marauder@fluke.UUCP (Bill Landsborough) (11/22/85)
Im sorry Randle but there is no such thing as "Vapor Lock" in today's automobiles. Vapor lock originated with the gravity feed fuel systems of the Model T era because what would happen is the gas would get close to boiling and bubbles would form in the fuel lines and try to go up as the fuel is trying to go down. The result was a stalemate or what is known as vapor lock. Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble could ever have any effect on it. Vapor lock tends to be the "scapegoat" when the mechanic can't solve the problem.
jeq@ihwpt.UUCP (j quist) (11/23/85)
> Im sorry Randle but there is no such thing as "Vapor Lock" in today's > automobiles. Vapor lock originated with the gravity feed fuel systems > of the Model T era because what would happen is the gas would get > close to boiling and bubbles would form in the fuel lines and try to > go up as the fuel is trying to go down. The result was a stalemate or > what is known as vapor lock. > > Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble > could ever have any effect on it. I've got a '72 MGB that would disagree. One can argue that since the fuel system of a '72 MGB isn't much different from a '58 MGA, the B doesn't classify as one of today's automobiles... Anyhow, I've seen vapor lock on relatively new cars. The conditions: Hot day, clogged fuel filter, and a quarter tank of gasohol. With a full tank, the problem would partly disappear (higher fuel pressure at the tank). Of course, a good mechanic would spot the clogged filter in short order, and not mumble mysticisms about vapor lock. :') Jonathan E. Quist Lachman Associates Inc., at AT&T Bell Laboratories ihnp4!ihwpt!jeq (Does anybody else out there dislike alcohol in your gas?)
gordon@cae780.UUCP (Brian Gordon) (11/24/85)
In article<2922@vax4.fluke.UUCP> marauder@fluke.UUCP (Bill Landsborough) writes: >Im sorry Randle but there is no such thing as "Vapor Lock" in today's >automobiles. Vapor lock originated with the gravity feed fuel systems >of the Model T era because what would happen is the gas would get >close to boiling and bubbles would form in the fuel lines and try to >go up as the fuel is trying to go down. The result was a stalemate or >what is known as vapor lock. > >Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble >could ever have any effect on it. > >Vapor lock tends to be the "scapegoat" when the mechanic can't solve >the problem. WHOA there. Want to come see it on my '83 Dodge Maxivan under load at high altitide in hot weather? The long under-car fuel line gets hot, vaporizes the gasoline and the fuel pump sucks vapor, not liquid. Cool the lines and the problem stops instantly. I'll buy the "scapegoat" observation, but that isn't the same as saying it can't happen! FROM: Brian G. Gordon, CAE Systems Division of Tektronix, Inc. UUCP: tektronix!teklds!cae780!gordon {ihnp4, decvax!decwrl}!amdcad!cae780!gordon {nsc, hplabs, resonex, qubix, leadsv}!cae780!gordon USNAIL: 5302 Betsy Ross Drive, Santa Clara, CA 95054 AT&T: (408)727-1234
tjsmedley@watmum.UUCP (Trevor J. Smedley) (11/25/85)
In article <582@ihwpt.UUCP> jeq@ihwpt.UUCP (j quist) writes: >> Im sorry Randle but there is no such thing as "Vapor Lock" in today's >> automobiles. ... stuff about vapour lock (yawn :-) >> Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble >> could ever have any effect on it. > >I've got a '72 MGB that would disagree. >One can argue that since the fuel system of >a '72 MGB isn't much different from a '58 MGA, >the B doesn't classify as one of today's automobiles... I also have a '72 B, but have never even had the slightest worry about vapour lock. Mostly because I've never been able to get the fuel pump to work for more than 20 consecutive minutes. Anyone want to buy a slightly used, and *very* slightly functional fuel pump? Trevor J. Smedley University of Waterloo {decvax,allegra,ihnp4,clyde,utzoo}!watmum!tjsmedley
tmorris@convex.UUCP (11/25/85)
Heres a major disagreement ! As a former GM tech , let me inform you that vapor lock is alive and well and living in Z-28 Camaros with H.O. engines. It occurs previous to the fuel pump , where the METAL fuel lines are close to the exhaust system. On a hot day , take one of these things out and do several good acceleration runs (like on an expressway ramp in traffic ) . Then when you stop at a light and idle for about a minute , take off and try again. You will RUN OUT OF GAS at about 3500 rpm in second gear. Let off the foot-feed for a second and everything will be ok . IF you test the fuel pump pressure , you will find it to be ok . If you check the fuel flow volume , you will find it more than sufficient. If you move the fuel lines away from the exhaust , it will cure the problem ! Another nasty side effect of poor design is that the car will flood and set a code 45 on the computer after being shut off HOT and restarted after about 15 minutes . I have read fuel pressures that are excessive under those conditions , as the pressurized tank reaches 5 to 7 psi before the vent lets it escape , and then the efficient fuel pump drives it up the rest of the way. The float can't handle it , and the carb floods at idle. Again , moving the fuel lines does it . tmorris@convex ,disclaim,disclaim !
johnbl@tekig5.UUCP (John Blankenagel) (11/25/85)
> Im sorry Randle but there is no such thing as "Vapor Lock" in today's > automobiles. Vapor lock originated with the gravity feed fuel systems > of the Model T era because what would happen is the gas would get > close to boiling and bubbles would form in the fuel lines and try to > go up as the fuel is trying to go down. The result was a stalemate or > what is known as vapor lock. I have no doubt that that is when vapor lock was first seen but even vehicles with mechanical fuel pumps are sometimes prone to vapor lock. Or at least they used to be. My brother has a 1942 Dodge Power Wagon (army type) and he had to install an electric fuel pump because the mechanical one would vapor lock when the engine got hot. I think bubbles would collect in the fuel pump so that the diaphram was pushing against bubbles instead of against non-compressible gasoline. Hence, no gas would get pumped. It seems like my old '61 Dodge pickup used to do that once in a while when I was climbing hills too. All this was at about 7000-10000 feet altitude though so it may be different at sea level. John Blankenagel
childs@fred.UUCP (David Childs) (11/25/85)
> Im sorry Randle but there is no such thing as "Vapor Lock" in today's > automobiles. Vapor lock originated with the gravity feed fuel systems > of the Model T era because what would happen is the gas would get > close to boiling and bubbles would form in the fuel lines and try to > go up as the fuel is trying to go down. The result was a stalemate or > what is known as vapor lock. > > Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble > could ever have any effect on it. > > Vapor lock tends to be the "scapegoat" when the mechanic can't solve > the problem. What is a car of this day? Porsche 914's of the 70's had vapor lock problems that had to be fixed by the re-routing of the fuel line. And a similar problem occurs on the 1984/5 Trans Am, and Camaro Z-28 with the 5.0Liter H.O. engine. This problem cause GM to stop selling the HO engine. The GM problem is like vapor lock, but isn't exactly the same. On warm days, or in high altitudes, the carb has a fuel return line that open prematurly because the gas vaporizes, thus encreasing fuel pressure, thus causing the fuel starvation problem. I do realize that fuel starvation is a symptom of vapor lock, but engineers can create the same problems with more hardware. For anyone interested, owners of above said GM cars, the problem can be fixed by GM (I think for free) by having them put a little fan on the carb to cool the line to keep vapors to a minimum. Other fixes are putting larger fans that always run while the engine is running to keep the whole compartment cooler, take off the trunk insulation, and put a plug in the fuel return line. I don't suggest the last two, but I have had the last three done to my 84 TA and the problem occurs about 1% as often as before. David Childs Integrate Solutions "There's always time to scare the cat."
ron@brl-sem.ARPA (Ron Natalie <ron>) (11/26/85)
> Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble > could ever have any effect on it. > > Vapor lock tends to be the "scapegoat" when the mechanic can't solve > the problem. What about the fuel line going to the fuel pump? 7-10 psi output pressure says nothing about the input. -Ron
marauder@fluke.UUCP (Bill Landsborough) (11/28/85)
In article <94400003@convex> tmorris@convex.UUCP writes: > > Heres a major disagreement ! As a former GM tech , let me inform you >that vapor lock is alive and well and living in Z-28 Camaros with H.O. engines. >It occurs previous to the fuel pump , where the METAL fuel lines are close to >the exhaust system. On a hot day , take one of these things out and do several >good acceleration runs (like on an expressway ramp in traffic ) . Then when >you stop at a light and idle for about a minute , take off and try again. >You will RUN OUT OF GAS at about 3500 rpm in second gear. Let off the foot-feed >for a second and everything will be ok . > IF you test the fuel pump pressure , you will find it to be ok . >If you check the fuel flow volume , you will find it more than sufficient. If >you move the fuel lines away from the exhaust , it will cure the problem ! If you are talking about boiling gasoline in the fuel line, creating air (or what ever byproduct comes of boiling gasoline), and having the fuel pump try to pump that air, then I agree with you. However the misnomer of "vapor lock" is always blamed on the engine heat and its ability to stop the gasoline dead in its tracks before it reaches the carburetor. Thats what people have been blaming automobile failure on for years and if your mechanic tells you that you have vapor lock, you should get a new mechanic. One could have, however, a sealed gas cap which prevents air from replacing the gasoline in the gas tank as it is used. As the vacuum gets greater it finally overcomes the ability of the fuel pump to draw fuel and you have a stalemate; until you remove the cap and then it will run fine.
elf@cylixd.UUCP (Leonard Bottleman) (12/02/85)
In article<2922@vax4.fluke.UUCP> marauder@fluke.UUCP (Bill Landsborough) writes: >Im sorry Randle but there is no such thing as "Vapor Lock" in today's >automobiles.... The fuel line from the gas tank to the fuel pump in my 1982 Dodge 024 is too close to the exhaust manifold and on hot days, after the engine has been running for a while, the fuel boils out of the line when you let the engine slow down to an idle. You then have to wait about an hour (the fuel lines are right on top of the manifold) to let the pressure in the line drop enough for the fuel pump to overcome it. That sounds like "Vapor Lock" to me. Leonard Bottleman RCA Cylix Communications ihnp4!akgua!cylixd!elf All flames routed to the Engineering Group at Dodge.
ems@amdahl.UUCP (ems) (12/03/85)
> Im sorry Randle but there is no such thing as "Vapor Lock" in today's > automobiles. ... > Today's fuel pumps push fuel at a pressure of 7-10 psi and no bubble > could ever have any effect on it. > > Vapor lock tends to be the "scapegoat" when the mechanic can't solve > the problem. Maybe it doesn't qualify as a 'modern' automobile, but I was in an old '53 Dodge pickup (in about '66) in the central valley of California in the summer in 115 degree heat. (That's in the shade and there wern't no shade...) The truck would run fine. But if you shut it off & sat so the heat built up, it wouldn't run. The solution? Put a wet rag on the long metal fuel line to the carb. Ran fine. That sounds like vapor lock to me. The fuel pump may make 7-10 psi, but it depends on a RAPIDLY running engine to do it. Starting is another matter... Then again, our fuel may have a higher boiling point now than then. (BTW, aviation gas is supposedly blended to avoid the lighter volitile components of auto gas due to the potential for vapor problems. Any aviators out there who use auto gas care to comment?) -- E. Michael Smith ...!{hplabs,ihnp4,amd,nsc}!amdahl!ems 'If you can dream it, you can do it' Walt Disney This is the obligatory disclaimer of everything. (Including but not limited to: typos, spelling, diction, logic, and nuclear war)
marauder@fluke.UUCP (Bill Landsborough) (12/04/85)
In article <538@cylixd.UUCP> elf@cylixd.UUCP (Leonard Bottleman) writes: >In article<2922@vax4.fluke.UUCP> marauder@fluke.UUCP (Bill Landsborough) writes: >>Im sorry Randle but there is no such thing as "Vapor Lock" in today's >>automobiles.... > >The fuel line from the gas tank to the fuel pump in my 1982 Dodge 024 >is too close to the exhaust manifold and on hot days, after the engine >has been running for a while, the fuel boils out of the line when you >let the engine slow down to an idle. You then have to wait about an >hour (the fuel lines are right on top of the manifold) to let the >pressure in the line drop enough for the fuel pump to overcome it. > >That sounds like "Vapor Lock" to me. > > Leonard Bottleman > RCA Cylix Communications > ihnp4!akgua!cylixd!elf > How can fuel be stuck in an open ended tube? As long as the fuel pump has fuel and it is working right, and the float is not stuck, the float bowl will call for fuel(because the float bowl is empty) and the fuel will be delivered. There is no Vapor Lock possible. What does sound more likely in your case is a defective float bowl needle and the fuel is forced past it and floods your engine so you have to wait for an hour to start it. I am finding that people are insisting on calling the inability for a fuel pump to pump air as Vapor Lock, however the original Vapor Lock was when gas bubbles would boil and FORCE the fuel to stop. None of the responses have talked about gas bubble FORCE. I do agree that air in a fuel pump can stop gasoline delivery and that gasoline can be boiled by hot exhaust pipes creating that bubble before the fuel pump. If you prefer to call that Vapor Lock then so be it. Bill Landsborough ---- "Love is patient and kind; love is not jealous or boastful; it is not arrogant or rude... Love bears all things, believes all things, hopes all things, endures all things." 1 Corinthians 13:4-7
elf@cylixd.UUCP (Leonard Bottleman) (12/06/85)
In article <2937@vax4.fluke.UUCP> marauder@fluke.UUCP (Bill Landsborough) writes: >In article <538@cylixd.UUCP> I write >> >>The fuel line from the gas tank to the fuel pump in my 1982 Dodge 024 >>is too close to the exhaust manifold and on hot days, after the engine >>has been running for a while, the fuel boils out of the line when you >>let the engine slow down to an idle. You then have to wait about an >>hour (the fuel lines are right on top of the manifold) to let the >>pressure in the line drop enough for the fuel pump to overcome it. >> > What does sound more likely in your case is a defective float bowl >needle and the fuel is forced past it and floods your engine so you >have to wait for an hour to start it. The first time this happened to me, I disconnected the fuel line going into the carb. and there was NO fuel at all. I then turned the engine over for a while, and still no fuel from the pump. I even went so far as to remove the gas filter, in case it was blocked, but I still didn't get any fuel when I turned the engine again. >I do agree that air in a fuel pump can stop gasoline delivery and that >gasoline can be boiled by hot exhaust pipes creating that bubble >before the fuel pump. If you prefer to call that Vapor Lock then so >be it. >Bill Landsborough Ok, my car doesn't suffer from Vapor Lock, it suffers from gasoline being boiled by hot exhaust pipes creating a buble before the fuel pump :-). It's still annoying! I guess it serves me right for buying a Dodge. Leonard Bottleman RCA Cylix Communications ihnp4!akgua!cylixd!elf