Anybody having problems with Vapor Lock?

I know I have! First I had to figure out why mine would shut off or not start after it was hot. Finally I figured it out. Today's gas when mixed with Ethanol has a much lower boiling point. Ethanol does raise the octane but when mixed with gasoline it lowers the boiling point. I won't even get into the corrosion issues. I can only get 90 octane with no Ethanol in my area.

I'm not fuel injected so...now it looks like a plumber visited my engine compartment...

Good article here:
https://www.azom.com/article.aspx?ArticleID=17736

 

Excellent reason to put an electric pump at the rear, preferably IN the tank. Pressurized fuel is less likely to boil than fuel being "sucked" forward by an engine-driven pump. ESPECIALLY if there's a bypass fuel pressure regulator that is sending excess fuel back to the tank.

Does your vehicle have a vapor-return style engine-driven pump and plumbing? That alone can help with vapor lock.

 

Yeah, I have an in-tank pump and return line (1/2"). Pressure at about 6.5 psi. I've insulated my underhood lines and wrapped my tail pipe "over the hump" area, where it's closest to lines as they transition through that area.

Time to get some summer gas in her and see if issue is solved since insulation installation.

 

My son's 51 has the vapor lock problem

 

My set up is the factory tank in the cab with 3/8" fuel line to a Stage 1 fuel pump, using the fuel filter in the carb inlet and no return line. It does the following, which I believe is a vapor lock problem: If, for instance, I am running errands on a warm day with the truck and I shut it off and park it for awhile and let it heat soak, it will act up when started and driven again. Part throttle cruising is fine, but if I nail it and run it WOT, it will run out of fuel above 4000 rpm. If you get back out of it, it will continue to run fine at part throttle cruise. No problem if it is really cool out, or if I do not let it heat soak. I believe a return line or an electric pump near the tank could fix this.

 

yesterday, thunderhead289 (luke) uploaded a video about vapor lock:

 

Anyone who thinks they have a vapor-lock issue: Install a fuel pressure gauge where you can read it from the driver's seat.

Take the vehicle out, run it 'til it acts up. Read the fuel pressure when it's acting up.

If your fuel pressure is zero or very low...you probably have vapor lock (or a poorly-vented gas tank.) If it isn't. you don't.

As said, a pusher pump is far less likely to vapor-lock than an engine driven, "puller" pump. And even an engine-driven, "puller" is less likely to vapor lock if it's got a vapor-return fitting and plumbing back to the tank. Pretty much all the GM cars with A/C got the vapor return style fuel pump with the 1/4" vapor return plumbing back to the tank.

 

Not too long ago our governor (Michigan) signed an order stating it was ok to continue the sale of winter blend fuel past the change over date. Evidently there was a surplus due to the stay at home order. Just FYI.

 

Ive been running Costco premium with no issues.

 

Is it non-ethanol Premium and did you have vapor lock problems before running Costco Premium? I run premium but not many non-ethanol places near me... and pretty sure I have vapor lock issues and trying to avoid adding an electric fuel pump...thanks

 

It has the ethanol added.
It's abt 40 cents less than everyone else.

 

I thought I was having vapor lock issues, turned out to me my XR-I points eliminator module was the culprit.

 

if you can add a few gallons of race gas, it should cure any vapor lock issues you may have.

 

My vap got locked with resin.

 

I've never had an issue with vapor lock, even way back in the 80's when I used to tow a boat with my GS.
The only fuel related drivability issue I've had was the rubber section of fuel line under the drivers door was collapsing (inner section)

 

Today's experiment involved reversing the electric fans....

I have two 13 1/2" Flex-a-Lite electric fans mounted to the inside of the radiator which pull air. I noticed the fans really throw a lot of heat into the engine compartment after the heat soaked engine is re-started. The engine temperatures are non the less maintained at 180 deg., at idle with the hood closed. The carburetor bowl temperatures however are around the 120 deg. level.

After reversing the fans under the same idle conditions the bowl temperatures drop to around 100 deg. Well after reversing the fans the carburetor bowl temperatures are indeed lower, dropping to 100 deg. F. The problem is, at highway speeds the fans can not overcome the airflow coming in to sufficiently cool the engine. This caused the engine temperatures to climb to 215 deg. When I would slow down, below 30 or stop, the temperature would return to 180 deg. I don't recommend reversing the fans, in my case I think I popped the relay, they now run all the time :-/

The fuel in NC is regulated to a Reid Vapor Pressure (RVP) of 9.0 psi, all year around. This is higher than some/most states (some have winter and summer blends) and this higher RVP results in a lower vapor point (boiling temperature). I estimate that the fuel I'm using boils at ~118 deg. F.

Many blends of race fuel have RVP's of around 4.5 psi. I'm going to try some 90 octane (leaded and no ethanol) and add some C10 or VP110. Will report back later....

Thanks for all the inputs so far!

 

I am also having vapor lock issues on my 67 GS.
I plan to install an electric fuel pump.
Looking at the Holley Red. Does anyone have suggestions on where to mount it?
Thanks

 

In trunk or under the car?