engine won't idle, foot off the gas and it dies

[NickDawson]

Hey folks - my pride in my recent mechanical triumph over the transfer case leak has been short lived.

We went out to the river today and the rover made the 15 mile trek on the highway just fine. About 1/2 way though the day the battery in the boat died so I pulled the rover down to the ramp to jump the boat (think I'm a rover novice? you should see me on the water, total mess) - it was in with the water level about at the hubs on the front tires (back dry)...ran fine during that ordeal...

When I went to leave the landing this evening I noticed that it stalled after starting, I assumed it was coke so I adjusted accordingly... but even after running for 5 minutes it kept stalling every time I took my foot off the gas, regardless of choke position.

It made for an interesting trip home - I took the back roads (should have just stayed on the highway) so every stop light required some coordination between neutral, gas and left foot breaking. If it was a rolling stop I could pop the clutch and gas it and it re-started.

I woldn't think water in the electrical system would be the case as it wasn't misfiring, with a little gas it ran fine.

Any ideas where to start (pun sightly intended)?

[Terrys]

Do you have a fuel shutoff solinoid on your carb (Like a Webber has) That is intended to shut fuel off at idle. If it became disconnected, that would explain the stalling without your foot on the throttle.

[NickDawson]

Do you have a fuel shutoff solinoid on your carb (Like a Webber has) That is intended to shut fuel off at idle. If it became disconnected, that would explain the stalling without your foot on the throttle.

the short answer is that yes I have a Webber

the long answer is that I have no idea what a fuel shutoff solenoid is ... but it sounds like a very good place to start. I'll do some googling and see what I can learn. Thanks for the tip!

[I Leak Oil]

Probably debris in the idle circuit. Remove the idle jet. Its a brass screw on the side of the carb facing the valve cover. Spray it out with carb cleaner and re-install it.
If you don't already have one, put an inline fuel filter on. The weber is very sensitive to trash in the fuel.

[adkrover]

I'm thinking junk in the gas too. When you drove down the boat ramp to jump the boat, it sloshed the sediment around in the tank and moved the old sediment to a place it hadn't been before and now it's in the carb. Best thing is to flush the tank, lines and completely clean the inside of the carb. Even better, replace the tank and rebuild the carb. And definitely install an inline filter no matter what you do.

Order a kit for the carb, get a good can of cleaner, lay newspaper all over the dining room table and take your time. It's not that hard to rebuild the carb. The trick is getting everything set properly when you put it back together. You can always take it to a neighborhood shop that can tune the carb once it's back in. You just have to find someone old enough that remembers what carbs are. If you're not sure, you can purchase a rebuilt carb and trade your old one in toward the new one (core charge).

[NickDawson]

Thanks for the tips guys...
I'm going to start with the simplest operation first and see if I can clean the idle jet as I Leak Oil suggested.

A rebuild may very well by in my future but my biggest concern is getting in over my head and then having to tow the truck to a service shopt with a box of parts in hand...

While Im thinking about it - the truck as the hand idel control, although I think its disconnected... moving the lever doesnt change anything as far as I can tell. I certinally didn't adjust it yesterday, so I doubt its related. However, should I take the time to get it operational again? Does it have any real value if I'm not doing PTO work?

[galen216]

Before you tear your carb apart make sure your vacuum lines are still connected too. Mine occasionally falls off at the distributor and makes it run rough and stall.

[NickDawson]

well you were all right...

After taking the filter off I noticed that the hose from the crankcase breather to the carb was rotted through. I ran for a replacement and some carb cleaner. Sadly that didn't fix anything (and I've since learned its the oil spray vacuum nipple?)

I just got a crash course in carburetors and their maintenance from a friendly neighbor and our mutual friend (who drove over in his newly rebuilt TV8)

we took the jets out (after I learned what jets were) and cleaned them, although both idle jets looked clear upon initial inspection.

We also took out both fuel bowls - one before the pump and one after with a filter. The one before the pump had a nice layer of sludge and the one in front only had a little residue.

After putting it all back together she's running like a champ - actually idling a little easier than before, although thats anecdotal.

Considering that the sludge theory is true and that it came from headed head first down the boat ramp - should I flush the tank or replace it? I've heard that draining a fuel tank dry and refilling can actually stir up more sludge.

I'm not saying that I'm looking forward to breakdowns, but I'm excited to know that some repairs are in reach. Of course I also owe a lot to this group - I wouldn't have even known where to start with out the advice.

Thanks again!

[adkrover]

The new tank should be an easy swap and is well worth the confidence of knowing it's new. Cleaning the old can be a messy job and as you know may not fix it for long.

In the mean time, just be sure to keep the tank better than half full (or half empty depending on your point if view). A low fuel level will cause the fuel to slosh around more and stir things up. And check the sediment bowls often for crud and clean accordingly.

[NickDawson]

Thanks adkrover

lets say, hypothetically, that the mixture screw was adjusted...maybe as part of the troubleshooting process. And lets presume that if it was adjusted that it was returned pretty much to the original setting...

In this make believe scenario what would be the best way to know for sure? Would one start looking at the plugs on a regular basis or just take it to a shop and have the exhaust tested?

[adkrover]

Tuning a carb is a bit of an art form. I get by using the "lean drop" method but there are better ways that include using a vacuum gauge and other voodoo. No matter which way you do it, you must first make sure the distributor is properly timed. Once you have the timing correct you can tackle the carb.

There are a few key pieces that all have to be set properly for a proper carb adjustment. The floats need to be set so the carb isn't starved for fuel or flooding. The butterfly valve (throttle plate) needs the proper air gap. The venturi jets need to be clean and free from any varnish build up that is common in old vehicles that may have been sitting and finally the idle jets need proper setting.

It's been a while since I did mine so I won't pretend to teach you but there are good book on info online that can walk you through it. It's not hard if you take your time. You will need to buy a timing light, fine tachometer and vacuum gauge.

[NickDawson]

Well I guess I celebrated too soon. Idle problems started again wile driving to the tire shop. Going to try cleaning the jets and fuel bowls again, anything else I should check?

Edited to add:
There is a new symptom - the exhaust coughs the occasional "puuffft, puufftt" while running, but as before, as soon as I take my foot off the gas, it dies.

Is there an idle speed screw on webbers like this? I feel like it should be a simple adjustment since the slightest bit of gas keeps it going
http://farm3.static.flickr.com/2480/3792888785_6b406f7af0.jpg

[NickDawson]

The plot thickens!

I repeated the jet cleaning tonight to no avail. When the engine is cooler it will run fully choked...so... I got it running and adjusted the mixture screw (i think thats what this is:
http://farm3.static.flickr.com/2667/3793966526_5fbc87c6b7_m.jpg

I screwed it all the way and and dropped the choke and it ran...too well...

So I started backing it off. Not exactly sure about the "lean method" but in airplanes we lean out the mixture until the engine runs rough and then give it a quarter turn back in... so thats what I did:


http://www.youtube.com/watch?v=tUVGN6aBNm4

and it seems to be running ok... but that screw is in a lot further than it was previously. I drove around the block a few times and still had some of the puttering ("puuffttt" sounds), but it really felt pretty good.

But I did keep an eye on the vacuum gauge - I'm not at all sure how to read it, but I will say that now its responding more like the day I picked it up


http://www.youtube.com/watch?v=ddToHTcxEs0

any thoughts or suggestions, or should I wave one dead chicken and consider the case closed?