The Stovebolt Site Forums The Shop Area Engine Shop carb issue, runs rough for while, then stalls, then gas leaks out the backs

(update 12/21 - issue fixed; read on)



hi.

just got a 55 3100.

strange carb issues (#4 below) - at least strange to me

knowledge level low about these trucks, but I am handy.

6 cyl 1 barrel carb.

so, I'm starting to check it out for the first time.

(1)
it ran kind of rough when it started so I shut it off and changed out the in line after-the-fact gas filter to a clear one. gas looks clean and flows for sure.

(2)
still running kind of rough so I turned it off, took off the air cleaner (no filter??) and blew out the carb with some carb cleaner.

(3)
still running kind of rough. messing with the pull choke helps a little, but not a lot. I am in the northeast, and it is cold here now, so i am not sure if that has a part to play. this truck cam from the southwest

(4)
if I let it run a while (like 5-10 minutes), it stalls - this has happened a couple of times now.

then when I look at the back of the carb I see gas leaked out. (pressure of some kind??)

because the leak is at the back of the carb it is hard to see 'exactly' where it is really leaking because the gas spreads everywhere so quickly. to clarify, it does not leak until it stalls like this. but, maybe it would leak without the stall as I have stopped running it for now.

if I had to guess, the leak is at or below where the silver bowl meets the part that bolts to the engine. (gasket issue?)

In the glove box I found the remains of a carb rebuild kit with a receipt dated 2013. So, I am guessing someone worked on the carb back then.

I checked out the screws on top of the carb and they seemed fine.

I found 2 large screw like bolts (straight blade screwdriver) that come up from 'the piece that bolts on to the engine' and screws into the 'bottom of the carb'. I tightened then down a tiny bit, but still have the same issue.

any ideas on the gas leak and how to correct it? (related or not related to the stall scenario). thought I would start there as gas leaking onto an engine is a bad thing.

thanks in advance.

engine was kind of noisy, so I changed the oil.

Welcome to Stovebolt. Many good people here who will help you. As you go along, Let us know your progression and if the problem is fixed.

Please let us know what engine is installed. Some earlier bolts have later engines in them and therefore once you are past the leaking carb, it will be easier to help out. If you don't have a shop manual, get one. They may be on line here.
If you don't know what engine it is, look for the number just behind the distributor and post it here. They we will know what we are talking about.

It sounds like there are a couple of issues here.
There may be some trash in the carb.
The float may not be set correctly.
The carb may be warped and therefore tends to leak.
Someone tried to fix this with the partial kit that you found, and it sounds like without success. I would rebuild it or have someone that knows how do it for you.

While that is being done, Pull your spark plugs and see if they are sutty or oily or a light tan or clean(new). That will tell you what is going on in the cylinders. Their condition is important too. Are they worn out? Burned? If so get new, recap and install.
You say it was kind of noisy, so you changed the oil. What kind of oil pressure do you have? Is oil getting to the rocker arm and push rod assembly under the valve cover?
Have fun.

Those two get my bet. It only takes a tiny bit of crud to keep the needle valve from seating. If it doesn't seat properly the gas doesn't stop filling the bowl and it runs over.

A couple of thoughts:

First, the leakage AFTER the engine dies:

http://www.thecarburetorshop.com/Troubleshooting.htm#Fuelleak

Now, as to why the engine dies:

Since there is sufficient fuel in the carb to leak out after the engine dies; there is sufficient fuel in the carb to run the engine. However, coils when they fail, tend to do so as they heat. I would check the ignition system before spending much time on the carburetor.

Jon.

Thanks for all the ideas and advice.

looks like I have some 'to dos'. I will report back.

in the mean time, here is what I have found and done:

1.
I pulled a spark plug and it was old and black and dirty. so, i replaced the spark plugs.

engine is a tiny bit smoother, but still have the issue (whatever that is).


2.
looked at the distributor cap, rotor, solenoid. solenoid looks ancient. cap and rotor look as old as the spark plugs were.

so, I will replace them (and I guess points and condenser too) once I locate the parts.


3.
I did some experimenting for the gas leaking. what I think is happening is that as the engine is stalling the carb is still getting gas, and since the gas is not consumed it causes the flood and spills as it stalls.

4.
the only way I can get the engine to run a bit longer is with the manual choke pulled all the way back (like when it is first started), but it smells like it is running really 'rich'. once I start to push it, in as the engine warms, it stalls even sooner.

is that indicative of anything?


5.
in some ways the roughness of the engine is like an engine with bad timing.

so I went over to the distributor and found that, instead of my newer vehicles where a distributor is tightened down 'solid' by a bolt, this 55 distributor can be turned a little bit back and forth within a particular 'range'. turning it like I could did not change anything as far as roughness.

is this amount of play 'normal'?

how does one adjust the timing?


6.
I set the idle up about 1/4 turn of the screw and that helps it run a little better, but the overall problem is still there.

thanks in advance

I had this problem several times, with a corresponding number of causes. The first was float drop, it was set so the float would actually rest on the bottom of the bowl, and when the fuel would evaporate it would become sticky and the float would stick to the bottom for a while, causing the same symptoms you indicated (mostly) then after the bowl filled, it eventually dissolved the GOO and started working OK. I have had 2 little itty bitty pieces of gunk stuck in the needle valve also causing the same symptoms. (here again, mostly) Then of course was the couple of times there was no reason whatsoever. And everything mostly just healed up evidently. The carburetors aren't sealed on top, there is a hole where the accelerator pump linkage passes through which is mostly where fuel runs out when it has unimpeded filling. I spent the better part of 3 months trying to figure out why my truck was running so poorly, new everything, gas tank, lines pump, filters, 3 different carburetors, points, condenser, plugs, wires, I tried pertronix,everything. Nothing helped, then one day it just started running like the good old days, and has ever since. Never did figure it out.

Well the reason should smack you right in the face Broke. The gremlin died of old age!
Carl

well if that is the case, I am certainly glad. So where do GREMLINS go when they die?

To some other truck of course. Now back to the OP question about the movable dizzy. yes it will move. The Vacuum advance moves the whole dizzy. About 10 degrees normally. To change the timing, loosen the clamp screw. CW is retard, CCW is advance. If it will idle, you can use a vacuum gauge to set the timing. Put the gauge on the manifold line that is at the center of the intake manifold. Adjust for max vacuum, then back it off a bit. You can then set the idle mix for max vacuum and you are done. A test drive up a hill will confirm. If it "pings" retard a bit and try again, when the "pinging" goes away you are done. I don't know what "solenoid" you might have on the dizzy? What you most likely have is an old "radio suppression capacitor. You can remove it if you like. If you are talking about the condenser inside with the points, well then I would change it with the cap, and points , and rotor. Add new plug wires and you have done a complete tune up. Fuel leaking from the carburetor is not good. Rebuild it and follow the instructions.You can check the vacuum advance by removing the line from the carb. And .....suck on it. If the line leaks it won't hold. If the advance leaks, it won't hold the vacuum. Fix as needed. Do one thing at a time. Test and go to the next if needed.

update #2

Thanks for all the ideas and advice.

still have some to dos...

but here is what I have found and done since update #1.

1.
I found a 'second' in line fuel filter in front of the fuel pump (flow-wise) that looked to be many years old. kind of smart in that it will trap stuff before it gets to the pump... but I wonder if it was put there because there are problems in the tank (which looks original)...

so, I replaced the second filter and fuel line hoses as I did for the inline filter and hoses right in front of the carb. the filters I got were clear plastic, and the gas looks clean.


2.
all of the comments about potential junk in the carb got me thinking. I remember years ago gumout (I think) used to sell a kit that was used to clean out a carb. one unscrewed the fuel line, screwed in the adapter and line that came with the gumout kit, hooked up the gumout can and run the engine on that for a while. I used that once many years ago and it worked wonders. could not find that now...

so, I unscrewed the fuel line inlet adapter (if that is the right name for it) and stuck into the carb the red nozzle straw that comes with gumout spray can and sprayed and sprayed and sprayed and sprayed. hooked it all back up and tested.


I found that after #1 and #2 above the truck ran a bit smoother, and i was now able to push in the choke a little more than before without causing it to stall,

but it still stalled and flooded and spilled gas after around 10 minutes or so... at that point it won't start again - so I learned to just let it sit and come back later.


3.
I ordered online (hard to find all of the parts local) a distributor cap, rotor, points, condenser, wires, coil/solenoid (as that was mentioned and looks ancient) and will put that on one at a time once I receive them. should be a couple of days.


I will report back once I do, and/or if I find anything else in the mean time.

thanks again.

any other ideas or experiences are welcome.

They will often crawl inside of a sock inside of the drier, then carry if off to use as a death bed. There you go. I just solved two of life's mysteries in one swoop.
Carl

you are going to have to take the carburetor apart. just speculating and discussing it on the forum isn't really the same thing. Even though carbking says it doesn't sound like the carburetor, checking the float level, (both high, and drop)
and inspecting the needle valve and seat is very easy and will eliminate those issues. It is possible the float is sunk/partially sunk. Whatever the case there is no way it should be leaking out the top if all of the above conditions are met. Which need to be met for it to run properly. Now I'm not saying it isn't something else, but I do know if you have so much fuel in the carb it is running out, the engine won't run. Can't really see how this would do it, but I have had a piece of rust the size of the period at the end of this sentence jam up my fuel pump at least twice. That is one problem with 50-60 year old vehicles, the fuel system is usually all goobered up. I fought rust in the tank for about a year, before I finally broke down and replace the entire system, (everything except the filler tube and the little hoses that connect the filler tube to the tank.)

Brokenhead is correct, imho. Pull the carb and rebuild with a new kit. You may not even see the trash that is in there, but a good cleaning and resetting floats is very important. Anything else and you are chasing ghosts. I had similar problems, and was finally cured when the carb was clean and reset and the fuel was filtered so no more trash could get in.
Let us know.

update #3

Thanks for all the ideas and advice.

still have some to dos... like identifying the engine...

but here is what I have found and done since update #2.

(1)
tune up Parts came.
I replaced the coil/solenoid, rotor, cap, wires (previously did the plugs, but did not do the points for now).

now the truck starts 'instantly', runs soooooooo smooth (unbelievably so, compared to what it was like before), and I can push the choke all the way in, even when it has not warmed up yet, and it does not stall. a dramatic change for the good.

so, yeah, there were electrical issues to resolve.


(2)
now the engines floods even sooner.... lol so, as many have said, it is the carb as well.

the advice to take it off and rebuild is a good idea. but it will take time to get the parts (and the guts do it). I have never rebuilt a carb before, though I do see some good youtube vids on it.

does it make any sense to take the top off the carb to see if I have a float or clog issue? or is it simply not possible to see if I have an issue that way - and I should just stop screwing around and bite the bullet :)

thanks in advance

I don't think you mentioned how long your truck sat before you started it, but if it's more than a year or two, there's a good chance the fuel system needs a thorough cleaning. Usually the tank gets varnish built up in it as it sits. Then, when you start using it again, the varnish breaks loose and begins to clog the fuel filters and mess up the carb.

I'm pointing this out because, while rebuilding the carb might fix your problem, it may be a temporary fix until varnish screws it all up. One of the first things I did with my truck was remove the fuel tank and take it to a shop to have it flushed and sealed. I would suggest you put that on your todo list and make it one of the steps you do early on.

I don't have your type of carb so this may not apply. But if it has soldered brass floats it is possible there may be a leak. If so, it will fill with gas and sink so never shutting off gas flow. Leave it sit and it empties. Had this happen to me with my rototiller.

Dennis

Update #4

Thanks for all the ideas and advice.

here is what I have found and done since update #3.

it is FIXED!

at least for now


(1)
I ordered a carb rebuild kit - figuring one way or another I would wind up using it now or in the future, so why not. but, it will likely not come for days, and I wanted to get the truck running now....


(2)
I searched the net for rebuild vids (to be ready when the kit came) and found a youtube vid by mike's carb about Rochester 1 bls flooding. how timely!

so, after watching the vid several times I took the top of the carb off (air horn?) leaving the bottom of the carb connected to the engine. it was 4 main screws, and a 5th screw that held the choke cable end, and I was able to take the top completely off. the 'bowl' had some gas in it (guess that is normal?).


(3)
I checked the floats and they were empty and looked good. when I set the air horn back in I could see the floats rise once the floats met the gas.

I checked the float 'measurements' using the 'guide/ruler' and instructions that came with the old used rebuild kit that I had found in the glove box. the settings were way off, so I adjusted them - but the way they were set I would think that they would stop the gas flow 'earlier' than 'later'. I wonder if someone did that to try and circumvent the 'real' issue... hmmmm


(4)
I checked the needle and seat and they looked good. but, after playing with the needle several times I found a tiny bit of friction that would cause the needle to ever so lightly stay/stick 'closed' (stopping gas flow). but, no matter what I tried I could not get it to stay/stick 'open' (which might cause an overflow of gas). hmmmm


(5)
well, I figured that since I had the carb open, and there was a little bit of friction, i might as well clean the needle and seat. so I polished the needle and seat using 'flitz' (great stuff) and a microfiber towel. I put the needle and seat back in, and the float, and I found that the friction was gone. the needle moved freely up and down when I turned the air horn upside down and right side up. so that was good.


(6)
put the carb back together, started the engine, AND NO MORE LEAKING! hooray!

ran it for 30 minutes off and on - no stall and no leak. started it; stopped it - no leak. drove it around my property (not registered yet) and no leak. previously, if I did any of that it would leak.


in summary:

(a)
originally I had multiple issues with the engine running rough and stalling.
so, a tune up helped the engine run better and prevent any stalling. looked like it had not been tuned up in years.
and, I changed out the 2 in line gas filters (one of them was hiding....).


(b)
originally I had some issue(s) with the carb flooding/overflowing. I adjusted the floats to spec and polished the needle and seat - I did not find any blockage or dirt or buildup of any kind.
so, if I had to guess, it was the float adjustment and/or the needle and seat polishing that fixed the carb issue since that is all I worked on.



thanks to all for the advice! all of your comments got me going in the right direction.

Way to be patient! The toughest scenario is when you have multiple malfunctions at the same time.
Carl

Getting a truck fixed and running good,this time of year, is a Christmas present! Congratulations!

No he didn't die he has occupied my truck now. I did a major tune up , no carb leaks , runs smoothe for about 20 seconds or so then dies. I even had it running and increased the RPM'S ,it took the gas right away for a short then started to die ,I gave it some choke but it died any way . I had a chat with it , told it I loved it , no good. So you see, the gremlin is in it somewhere.

Get another person to help you. Then take the gas line loose at the Carb. Put a piece of rubber hose on the end and place the hose into a clear plastic bottle. Have your helper start the truck and you catch the gas in the bottle, if any is coming out. Bet there isn't. At least not enough to keep it running at higher RPMs. It sounds like a fuel delivery issue to me. JMO