lines going to it and it still dies. Maybe it needs to be completely hooked up in order for those related systems to work properly. I put my hand (with gloves on) over the mouth of the carb and idle didn't increase before it died, it just died pretty fast. Just got a compression gauge, so next on the list are a vacuum gauge and external tach, but I'm pretty sure I have pretty good vacuum. My other post has my compression numbers, which are all around 100-110 for all cylinders. Low I know, but I don't think it's indicative of the internal vacuum leak Mike mentioned, unless all the valves are burned or otherwise not seating properly. Goofed around with my carb, but since this problem started before I had done anything with the carb I don't think that's the problem.

At any rate, I'm leaning right now on the probability that it has something to do with the inner male connector on my BVSV being broken, so I probably need to figure out a way to get that hooked up again.

MDH33
07-27-2007, 01:24 PM
Does your carb have that electric idle solenoid on it? You'll hear it click when you turn the key if it's working.

You might still have something plugging the idle circuit inside the carb.

On a positive note, mine is finally idling after rebuilding the carb and dialing in all the adjustments. :thumb:

subzali
07-27-2007, 01:50 PM
Sweet! Yes my idle solenoid is working (well at least I hear it clicking)...I guess you could be right about something in the idle circuit...I might play with that if I get a chance too.

subzali
07-27-2007, 03:36 PM
...I think my idle solenoid is working. I'm pretty sure I can hear it, but the keyswitch clicking is pretty loud, so it's kinda interfering with me hearing it. I disconnected the brake booster (again) and plugged the intake port and now it will die about 2/3 of the time, it seems like the engine has to be at like 2500-3000 rpm for 15 or 20 seconds before I can get it to do it somewhat regularly.

I am getting a strong smell from the exhaust each time the engine quits, and the fuel is usually pretty high in the sight glass right after the engine quits. Maybe this means something (engine dying because it's too rich? :confused:), but all I know is this is really starting to aggravate me, cause it's not completely regular.

In order to get to the idle circuit to clean it out, does the whole carb have to come off/apart? At that point though I might as well send it to Jim C or Mark A and have them rejet for altitude and tune it...$$$

MDH33
07-27-2007, 04:51 PM
In order to get to the idle circuit to clean it out, does the whole carb have to come off/apart? At that point though I might as well send it to Jim C or Mark A and have them rejet for altitude and tune it...$$$

Yes, it should come off. You will want to disassemble it, dip it in carb cleaner overnight and then blast out all the parts with compressed air to make sure the passages are clear.

I contacted Jim recently about a rebuild and he was 5-6 weeks behind he said. So I opted to give it a try myself. With help from MUD and Rising Sun I was able to get it done. :) If I'm able to figure it out, you shouldn't have any problems. I got a rebuild kit from www.siriusconinc.com

Just take lots of pics and notes as you disassemble so that you know how it goes back together. :D

Order a new fuel filter too. If it's crud from your fuel plugging the jets, you don't want it to re-clog your newly rebuilt carb.

subzali
07-27-2007, 08:09 PM
I just put a new fuel filter on, did the rebuild kit come with new jets that would be better for this altitude? I'm just kinda gunshy since my last carb rebuild didn't go so well, but that was the first time I ever tore into anything major mechanical, I didn't have much of a manual, and it was a Quadrajet carb...:rolleyes:

subzali
07-29-2007, 09:42 PM
Well I think I found out what was going on. For my nighttime reading last night :rolleyes: I was reading the emissions manual (brand new :D) and found out how the BVSV works. When I found that once the coolant is warm it stays open then I realized that I just needed to connect the two BVSV tees together in order to solve my broken BVSV problem rather than plug the two tees. I did that and tightened the intake port for the brake booster when I was reconnecting the brake booster and the truck hasn't quit on me all day today, running Spring Creek and driving around. If that means I'm out of the woods...wait for my next thread with tech questions! :D

subzali
08-23-2007, 11:52 PM
Well that didn't get me completely out of the woods, though it seemed to help.

But - !

Tonight it was all rainy so I couldn't do my painting project I'm trying to work on, so I helped my dad with the tractor, replaced the headlight in the red truck that was burnt out, and thought to myself - what next? And then I had a bright idea - I decided I would tear into the carb and see if there was anything obvious. So I did - and there was (I hope). The bowl had a bunch of gookies (technical term) in the bottom, which I think would explain how/why this is somewhat intermittent and why it always starts right back up after it quits. Too early to tell, and I just cleaned that out and buttoned it back up, but I went for a drive and made about 10 stops after getting the engine above 2500 rpm or so and it didn't quit or sputter even once, just idled nicely once I slowed down to the point where I could hear the engine again :D

So like Martin it appears that even a simple carb cleaning might have been all the doctor ordered. But again we'll see, I'll drive it around tomorrow and just hold my breath.

Uncle Ben
08-24-2007, 12:33 AM
Matt,
Your "gookies" sound like water! Did it look like a yellow-brownish sludge? Go to an auto parts store and get a couple bottles of Heat or other gas system antifreeze, and dump 'em in the tank. It is a alcohol base and will bond with the water, put it in suspension and help it "burn" right out!
You might have to do it in a couple tanks full of gas but it will clean out the water.

Well that didn't get me completely out of the woods, though it seemed to help.

But - !

Tonight it was all rainy so I couldn't do my painting project I'm trying to work on, so I helped my dad with the tractor, replaced the headlight in the red truck that was burnt out, and thought to myself - what next? And then I had a bright idea - I decided I would tear into the carb and see if there was anything obvious. So I did - and there was (I hope). The bowl had a bunch of gookies (technical term) in the bottom, which I think would explain how/why this is somewhat intermittent and why it always starts right back up after it quits. Too early to tell, and I just cleaned that out and buttoned it back up, but I went for a drive and made about 10 stops after getting the engine above 2500 rpm or so and it didn't quit or sputter even once, just idled nicely once I slowed down to the point where I could hear the engine again :D

So like Martin it appears that even a simple carb cleaning might have been all the doctor ordered. But again we'll see, I'll drive it around tomorrow and just hold my breath.

Shark Bait
08-24-2007, 12:51 AM
Then maybe change the fuel filter. Wonder what it looks like if you drain the fuel tank? :eek:

subzali
08-24-2007, 07:25 AM
I just put a new fuel filter on in maybe in April or so, after I had the head work done. At that time I also drained the fuel tank to try and find my anti-siphoning plate that somehow got punched down into my fuel tank :confused: It all looked good, no rust under or in the tank, so I just cleaned up all the junk on the floor pan and put it back together. The gookies were actually solids (maybe grease particles plus some other stuff?) that could easily have been getting stuck in the jets but then settle out after the truck quit and then I restarted. Does that make sense and seem to mesh with the symptoms? I'll go get some Heat though and try it, it can't hurt and I want to drive the truck around anyway today ;)