Boiling carbs?

I've never seen this on cars with standard pumps or electric pumps regulated down to 3lbs.or so.....   I would check fuel pressure, and float level just to be safe....  Just my .02 drachmas....

The problem is usually excess fuel pressure or heat.  I would guess high underhood temps, not fuel pressure.  You could start my testing carb temps after shutdown with a laser heat gun, borrowed or bought.  Ways to cool down fuel temp include rerouting fuel lines, wrapping with heat-reflective tape, or a phenolic spacer at carb base.

 

Higher HP engines just produce more heat, the hard part is handling it.  Getting more air into the engine compartment is almost always a big help. 

Carey's right as usual, Tom. Living in a hot zone, I shut off my fuel pump whenever I stop.

Best to leave zero pressure in the gas line.

 

I have had occasions where I smell fuel in the hot garage after a drive, but I've never seen any puddles, and it's certainly hot enough here this time of year to induce them.  I'm going to echo Leon regarding float level, and Jim regarding having a fuel line too close to a heat source.

Made the short drive to work in 60 degree weather & turned off fuel pump near work.  Boy, it runs out of gas fast!  I stalled & had to restart.  Drove a little closer & tried again.

No sign of fuel upon stopping.

Buckwheat warned me that the pressure would do in my seals. 

Maybe I'm looking at a carb rebuild?

The big variable was that the engine was out and in a few weeks ago.

Also, yesterday morning, after driving to the zoo and the starting up to move to a new location, idle was really low.  Bill told me it was heat soak causing the carbs to boil over.  Sure enough, after sitting for a few hours, idle was back to normal.

Based on the chain of events, I'm thinking fuel lines may have gotten re-routed too close to heat source.

Off to Bill 'a again later next week to check it out.

In my opinion, shutting off the fuel pump early is fixing a symptom, not the cause, effective though it may be. I'm with the others that your problem probably lies elsewhere with excess line/carb heat, float level, or dirty/leaking float valve.

Thanks everyone.  Carey only suggested that as a temporary remedy.  I'll try to root cause next week during the Ford shutdown.

Since both carbs started acting up at the same time when the temperatures warmed up, and the engine was just reinstalled, I suspect a heat issue near the fuel line.

The odds that both carbs developed the same issue at the same time points me further upstream.

Laser heat guns, $37.00 at Harbor Freight.

I ordered one from Amazon Prime for $17 free shipping.  Will have on Tuesday.

If your fuel lines are getting too hot I'm surprised you haven't experienced vapor lock.

The digital temp gun is a good idea, but how will you know what too hot is?

Hmmm.  The other variable is that I started using Stabil 360.

Shutting off the fuel pump and draining the bowls cures the symptom.  

 

I really can't believe that the lines are too hot because I'm not having any other symptoms.

 

This is the 5th season and I have an external oil coiler and a CHT gauge and both oil and cylinder head temps remain unchanged.

 

It seems unlikely that both carbs would go at once, but, as unlikely as that may be, I'm thinking float valves. 

 

All will hopefully be revealed on Wednesday.  I have a thermometer arriving on Tuesday and it's raining here Sunday, Monday, and Tuesday, and I will wait to drive across town for better weather.

 

Fortunately, this is Ford shutdown week, so I have more time than usual to muck about.

It's more common than you might think.  I had a boiling issue when I had a tie-wrap fail on me and let the line sit across a hotspot on the bottom tins.  Just look at where the fuel lines enter, split, and feed each carb.  If you find it near the "floor" of the engine compartment at any spot, you might have located your problem.

Thanks Lane.  Honestly, that makes the most sense since the engine was recently pulled.  Let's hope.

I was running in almost 90 degree weather yesterday.  CHT right on target, but oil a little hotter than normal. External oil cooler doing it's job, though.

 

Draining the bowls before keying off really stops this issue even in this heat.

 

I noticed the other day that the belt appears a little loose.  I wonder if my fan is turning fast enough.

 

All speculation until Wednesday.

Also, I checked out the fuel lines and don't see anything obviously wrong. They might be touching the fan shroud on both sides as they route to the carbs.  That might be the issue. 

 

The main feed enters the engine compartment on top of the trans and there's a t-junction behind the fan shroud and the fuel lines route to each carb from there.  

 

The main line seems to be sandwiched between the trans and the body, but doesn't appear pinched.

 

I'm wondering if drilling a hole and routing the fuel lines through the body just above that point would make things cooler for my fuel lines.  Of course, doing that would probably mean pulling the engine :-/

Tom, my carbs never boil. 

 

 

Oh, that's right, I don't have any.  Just kidding you really enjoy your car and I hope you sort it quickly.  

 

Gotta go, Sandy needs me to run to Walmart in the fuel injected IM.  See ya!

Checked out car at Bill's.  Everything looks okay.  Probably was all due to me not keeping the revs up on a hot day.  I will continue to make a good habit out of turning off my fuel pump close to home and probably ask Carey to add some spacers this winter. 

 

Enjoyed a glorious ride to and from Bill's :-)

Tom, I turn off the pump and let it run for about 10-15 seconds, just long enough to drop the fuel pressure. I don't like to let the carbs run dry - it has led to plugged idle jets a couple of times.

 

"It Makes Lane nuts "

 

Yes.  Yes it does.

Just an update with no real information.  A couple of weeks ago, I started wondering if my fuel pump pressure might be the issue.  I have a CB fuel pump so I called CB to ask them if they have ever heard of such a thing.

 

I called late morning Eastern time and the lady on the phone said she didn't know if anybody would be in to answer my question.  She put me on hold and the next voice I heard said "this is Pat."  I enjoyed getting to talk to Pat Downs for the first time.

 

He had never heard of a fuel pump failing that way and he thought it was float adjustment.

 

For now, car is running great and turning off the fuel pump is addressing the symptom.  With a little luck, I'll make it through the driving season.

 

On Friday morning, I noticed a new spot on the right side of the garage floor.  I've become pretty adept at telling the difference between gas, engine oil, trans oil, and brake fluid leaks (because I've had them all :-))

 

I took the afternoon off, dropped my exhaust and discovered the right breather tube had come loose from the valve cover.  I reattached and tightened the hose clamp and was back in business.

 

I am the poster child of the reluctant mechanic.  I never enjoy having an issue, but my confidence is going up with time :-)

TOM,

You've got a great character trait in your apparent ability to remain calm and analytical in the midst of a potentially serious crises...Took note of that at Carlisle when you were broken down on the shoulder of the road, knee deep in weeds... in the middle of the boondocks.   

Good job, Tom.  Glad you solved that issue. Great feeling , isn't it? 

I am glad you are sorting through these issues, Tom. They aren't that bad, most of them are simple.

 

I've noticed no more idle jet clogs for me either. It is because either a) I've stopped needing to mess with the carbs or b) the new air cleaner tops/filters are keeping the dirt out.

Danny,

 

Are your filters a foam element or something like a pleated Filstar filter?

Carl, cone K & N type. I think it is the position, the fact that they aren't directly over the carb tops.

Danny, do you oil your filters?

 

 

Yup, that photo is CB's. Mine were slightly red for a day or two, now they are getting black. I only clean them once every spring, unless it's a very dirty year.

I installed a K&N filter in my Ranger and ended up swapping it out for a stock, paper filter.  Seems the oil was playing havoc with my MAF sensor.  Luckily, we don't have MAF sensors on our engines

That's got me thinking about what type of air monitoring sensor I have with my FI kit.  I'm ashamed to say I have no idea how the CB kit monitors air flow.

CB's Air Flow Monitor:

 

Good one, Gordon.

Turns out my airflow is controlled by either the TPS (throttle position sensor) or MAP (manifold air pressure).