1972 Beetle Loses Power at Sustained High Speed / RPMs

Hi all.

Bear with me, I'm brand new to this.

I have a 1972 Beetle that I recently bought. It has run perfectly until a few days ago when it stalled on the freeway. I was eventually able to limp home, and I replaced the fuel filter, which looked like it might be clogging, and cleaned the screen in the fuel pump. It ran fine the next day until I was driving home and got on the freeway again; it died in the exact same spot. This time I could not start it and had to tow it home.

I replaced the air filter and opened up checked the carburator, which seemed to be in normal working order (nothing obviously wrong with it, anyway, but this is the first time I've looked at one, so what do I know?). At this point it would start, but stall after a couple miles and need to cool down in order to start again.

Finally, I broke down and took it to a mechanic. He found a bad valve and fixed it, claiming that was the cause of my problem. He also did a general tune up, replaced the plugs and points, and replaced the condenser, which he said was the wrong part. The car was running great when I left there.

Unfortunately, within a minute or two of getting on the freeway, it stalled again. It was definitely better than before, and I was able to get off the freeway and drive normally on surface streets to my destination.

Basically what happens is I get up to speed (around 65-75 MPH) and ease off the gas, at which point the engine seems to misfire a bit and lose power in spurts. I respond by giving it more gas, and it loses power altogether, and the engine dies as soon as I take it out of gear. After sitting for a few minutes, it starts again but runs rough and quickly dies again when the RPMs get high.

It seems like a carburator problem to me, but I am at a loss as to how to correct it. Any ideas or suggestions would be greatly appreciated.

Thanks, lukas

Reply to
lsimonis
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Could be overheating. When it happens, does the engine seem hot? Can you pull the dipstick and hold it in your bare hand while you check the oil level? Is there enough oil? Are the engine bay tin and seals in good shape / in place? The engine bay must be sealed, NO air must enter from under the car. Very often there's tin pieces or seal missing, and the hot air from the exhaust system rises up into the engine bay and finds it's way into the fan... and hot air won't cool the engine enough.. the engine then starts overheating, and thus producing even more hot air, and making itself run even hotter... and soon this it will die.

Jan

Reply to
Jan Andersson

It does indeed sound like a fuel problem (but maybe not carb itself).

Troubleshooting this kind of problem is tough even for the experienced.

If it were mine, I would want to know if there is fuel in the carb bowl when it dies. This will tell you where to go next and beats by a mile the "let's change this part and see what happens next" approach.

You could also check to see if there is spark when it dies but this does not produce as clear cut an answer.

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How deep into this do you want to get? It's possible to check the carb fuel level but there are dangers involved with a hot engine.

You can observe the accelerator jet discharge as the throttle opens and this will *sometimes* tell if the carb has fuel or not.

Some less direct approaches: If this is a Standard Beetle, there is a mesh screen in the fuel tank outlet. These get clogged after, say, 34 years. You can remove the screen but the tank needs to be near empty. Possible to view the screen by taking the fuel gauge sender out.

Super Beetles don't have the screen but may have an in-line filter under the tank.

Next, starvation can be caused by a tank that doesn't vent. Easy test is to go for a drive with the filler cap loosened.

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Well, this may point you in some of the directions I would take.

Speedy Jim

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Reply to
Speedy Jim

Wow, thanks for the quick response and the good advice. Sounds like I might be in over my head, but I'm ready to get my hands dirty.

Jan, you might be onto something with the overheating. There's plenty of oil in there, but it's probably way overdue for a change (I know, I know). I have noticed it gets surprisingly hot (have the third-degree burn on my calf from the exhaust pipe to prove it). I'll change the oil and see if it helps. I will check the seal on the engine bay, too.

Jim, I did check the screen in the fuel pump and it is clear (wish I'd talked to you first, I did it with a full tank and damn it was messy). I'm not confident I can figure out how to check the fuel levels in the carb, but I'll give it a shot. And I'll try loosening the filler cap next time this happens.

I ordered the Muir book and the repair manual, so hopefully I'll be less mystified after I do some reading ;-)

Thanks again. I'll let you know when I sort it out.

lukas

Reply to
lsimonis

A quick way to test the free flowing ability of the fuel system is to use an electric pump hooked up to your feed line at the carb. Just let it pump as fast as it will. If there is any obstruction, fuel flow will be shut off or severley slowed within seconds. If not, its in the carb or fuel pump. Have you checked the coil? It sounds as if it could be a bad coil too.

Reply to
Butthead

I had a similar problem on my 64 back in 1969. It started to miss and lose power at speed. It got so bad we had to stop at a VW dealer and had them check the ignition system. Seemed to run ok for a few miles then the same thing. Pulled into a gas station at the next off ramp and the attendant looked at the engine took out his pocket knife and pulled off the slide on connector on the coil. It had some corrosion on it so he scraped it clean and said he couldn't help us. Well I started it up and away we went. It was still running perfect when I sold it four months later when I left for Viet Nam. Apparently it had built up enough corrosion resistance that when it needed good spark under load it just wasn't getting enough juice to do the job. Check all your connections in the ignition system and make sure they are good and clean. How old are your plug leads. I had a miss under load with my 95 Isuzu Rodeo and when I replaced the plug leads it went away and my mileage improved a mile or two per gallon.

Wes Pearson

Reply to
Wes Pearson

The fix for me was an electric fuel pump I installed under the fuel tank. I never found the exact cause but it never happened in the winter. The group was a big help for me. I got the fuel pump from Auto Zone which had one listed for 74 vw from mexico which has worked fine with 3 lbs rated flow. I also suggest a fuel regulator. The pump cost about $35.00 and the regulator about 25.00. Dennis

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Reply to
Dennis Wik

In my two cases, it was two different things, so bear with me. First was on my '66. The coil started going bad, with a mid throttle miss, which by the next day left me pretty much stranded in the middle of a 4 lane intersection. I had to rev it to the moon in order to get it off the side of the road, that's how often the coil was firing.

2nd was in a '67-'69 bastard of a car. The fuel line from front to rear was clogged just enough to starve the engine on the freeway. I could drive 2-3 miles, and the engine would lose powerr and die. Wait a few minutes, and it could suck enough to get me a another couple miles, then do it all over again. This is where *I'm* leaning as to where your problem lies. What I did to fix it was get a roll of mechanics wire from the HELP section of the auto parts store. Disconnect both ends of the fuel line (you'll have to remove the tank for this). Straighten the wire out and wad up the end to about the size of a small pea. Feed that in the line and make back and forth motions, feeding a little more each time. You'll probably get almost to the outlet on the other end, but most likely not, due to the curve it takes on the way out. Just pull it back out and go from the other end. Once it's clear, flush all the loose crap out with some gasoline and/or compressed air, hook it back up and see if that helps. Put a fuel filter near the outlet next to the tranny so as not to clog the carb with anything that may still be loose or comes loose later. You can get a generic $1 filter from the counter at the auto parts store, or a FRAM G-2 for about $4, which has barbed ends so it's harder to pull off. Use hose clamps in either case.
Reply to
jeckler

Update: I'm going to try replacing the fuel pump. I took it back to the mechanic and we disconnected the fuel line from the carburator to make sure it was getting fuel from the pump. There was a steady flow when the engine was running well, but when the problem was happening it wasn't flowing at all or came out in spurts. I don't think it is clogged, since it flows fine sometimes. So I guess the pump is broken. Too bad, because it is a nice chrome pump, and the replacement I could find on short notice doesn't look as good. Oh well, if this fixes it i can start looking for a better one and replace it later.

Reply to
lsimonis

Keep your nice chrome pump (IMHO). Pumps don't usually work sometimes and then quit for a while, only to have miraculous resurrection later.

I don't think you have exhausted the clogging and/or tank venting possibilities yet.

Speedy Jim

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Reply to
Speedy Jim

More thoughts: A fairly easy test you can do-

Take the fuel line hose off the pump *inlet*. You may have to make some "creative" extension to the hose. Put the hose end in a suitable fuel container.

You should be able to get flow by gravity. If necessary, jack the front of the car up slightly.

Run maybe 1 gallon of fuel out this way. If you get a strong, steady stream that doesn't diminish, then I'll concede that there is no blockage and/or vent problem.

Jim

Reply to
Speedy Jim

Hopefully you have solved the problem by now. I suspect more fuel line crud but don't overlook exhaust damage. If there is a blockage it will restrict flow and cause overheating also. Similar to fuel starvation. Long shot, but check it out also. -BaH

Reply to
Busahaulic

Good thing the mechanic replaced the condensor. I found out the hard way just what a bad condensor could do. Drive a while, (15 to 20 min even) then sputter and die... let it cool... drive a while.. sputter and die... didn't know what it was... but the points were getting burnt too...

Reply to
KWW

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