Just venting Re: vapor lock

[ElZilchoTX]

Driving home from a car show today we stopped to pickup food. While my wife ran inside I stayed with the kids in the car with the A/C on. After about 10 min my wife can out to the car with the food. Unfortunately we couldn’t back out of the space due to our parking neighbor not closing their doors. Needless to say the formula of black car with a mechanical fuel pump in 95+ degree weather equaled the car stalling.

Upon piping the hood I see a dry glass fuel filter and a fuel pressure gauge reading beyond its mechanical limits. The dreaded vapor lock.

Poured a half gallon of water over the fuel lines and pump, let it rest for 15 min. Iced it down for another 5 and drove happily back home with no issues.

Isn’t even summer yet...*sigh*

["Cadillac Kid" Greg Surfas 15364]

You are right, we have two seasons here. Summer and "not so" summer, and we are into summer. 106 next week. Earliest summer in the 24 years I have been here.
Greg Surfas

[64\/54Cadillacking]

It seems like every year, and when the season changes, the gas formulations keeps changing making our cars run worse. I don’t know how gas is in other states, but I know in CA we go from winter blend to summer blend starting in April (which is really stupid and a scam since we never truly have winters in SoCal).

This screws with my 64 and I need to readjust the carb when the changeover happens. Speaking of fuel pumps, mine just crapped out last night. I really believe that new gas is destroying fuel pumps too as this last one I installed only lasted about 2 years.

[ElZilchoTX]

Yeah, not looking forward to the 100+ upcoming weather.

My fuel pump is brand new and is sketch already. I may add a low pressure pusher pump to assist the mechanical one

[Jay Friedman]

In some areas of the country you can find stations that sell ethanol-free gasoline.  Look on www.pure-gas.org.

[cadillacmike68]

The 68 has never stalled on us and its 95 + nearly all the time here. Except for these past 2 weeks. 

But then again the climate control isn't on all the time either. But I've run it solid for hours at a time in rain, etc and it's never stalled. Temp gauge skyrockets but no stall.

[ElZilchoTX]

Yeah, my temp gauge never went past 1/2 way. But still scored the award of vapor lock

[cadillacmike68]

I remember when I was a Lieutenant and my jeep vapor locked on the way to a training exercise in Canada. We limped in several hours after the rest of the battalion got there, barely made it to supper and had to sleep in the jeep's trailer that night.

And yes it rained.

[ElZilchoTX]

I am questioning the routing of the fuel line under and up the front of the motor (behind brackets and through the water pump).

My fuel line is even wrapped with thermo-tec heat insulation from the bottom of the motor to the carb on the feed side (but not the return).

Not sure what else I can do other than add a “helper” pump to keep it moving.

But I am at least glad it wasn’t on the road or at a light. And it beats overheating or blowing a head gasket.

Funny thing: lived here all my life. 45+ cars in my life, at least 12 of them carbed, this is my 1st vapor lock. So glad for the fuel pressure gauge under the hood that made the diagnosis very easy...thinking a second gauge in the glove box would be nice.

[ElZilchoTX]

Middle of the night epiphany: my dual exhaust is probably too close to my fuel lines...not to turn this into a tech thread. Just an update

[robert G. smits]

I installed a low pressure pump at the tank of my 41 ten years ago.  The only time I use it is for starting after sitting for several weeks and to clear the occasional vapor lock,  Cheap insurance!!!

[ElZilchoTX]

Yeah, I think I’m sold on the idea.

Definitely going to climb under her and check exhaust to fuel line clearances as well.

I avoided driving her today as the high is expected to be around 98. and not driving my Cadillac is unacceptable behavior.

["Cadillac Kid" Greg Surfas 15364]

64 Lacky,
California is "special" and you have two seasons as far as gasoline is concerned. 1. Normal season. 2. Smog season.  I know because I lived there for 52 years.  Gas is reformulated to reduce its vapor pressure in the "smog" season.
Depending upon the blender and the mix it CAN effect operation and performance, but in some instances such as with a major oil company, the difference can be minimal.
Greg Surfas

[metalblessing]

I havent run into vaporlock yet fortunately BUT I was just reading yesterday about thermal shield wraps for fuel lines. I was considering trying this out just a safeguard. I dont have any idea how effective it is though. Thought I'd mention it since it seems relevant to the topic. If your exhaust is radiating heat to the line, maybe putting this between them will help?

http://designengineering.com/products/reflective-materials/

Maybe other guys here have experience with this stuff, i just found it interesting

[ElZilchoTX]

Yeah, I heat shielded the hose under the hood but not the lines near the exhaust. looks like I need to buy some more...

[HerbP]

I installed a low pressure pump at the tank of my 41 ten years ago.  The only time I use it is for starting after sitting for several weeks and to clear the occasional vapor lock,  Cheap insurance!!!

I did the same on my '40 LaSalle, and use it the same as you do...works great!

[ElZilchoTX]

Found 2 spots where the exhaust runs directly under the fuel and return lines...within mere inches. I will be heat shielding the lines and thermal wrapping the exhaust pipe in these two areas. In addition I am adding a pump back by the fuel tank. Whomever ran this exhaust didn't think things through.

[Dan LeBlanc]

Remember - 1962 cars were offered with single exhaust that ran along the driver's side whilst the fuel lines ran along the passenger side.  In stock configuration, vapor lock on an a/c 1962 car with a proper return line is almost unheard of.

[ElZilchoTX]

Dan- agreed. But at some point someone made her dual, without thinking too much about exhaust routing. Hopefully the thermal wrap will do some good

[Scot Minesinger]

Yes, my 1970 RWD Caddy DVC is modified to dual exhaust and I wrapped the passenger side exhaust whenever it was even close to the fuel lines (especially where they go over rear axle) and never had an issue.  I drive mine all the time, the hotter the weather the better.  However the ac is not on much, because if it is above 55'F and not raining the top is down.  If top is up it is either raining (probably ac is on then) or cold.  Sometimes I get caught in those summer thunderstorms.

Take a look at exhaust, that is probably your issue.

A while back thought I had a vapor lock issue and looked at re-routing the fuel lines, but as Greg has said in some form "90% of my carb/fuel problems are electrical", turns out it was ignition.  Anyway the routing of the fuel line although not necessarily optimal for not picking up engine heat, when you consider what could happen in a crash, it is the best routing and decided not to change it. 

Insulating exhaust so it cannot reject heat to fuel lines is always good, but not a fan of insulating the fuel lines because if the gas is hot, the heat cannot be rejected easily.