vapor lock

[opelgtmaster3]

on monday i was drivering and the car acted like it was going to die. it did it several times. so i pull over and let it run for a few minutes. and it claered up. so i stat to drive agian and the car just died. so i sat in the 102 degree
weather and in the sun for two hours trying to getthis car stared. then i look in my rearveiw mirror and my friend pulls up. he came up to me and sayed let me guess vapor lock. i said yeah. and he says me too. it just deid over at the corner of the street and i say you you so i coosted over here. now what are the odds of two car vapor locking right next to each other. how can you prevent vapor lock from happening.
thanks aaron

[kwilford]

Originally Posted by opelgtmaster3 how can you prevent vapor lock from happening?

Live in Canada?

[opelgtmaster3]

i wish i could. but i live in pueblo colorado. and i have to get out of the navy before i could live where i want

[kwilford]

Originally Posted by opelgtmaster3 i wish i could. but i live in pueblo colorado. and i have to get out of the navy before i could live where i want

Hmm. There's a navy in Colorado? Which way to the ocean?

OK, enough jocularity. We get vapour lock in Canada, but this week, it's been a bit cool here in Calgary. Something to do with losing the Stanley Cup in the 7th game, when we almost had it won in game 6

Vapour (vapor for Americans) lock is quite common in older carburetted cars, and especially GT's. The gas tank strainer gets a bit plugged, the gas line that runs in front of the engine gets too close to the hotter engine parts, the heat shield gets removed from below the carb, and the gas wants to become a vapour more than a liquid. Which is hard for the fuel pump to pump, and also hard for the carb to properly mix and deliver to the engine. Common solutions? Re-install the heat shield, and also the thick carb gasket (reduces fuel boiling in the carb bowl). Re-route the fuel line away from the front of the engine, and away from the radiator, and also cover it in an insulating sheathe (Otto, aka tekenaar, has posted some photos of his solution). Another good solution is install an electric fuel pump back near the gas tank. The "sucking" that the mechanical pump has to do in order to pull gas all the way from the tank can exacerbate vapour lock, so putting the pump closer to the tank helps a lot.

Any other suggestions?

[bosco]

Good reply Keith,
Its been at least 108-110 on several days this year and I've had no vapo(u)r lock problems yet, nor have I had much uneven running after restarting a hot engine. I'm using the heat shield, the thick carb gasket and insulated fuel lines where they run near the front of the engine. I've also installed a sprint exhaust which I think makes a BIG difference in hot weather.

[opelgtmaster3]

i've been to calgery, and i went to the bobsled palce and saw the jamaca bobsled.
i do have a electric flue pump buts its in the engine compartment. i didnt put it there, the guy i bought the car from did. so where can i get that insolation stuff? the reason i live in colorado is because im in the delayed entery program. so i leave to boot camp in december 1st. i go to the great lakes naval base for trainning than im off to pencecola florida for school.
i also have the heat shield for the carb and the thick gasket.
thanks aaron

[greensmurf20]

the best way i've found to route the fuel line is to go from the fuel pump, and all away below the motor on the crossmember. just let the line fallow the crossmember and run the line back up the inside of the wheel well on the passenger side and from there to the carb, keeps the fuel line far away from the engine. also heard some of the local hillbilly mechanics say a wooden clotheline pin clamped on the fuel line about 2 feet from the carb somehow cures vapor lock.....can't speak for its effectiveness, never had the chance to try it. dont sound logical, but some of the weirdest most simple things work.

[tekenaar]

Originally Posted by greensmurf20 the best way i've found to route the fuel line is to go from the fuel pump, and all away below the motor on the crossmember. just let the line fallow the crossmember and run the line back up the inside of the wheel well on the passenger side and from there to the carb, keeps the fuel line far away from the engine. also heard some of the local hillbilly mechanics say a wooden clotheline pin clamped on the fuel line about 2 feet from the carb somehow cures vapor lock.....can't speak for its effectiveness, never had the chance to try it. dont sound logical, but some of the weirdest most simple things work.

You have "local hillbilly mechanics" in MI?!!!

Are you using a metal can fuel filter? You'd be amazed at how much underhood radiated heat they absorb, exascerbating your problem. Use a plastic, see-thru filter.

In a GT, the fuel pump doesn't actually have to "suck" fuel from the tank, as long as the tank sock isn't plugged up. This is immediately obvious if you ever remove the tank fuel line at the pump . . . it will completely drain your tank, if not plugged. A partially plugged tank sock WILL, however, contribute to "vapor lock" because then the pump does have to suck to produce the volume required at higher engine RPMs.

Since the tank fuel line is nylon, it doesn't readily absorb heat and isn't really a contributor to your "vapor lock" problem, per se. "Vapor lock" in our Opels occurs primarily between the mechanical pump and the carb because all the stock metal parts, fuel line and fuel filter, are exposed to radiated underhood heat.

My completely stock '69 Kadett is the only Opel with which I've ever had a vapor lock problem. I cured it by replacing the metal can fuel filter with a plastic one and wrapping the steel fuel line with wire loom plastic. Haven't had problems with it since . . . even in Texas heat!

[bosco]

So is there a two outlet (for 73 GT) plastic filter?? I can imagine it would be alot cooler than the metal one.

[opelgtmaster3]

there is a two outlet plastic fliter. i have one right by the carb. but when the car vapor locked i took off the fuel line that goes to the fliter and i turned on the key (because i have an eletric pump) and no gas came out of the line i took off the airfliter and the carb was dry and so was the fuel filter.
thanks for the help guys.
aaron

[oldroadiedog]

I'm going to re-start this thread and see if what my '72 Opel is experiencing is vapor lock or not. This car is recently re-built with a 32/36 DGEV Weber. When cold started it fires right up but after having been driven a while, turned off (like to fill up with fuel) it can be really difficult to start. Repeated cranking will finally get the car to start but I've got to work the gas peddle pretty hard. Posts indicate that vapor lock occur while driving but I haven't seen this. It does have a electric fuel pump mounted on the drivers side frame rail just before it rises into the engine compartment (per instructions). After the pump there's a in-line glass type fuel filter which goes next to a short segment of flexible fuel line to the stock metal line around the front of the engine. I've got a fuel regulator before the carb set at 3 PSI.

I need to correct this problem so my wife can enjoy an occasional drive and to prevent undue wear and tear on the starter.

Han

[Willy_g77]

Originally Posted by oldroadiedog I'm going to re-start this thread and see if what my '72 Opel is experiencing is vapor lock or not. This car is recently re-built with a 32/36 DGEV Weber. When cold started it fires right up but after having been driven a while, turned off (like to fill up with fuel) it can be really difficult to start. Repeated cranking will finally get the car to start but I've got to work the gas peddle pretty hard. Posts indicate that vapor lock occur while driving but I haven't seen this. It does have a electric fuel pump mounted on the drivers side frame rail just before it rises into the engine compartment (per instructions). After the pump there's a in-line glass type fuel filter which goes next to a short segment of flexible fuel line to the stock metal line around the front of the engine. I've got a fuel regulator before the carb set at 3 PSI. I need to correct this problem so my wife can enjoy an occasional drive and to prevent undue wear and tear on the starter. Han

im having the exact problem. i recently put a rebuilt weber 32/36 on my gt. and it will start and run like a champ. then if you shut it off of just a second it will fire back up. but if i park it and get gas and go in and pay and come back out it will be a pain in the butt to get started.

[baronbors]

Originally Posted by Willy_g77 im having the exact problem. i recently put a rebuilt weber 32/36 on my gt. and it will start and run like a champ. then if you shut it off of just a second it will fire back up. but if i park it and get gas and go in and pay and come back out it will be a pain in the butt to get started.

I too had the same problem - I hated to drive it on an errand and turn it off because of the continuous cranking need to re-start but since installing an electric fuel pump and electronic ignition, the engine has started each and every time immediately. Pertronix RULE!!!

[oldroadiedog]

Part of the engine re-build included electronic ignition (not Pertronics though) so I'm inclinded to think that there's plenty of spark and good timing. There's something going on with the fuel and/or carb. I may try and insolate the metal line at the front of the engine as an earlier post suggests.

Han

[Dmcbrass]

I have a similar problem with my GT. In warm weather, the engine floods after setting for a few minutes. I also have a Weber 32/36. I have come to the conclusion that the gas boils in the bowl and then overflows into the intake manifold. When I return to the car I smell gas and the only way it starts is to push the gas to the floor and crank the engine. I have thought about lowering the float setting but am hesitant due to the fact that the engine runs really well. I am beginning to believe that this is a design issue with the Weber 32/36. I've never seen a Solex do this. It could be a combination of float setting, ambient temperature and a carb design that is somewhat prone to this problem. I have run the car with and without the heat shield and get the same results.

[Willy_g77]

i just added pertronix with flamethrower coil and this problem still occurs. im still using mechanical fuel pump. i am stumped! not like that is hard or anything .. but... this is the only problem im having with the gt right now. any cures for this?

[oldroadiedog]

If the gas is boiling in the carb bowl as Dmcbrass suggests then what if a small fan were mounted to bowl cool air on the carb? Ducts could pull the air from either below the engine compartment or from the nose area. I got this idea after looking at a '80 280ZX which has a blower fan to cool the fuel injectors. In that case, the duct draws air from the under the passenger side of engine. The fan is mounted on the head and then leads to a molded plastic duct that splits and flattens over the top of the valve cover to shoot air on the injectors. So maybe reverse the mounting on the Opel GT to draw from drivers side. There's an example at a used car lot near-by. If members are intersested maybe I can get some photos unless someone else has some already.

[soybean]

When I replumbed the Brown ones fuel lines to 5/16 steel lines and used an electric fuel pump, I also put a two row oil cooler from Summit Racing in the front tunnel. It's in front of the radiator by about 2 ft and seems to help keep the fuel cooler. Did you keep the heat shield on the carb? Jarrell

[oldroadiedog]

If that's a question for me... yes, I do have the heat shield. The carb fan is just an idea at the moment. Stolen from the Datsun engineers!

I do have an electric fan in front of the raditor in addition to the stock fan. It would probably be worth experimenting on leaving that running for 5 or 10 minutes to push the hot air out of the engine compartment after turning off the engine. Then see if the carb exhibits the same symtoms on re-start. That will be something I can definitly try this weekend.

[soybean]

Originally Posted by oldroadiedog I do have an electric fan in front of the raditor in addition to the stock fan. It would probably be worth experimenting on leaving that running for 5 or 10 minutes to push the hot air out of the engine compartment after turning off the engine. Then see if the carb exhibits the same symtoms on re-start. That will be something I can definitly try this weekend.

I used an adjustable electric thermostat on mine with the probe, pushed into the upper part of the radiator under the return hose from the engine. On hot days it has run as long as 4 to 5 minutes. The small fan idea might work well. I wouldn't mind seeing a picture of how they have it set up. Jarrell

[oldroadiedog]

Well I think I've confirmed the problem is the fuel boiling over. I went for a nice drive to get the engine plenty warm and then parked and turned off the engine but left the electric fan running for 5-7 minutes. No problems re-starting. The outside temperture was probably 65-70? which probably helped. I like the idea of having a termostat control that fan now.

[soybean]

It's an Advance Auto Imperial adj Thermostat part nos. 226203. Hth, Jarrell

[hrcollinsjr]

I didn't read all of this thread so if I repeat something that you've already confirmed to be okay please forgive me.

It shouldn't be hot enough in TN to be causing a carb boiling problem. I would make sure my float level was set correctly, fuel pump was okay, and the routing of the fuel line was such that I didn't pick up a lot of additional heat directly from the engine and possibly insulate the fuel line once it entered the engine compartment.

HTH,
Harold

[tekenaar]

Originally Posted by oldroadiedog If the gas is boiling in the carb bowl as Dmcbrass suggests then what if a small fan were mounted to bowl cool air on the carb? Ducts could pull the air from either below the engine compartment or from the nose area. I got this idea after looking at a '80 280ZX which has a blower fan to cool the fuel injectors. In that case, the duct draws air from the under the passenger side of engine. The fan is mounted on the head and then leads to a molded plastic duct that splits and flattens over the top of the valve cover to shoot air on the injectors. So maybe reverse the mounting on the Opel GT to draw from drivers side. There's an example at a used car lot near-by. If members are intersested maybe I can get some photos unless someone else has some already.

And here it is fabricated for a 2.4 FI in a GT:

[soybean]

Now that's slick Otto. Looks good and functional as well. Jarrell