Model B carburettor problem

T

tiger.1000

Well-known member
Having stripped and clean the Zenith carburettor on my carburettor on my 1932 Model b, it ran fine but after a few miles once more developed another misfire and back fire through the exhaust.


Removal of the carburettor established that the throttle butterfly and visible jets were becoming contaminated with a glue like sticky substance which was removal with cellulose thinners but not petrol.


Prior to my acquisition in the early 80's I am aware that the previous owner
had the inside of the petrol tank coated with a substance which prevented corrosion.


Is it possible that this treatment is slowly breaking down and contaminating the fuel system and if so is there a remedy WITHOUT removing the fuel tank?
 
Here's the throttle butterfly. One side heavily contaminated, the other spotlessly clean.


Perusal of the inline filter shows nothing to suggest that it is coming from the tank?
 

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Tiger...I believe you are correct in assuming that the gas tank sealer is the culprit. If it were mine, I would remove the tank and clean/reseal. I have used POR-15 with good results. You can have a local radiator shop clean and seal it also. I would also remove and replace the fuel lines from the tank to the pump (pump will need a good cleaning also).

Before you do all of that...you might rig up a temporary gas tank (can) after you have cleaned your carb and pump. If it runs good without any more problems, you will know where the "goo" is coming from.

Good luck,
Pat
 
Pat,


I emailed Dave Renner and he is under the impression that it is stale petrol, something he has seen on many occasions ! Today I have drained the tank (8 gallons); stripped the carburettor and put it in to an ultrasonic tank for one hour.


Perusal of the innards of the tank suggest that all is OK internally...time will tell


Interestingly, I have an inline fuel filters (x2) and there is no residue in either filter nor indeed in the AC fuel pump. Problem only seems to occur during combustion.
 
Bad gas, used to see that a lot. Was particularly hard on 2 stroke snowmobiles because it plugged the brass jets and caused them to run lean thus burning up the engine.
 
Looks like the deposits are coming from the intake manifold you may want to check and see if it is clean.
 
In a similar case with my red F1, I believe it was caused by five gallons of old corn gas I dumped into the tank to empty the container. It dissolved the 65 year buildup of Ethyl from the lower half of the tank and coated the intake manifold and throttle body of the model H carburater with brown glaze. It got a new tank and vinegar soak for the manifold.
Hope that will set it right again.


Bruce
 
Manifold clean. I have drained the old petrol, ordered a can of SeaFoam and see if I have a cure. Thanks all for your input.
 
Stinking gas... Environmentally safe until you have to spray 6 cans of carb cleaner in the air to get the gunk out of your fuel system...DUH!
Glad you got it taken care of.
Chap
 
A warning to us all and really a case or prevention is better than cure. I really should have known better ! Modern ethanol based petrol is not like the old stuff. Problems ahead if preventative methods are not put in place.
 
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