Oliver 1850

I have an Oliver 1850 gas engine. The tractor runs fine and drives fine for 15 to 30 minutes then it acts like its running out of fuel. I have to choke it to drive it back to shop. After s few minutes it runs fine again then same thing after several minutes. Carburetor has been repaired before this issue. Can anyone tell me what this could be? Sorry forgot to put this in there. When i unscrew the plug on the carb it seems to have plenty of gas flowing out. The gas shoots out fine.


This post was edited by Medic52 on 04/30/2023 at 07:52 am.

Plugged or malfunctioning fuel tank vent?
Fuel line/filter/screen plugging with
debris from the fuel tank? Just thoughts.
I have a 56 Chevy that I thought I had
cleaned the tank well but after driving
for a half hour or so, would start bucking
and wanting to stall. The fuel filter
would be plugged solid with debris that I
apparently didnt get cleaned from the
tank. Took about a year of changing fuel
filters.

Hello medic welcome to YT! What are doing with the
tractor while running it when it is ..runs fine..? Those
bigger gas tractors use a lot of gas when working hard.
If you look at the data from testing on that tractor
when it was new you will see it will use over 8 gallon an
hour under a heavy load. This means under full load
you need a little more than a pint every minute coming
in the carb. I am going to copy and paste the rest of
this in from another post I made on a Ford today and
hopefully I get it all changed to apply to your Oliver.
There a should be a drain plug in the bottom of the
carb. Get something to catch the gas, a clear container
is best so you can see if there is crud in it and/or what
the crud looks like that comes out. It will flow faster at
first as the gas in the carb bowl drains out in about 5
seconds or so. But then it should continue running at a
smaller steady stream. If it slows down to barely much
more than a dribble your carb is simply not getting
enough gas. You should do a 2nd round test with an
actual pint measure to see what the actual flow is. I am
going to say for the most part just driving the tractor
down the road by itself up and down hills it might
require 4 gallons an hour. So get a pint measure and
open the carb plug let the first 8 seconds or so drain
into something else. After that catch the flow in your
measuring pint. To get almost 4 gallon an hour you
need to fill that pint in 2 minutes. If your fuel flow is
inadequate I believe there is a fine screen in the fitting
that screws in the carb for the gas line to connect to,
see link. Turn off the gas and pull that out to check it
for being plugged. When you have the line off open the
gas valve and direct the line in the container and check
for a good flow there. If the flow there is questionable
you will need to check out the sediment bowl below
the tank which should have a round screen in the top
of it that sets above the top edge of the glass. Also
sometimes crud or debris gets in the opening where
the gas flows out of the tank into the top of the
sediment bowl. Take a good flashlight and look down in
the tank and see what kind of debris you see floating
in the bottom that may plug things up. Aside from this
a faulty ignition coil can act similarly, usually when
they go bad they get very hot. Also a faulty condenser
can mimic this issue as well. These days getting a new
one that is good is a real crap shoot.
Example carb inlet strainer fitting

Have you changed the coil yet? Swap the coil for
either a new or proven coil, and give that a try. If a gas
engine runs fine until it gets hot or comes under load,
it can often be an electrical issue

The fact that it runs better when choked and needs just a few minutes to recover makes it sound like a fuel restriction as used red posted. It is just a mater of verifying it with the test that he described for you, and then opening the line at different points to find where you have good flow and where you do not.

Sounds like vapor lock to me. Try running it with the gas cap loose, the vent might be plugged. Somebody hasn't cut the gas line and cobbled
an inline filter into it have they? If they have, there's your problem. Throw it away and splice the line back
together.

One other possibility, and it sounds far fetched, are the points opening far enough? My 1550 would do that. I'd
open the points a little and it'd run good for a long time again. I fixed that problem with electronic ignition.

Runs for that long, it's not likely to be the carburetor, BUT you can't rule it out especially if you're a rookie at fixing carbs.

It's a fuel flow issue. Pull the fuel line to the carburetor and let it run into a clean fuel can. Just let it run. Most likely it will stop or slow or be slow to begin with.

I agree with Bruce, Check your coil.

Gas flow and condenser would be the first 2 things I'd be looking into.

Fuel cap vent.

Well ya got losts of advice , all touched on FUEL ISSUES couple Coil / Points issues . NONE touched on spark plug issue as to the correct plugs or a timing issue . I am NOT the resident Oliver GURU i leave that to Willy our local Oliver GURU and i have a good idea of what is going on But no one believes me so i ain't sayen . . Now i am not sure if you have the Holley carb on it as they are a real pain and vary expensive to do a real rebuild on as one kit does NOT have everything ya need . I have rebuilt a hand full of them and have one of them high dollar carb kits ontop of my computer desk now . . So check ing. timing and dist function and spark plugs . Your problem sounds the same as every other BIG gas tractor built in the mid sixty's to mid seventy's as i have a bunch of them in my area still tryen to do what they did when they were young just like us old goats , we can't do what we did 25 years ago.

I agree with the suggestions that it is either the fuel flow,
condenser, or coil. The condenser and coil are the more heat
sensitive ones. I am guessing if it runs good its almost definitely
not points or plugs. My money on fuel flow since choke helps.
Does it have a sediment bowl? Those can get dirty and cause
issues. Debris floating in the tank can also be an issue if it floats
around and plugs the tank petcock, and then when you turn it
off and the suction goes away the debris floats out of the
petcock.

(quoted from post at 18:34:28 04/30/23) I agree with the suggestions that it is either the fuel flow,
condenser, or coil. The condenser and coil are the more heat
sensitive ones. I am guessing if it runs good its almost definitely
not points or plugs. My money on fuel flow since choke helps.
Does it have a sediment bowl? Those can get dirty and cause
issues. Debris floating in the tank can also be an issue if it floats
around and plugs the tank petcock, and then when you turn it
off and the suction goes away the debris floats out of the
petcock.

Click to expand...

In my experience when a coil is failing it takes it 45 min to an hour to cool off and run again. Medic 52 stated that his will go after just a few minutes, which is consistent with slow fuel flow catching up.

Check for intake vacuum leak

Been 18 years since I retired but here goes:

Permeability of the coil's core is temperature sensitive and decreases with temperature meaning that the inductance, hence amount
of energy it can store to dump into the spark plugs, diminishes. Allowing the coil to cool temporarily shrinks the conductors,
opening the short and reverses the loss. I never have researched the exact mechanism within the coil that produces the heat that
wasn't produced when it was new. Possibly shorted turns (insulating varnish encircling the wires which has worn off due to
operational effects might be the answer since heat makes copper expand and when it cools it shrinks back and opens the short.

The coil has a volt per turn value based on the design/circuit parameters. If one turn does not produce it's required voltage the coil
essentially pumps all its energy, dissipating heat, heating the core, into that turn to bring it up to the required value and that could
be the reason the coil fails when it gets hot.

The condenser (capacitor) is made up of layers of conductor and insulator and probably aluminum foil and oil soaked paper or
plastic. My experience with these components is that once they short they shorted and its not recoverable due to the nature of the
material that is burnt during the short that remains in place.

I too have had coils fail as yours probably has on some of my gasoline engines over the years.