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Thu Jun 05, 2008 6:56 am

I have been troubleshooting a problem over the past few days and thought I'd share what I have found so far to see what the experts here think.

My car sputtered then stalled recently and would not start back up. I had to call my wife and have her bring me my truck and tow bar to get it back to the house. The next morning the car started right up.

I went through a normal tuneup just to make sure everything was working the way it should be. I changed the oil, adjusted the valves, set the points, set the timing, and checked with a dwell meter. The condenser tested ok and I was getting a good spark at the coil and at the plugs so I didn't think it was an electrical problem.

All along I thought the engine was fuel starved so I went through the fuel system next. I checked to make sure there was a good gravity flow through the line to the fuel pump. Then I rebuilt both the fuel pump and the carburetor just to be on the safe side. I didn't see any problems with either. I went on a test drive and everything ran fine.

I let the car sit and idle after the test drive and a few minutes later the car started started sputtering, stalled, then would not start back up again. I took the top of the carb off and found that the float bowl was almost completely empty. I went to do a little more research here in the forums went back a while later and the car started up as soon as I turned the key. I decided to take another look at the float bowl and this time it was full.

Both times that my car has stalled like this it has been over 95 degrees outside. Edit: The first time it happened I had driven around town, stopped and parked at the store to get something, started back up, and then stalled shortly after getting back on the road. My guess is that I am having a problem with vapor lock. Does that sound about right? If so, what can I do during these 90 to 100+ degree days to avoid vapor lock. Someone suggested putting foil and/or clothes pins on the fuel line to act as a heat sink. I am open to any and all suggestions right now as I am a little nervous to drive my car for any distance.

Thu Jun 05, 2008 8:29 am

Bill put your fuel filter behind the fire wall tin, 5 to 6 inches away from the fuel metal tunnel line. Also check your your Manifold make sure it= the heat risers are not clogged. In addition, the heat riser gaskets can be the cullprit as well. go to your local hardware store and get some metal flat sheet stalk. not very thick, a little thinner than the heat riser gaskets. cut the sheet stalk to heat riser demension gasket demensions. drill a 1/8 to 1/4 inch hole in the center of the new metal heat riser Gasket then install.

This will allow for proper circulation of heat to the manifold riser Yet not so much as to Overheat and cause either vapor lock or fuel evaperation in the fuel system. Should help your situation Eric

Thu Jun 05, 2008 9:42 am

First make sure you are not getting "vacuum lock". Take the lid of your gas tank, do you hear air wooshing in? If so, put it back on and I bet the car starts.

Some people call that vapor lock, but it is really not. Vapor lock is when the lines get "air" (not really) in them from gas boiling. Yes, it has to get REAL hot for that to happen. It can happen with VWs where that steel line runs along next to #3. But only in real high heat and after getting the engine really hot (like sustained highway run, then sitting in traffic idling). Vapor lock based on your description is unlikely IMO.

I would suspect a fuel flow problem. It sounds like you did a lot of the right things, incl. checking the fuel bowl. Did you pull the fuel petcock? Examine the screen? Sometimes a blockage can enable the car to run well for a minute, but over running time can get worse. I once had a 68 with small twig stuck down in the intake hole at the bottom. It would allow fuel to trickle past, but at a full run would "cork" the hole and shut down the engine.

Check you fuel path end to end, run some carb cleaner through the steel chassis line, and don't assume it isn't your fuel pump even though you rebuilt it.....

Keep us posted...

Thu Jun 05, 2008 10:15 am

I'm not getting "vacuum lock" at the gas tank and the filter in the tank looks clean. I forgot to mention before that I checked those things.

After reading just about every vapor lock thread on the site this morning I think it is vapor lock. The only time that I have had a problem with the car restarting is after driving down the highway and after idling in traffic. Both times it was close to 100 degrees outside and I only have the problem after the engine has sat for a short amount of time turned off. I do think my heat risers could be cleaned out some also. I'll clean them out the next time I pull my engine. I'll post updates as I find out more so that others can use the info when troubleshooting.

Thu Jun 05, 2008 10:23 am

Bill I forgot to mention that, what led me to the problem at hand was infact Dieing at idle and unless i kept the rpm's up on a hot day it would just die. Other than pull my Hair out I wasted many un-neccessary dollars with the fuel system. It wasn't untill an old timer gave me the solution and now where i live in So-Cal is Lower Desert with 120 degree summer days and my trusty 1970 sunroof stock OG 1600 hasn't given me any trouble. Good luck! 8)

Thu Jun 05, 2008 11:41 am

Bill, I had this very same problem a 3 months ago. I have a glass filter bowl on top of my fuel pump so I could actually see the vapor lock happening. The culprit turned out to be the incoming metal fuel line, it was too close to the exhaust manifold/heaterbox where it enters the engine compartment. I just bought a piece of rubber fuel line, sliced it lengthwise and slipped it over the metal fuel line to insulate it from the heat generated by the exhaust manifold. No problems since I've done that. Maybe we'll see you tonight at the 1st Thursdays?

Thu Jun 05, 2008 11:47 am

I had thought about doing that with some hose since some foil and clothes pins would look pretty ghetto. LOL :lol:

Thu Jun 05, 2008 12:18 pm

I would cover up and re-route the line as far away as possible from the heater box. I know this is not an oval but kinda like this...

Just a little bit higher and a sharper bend. Yeah the clothes pins would look a little bit ghetto :lol:

Thu Jun 05, 2008 12:33 pm

Same damn thing just happened to me in my ghia. It was running great then started to behave like it was running out of gas then just turned off. It would turn over but stay on.

I bought an electric fuel pump, installed it under the tank and voilla! Car has been running excellent.

Wed Jun 11, 2008 8:46 pm

this probably isn't your problem but I have seen a LOT of problems with sticking needle valves, especially Viton rubber tipped ones, they stick from new and most aren't even usable out of the rebuild kit, I always reuse known good all steel Solex needle valves, and also check your float where the needle valve contacts the float at the brass tab, the needle valve always wears a dimple into the top of the float and can make the needle valve stick also, these problems both result in an empty carb bowl when you take the top off to look but just taking the top off may temporarly fix it for a while, I use a 3M white plastic bristle disk on a air grinder to polish the float tab whenever it looks the least bit worn at the needle contact point, these two details can make a world of difference in cases of weird stalling problems

Thu Jun 12, 2008 9:45 am

The float does have the slightest dimple in it so that could possibly be it.

Temporarily (until I get some fuel hose to use an an insulator) I clipped on some clothes pins to the fuel line to see if it would actually work as a heat sink. It got up over 100 degrees yesterday and I was able to drive around town, idle in traffic, park, and re-start without any problems. It isn't pretty but in a pinch it seems to have worked.

Thu Jun 12, 2008 9:54 am

billmetric wrote: this probably isn't your problem but I have seen a LOT of problems with sticking needle valves, especially Viton rubber tipped ones, they stick from new and most aren't even usable out of the rebuild kit, I always reuse known good all steel Solex needle valves, and also check your float where the needle valve contacts the float at the brass tab, the needle valve always wears a dimple into the top of the float and can make the needle valve stick also, these problems both result in an empty carb bowl when you take the top off to look but just taking the top off may temporarly fix it for a while, I use a 3M white plastic bristle disk on a air grinder to polish the float tab whenever it looks the least bit worn at the needle contact point, these two details can make a world of difference in cases of weird stalling problems

Bill, how can the dimpled float cause the needle to stick? I'm curious. Do you think it just puts a side load on it or something? Not sure I understand how it could cause the needle to stick...

Fri Jun 13, 2008 10:09 pm

Hi John, I think I may actually have an old carburetor rebuild kit instruction sheet that mentions sticking needles, goes into fuel additives gumming up the needle seat and the worn float contact problem, because of the pitifully low pressures put out by the factory fuel pump any little problem with the float can hang up and cause the needle to stick in the worn spot, depending on the style of needle valve especially the stock old style ones with the smaller tips, once the float gets up to the top there is some sideways load on the needle and the pin sticks in that dimple, eventually under the right conditions it will stick, I'm sure you have seen sticky needles before but the worn spot in the float will just aggravate the problem, this is only going to happen when the car is sitting idling or driving on a very smooth stretch of highway because a good bump will dislodge the float of course, I am not sure if a real split carb would suffer from the float tab sticking since the really early 28 and 26 carbs had the separate brass float and tab thing, I converted mine to a later plastic float though because the brass one was full of holes and didnt look like it was going to work