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.
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
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
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
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..
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