I have searched for previous references to "vapor lock" and I found numerous references to the problem, but very few for prevention and fix.
This weekend, we finally had some summer like weather Temp was in the 70's and 80's. I used my 73' 2.0 (stock FI) for running a bunch of errands. The temp guage showed that the oil was warming up, but it never moved very much above the lowest line. I noticed that after my 3rd and 4th stop at stores, I had difficulty starting - it would fire right up, but then it would barely idle regardless of what I did with the accelerator - it would not respond to the accelerator at all. Some of the time it would stall, then I could restart and it would fire right up and run well.
On my way home, when I started up from a stop sign, the engine just died like it was starved for gas. It would not start even though it cranked just fine. It didn't matter what I did with the accelerator. I then did what every good thinking guy would do - I opened the engine lid and stared at it. The engine was still there.
After getting a ride home, I returned about an hour later with jumper cables in case I ran the battery down. I tried starting it first and of course it fired right up!
I am assuming that it is vapor lock, but I don't know how to confirm that.
The question I have is: How do I prevent this from happening again? I do know that it runs fine when the temps are cooler, but I would like to drive it this summer.
The archives mention relocating to the front, but I am very reluctant to do that. What else can I do to prevent this? Once it happens, is the only solution to let it sit for a while, or can I do something to get it going quickly?
Thanks.

Warrenoliver

I had the same problem for a few weeks. The problem was that where the fuel pump was mounted, it had rusted away and the pump was just hanging by the fuel hoses. Not good. I also didn't have the heater boxes and hoses on, so the exhaust heat would hit the pump directly. Check in the engine compartment if there are any fuel hoses in contact with the engine case because this too will cause vapor lock.

What I did if I got stuck somewhere, I would immerse the bottom end of the pump in a cup of water till it cooled down and then I would be fine for 10 minutes.

I have found that this can some time happen when a car is stored for the winter and tank was filled with "winter" formula gas. Not sure why this is the case, but once the old winter gas is ran out and new "summer" formula is used no more vapor lock.

You can also install a hot start kit.

Warren,
That sounds exactly like the problem that I was having several years ago. The temps and conditions you describe don't seem to necessarily indicate vapor lock. My vapor lock problems arise when it's really hot (90+), running hard and with very little fuel in the tank. Keeping the fuel level in the top half of the guage seems to alleviate the problem in all but the most severe conditions.

The problem that I had that was just like you described was attributable to bad intake manifold seals. After replacing them, the car ran fine, idled perfectly and no longer did I have any "hot" starting problems.

The first thing I would do would be to top off the gas tank and see if that improves the driveability in that the "cooler" gas in the tank is less likely to get so hot as to cause vapor bubbles that can "lock" your fuel pump. If that doesn't help, I'd look at the aforementioned intake seals.

Paul

Back in the early 90s when I had my fuel injected 1.7 as well as my wife's Daytona we lived in a desert in Eastern Washington, where it would regularly get over 100 degrees for a week or more at a time. The 914 was my daily driver and I got vapor lock in both cars pretty often so I was able to make some pretty interesting observations. At the time gas was a staggering $1 per gallon (and it hurt!). You could get higher octane from using ethanol, and it seemed like a good idea in the Harley's and the Porsche (keep them from pinging) but I found that it had a lower boiling point and was therefore more prone to vapor lock. keeping the tank over half-full would keep the gas in the fuel loop cooler and allow driving in 100+ weather without vapor lock.

Under the passenger side long, right next to the motor, and in the corner near the firewall is the fuel pump and filter.

If your heat exchangers are all hooked up and the correct hose is connected to the car, and the flapper valve is mounted properly, yo should be ok.

If not, if the heat system is blowing hot air at the fuel pump, you will get pretty good vapor lock.

I do agree, run through what gas you have from winter, go out for a few cold night runs on the highway...dont stop/start the car till you are in the driveway...

Fill up with premium, and change the fuel filter (every year)
Change the oil (moisture from winter storage)

Tune it up and drive it like you stole it.

If it keeps up, learn how to park (we have all learned) park on a hill, learn how to roll start/jump start your car.

Rich

Being a farm boy, I have lots of experience with starting an engine without using the starter. Heck, sometimes I still have to pull start one of my tractors.
If it has vapor lock, will it start? Seems that it won't matter how I spin the engine, if it ain't gettin gas, it ain't gonna start.
I had the Cap'n go over this car before shipment to me. I am assuming that since he replaced all of the lines, he ran them correctly.
I will try the new gas trick.
Thanks for the suggestions.

I live in New England, and its not super hot here...I moved my fuel pump, like the factory did in the later year cars.
The factory had a reason, heat and vapor lock was one of them....
Its a simple thing to relocate the pump.

I also recommend that you remove and clean the distributor, and clean and re-grease the advance plates.
I Always reccomend this...its my favorite $0.05 thing to do...
Every one I have ever seen needs this done.

In hot situations, if this has not been done, it can heat the distributor up enough that the plates will not return to the non-advanced setting after you shut the car down....now you can not start the car...seems like vapor lock, because you will see a good solid spark when you check the plug... but it wont start because the timing is 28 degrees advanced and the motor it turning at 200 rpms...
Next time it happens, see if you have fuel pressure.
Get and inline fuel pressure gauge, plumb it in the engine bay and leave it there for a while...safe and secure..
If it happens and you have good 28-35PSI fuel pressure, then it could be loose FI grounds, they also get affected by high temps.
If you are brave...when it happens again...there is a little 7 or 8mm bolt tapped into the top of the fuel rail (for a fuel pressure tester)
Just take that out, slowly...let the air out..put it back in...off you go.

Or, call the Capn...he could at least tell you what he did, and did not do.
He cant fix everything, it would cost a fortune...so he fixed some stuff..checked that other stuff ( at the time he checked it) was within specs...and sent it home..
These old cars always find new and exciting ways to mess with us...

Rich

replace the fuel filter, get a fresh tank of gas and try again ...

vapor lock only happens when the fuel in the pump/lines boils. it's gotta be pretty damm hot for that to happen ...

just running errands around town won't get you there ...
Andy

Andy,

I agree that it wasn't all that hot here yesterday. Although copared to the temps we had 2 weeks ago it felt damned hot!. Man some of us got farmer tan sunburns!
I will try the fuel filter change and the new tank of gas and see how it goes. Makes me kinda nervous now not knowing if or when it will die again.
Where do I get that fuel filter. Is that something I can get at any FLAPS, or should I order it from Pelican?

Warrenoliver

Most FLAPS won't have it. Don't let them sell you the cheapie clear inline filter, either--it's made for low-pressure carb fuel systems, and the high pressure EFI pump will shred it.

Pelican is one source for the correct part. There are others, of course. Your FLAPS might (or might not) also be able to special-order it...

--DD

I live in a place that commonly reaches 120- 128, no vaporlock. Do check and see

that your fuel lines are not making contact with your engine near tha fuel pump.

Now you are in the rust belt, have you checked the fuel tank for rust? Little pieces of rust can clog

your fuel filter under preasure and fall away when you shut it down. It will then be drawn back after

driving for a while. Been there.

Hi Warren,
I live in Visalia, CA where it get's VERY hot during the summer. I was experiencing vapor lock and this is the advice a member of the "other club" gave me and it solved my issue to this day....

As you know by now your fuel pump and filter are located very close to the passenger heater valve. Go down to Home Depot and buy a small package of the insulation (blanket) that people wrap hot water heaters with...insulation with a "aluminum foil" layer. Now take a piece of this shove it in the cavity near your fuel pump surrounding it completly. That's it!

You can always relocate your fuel pump, like many do, but this member's suggestion worked for me.

I was at a Southern CA Tech BBQ this weekend and my car was on the rack and everyone got a good laugh when they saw the shiny insulation tucked mysteriously up near my fuel pump (comments like...we found your stash...), but hey, it WORKS!
Good Luck...

The best thing to do is a sub-system check, make sure you have quality spark, I assume since I have a V8 the stock EFI system can be checked with a node light, make sure both banks are getting injector pulse. Chassis and engine grounds as well ..... I wouldn't assume vapor lock to fast..

one thing wisc. got that us in ca. dont is HUMIDITY! 80 degrees there can be hotter than 105 here in the central valley when it comes to heating an engine.
p.s. i lived in wisc. the summer and winter of 78'

relocate your fuel pump, it'll be worth it