66 Beetle, Backfiring out of Carb on Acceleration

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wdollie6
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66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sat Sep 04, 2021 9:54 am

My prized 1966 beetle, original 6 volt, 1300 beetle. has developed a backfire on acceleration, out of the top of the carb! I have checked valves (right on), points (right on) and timing (off slightly) and rebuilt the 30 pict 1 carb but no improvement. I have verified fuel flow through the pump and ensured that the acceleration pump on the carb was providing a consistent stream of fuel through the brass elbow in the carb., also ensured it was pointed properly. Nothing I have done has improved the situation.

Help!
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sat Sep 04, 2021 9:56 am

... and yes during the carb rebuild I ensured that I removed the two balls, cleaned and that they rattled upon reassembly..
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Tue Sep 07, 2021 6:13 am

Found the problem, throttle shaft bushing on drivers side was worn out. Sprayed carb cleaner in that area at idle and clearly the bushing is worn, all other areas, manifolds, etc. were fine. So off to Volksbitz for a rebuild. My son and I temporarily put a 30 pict 2 in its place but it is worn as well, functional but sloppy. Unfortunately the 6 volt doesn't manage the 12 volt choke well so it takes a while to come off choke, in reality never does because the choke shaft is sloppy as well, bushing is worn. Idle has been a challenge on this carb vs. the 30 pict 1 which idled well but had a long dead spot during acceleration.

Probably should consider rebuilds of the fuel pump and distributor as well as these have never been touched, the engine ran great from day 1, quite a few years ago now.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Tue Sep 07, 2021 6:14 am

Actually had to look back, purchased her in 2005, time has flown by...
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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Amskeptic
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by Amskeptic » Sun Oct 24, 2021 6:06 pm

wdollie6 wrote:
Tue Sep 07, 2021 6:14 am
Actually had to look back, purchased her in 2005, time has flown by...
Update? My 30 Pict3 is sensitive to crap in the carburetor. Everything is perfect, but the low-end hesitation is noticeable until I clean it out but good.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sun Dec 05, 2021 6:14 pm

Just received my carb back from Volksblitz, looks great, probably install tomorrow, will report in after. I had completed a complete rebuild from a kit I bought from Rock Auto but bushings were so bad, made no difference.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sun Dec 05, 2021 6:15 pm

As part of rebuild cleaned all jets, passages, etc..
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Thu Aug 11, 2022 6:46 pm

Didn't realize I had created this post. I installed the rebuilt carb in December of 21' but never started the beetle until the spring of this year, winter and all. I was also deep into the Fastback project so never focused on checking if the problem was solved, finally today started up the beetle (after addressing a starter issue) and sadly the backfiring out of carb is still there, along with the hesitation upon acceleration from idle.

Last summer I had replaced a rusted out muffler with a new muffler that supposedly fit every beetle from the early 60s through the 70s, I can testify that is not the case. I fought hard to get it installed as nothing lined up, ended up using pry bars, etc. to get it in place. It seemed like the carb issues corresponded with the muffler change, so today after realizing the hesitation and backfiring issue still existed I replaced the muffler with an old good one that I bought with a couple of engines last fall. It slid in place and everything fit up with no pry bars/hammers necessary. Unfortunately even though there were signs of blow by at one of the riser gasketes the change did not solve the problem.

Colin suggested several steps to take, hopefully they will identify and address the issue. Not much summer left here so would like to get it out on the road. In addition it needs to be inspected and registered, ooops.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sun Aug 14, 2022 7:40 am

Okay so made some tweaks suggested by Colin and took off for a 20 mile jaunt, everything was outstanding, ran great! After parking in the driveway and shutting down, I decided to attempt to restart it, no go, starter barely turned over. So now torn between a battery issue and/or a starter issue not sure which direction to go. Seems like the starter wouldn't be impacted so maybe a weak battery or a charging issue? I'll see if it starts this morning while it is cool, if so will check charging voltage at battery to see what the gen output is.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Wed Aug 17, 2022 8:15 am

To address the above I removed and cleaned both the battery and chassis ground straps as well as the landing areas. Took the car on a long run and same issue when I returned, barely turned over on attempted restart. The good news is for whatever reason my intermittent no start issue seems to be gone, probably a result of finally running it consistently for the last week or so.

My plan next is to check timing and valve adjustments again to take that off the list. Also since the battery is almost 5 years old I'm going to replace that as well, would love to find an AGM 6 volt battery that would fit in that space. Yesterday when I cleaned the ground strap for the battery I found a pile of acid residue below the battery and yup it had eaten two holes in the metal I had replaced when I redid the floors and eon ago. Cleaned that up, fixed, then recoated with Master Series; two coats silver, one coat black, hopefully that will be a little more resistant to the acid. Need to find a plastic container of some sort for that area.

So the hot start issue continues, hopefully it is just the battery but still haven't ruled out the switch or the starter. Thoughts?
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Wed Aug 17, 2022 8:20 am

Ooops, should not have said "no start issue", should have said "no turnover of starter issue".
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sat Aug 20, 2022 10:22 am

Replaced battery this morning with standard, old school battery, apparently 6 volt AGMs not available at this time. Not sure if that is because of supply chain shortages or if they have stopped producing them because of demand. I also have my eye on a 2 gallon plastic gas tank that nicely slips under and around the battery itself, will have to cut the top off of course.

The battery change has made all the difference, came back from another 20 mile run, shut it down and immediately attempted a restart, immediately came to life, hadn't been able to do that in a long, long time. When they tested the old battery at NAPA they wondered how it was starting the car at all. Its always the simple things! That being said the ground cables needed to be cleaned and shined, the muffler needed to be changed and the ignition switch is still questionable.

I also now have a split second hiccup that I will need to identify. First step will be checking the fuel filter underneath in the front. Recently I have been unable to start my chainsaw and lawnmower which have never troubled me before, I drained the gas put in new and they were fine again. Strange thing was that all my storage tanks were empty this spring, after filling them up all had newer gas. Bad gas from the station, who knows. I'll advise once I have determined the cause of the hiccup. Other than that she is running like a top at this point.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Fri Aug 26, 2022 7:00 am

Okay, another problem cropped up last night when attempting my first night run with the 6 volt headlights, mind you the bug has been running great since the other issues were cleared up. Driving along at dusk, pulled the headlight switch out and the car started running a little rough, turn of the headlights and it was fine again, what? I attempted to see if the wipers had the same issue, not the case, could turn those on with no bucking of the car, what? Is this a headlight switch issue (original switch) or generator/regulator or something else? When I rebuilt the car I had put in a brand new harness so can't believe the wires are a concern.

If anyone has experienced this before please advise.

Thanks.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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wdollie6
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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Sat Aug 27, 2022 8:19 am

Also forgot to mention that the generator light works (turn on ignition both oil and gen lights work) but does not go on during the the time these issues are occurring. Not sure what that tells me but I am sure some one has experience with this. Also I have checked all related connections in the light circuit and everything was tight and shiny except of one of the low beam wires at the fuse, which I corrected. I will run voltage drops at the light switch to determine if it truly is a switch issue. Lights off I am running about 6.24 volts at battery, lights on it drops to 6.08 or so. Interestingly enough at the fuses the voltage for the low beams are a full volt less while high beam drops it to 4.8 or so, so losing voltage someplace along the line. Again probably the switch as all other wiring is newish.

Thanks in advance for thoughts and help. I will advise once I have readings at the light switch.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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Re: 66 Beetle, Backfiring out of Carb on Acceleration

Post by wdollie6 » Wed Aug 31, 2022 6:36 am

After contemplating next step I decided to disassemble my old rectangular switch, because well, why not. Good thing I did as one of the internal rivets had fallen out, not sure where it goes, and one of the small springs was sitting loose in the switch (might have been when I opened it up?). In reality other than those two issues it looked reasonably good.

In order to drive the beetle I decided to take the power wire from the light switch and directly connect it to the wire from the ignition switch, via a double spade, wow what a change. It sounded and felt like a 12 volt beetle, cranking power was up, immediate start, etc.. Not sure if this means the headlight switch was bad, however it certainly made for a significant change

Will be receiving new switch today so we'll see if it performs the same way. Since none of the lights were hooked up I am also wondering if the improvement could also mean that one of the downsteam devices is challenged. Once I have installed the new one will move my testing to the blinker and high/low beam relays to see if they have similar problems.
1972 Superbeetle Convertible
1972 Westy Bus
1972 Beetle
1970 Fastback
1966 6V Beetle with Sunroof

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