73 std Beetle (Crusty) Engine Trouble

Morning Guys,

I am having an issue with my stock 73 bug I am working on. The car runs perfect going down the highway for about the first 10 miles. I am normally running about 55MPH. After about 10 miles, the car then starts to skip/sputter and will drop down to about 30 MPH with it floored and eventually slows all the way down until it shuts off. The car will not crank back up until it cools down which is about an hour. My first thought was that rust was getting into my rebuilt 34 PICT carb because the car sat for about 10 years. I have two 34 PICT’s that I have rebuilt twice and swap out on the car and they run perfect on my bus without any issue. I wasn’t sure if there was rust in the fuel pump so I went ahead and put a new stock fuel pump on the engine. I also have new fuel lines on it. I really don’t think either of the carburetors are the issue because the car cranks right up when it is cold and it idles/revs perfect.

My next thought was that I have a bad condenser on the vacuum advance distributor. I went ahead and ruled that out by taking the running 009 distributor off my rail buggy and blocked the vacuum line on the carb. The car still had the same issue and left me on the side of the road. I noticed the Coil was hot so I took a working one off my rail buggy and still got the same results later in the day. I thought I might have a vacuum leak so I sprayed carb cleaner at all the normal places and the engine never changed. Have any of you guys run into an issue like this or have any suggestions?

I had this happen on my 72 as I moved to GA in 1983. Stranded me in WV mountains for an hour or so until I pulled the incoming fuel line off the pump and in the silence of the mountains, I heard a faint rush of air through that hose and no gas was present in the line. Gauge showed tank full so I uncapped the tank up front to look in and the tank actually "burped" at me and gas poured out of the tube in back. Turns out there was a vacuum created and it couldn't pull fluid from the tank. The car cranked up fine and I just left the cap slightly open the rest of the journey.

Thanks for the tip! I didn't think about tank venting. I will have to try that when I get off work. I will let you know how it goes. Does anyone else have any suggestions I could try if the gas tank vent cap doesn’t solve it?

I was thinking the same thing. Try driving it with the gas cap off.

You could also try seeing if the main fuel line through the tunnel is clogged. If it is partially blocked- it will eventually not keep up enough fuel flow. But stop for a while, at it will fill up and run great.....until...... Also, a kink in the braided lines will behaive the same way.
To clean the metal line-
Disconnect the braided lines from it, front and rear, and an old throttle cable (with the pedal end snipped off) will slide through and can clear out any crud.

I was able to work on the car today and the gas tank vent did not the fix the problem. The car is pumping gas without any issues. I replaced the coil again and set the valves and timing. The car was running great. I hit the road and went about 30 miles. The ride was all around 55-60MPH. I thought everything was fixed when all of a sudden the car started to sputter and shut off. I went to the motor and the coil was boiling hot. I sat in a church parking lot for 1/2 hour and the car cranked right back up and I drove it home. I'm thinking the alternator might be sending too many volts to the coil. I put a meter on the + side of the coil and at idle and i read 14.5 volts. Is that around the correct voltage at idle? All my other cars have generators. The alternator does not have a built in regulator. Thanks for the help guys!

That voltage is fine. If it were higher 16-18v then we would have a problem. The thing to check is the resistance across the coil, from terminal 15 to 1 or plus and neg. For 12v coils I think its supposed to be 3 ohms and 6v should be 1.5 ohms. I think thats right it might be the other way. If you get some crazy resistance reading across the coil I'd sit it aside. My coil gets hot but the oil cooler is right behind the coil if its mounted in the stock position. I'm racking my brain as to what this could be. It's obviously a heat realted issue and I'm thinking the fuel pump is hot and causing a vapor lock situation. Do you have a fuel pressure gauge you could check your fuel pressure and see if it is flooding out after the pump gets hot and expands the fuel and causes even higher pressures. Odd issue.

I've also read that sometimes the bakelite spacer/guide that the fuel pump push rod sits in can swell (due to heat) and cause the fuel pump push rod to seize. May want to remove the fuel pump and check that the pushrod moves freely and that it is perfectly straight.

fluxcap wrote:I've also read that sometimes the bakelite spacer/guide that the fuel pump push rod sits in can swell (due to heat) and cause the fuel pump push rod to seize. May want to remove the fuel pump and check that the pushrod moves freely and that it is perfectly straight.

X2. Do you have an electric pump you could run temporarily?

I thought the old original fuel pump might have been the problem to begin with. I had rust/dirt get into the carburetor and clog up my idle jet the first few times I ran the car. I decided I should go ahead and change the pump incase the pump had debris inside it. The car would sputter/shut off with the original fuel pump installed. I have a filter between the pump and the carb and it was always full of gas when the car shut off. The carburetor bowl was also full every time. The car never smelled flooded right after it shut off. I put a new fuel pump and flange on the car this Monday. The rod was straight and it did not have any problems moving in the new flange. I’m not sure what kind of fuel pressure I am getting and I don’t have a tool to test it. I have an electronic fuel pump on another project car that I have never tested. I guess now would be a good time to try it out. I would really like to rule out the carburetor, fuel pump, and tank vent. I’m almost positive they are all functioning properly. I really feel that I have some sort of electrical issue. When the car sputters out and shuts off, I have a very weak spark at the points. When I try to crank it hot, it spins over but doesn’t seem to be getting fire. Eventually the car will smell flooded from trying to crank it so much. Once the coil cools back down, the car has a very nice spark and will start the motor right up. I have tried three coils on the car now and they have all run really hot. I also have two new condensers I have used on it. I will have to get out the ohms meter and see what I’m getting on the coil. I need to go the Advance and buy a coil with a lifetime warrenty . I sure want to get this problem solved so I can start driving the car to work. What do you guys know about external resistors? Do you think that might work or make it run like crap?

Where is the coil getting its power from and a bosch blue coil is your best bet. Advance won't have the correct coil for your application. Aslso what type of dizzy are you running

Your dizzy could be a problem

type4revolution wrote:Where is the coil getting its power from and a bosch blue coil is your best bet. Advance won't have the correct coil for your application. Aslso what type of dizzy are you running

I have a vacuum advance with new points and condenser on the motor right now. To rule the dizzy out, I used a running 009 off my rail. I got the same results with both of them. I would hate to spend the money on a Bosch Blue coil with a chance I might burn it up.

I think maybe the Air Shut off Solenoid could be bad. I had one open up on me going to work and when I came to a stop or pushed the clutch in it would die. But I still had good power.

Does this vw have any battery drain when it sits and where is the coil getting power from

So far, lets get the list up here. You have eliminated (through swapping parts):

Coil
Fuel Pump
Carb
Dizzy (and related electrical)
Tested voltage (anywhere from 13.5 - 14.5 is about what you would expect)

Here is what I would do to eliminate a problem with wiring at the coil. Unplug the factory wires and run a jumper from a 12 volt source and drive the car. Just remember to not leave it on when the car isnt running. Also, while on this test drive, if the car shuts down again and shows signs of weak spark, quickly change the coil out and see if it starts right back up. This is just going to be process of elimination. Another question, is the engine itself getting hot?

Thanks for all the help guys. I have some good suggestions to work from. I was able to check the Ohms on the three coils last night. The readings are as follows:

Coil 1 3.3 Ohms positive terminal to negative 5.7 Ohms Positive terminal to center connection that goes to Dizzy

Coil 2 3.4 Ohms positive terminal to negative 8.3 Ohms Positive terminal to center connection

Coil 3 3.4 Ohms positive terminal to negative 8.0 Ohms Positive terminal to center connection


I’m picking up a cheap new coil today that I will be able to return if I don’t need it. I also wonder if the actual ignition switch in the column might be breaking down and causing the problem. I did build a jumper cable to go from the battery straight to the coil. I did crank the car up that way but I never drove it with the cable. I will have to try this out.

I have not noticed any battery drain with the car. I was out of town for a week and the battery cranked the car right back up when I returned. I will have to check the voltage after it sits for awhile. I got the battery new back in June for my rail buggy. I’m using it in the car since the Buggy is out of order.

I really hope I can find the issue with this car soon. I feel like it could be something so small and stupid.

I had a condensor go out a while back. It would sort of do what you are describing, but it wouldnt go completely dead. It would just run so bad until it cooled off for a few minutes. I also had it happen once with a clogged fuel tank. It doesnt seem that either one of those is your problem. Is there any common items that you are using between the two dizzys? Or are you changing everything when you swap?

macollins105 wrote:Thanks for all the help guys. I have some good suggestions to work from. I was able to check the Ohms on the three coils last night. The readings are as follows:

Coil 1 3.3 Ohms positive terminal to negative 5.7 Ohms Positive terminal to center connection that goes to Dizzy

Coil 2 3.4 Ohms positive terminal to negative 8.3 Ohms Positive terminal to center connection

Coil 3 3.4 Ohms positive terminal to negative 8.0 Ohms Positive terminal to center connection


I’m picking up a cheap new coil today that I will be able to return if I don’t need it. I also wonder if the actual ignition switch in the column might be breaking down and causing the problem. I did build a jumper cable to go from the battery straight to the coil. I did crank the car up that way but I never drove it with the cable. I will have to try this out.

I have not noticed any battery drain with the car. I was out of town for a week and the battery cranked the car right back up when I returned. I will have to check the voltage after it sits for awhile. I got the battery new back in June for my rail buggy. I’m using it in the car since the Buggy is out of order.

I really hope I can find the issue with this car soon. I feel like it could be something so small and stupid.

Get one of those white plastic electrical parts of the switch and unplug the harness off the back of the switch, unlock the steering wheel with your key and leave it in and plug in the new white electrical connector to the wiring harness plug you just removed.
Make sure car is in neutral and parking brake is set.
Take a small screwdriver and gently turn the center of the white electrical connector to the right 2 spots, you'll feel it.
when engine starts dienguage the starter and go for a drive.
If it dies again, then the switch isn't a problem. If it doesn't die, then the switch could be the answer.
At least with this way you'll know before you take the time to tear apart the steering column / steering wheel.
KC

I have some good news on Crusty. I replaced the coil with a brand new one and replaced the wire from the coil to the dizzy. I reset the timing and points and also checked the sparkplug gaps. So far the car is running great. I drove it a lot this weekend without any issues. It is a lot of fun to drive! I am having a problem with my fuel gauge sending unit. The original one was really rusty so I decided to buy a new one. It was a cheap oem brand sending unit. The thing only worked for a few minutes and then went to full and stayed there. I pulled the unit this weekend and there was a hole burnt into it. I pulled another sending unit from a 74 beetle and it worked for a few miles then when I made a sharp turn, it dropped down past empty and won’t go back. I went ahead and unplugged it because I’m a little scared it could possibly cause a fire. Any ideas what might be burning these things up. What is a good replacement unit? Thanks for the help guys!

Glad to hear crusty is alive and well. Best wayy to fix a fuel gauge prob is clean all the ground going to gauge and dsah replace everything sender gauge and vibrator . Make sure no more than 15 volts at gauge cluster with car running and you shound be good to go