Vapor lock and heat issues

zoomer

zoomer

Member
Supporting Member
Having issues with my 56 chev with a 283

Wondering if any of you guys have suffered or are suffering with vapor lock . I know it’s been pretty hot here in Alberta lately but this problem has been creeping up on me for awhile now so it’s not just the ambient heat getting to the car , its pretty hot under the hood all the time.

I have run insulating tubes over entire fuel line tank to mechanical pump , pressure reg and then to carb. Even made a sheet metal guard in front of the pump to deflect heat from rad blowing over it . After about half an hour driving it will run real ruff and eventually stall out .Inline filter looks empty . But after 5 - 10 min on side of the road it starts back up filter fills and I can limp back home . It’s empty by the time I get back. All I can think is it’s vapor locking.

Any thoughts from experience

Brian
Calgary
 
Vapour lock was an issue I had years and years ago on a Pontiac 350 in my Moms Firebird. An older hot rodder showed me to insulate the fuel line that runs from the pump and across the top of the manifold to the carb.
Being that is an ‘easy’ fix, I would also look at the fuel tank with the thought of crud blocking your your inlet line. Are you running a filter between the tank and the pump? Can you check that for what it is filtering out of your fuel…maybe a story there.
I had a buddy that had his fuel filter plugging up due to a tank liner (old fix method for hard to replace fuel tanks) that was starting to disintegrate….the pump would only pull what it could to run, then needed time to ‘refill’ the filter to pump…that kept him busy one summer.
Good luck, Please keep us updated.
Greg
 
Hey Greg

Ya I have insulated everything from tank to pump ,pump to regulator ,regulator to carb. Don’t have a filter between the tank and pump just between pump and regulator. I should have one at tank I guess.. Tank is new but guess it could have had crud in it still. I had rinsed with some gas before installing awhile back. Will check that out.
Have also been told I should install an electric pump out back but will be last resort ,the good ones are pricey.

Have you had a chance to check out that power glide you picked from me last year? Just wondering if it was decent to run or use as a core?

Thanks for the note back , will check back how things turn out with this crappy issue just to drive drive drive !
 
All fuels except premium have ethanol whose boiling point is much lower than gasoline. Use premium fuel only! Having driven hot rods to Bonneville for speed week several times I became familiar with the issue. If you feel a missing in your engine drop down a gear to keep the revs up. Also fuel line routing is very important. Keep filters well away from manifolds and heat sources.
 
Thank for reply’s

I have been using Shell premium only for quite awhile now . Last weekend I rerouted the fuel line front to back to get away from exhaust tubes. Only thing that is really exposed is the mechanical pump and it’s a brand new Holley . I did make up a temporary shield in front of the pump to deflect heat from rad fan blowing right on it .

As to what Greg said guess I will drop the tank and pull the sending unit to have a look at the sock , maybe it is plugged up with something and it’s not vapor lock but all things sure pointed that way.

Brian
 
An electric pump has to be mounted right at the tank. I know some folks who have both mechanical and electric. They have a switch for turning on the electric when it might be needed. My 454 powered 39 Chevy had an electric pump at the rear. And it went to Bonneville four times…..no issues. My 351w Ford wagon only had mechanical and I had to coax it several times with higher rpm.
 
Ya I’m thinking electric is going to be the way to go. Think I will just have to pawn some of the wife’s jewels and go get one.

thanks for the notes

Brian
 
It has a vented cap but something to check. Maybe be it’s blocked somehow

thanks for heads up on that
 
Even with no ethanol gasoline is not what it used to be. Back when we all had carburetors summer fuel was blended to have a higher vapor pressure to stop vapor lock. Now days with virtually all cars having fuel injection and higher fuel pressures it is no longer blended for higher vapor pressures. Thus vapor lock. Premium is no better than the other grades in this respect.

One way to cure it is with a fuel pump with a return line to the tank. This helps keep the fuel cool enough to stay liquid. Another way is a bypass regulator that will also return fuel to the tank. An electric booster pump also will help. Minimize the rubber fuel line in the system as it holds heat more than steel or aluminum lines. A cool can will also work, but run it before the mechanical pump, and cold water will work fine. Or WSW antifreeze works even better if you are so inclined.

These fixes worked for me.
 
Wow, this thread is very applicable to me as coming home in my new to me '49 I was on the road side for a while with may have been a vapor lock. This gives me more ideas!! Thx!!
 
Update on my issues. Have run new steel fuel line from to back outside the frame away from exhaust pipes installed a new Holley electric red pump which can be run without return , insulated lines where ever close to a heat source. Regulator set at 5 psi because edelbrocks like that.

Went out for a run yesterday car started to run rough after an hour running. Stopped to have a look at filter and it was 3/4 fuel so surmise it wasn’t a fuel starvation issue now . Pulled into garage and it died.

i did find however the coil was dam hot couldn’t touch it hardly . Thinking maybe I have two issues all caused by excessive heat under the hood. Vapor lock which I may have fixed with new lines and electric pump and now maybe coil is on the way out.
 
I have an aftermarket distributor which failed. I got a new one no charge. They omitted instructions the unit had to be on a relay. Same symptoms as yours.
 
I am running a pertronix dizzy. Have the coil power to coil then the two wires from dizzy to coil .

How did you wire in a relay , on the coil power wire to ignition source?
I’m not much of an electrician
 
Talking to a friend who had the same issues but turned out to be an MSD heating up problem. I've always run Pertronics so maybe this MSD is also the culprit?
 
zoomer said:
I am running a pertronix dizzy. Have the coil power to coil then the two wires from dizzy to coil .

How did you wire in a relay , on the coil power wire to ignition source?
I’m not much of an electrician
Click to expand...
The Pertronix would not need a relay.
 
After many stalls a friend called MSD who insisted their product is reliable. They blame it on spikes from an overkill alternator killing their module. So?
 
Funny this came up working on it today. After all the work I did moving fuel lines ,insulating them ,installing electric pump, even moved my coil to under the dash ,trying To find ways to get better air flow under the hood it still stalled out when things heated up.

Was reading an article on engine tuning with a vacuum gauge so made me think I should check my engine vacuum. Well turns out Manifold vacuum was only 5. So decided to,play with timing to see how it affected vacuum. Kept rotating the dizzy to increase vacuum. Ended up with rpms at about 1200 ,Timing at about 28 to get to 18in of vacuum. Engine smoothed right out from where it was shaking and me thinking it was just the cam doing it . so lowered the idle screw down to about 800 and it seems to like it there. Goes in and out of gear without stalling too. YEA!

So figure all this excessive heat in the engine room was due to the really retarded timing . Have no idea why it ran the way it did. Either the timing pointer is the wrong one or the damper numbers are not right for my motor so will get a timing tape for the damper and find true tdc and go from there. Other wise it is running pretty good today and have put about 40 miles on it without a stall what so ever. Motor even run cooler at 170 it was at 190 . I can touch everything under the hood now as before I couldn’t because of the heat.
So fingers crossed I will be good now
 
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