Boiling Fuel?

[investig8]

Hello all,
Last weekend I took Fiona out for a car show. I left the show about 5 p.m. with an afternoon temperature of about 100. On the way home I had two separate incidents where she sputtered and fell flat, like the ignition was turned off but it each one only lasted about 10-15 seconds and then she picked right up and ran just like a sewing machine. I have read several discussions on this sight about fuel filters, which I will certainly change, but also about fuel boiling in the line or filter when hot. Living in south/central Texas, summertime is always HOT. Is there anything I can do to help prevent the fuel from boiling? Insulate the lines or filter or both?
As always, I appreciate the group's wisdom...
Dennis

[greeno]

Assume you’re running engine mounted mechanical pump?

I’ve seen heat shield used to various degrees of success, but an electric fuel pump will definitely not vapor lock.

[John Mc]

Is your heat shield for your fuel pump in place?

I had that problem. Putting in the heat shield made a big difference.

I've heard of people rerouting and insulating the fuel lines

[NAM VET]

I assume you are fueling with non-alcohol fuel, which of course boils at a lower temp. I have had boiling fuel in a clear filter in my engine compartment. I have since re-roted my fuel lines in the engine compartment and wrapped them with insulation. I have a Facet electric pump. No problems since. NV

[PoW]

You are probably running "winter" gas in your truck. It is formulated with higher vapor pressure to allow easier cold weather starting.

Summer gas has additives to reduce the ability to boil in fuel lines.

https://www.gasbuddy.com/go/summer-blen ... d-gasoline

PoW

[NAM VET]

When I had my 427 Cobra, I could tell exactly when here in SC the winter formulation was replaced with the summer blend. Eventually when all of my local stations went to the "lower?" vapor pressure "winter blend" year around, I had to sell my Snake because in city traffic my carb would boil overr no matter what modification I tried. I am fortunate that so many lawn maintenance companies need the non-ethanol fuel here that there is a station just a mile from me that pumps it. Which is all I use in my Truck and other power products.

Anyway, all my fuel lines are wrapped from the hard line low under the radiator to my carb inlet, far away from my headers. No more boiling fuel in my clear filter. Plus I run a 24V Facet back under the rear frame rails. hal

[outpostm37]

Living in the heat of Arizona, I have had issues such as yours.
What I have done:
1) Installed a Facet electric 24v pump near the tank, removed the mechanical pump and made a block off plate.
This pump gave me 4-4.5psi pressure. Perfect for the Carter Ball and Ball carburetor.
2) Moved my fuel line to the carburetor further away from its position near the exhaust manifold.
3) Insulated the metal fuel line leading to the carburetor.
4) Close off the heat valve at the exhaust/intake manifold.
5) Installed the thicker carb to manifold gasket.
These old flat head 6 cylinders are NOT cross flow head engines. With the exhaust and intake manifolds on one side
of the block these percolation issues are very common.

[NAM VET]

in the 5 or so years since I got my truck, I have had three different 24 v pumps, and installed them in about 7 or 8 configurations. My mechanical pump was never plumbed to pump gas, only operate, sort of, the wipers. It was long since removed and a block off plate installed, now hooked up to an AN ss line for my switched full flow oil pump/oil filter stem.

First, the prior owner had an effective sort of 24v cylindrical pump, then I mounted a small cube Facet pump, and later a low pressure marine grade 24 Facet pump, from Pegasus Auto Racing. I mistakenly thought I had a defective Facet not long ago, and installed another identical pump. Charles Talbert had switched my cube one to the cylindric Facet when my truck was up there.

I have tried my fuel filters in the engine compartment, and also tried them pre and post pump back under the rear frame rail. The cylinder Facets have an easily removed and cleaned fine screen filter on the bottom, replacements and gaskets are available also from Pegasus. But the pumps are free flowing, so it is necessary to clamp the input line (I use higher grade fuel injection hose), or it will run free without the in-pump filter in. I don't like clamping fuel lines, not good for them, and if it slips off, it can be a real fire hazard. Lone ago, a fuel leak on my TR8 about killed me, it did about burn my home down.

So.... I have tried to reduce the fuel pressure drop with my extra filter, (these pumps push fuel a lot better than they pull fuel), and also make it a lot safer to change my metal filter and Facet filter without running fuel from a disconnected fuel line. Hence I added a shut off valve before my pump. It is easy to install fuel filters, but some have barbs on the inlet, and are about impossible to just pull the hose ends off, and require cutting the fuel hose. Wix plastic filters have the barb's, whereas the metal filters don't, much easier to change the metal filters than the plastic ones.

I also wrapped all my engine compartment hard liens with insulation hose, I have had fuel boil in a plastic filter there before, so now just a rear filter after the Facet. I had my filter pre-Facet but was concerned about fuel pressure drop. By the way, Charles Talbert wired my pump to my oil pressure switch, so if my engine dies in a crash, it will only run with the fuel in the carb. Much safer. I added a dash switch so I can prime my carb without cranking my motor to build oil pressure.

I run my engine compartment fuel lines to an Aeromotive low pressure fuel pressure adjuster, with a dampened gage, and my fuel pressure is thus set to 3.5 psi at the carb. I have had my share of misadventures with all this, but this is what I finally have settled on.

By the way, Charles T completely rebuilt my original fuel pump to better than new, for $400, and I will never install it, so let me know if you want it for much less. When I check and change my Facet fuel filter, it is pretty clean so there must not be much rust or debris in my gas tank. I made and installed all new fuel and vent lines on my truck. So here is what I hope will be my final fueling system, set for easy and safe inspection and operation. I will post it just below, so I don't lose all this.

hal

[NAM VET]

[investig8]

Thanks to all who replied to my issue. In answer to the questions raised, I am running a standard mechanical fuel pump for a 230 cu. in., not the vacuum type that was original. The fuel line from my fuel pump to the carburetor is rubber with a plastic in-line filter. I had the fuel tank vatted and cleaned when I was working on her, but was not coated inside and therefore may have picked up some flash rust before I got any real amount of fuel in the tank. I am replacing the fuel filter and will look into routing the fuel line farther away from the manifolds, even though I do have the heat shield in place. Will let everyone know how it goes.
Thanks again,
Dennis

[investig8]

Hey everyone... wanted to offer a huge "thank you" for all who provided insight into my fuel problem. Today I took Fiona to a car show about 25 miles away and coming home it was mid-90s with a heat index of near 100. She didn't miss a lick!! I purchased and installed the insulated wraps for the fuel line and filter that was recommended... Thank you, thank you, thank you!!
Dennis

[John Mc]

Glad to hear things are working out for you.

I had two issues causing me vapor lock. One was the missing heat shield as mentioned above. The other was a crack in the exhaust manifold that was dumping hot exhaust into the engine compartment - not a lot, but enough in just the right place to cause a vapor lock problem.

[just me]

Being in the Sonoran desert, heat is a normal thing.
I run the stock pump.
I run the factory heat shield.
I routed my fuel line from the pump to the inner fender.
It runs up the inner fender, through a metal filter and back across to the engine at the level of the bowl inlet.
I have NO boiling or vapor lock issues.
I do have heat soak issues that cause the bowl to boil over into the manifold and make hot restarts difficult. I need to install longer studs and make a heat shield for the carb, too.

[outpostm37]

just me
There is a thicker carb to manifold gasket available that gives a little more heat insulation that may help you.
With the alcohol in the fuel, and desert heat, a phenolic fuel bowl would be nice. But these do not exist for this carburetor.
My 340 engine works well with the old Thermoquad vs. the all metal Holley carburetor. in the summer heat.

[Explorer0863]

Hey everyone... wanted to offer a huge "thank you" for all who provided insight into my fuel problem. Today I took Fiona to a car show about 25 miles away and coming home it was mid-90s with a heat index of near 100. She didn't miss a lick!! I purchased and installed the insulated wraps for the fuel line and filter that was recommended... Thank you, thank you, thank you!!
Dennis

I’m getting close to the fuel supply phase of my rebuild. Deleting the original fuel pump and ordering a Facet electrical pump. I can’t find anything specific about the “insulated wraps for the fuel line and filter…” mentioned here. Can you or any forum member elaborate pls? Also, what is the fuel line diameter?