Need help with a Studebaker Lark fuel system... OT

[blueskies]

Not Plymouth related, but hoping the genious collective here might be able to shed some insight on a fuel system issue...

 

My son Ben bought his first car last fall, a '61 Studebaker Lark.  The car is in great shape, but the previous owner wasn't what I'd call "mechanically inclined"...

 

The car has a fuel system issue, where it will run fine for 10-15 minutes, and then run out of fuel.  After it sits for 1/2 hour or so, it will start up and run fine again, until the cycle repeats.  Doesn't matter if it is hot or cold.

I did some searching on the Studebaker forum, and found that the previous owner had the exact same problem and posted about it in 2007, apparently it was never resolved.  The engine is an OHV

 

So, to date, we have removed the fuel tank and cleaned it out (it wasn't overly dirty), the pickup tube in the tank is clear, new fuel lines and filters.  We have removed and cleaned the carb twice (the second time just to be sure there wan't a blockage somewhere).   Also, replaced the coil and condenser, the points look new. The gas cap is a vented type, be we even tried running the car without the cap to be sure.

Here's what is going through my mind... getting nowhere fast.


The carb is still clean from the thorough cleaning we gave it this spring. There are no obstructions in any of the ports, jets, or float valve. No screens or other areas that could have been plugged.

The float needle looks good, and doesn't seem to be sticking.




I decided to check out the fuel pump while I was at it. The pump doesn't look like it has many miles on it, and the diaphram is good. It pumps just fine, no obvious visible issues. No restrictions in the fittings or valves.




I did find one oddity though... The upper portion of the pump had 4-5 tablespoons of engine oil inside, and it was leaking out of the weep hole on the side of the pump casting... It looks like there is maybe a bad seal on the diaphram shaft in the top of the pump, I don't think oil should get into the pump body. I'm wondering if this could be an issue pumping the fuel, if it gets a bunch of oil in there it might restrict the pumps ability to move fuel. If the oil leaks out the weep hole, then it would start over again...

Thoughts?

I have now been through the entire fuel system from tank to carb, and can't find any issues, other than a section of hard line that is 1/4" diameter, which I think should be 5/6" and the oil in the pump body.  Planning to replace the fuel pump, as soon as funds allow, and installing a 5/16" fuel line from tank to carb.

 

Any other thoughts on what could be the problem? 

Pete

[William Davey]

Pete,

   I'm no Zen master, but that oil seems excessive.  I'm guessing 4-5 table spoons would nearly fill the upper cavity of the pump casing and prevent the diaphragm from moving.  Maybe the oil drains out in 30 minutes and it takes 15 minutes of running to fill the cavity back up.  Can you see the vent hole with the engine running?  If oil is squirting out the hole then you've identified the problem, but not the cause.  

 

Edit - another thought - can you pop the top off the carb as soon as it quits and verify whether the float chamber is full or empty?

Edited September 25, 2015 by William Davey

[Don Coatney]

Dang Pete Ben cannot be anywhere near driving age. Tulsa seems like yesterday. I agree replace the fuel pump.

 

[Plymouthy Adams]

I saw a Stude Lard (was going to change this but I left it as is..lol)  at the swap meet Thursday..first thing come to mind was Pete and his son...second was to see if it was a Daytona..it was not..

Edited September 25, 2015 by Plymouthy Adams

[blueskies]

Dang Pete Ben cannot be anywhere near driving age. Tulsa seems like yesterday. I agree replace the fuel pump.

Ben was five when Joseph and I drive out to Tulsa....

 

Here's a few pics of the road trip we took last fall to pick up the Lark in Yreka, Ca.  About 12 hours one way from here to there.  Ben bought the car on ebay.

 

The car as we found it upon arriving at the sellers house in Yreka.  Pleasantly surprised at the condition of the car, it was as advertised. (except for that bit about it only running for 10 minutes...)

 

Happy new owner.

 

Somewhere in Oregon...

Edited September 25, 2015 by blueskies

[greg g]

have you looked at the flex line from the frame to the fuel pump? Is it collapsing under vacuum?

[blueskies]

Pete,

   I'm no Zen master, but that oil seems excessive.  I'm guessing 4-5 table spoons would nearly fill the upper cavity of the pump casing and prevent the diaphragm from moving.  Maybe the oil drains out in 30 minutes and it takes 15 minutes of running to fill the cavity back up.  Can you see the vent hole with the engine running?  If oil is squirting out the hole then you've identified the problem, but not the cause.  

 

Edit - another thought - can you pop the top off the carb as soon as it quits and verify whether the float chamber is full or empty?

The carb is a funky Carter AS...  It is a convoluted process of opening it up, first taking it off the engine to get to the bottom linkages that run through the body of the carb.  I don't think there is any way to do a quick check to see if the bowl is empty.

 

I think your theory of the pump filling with oil, becoming useless when full of oil, and then draining out while it sits is spot on.  I can't see how the pump could move any fuel if the area above the diaphragm is full of oil.

 

The next test, while we wait for a new pump, will be to run it till it quits, and then put the pressure gauge on the line and see if it is pumping anything.

 

Pete

[blueskies]

have you looked at the flex line from the frame to the fuel pump? Is it collapsing under vacuum?

Rubber lines look fine.  Blew compressed air from the carb to the tank to make sure line was clear before pulling the tank, and could hear it bubbling away in the tank.  The inside of the tank looks decent.  Flushed it out anyway.

 

Someone suggested on the Studebaker forum that having a fuel filter near the tank could be part of the problem, if the fuel pump can't pull enough vacuum to overcome the air bubble in the filter.  Going to pull the filter near the tank now that I know the tank is clean.

 

Pete

[Dennis_MN]

I fixed a problem on my neighbors Ford truck fuel pump issue. We bought a 6volt electric fuel pump and used that in place of the original. We left the original in place so it looked ok. So my suggestion is to go to Napa to get a electric fuel pump.

Dennis

[Ulu]

Yup. Easy fix, IF the pump is the issue & it sure sounds like it. just make sure you don't mount one upside down. I did once on my Edsel. Ran 5 minutes & quit. 

 

But for diagnostic purposes you might put a fuel pressure gage in the line where you can check it.

I also have a Vis-a-flow glass float bowl that lets me see the fuel level for tuning purposes. (Not for daily use!)

 

That won't help you though. Not with that carb.

 

As for filters, purge the bubble out! if it reappears you have another issue.

 

I like the Lark styling & in its own way it's charming. My Dad wanted a Studebaker wagon, but eventually bought the less expensive & more modern & reliable Valiant wagon.

[Ulu]

PS, I saw the Stude coupe...

 

Mom had a Starlite Coupe. 1951.

Couldn't figure out the clutch, & refused to drive until dad bought her an automatic car.

Edited September 26, 2015 by Ulu

[blueskies]

Pretty sure it is the fuel pump...  I reinstalled the carb and the cleaned out old fuel pump yesterday.  It fired up and ran in the driveway for a half hour or so without quitting, so I ventured forth to the grocery store a mile or so away and it made it home.  It seems as if the oil on top of the fuel pump diaphram is restricting the pumps ability to function...  Once cleaned out, it worked ok.  Just a question of time before it gets full of oil again though, so a new pump is on the list.

 

Thanks for all the replies.

 

Pete

[greg g]

So is the vent for the upper chamber of the pump clogged.  Seems that if it were it would create a partial vacuum there that would suck oil out of the crankcase instead of air.  

[blueskies]

So is the vent for the upper chamber of the pump clogged.  Seems that if it were it would create a partial vacuum there that would suck oil out of the crankcase instead of air.  

The weep hole is clear, and when the chamber gets enough oil in it, it spatters out the weep hole.  I think the seal that is in there, on the diaphragm shaft, must be bad.

 

Pete