g3bill2

Might help if you hold a pencil to what parts you're talking about and snap a pic. then explain. I'm wondering if you have a hill somewhere and were in 3rd gear how it would go or accelerate from 20mph to 40-45?
The box? hot idle compensation valve? think it has a replaceable rubber on end of flat spring?

zombie_stomp

I'll point out what part (or parts) are not on my existing carburetor once the reman carb arrives. Meanwhile, I'll need to get my photo hosting going again so I can share photos.

zombie_stomp

The reman carburetor is scheduled to arrive on Tuesday. I ordered it from National Carburetors in Florida for about $180 shipped.

In the meantime, I did start testing for vacuum leaks with starting fluid. The open rectangular casting on the driver's side with the little hole seems to be taking in starting fluid, raising the idle. Not sure what it was supposed to do, but it should be closed off at least. The best guess I can venture is that it is sort of an expansion valve, having to do with temperature (it is labeled 'thermostatic valve' in the manual and doesn't connect to anything else.)

Also several of the vac lines nearby on the engine side all take in starting fluid at the connection, raising the idle.

I may need to look into buying a new vacuum "ribbon"- the many vacuum lines molded into one unit. They may be too close together to replace with individual lines.

g3bill2

I tried to find the correct size vacuum lines but dealer and internet without luck cause they all have a larger outside diameter. There was one mfg. that had correct size on a site but quantities were much too large. I still have all the original vac lines and where needed clipped the ends just enough. If on the 4 hose ribbon its only the ends that are bad I'd just cut them back maybe 1/2" and use about a 3/4" piece of copper tubing slightly larger than inside diameter of hoses to splice with new hose in middle of ribbon so ends will be as original. Guess ya could just splice with 4 pieces of 2" copper tube and leave it exposed without new hose spliced in. If using hose for the splice might look at size of silicone hoses for the splice, I got some blue color silicone hose to use for window washer from a hobby store and seems to hold up ok.
Also Gorilla Super Glue is supposed to be a little bit flexable and might seal cracks in rubber or connect 4 hoses?

Did anyone check the dealer for those ribbon hoses?

zombie_stomp

I was just sort of probing for a source of tubing if it was available somewhere I'd overlooked, but when sprayed with starting fluid, that one did nothing. I just wanted to replace it because something slight happened to the idle when I touched it when I started it this morning. As random as some of the sputtering has been, after hitting it with starting fluid and nothing else happening, I hope to classify touching it/idle changed as random chance occurrence. However, if I find a 4-hose vacuum ribbon line used, I will create a fresh-ended splice jig as suggested if I run low on options.

As for the leakiest as tested with starting fluid ends- all these were near the head and have likely seen most of the heat aging out of any of the vac lines, and are near that open rectangular casting with the hole inside which seems to be open.

Replacing the vacuum lines near that feature of the carburetor first will determine if it is indeed an open hole to the inside of the carburetor, which I am pretty certain of. (Or I could use a spray tube from another spray product to make the application of ether more accurate, but replacing the lines is going to be done anyway, though I may still need to try that.)

Tomorrow I can replace the vacuum lines and retest, I can also replace the fuel lines and blow compressed air through the supply and return lines to the gas tank. I will need to do so cautiously, last time I did that it blew a bunch of gasoline out of the tank. That was with an old Volvo that had a very short filler neck right on the in-trunk gas tank. So hopefully that won't happen!

The tank line test might be helpful in determining if it is a fuel supply problem some of the time. With the hard starts, the fuel bowl has shown to be full when I got out and checked, and the only other time I've been able to view the fuel bowl level has been when the idle became smooth. To be sure it was within proper range of full when the idle dropped and required throttle would require a partner. But the fact that it idled at all is pretty good indication that the fuel was reaching the bowl enough for the carburetor to fill in the fuel supply with added throttle application. That was probably the accelerator pump compensating for a non-working idle circuit or other somehow clogged area of the carburetor.

Sometimes I am going down the road and experience what feels like a sputtering of fuel supply- dead spots in power delivery. I'm just cruising and 'pop, pop....pop....................pop', it will be cutting out in tiny bits. This always means the engine will die if I come to a stop and take my foot off the throttle. That kind of complicates the 'idle circuit' of the carburetor theory, since it feels like ALL of the carburetor is cutting out in those short, randomly placed pops. When I think about that, I almost suspect something else is going on in addition to carburetor problems.

I just got back from the store. It's a little colder tonight, probably low 50's to mid 40's. The truck had been sitting for several hours so was dead cold. I pressed the throttle to the floor to engage the choke, and it popped a couple times but didn't stay running. Starting fluid. After about 10 cranks fired right up. It stayed idling smoothly after that on it's own. Died a couple times because I was trying to drive it cold still. (This is probably because the fast idle vac. Thing is missing and so requires more throttle when starting off in gear.) 10 more cranks, no starting fluid, started again and stayed idling.

Not quite warmed up fully, but after the store it starts right up. On the drive home, starts that random tiny power loss sputters. Dies as I let off the gas and roll into the driveway.

New vacuum line tomorrow, new reman carb Tuesday. Will report back at each step of the way what I find in painstaking detail.

zombie_stomp

Ok, so the reman carb is in and it doesn't seem to have changed the problem of the idle death problem. I'll have a few more cold starts to see if I still need to use starting fluid sometimes.

Needing to stay on the gas to keep it idling persists. When I first installed the carb, it started as soon as the bowl filled up, and idled fine once I got the idle speed turned up enough. I got out, listened to it purr for a while, and then it just cut out. After I restarted it, it needed pressure on the gas pedal to keep idling. I took a short drive and all the while it needed pressure on the throttle to keep idling.

It seems that after a certain phase of heating up, something triggers that shuts it down from idling properly. Then only at random times will it idle on it's own. I'm thinking there is some obscure part that is in the vacuum system that is only happy at certain times. I'm thinking maybe a vacuum hard line or part that is responsible for cutting the choke (I replaced all the vacuum lines on the side that the idle changed with the starting fluid spray, I'm suspecting a splitter fitting or one-way valve or whatever is inline with those components.)

I've fairly certainly ruled out the fuel system components upstream from the carb. I was skeptical that the supply system to the carb was working correctly when I first pulled in after the test drive because the fuel bowl sight glass appeared empty. But I replaced the fuel lines and even the pump, and when I had the pump off, I blew compressed air down one hose and fuel spewed out the other hose, so I quickly blew air down that hose too and that one made a bubbling sound at the tank where the other one had made a pressurizing hiss at the tank.

We're down to agonizing details on this one now. Before I rack up expensive mechanic bills trying to diagnose this weird, obscure problem,
I'd also like to include that I switched from the aftermarket Gerry-rigged coil back to the stock one, and that ran just fine too. Someone must have put that in there as a last-ditch effort to try to remedy the problem. I can't imagine any other reason. Nor can I imagine any other reason they would have removed the heat shield that supplied the air cleaner with hot air at a certain phase of warm-up. I did that on my old s-10, and it did nothing like this, so restoring that detail would likely correct any of the problem.

I want to blame the cut off o2 sensor wire and new catalytic converter, but I dkn't know if that cat not displaying 02 readings would kill the idle at such random times based on my previous experience with how it's been doing this at strange intervals. It's not like a fuel injected engine with a computer that runs all of the fuel delivery based on many different sensors. It's more mechanical. I just wish I could figure out what changed at what point in the ownership of the truck in order to have potentially caused this set of problems and re-trace the steps.

zombie_stomp

This YouTube video demonstrates exactly the same problem I've been having:
http://youtu.be/dwStLMcP_U0

I just looked around on the comments of that video and the author says he had a carb to base gasket leak, which he fixed and the truck is running fine since then. So what I will do next is remove the carburetor, apply some silicone to the gaskets, let it fully cure, and try again. If that fails, I will try to replace the intake manifold gasket and try again. If that fails, I will look elsewhere.

g3bill2

You might be right to consider the one way valve and check each. Any of those vac switches could be bad but doubt it. I checked each one per the manual to be sure.

I had a bucking or missing where it would cut off then back on in a second or two and couldn't tell if it was carb or electric related, also was hard to start at times. I did lots of the repairs you're doing but had an accident and had to have everything checked at a BAR station. They found the computer board soldering points had loosened. Then I remembered one night coming over the grape-vine I was getting tired and antsy then streched my legs and must have pushed the computer box harness connection. They re soldered it and haven't had that problem in over 3 years. Doubt this is your issue but when at idle might just touch the connection lightly with fingers?

Guess carb to intake mamifold is a pretty common leak area. Just thinking I had a leak there on a wagon i think or maybe the 22r? many years ago. Must be worse with aluminum surfaces as they warp alot over time. Even the cast iron exhaust manifold on my toyota was warped, had that surfaced before reinstalling. Now I never remove a casting without checking for straightness before installing.

zombie_stomp

I am not sure what influence the little computer on this truck has over running conditions. Yours is also carbureted? If so, and if what I'm about to do doesn't fix, I will try that. It's been doing the not idling thing a lot of the time today right after the carb swap.

I looked at videos and I may have posted the link here already, but the guy had a carb base gasket leak that showed the same trouble I'm having in his video. It seems about right for some of the base gasket leaks I've had on an old moped, it was 2-stroke, so the base of the cylinder has the same type of influence on the fuel system since it is part of the intake.

I am going to install some hand-cut gaskets with some threebond 1184 which has good void-filling properties and let it cure and report back tomorrow.

The new carburetor had two pretty big dings into the mating surface I had to file down, and the fact that it has been doing the running problem more now that the gaskets have settled is a good indicator along with the video and it's solution. Whatever it is seems like a pretty big, simple thing. Like a base gasket leak.

g3bill2

Sounds like you didnt use some RTV on the gasket before installing rebuilt carb? As long as you're having so much fun doing the project might be a good idea to just remove the intake manifold and surface it if theres any sign of leaks, its probably warped some at least and wont cost much to surface it if needed. Its a pretty straight forward easy job esp with carb off. If you do, be real careful removing the sensors with 6 point socket so its straight on.

The emission control computer. Sensors from coolant and 02 sensor, speed and couple others, Cat over heat? The idiots that replaced my muffler last time cut that wire;-(

1st year fuel injection 1985

zombie_stomp

The idiots that put in aftermarket exhaust and cat also cut the wire, but it's carbureted 1982. I'm not sure where the tiny computer ties in to the running conditions of my rig, but so far seems to be running better since I swapped out base gaskets and used not RTV but rather Threebond sealant. It's anaerobic so once I start tightening down and keeping it free from O2, it starts curing. I gave it longer than the 'seals in 20 minutes' time on the label and took the truck to the store.

On the way there it still wanted to die without throttle a little bit, but got better later. Time will tell, but it seems that each time I mess with the base gasket of the carb, it is better every time. I may need to play with the flatness and gasket of the intake manifold. I hope I don't, but I may from the looks of the problem.

g3bill2

When i removed the trans or maybe it was the breather tube behind the back of valve cover I bent the EGR, made a weird noise so bent it back as well as i could? Not real sure I got it right but the noise stopped and thought thats all that mattered for the moment? If theres any strange noises like suction or pressure from that area might want to check it? If it weren't so cramped in there i'd remove mine and check it. I didn't realize the EGR was so delicate or wouldn't have forced the wrench like i did. Just kick myself

zombie_stomp

I'm pretty sure I fixed it with the base gasket. New gaskets cut, coated with threebond 1184. Glad I bought that stuff, as my mechanic friend told me the RTV I already had was bad with gas.

So far it hasn't done the no-idle condition once. I will also go through the PCV system with a new hose, valve, and grommet.

5440

I had similar issues 4 yrs ago. I rebuilt it this time using an ultra sonic cleaner with the proper carb solvent and was able to put in larger prim jet (Weber jet) and relaxed the spring tension (about 5 o'clock)on the sec. plate. This carb now runs better the my old Weber 23/36. I think the ultra sonic clean made the biggest difference.

zombie_stomp

&"@*# DAMN. IT.
The running problem is back. In full force.

I don't get it, it only did that a little bit right after reinstalling the carb and then cleared up for the next 2 whole days, which is the longest it's been happy for since I got it. It used to actually clear up for longer amounts of time but when it was bad it as still really bad. Last 2 days hadn't been doing it at all.

If it IS still the carb base gasket again, it may be because of how I scraped a lot of the really hard gasket adhesive from the carb spacer, as best I could. I need to sit down with a nice flat piece of glass and fine sandpaper and really resurface that thing really well before I do reinstall it.

If that does the same thing, I'm really going to have to go ahead and do the intake manifold flattening. Should I invest in a nice thick piece of glass to surface it and the carb spacer with? I need to do it myself since this is my only motor vehicle and it's getting cold out there.

g3bill2

Cant you tell where its leaking with the starter fluid? If you know it needs to be surfaced you might want to drive with tools and new gaskets to a machine shop that will do it while you wait . With tools in hand do it all there. take a small fan and long cord to cool it down so you dont burn your delicate habds. Thinking like you must be a leak you missed cause it did get better. That is depressing though....

maybe setting the idle up a bit before spraying the starter fluid if you dont notice at low idle???

Machined steel table saw tops are pretty flat. Might take forever by hand if its too warped


...

zombie_stomp

Today I found a piece of nice thick glass next to a construction dumpster, so I can use that and some finer sandpaper selections I got to at least flatten the carb flange and the kinda hacked up spacer. I would think the threebond would have taken up the differences and imperfections, but I could be wrong.

Today I also changed the fuel filter and both of those hoses, but no change. It was doing the running problem before and after. Oddly, the filter that was on it that I dissected had crud both inside and outside of the element, and the direction of flow arrow was connected to the line that goes back to the gas tank. I didn't think this was a filtered return line, that doesn't make any sense. So I reversed the lines to what I feel is correct, but none of that made a difference. I did reverse them again when the problem persisted, but there was no difference.

I'm going to have to buy more starting fluid and vice grip the throttle again to keep it running while I probe for leaks. I did the throttle trick until it warmed up and eventually started idling well so I could set the timing. One of the spark plug wires shocked me, but I don't think it's the problem. Will replace soon anyway. It's got a mind of it's own when it will leak vacuum or whatever.

As far as the intake manifold, I could go to one salvage place I know that has a lot of these trucks and pull one, get it surfaced, and then do the swap all in a day at home and sell the other one.

Next I'll spray starting fluid to see if it still seems like it's leaking air somewhere on the carb or if it's manifold. It might not be possible to tell since they are so close together. Then I will flatten the bottom of the carb and the spacer which is scraped up pretty good from gasket removal, and try resealing it one more time before going after the manifold and maybe whatever else.

I hope the side of the head is flat! If nothing else, this will also be an opportunity (if I have to do the manifold) to degrease that side of the engine from years of having a leaking valve cover gasket.



Also, as far as the

g3bill2

""One of the spark plug wires shocked me, but I don't think it's the problem. Will replace soon anyway""

This might have caused some rough running? If a spark from wire jumped to any ground, little or no spark to plug of course...

Have you ever seen a real bad set of plug wires in a running motor at night. Its like the 4th of july with sparks flying everywhere. Wasn't even thinking of plug wires as most these days are silicone and seem to last decades.

zombie_stomp

It was only one of the wire boots on the distributor shocking me, so I'm pretty sure it is not arcing to ground, but I will try to eliminate that possibility ASAP. Besides, nothing moving, how could that be the problem as random as the problem has been? Sometimes it's been when it's warming up, other times when it's been cooling off... Who knows?! I will eliminate ignition system stuff soon by inspecting and replacing it part by part though. Just to make sure.

msane99

Is the EGR functioning properly? If its stuck open you would be sucking lots of air. I've had them get so nasty with carbon the diaphragm would not close. It would cause very similar issue to what you are describing. just a thought. I saw someone mention this, and it will give you similar characteristics. Sometimes you can tap the saucer on top gently and encourage the diaphragm to close. then unplug vacuum line that opens it plug it, and try it out. Usually if its stuck open the brake pedal will be a little more stiff than what it would with no vacuum leaks(power booster not getting enough suction)

Maybe worth checking out?