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Travellin’ Riverside Blues - More Fuel Problems


keithb7
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Go to solution Solved by Sniper,

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Well, it was almost a completely uneventful cruise. Not quite. 
 

I spent the afternoon out in the country side. I headed back to town. Later I stopped to put in some fuel and left the gas station. Headed home. Warmest day of the year so far. 85 F. 
 

About a 1/4 mile from the gas station. The final hill home.  Right at the hill base, I just was starting to climb. Cough. Sputter die.  No cars around. I coasted backwards to a safe pull out.  I Pop the hood. Raw fuel is steadily dripping out of throttle plate pivot point at the base of carb. It’s steady dripping out. Sizzling and evaporating at it contacts the intake manifold. 
 

I’m currently letting things cool down.I  Locked her up and walked to a pub near-by for a beer and a burger. 
 

Hmm. What is going on here? Some clues:

 

Hottest day yet since I took ownership of the car. 

 

Just stopped for fuel and check fluids.  a few mins before. Heat soak?

 

I’m only running non-ethanol fuel. 94 octane. 
 

Fuel pressure is regulated to about 4.5 psi and  at has been fine for the past 150 miles. Cooler ambient temps though. 
 

Can non-ethanol fuel vaporize? Yes I think so. At a certain temperature I’ll bet . Maybe I’m there? Non ethanol fuel would likely have a higher boiling point than ethanol fuel, but will indeed vaporize.  I’m thinking the fuel today did not vaporize. It boiled. 
 

There is no heat shield plate at the base of the carb. I may add one. There is no heat shield between the mechanical fuel pump and the exhaust manifold. I will add one.  There is no phenolic spacer at the carb base. I’ll consider that too. 
 

What I can’t seem to wrap my head around is the fuel percolating out of the carb throttle valve linkage. Maybe the fuel in the  carb bowl boiled, forcing its way out the vent tube? Raw fuel streamed down into the Venturi?  Flowing down the walls of the carb throttle body. Then on to the throttle valve. It was closed so it worked across the valve plate, then out the pivot pin. Exiting the carb at the base. That seems likely.  The engine was over come with raw fuel. It flooded. Sputtered and died. 
 

It’s been over an hour now. Beer and the burger are gone. I’ve had time to think this through. Off to try driving it home again now. 
 

Any tips are welcome. I keep learning the hard way. Lol.  An electric fuel pump may be in my future but I’m not convinced today’s plight had anything to do with the mechanical pump. 
 

Seen here, we are in detention. The funny  part is, this is the exact same piece of road I was driving when the fulcrum pin walked out of my mechanical pump of my ‘38 Plymouth. I rolled backwards to this exact same spot. I Popped the hood and plumbed in a 6V electric pump in record time. Fired it up and drove home. 
 

AB8E39FB-7528-46F4-BAC6-530425E27861.jpeg

Edited by keithb7
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I think you're on the right track with heat shielding. Vapor lock and fuel boiling has been around forever. I remember seeing a lot of cars back in the good old days with aluminum foil clothespinned to the underhood fuel line. On the good side you know it won't actually leave you stranded, just delayed. I had a Ford pickup that would do almost the same thing. I was never able to fix it although I admit I didn't try very hard. It wouldn't die while driving but if you shut it off during hot weather you were in for a long wait. I learned to work around it and when I couldn't I used the time for meditation.. Kept me from burning the truck to the ground. 🙂  

Two thumbs up for the Zep reference, too.. 

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  • Solution

Maybe it's the angle of the hill binding up your float?

 

I venture to guess it gets much hotter here than where you are yet I have zero issues with hot starting or fuel issues when hot.  Lat year I drove it in 110+ degrees F with no issues.   

 

I run whatever pump gas there is, usually Shell brand, says up to 10% ethanol. 

 

I would take a very close look at your float action, angling the carb to see if it binds.  My thinking is that if it were heat related it'd happen on the flat too.  Maybe whack the carb when it does this and see if it stops flooding. 

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It Flashed up easily after the cool down period. I drove it up the hill home without any issues.  I’ll get it sorted in the next little bit here. 

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I'm with Sniper, check the float. If you were having percolation issues, I would think it would have started hard after fueling up. The fact it fired up and went down the road makes me think your float was hanging up for some reason.

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Me too on the float.  Or maybe needle valve sticking.  Percolation is almost always a heat soak after stopping symptom.  Rarely if ever does it affect a running engine   
 

But it is possible that the fuel in and after the pump gets hot enough to raise pressure and overcome the float.  Wouldn’t hurt to add a fuel pressure regulator 

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Hi Keith,


I had a similar problem. My '39 ran great except when starting up a very steep hill. It would want to choke and die. I disassembled the carb. All looked good except the accelerator pump leather seal was eaten away at the bottom. On the theory that extra fuel was spilling through there from the fuel bowl at a  high angle I replaced the pump with  a new one. I don't know if my theory was correct, but it solved the problem.


Pete

 

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And one here too.

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Yes we can do that...time it right and I can show you a couple nice big Airflows too!

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5 hours ago, Skrambler said:

Why do I hear guitars whenever I see updates on this post?

Distant Led Zeppelin I believe?🎸

Or Robert Johnson.. 

If Keith doesn't get this fixed pretty quick he may start thinking "If today was Christmas Eve and tomorrow was Christmas day." 🙂

Edited by MackTheFinger
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On 5/16/2021 at 6:28 PM, keithb7 said:

... 
There is no heat shield plate at the base of the carb. I may add one. There is no heat shield between the mechanical fuel pump and the exhaust manifold. I will add one.  There is no phenolic spacer at the carb base. I’ll consider that too. 
...

 

additional information - spark plug wire sleeve repurposing

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I finally got into the carb recently. I found a couple of things. 
 

The carb mounting nuts were loose. I would certainly have a vacuum leak there. Especially when cold, I noticed something wasn’t quite right. I could feel it. This is where experience and intuition can guide you.  From memory my ‘38 Plymouth was running better, I knew it. Just had to keep digging to get it sorted. 
 

The float was set to 5/32. Supposed to be 5/64. Way rich. 
That explains a few things. 
 

I also installed a heat dam at the base of the carb for preventative measures.  See photo.  Careful with these. Ensure gasket and plate cutouts are in the correct place for vacuum orifices in the carb base.  The gaskets are cut with odd openings for a reason. 
 

Also, not done yet but I will also install a heat shield plate over my mechanical fuel pump. Test drive coming up!
 

 

48C1F106-FBCF-468E-9629-CCBAF55CBA24.jpeg

Edited by keithb7
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