Cutting out issue I cant solve. Any advice?

[mabbo]

Hi,

I have a 55 Beetle thats 100% stock and really original. I have a running issue I cant get to the bottom of thats been happening for the last couple of years now and Im struggling to sort - I dont use the car very often and cant seem to find enough time to work on it until its fixed. Im pretty much out of ideas and wonder if any of you guys had any ideas?

The car starts right up, then when I drive its fine for a while but will cut out, usually after around 4 or 500 meters. It feels like it loses all power more than running out of fuel. It usually starts right back up and will then drive fine and then cut out again. It sometimes gets further but I cant get close to a mile without it cutting out. When its running its running perfect.

When I start it, it starts right up and will idle nice - Im pretty sure if I left it to idle it would sit there for hours ticking over but I havent tested it for more than 10 to 15 min.

It used to start up fine then cut out while driving then wouldn’t fire back up until it was left a couple of mins. After a few min it would start up and drive fine, but it seems to have stopped doing that now and starts right back up.

I thought it was the coil or condenser breaking down so I fitted a new condenser and a used 6v coil from my friends truck. This is the next thing to try just in case iv replaced one bad coil with another. Ive also fitted a new distributor cap, rotor, points and I put a set of plugs in it. I havent replaced the leads but I have tried replacing the one from coil to cap. Ive also fitted a temp wire from the regulator to the coil as I thought I might have a faulty coil or issue with the wiring loom. This didnt help either. I could try a wire directly from the battery to eliminate the wiring to and connection on the starter… Other than trying that and a new coil and battery, I think Ive eliminated everything electrical?

None of that fixed it so thought it may be a fuelling issue so Iv fitted a known good carb and rebuilt my fuel pump. Neither made any difference. I might take the fuel tank out and reserve tap off to check thats not getting blocked as there was a bit of crap in the fuel pump when I rebuilt that. Other than that the only thing I can think to eliminate from the fuel supply is maybe fit the fuel pump and pushrod from my 58.

Anything else I havent thought of?

Thanks, Neil

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[BBursell]

Blocked fuel line between tank and pump perhaps?

[frenchroast]

Two things I start with:
1. Check the ground strap if you haven't done so already - make sure it's tight and clean. My gti would act flaky like this until I fixed the main ground off the battery.
2. A failing ignition switch can cause this (the electrical connections, not the key cylinder).

P.s., nice bug!

[Torben]

Nice bug.

My 54 VW had the same symptoms last year. It was the wire between the coil and distributor which was corroded internally and didn't conduct the electricity when hot.

Regards

Torben

[VW_Jimbo]

Your description of the issue is of 2 systems failing at the same time. That would be really rare and odd. So, in light of guessing about what is wrong, how about looking at something. I am highly suspicious of the fuel system. But you say it starts right back up. How about, after it dies, take the top cover off of the carb, 6 screws I believe, and check the fuel level. If it is normal level, we can ignore the fuel variable and concentrate on spark. If there is a limited amount of fuel, then let’s look further into why!

Couple item that shot out. Your fuel inlet line looks like it is really close to the preheat tube. Might be a chance for it to boil the fuel inside the steel fuel line and cause it to vaporize. Fits your symptom and time line.

Your choke might be failing, or staying closed. Might check its operation. Maybe the cable has failed and no longer pulls the choke open.

Air cleaner is plugged up?

Honestly, I could write several more items, but testing for spark, immediately after it dies and/or checking the fuel level, really would be the starting point for the direction to go into.

Hope that all helps out!

Good luck!
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Jimbo

There is never enough time to do it right the first time, but all the time necessary the second time!

[Zwitterkafer]

Had similar problem a few months ago. The seal in the fuel tap had swollen and almost completely plugged, causing fuel starvation. The main fuel line was OK, but always a good idea to blow it out to be sure. It doesn't take much crud to mess with the hexagon valves in the fuel pump. Nice Bug!!
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"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[D. Haviland]

[sunroof]

What Jimbo said. When it dies, take off the top of the carb and check for fuel level. Also a quick check for spark is to pull the distributor cap off and rotate the engine slowly past #1 TDC with the ignition on and listen/watch for spark. But I would be willing to bet that the rubber in the fuel tap is swollen shut. Ethanol attacks the old rubber seals. Ask me how I know!

If you find the seal is swollen shut, this would be a good time to replace all the rubber hoses with new ethanol tolerant ones, Very important if you haven't already done it!

Beautiful car BTW, thanks for posting pics.

Don
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Better and better mistakes!

[tcoop1100]

Neil-
It sounds like a clog in the fuel system to me, too. I would check the in-tank filter on the tap and the filter inside the fuel pump, especially if they've never been apart. The filter in the tank will corrode and allow rust flakes from the tank to clog the line back to the pump- something I've dealt with in the past.
Great car, by the way. Drive it more!

Edit: I reread and saw you rebuilt the pump. I guess the tank is about the only thing left.
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Aloha,
Tim
January '57 Sedan, April '64 40hp big bore