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Volfandt
Samba Member
Joined: March 15, 2012
Posts: 500
Location: Knox County, East TN
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 Posted: Tue Oct 01, 2013 6:03 am Post subject: |
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Back in the beginning of summer IIRC I had a similar hot start problem on my basically stock 1600DP w/a 34PICT/3.
Cold starting was fine but hot restart got so bad I'd leave the engine idleing on short interval stops.
Performance started suffering as well as it was starting to die at stops so I finally decided to troubleshoot/repair.
In my case the problem ended up being a bad carb float. It was about 1/4 filled w/fuel which made it too heavy to completely close. I could see fuel percolateing down the venturi after shutdown.
I replaced te float, readjusted the carb w/a vaccum gauge and haven't had a performance or restarting problem since.
Now my hot start procedure is to not touch the pedal, engage the starter and once the engine "catches" I give it gas. Normally it fires right up.
In the rare cases when it doesn't I'll stop cranking, give the carb a squirt (by depressing the pedal) then crank again, this gets it going.
I'm running a larger main jet which makes the engine run on the rich side when idleing and at low speed. This may contribute to it starting better but I haven't tried to narrow it down any further since I'm happy with the starting and running at this point 
Dave
_________________
1972 Karmann Ghia, the Dragon slayer.... |
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KGCoupe
Samba Member
Joined: July 01, 2005
Posts: 3580
Location: Putting the "ill" and "annoy" in Illinois
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| Posted: Tue Oct 01, 2013 6:46 am Post subject: |
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| davidw99 wrote: |
| Had the same problem. Having the valves, points and timing spot-on helped but did not solve the problem. Even tried to hunt down that elusive, mystical "vapor lock" problem. Ends up I had a bad coil. Did know until it finally went but I think it was sub-par out of the box. New coil and no problem starting when hot. It never was a vapor lock problem since the car would flood trying to start it. On a stock car I think vapor lock is an incorrectly over diagnosed cause. These cars would never have sold if vapor lock was as prevalent as one would think by reading this board. Just my opinion. I guess my point is that the cause of a hard hot start can be a myriad of different things. I never would have suspected the coil although I did see it mentioned by a poster in one topic on this forum as a possibility. Apparently the problem can surface when the coil gets hot. I'll let someone else explain why that is. |
For anyone else experiencing a similar issue, perhaps heating the coil with a hair dryer (or heat gun if you have one) when the rest of the engine is cold could be a good way to confirm or eliminate the coil as the problem.
When I worked as an electronics tech, we often used a heat gun or a can of freeze spray to isolate bad components. |
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Altema
Samba Member
Joined: June 20, 2010
Posts: 2904
Location: Lower Michigan
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| Posted: Thu Oct 03, 2013 9:54 am Post subject: |
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| davidw99 wrote: |
| Had the same problem. Having the valves, points and timing spot-on helped but did not solve the problem. Even tried to hunt down that elusive, mystical "vapor lock" problem. Ends up I had a bad coil. Did know until it finally went but I think it was sub-par out of the box. New coil and no problem starting when hot. It never was a vapor lock problem since the car would flood trying to start it. On a stock car I think vapor lock is an incorrectly over diagnosed cause. These cars would never have sold if vapor lock was as prevalent as one would think by reading this board. Just my opinion. I guess my point is that the cause of a hard hot start can be a myriad of different things. I never would have suspected the coil although I did see it mentioned by a poster in one topic on this forum as a possibility. Apparently the problem can surface when the coil gets hot. I'll let someone else explain why that is. |
Glad you found the cause of your specific hot start issue, as there are many that could affect a car, including a bad coil, starter, stater solenoid, and so on. On the perfomance cars I worked on, many of them had the coil bolted to the top of the intake manifold, and one thing I would do is move it off the engine to make it last longer. Heat breaks down the internal components and they no longer work reliably when hot. On my own 12 second daily driver, the headers wrapped around the starter and caused it to overheat, so I had to let it cool off for about 10 minutes before restarting in the summer. It was not a problem in the winter though... 
I've had lots of parts be bad or substandard when new, unfortunately, including the battery in my current daily driver. Always had to get a jump if the car sat more than a day. They tested the battery and it had full voltage, but only 45% cranking capacity. The new warranty replacement of the same brand and model battery works great, and the car can sit for a week now (while I drive the Ghia, lol) and fire right up whenever needed.
I know that my coil is good, and saw first hand as fuel was dripping into my intake manifold. VW was well aware of this specific problem affecting their design, and they spent extra money to deal with it. The fuel pump is just in a bad position when it comes to heat. |
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akear
Samba Member
Joined: August 18, 2013
Posts: 359
Location: Los Angeles
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| Posted: Mon Jan 13, 2014 7:37 pm Post subject: |
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| I have this problem too. It was in the 80s in LA today (sorry rest of the northern hemisphere), and after parking the car for 30 min or so it would not start and was definitely flooded. It did this before on a warm day and always takes a few cranks to start when warm (even with pedal to the floor). So I understand the bypass solution here, but is that really fixing the problem? I have the 30/31 PICT replacement carb and replacement fuel pump, but doesn't everybody with a "stock" engine have these or similar replacement parts? Is everybody putting in the bypass?? I wonder if this isn't just masking another problem with the carb or pump. I'm also questioning if more fuel lines and fittings in the engine compartment are such a good idea. I'd appreciate any additional advice. Thanks. |
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ccihon
Samba Member
Joined: September 12, 2012
Posts: 227
Location: Columbus, OH
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| Posted: Tue Jan 14, 2014 5:54 am Post subject: |
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I was OP of this topic - so can report my solution was not to add additional bypass etc but to replace the common-style pump with an original Pierberg unit that seals outflow when the engine is stopped. I verified using a pressure gauge that the line between pump and carb remained pressurized with the first pump, but drops to zero with this one. Makes sense - there is a valve and seal in the top of the pump, and I think a built-in path for pressure to relieve back to the tank side. I also have the H30/31. As others have suggested, make sure also you have good strong spark, timing and valves set to spec before chasing fuel issues.
Since changing this I have had no issue, although I hold the pedal to the floor for hot starts every time. It will be a while before we will see more hot starts in Ohio, though. |
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akear
Samba Member
Joined: August 18, 2013
Posts: 359
Location: Los Angeles
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| Posted: Tue Jan 14, 2014 6:22 am Post subject: |
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| Thanks, ccihon. It makes sense that if there is no cutoff in the new replacement fuel pumps, the best solution is to go back to the original. I will try that. Ignition is also on the list, as I have the 009, and while the car runs well, I suspect it would run much better with an SVDA, and I might as well throw in a new coil while at it. I will do these one at a time though to isolate changes. |
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akear
Samba Member
Joined: August 18, 2013
Posts: 359
Location: Los Angeles
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| Posted: Tue Jan 14, 2014 9:51 am Post subject: |
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| Wow there are a lot of different versions of Pierburg pumps advertised in the classifieds. Some say for 36hp, some for 40, some say for all. Seems to be two basic differences in design ... One with a cylindrical top and one with a wavy top. Is there a good reference for explaining the differences and which is correct for a 1600? Thanks. |
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ccihon
Samba Member
Joined: September 12, 2012
Posts: 227
Location: Columbus, OH
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| Posted: Tue Jan 14, 2014 10:09 am Post subject: |
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The original Pierberg pump can be hard to find and often needs a rebuld kit - also hard to find quality kits. I think the original for your car would have had a "square top" - here is a brazilian copy - might offer what you want but I mostly link it because it is a visual duplicate of the one I have:
http://www.thesamba.com/vw/classifieds/detail.php?id=693414 |
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ccihon
Samba Member
Joined: September 12, 2012
Posts: 227
Location: Columbus, OH
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| Posted: Sun Jun 01, 2014 3:10 pm Post subject: Again! |
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Resurrecting my own old thread as the warm weather has brought the return of my issue.
Actually, I can generally start the car hot - what I am experiencing now is different. After two recent trips in 80-plus weather, I have had a consistent issue I need some advice on. In both cases I parked the car for 20-30 minutes and returned, and started the car readily with the throttle to the floor. Problem was that very soon, in the first minute or so of driving, the car ran poorly and came to a stop, and seems to have become fuel-starved. Rather than being flooded, there was most definitely no fuel, or very little, available until it cools down. Not sure if that's a sign of a defective pump. I pulle the carb line a cranked the engine - a bit of fuel but not much of a stream.
Very little fuel seems to have been entering the carb, and could only get the car to putter a bit on cranking if I pumped the pedal vigorously. In these cases the top side of the engine with the fuel pump and carb was most certainly hot, and I imagine it was essentially a vapor lock issue. I have a vented fuel cap and there is no issue with fuel flow from tank to carb. I also have a square top pierberg-style pump that normally gives me no issues. I need to look back through this thread and others to see what needs changing, but am open to suggestion as the hot weather is here. |
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ccihon
Samba Member
Joined: September 12, 2012
Posts: 227
Location: Columbus, OH
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| Posted: Sun Jun 01, 2014 5:15 pm Post subject: |
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| so as I typed that last post, the car was not starting and parked a block or so from home. Let it cool for 45 mins or so and arrived back - pump was still rather hot, and I pulled the hose from the carb and cranked....could get no real flow. Pulled the pump and put on a "disposable" Brosol unit - started right up. I think my fancy OG style pump doesn't like the heat - maybe a rebuild will solve. I'm tempted to go with an electric pump...need to research the best way to do that. I'm thinking mounted under tank behind the front wheel, regulator, run-stop cutout wiring. |
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asbug
Samba Member
Joined: January 01, 2008
Posts: 287
Location: N.W. Ga.
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| Posted: Sun Jun 01, 2014 6:41 pm Post subject: |
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Thanks for the update, sorry problem has returned. Mine is a little hard to start, I have a disposable brosol unit on my 1776 SP. I have to crank it over for a second or two but it then catches. Let us know what you find. I plan on putting stand offs to help dissipate the heat when parked. My vert has the old style metal rain tray type engine cover.
_________________
1969 Ghia Vert - Jenny.
2004 B5.5 Passat Wagon - no name yet.
2012 Routan - Urban Assault Vehicle. |
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ccihon
Samba Member
Joined: September 12, 2012
Posts: 227
Location: Columbus, OH
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| Posted: Sun Jun 01, 2014 6:54 pm Post subject: |
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I also have the metal tray - it had been cut open by the original Florida owner, I have since patched it to keep the engine from getting rained on, but can see where letting the heat out the top could help.
I think I will mount up an electric unit - will report back with the results! |
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c21darrel
Samba Member
Joined: January 22, 2009
Posts: 8211
Location: San Dimas
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Altema
Samba Member
Joined: June 20, 2010
Posts: 2904
Location: Lower Michigan
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| Posted: Mon Jun 02, 2014 4:52 pm Post subject: |
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| ccihon wrote: |
I also have the metal tray - it had been cut open by the original Florida owner, I have since patched it to keep the engine from getting rained on, but can see where letting the heat out the top could help.
I think I will mount up an electric unit - will report back with the results! |
I have the later removable tray, and having it out makes a nice difference in the running engine temps, but not as much difference to the fuel pump temperature after shutdown. For the hot start issue alone, the electric pump or a new mechanical pump would be more effective than the tray being cut out.
Paul |
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akear
Samba Member
Joined: August 18, 2013
Posts: 359
Location: Los Angeles
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| Posted: Tue Oct 14, 2014 2:21 pm Post subject: |
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I had difficulty starting my ’70 when hot which has finally been solved. The car now starts up almost instantly hot or cold. The biggest difference and improvement was going from an H30/31 carb to a rebuilt 30PICT-3, but I’m not sure if that’s because the H30/31 was trashed (was extra rich and I could not lean it out) or if the stock configuration is just generally better. Anyway, I made a number of changes, not all to address the starting difficulty, but thought I would share what I changed and whether the changes helped or not.
The car came to me as a stock 1600 SP, but with the aforementioned H30/31 carb, 009 dizzy, and non-rebuild-able replacement fuel pump. I had the hot start problem as described in this and other threads. When the car was warm and particularly if hot outside, and if it had been sitting for 10-15 minutes, it was very difficult to start up again. With pedal to the floor, the car would crank and crank for a long time before finally sputtering to life. On a few occasions it would not start at all, but if I let it sit another ½ hour or so I could get it going again. Definite gas smell and no doubt the engine was flooding.
Fix #1—Rebuilt Pierburg fuel pump. Bought an OG pump from Samba classifieds and a rebuld kit from Wolfsburg West (BTW, I only used diaphragms and gaskets from kit; rest was junk). Car seemed to start better but not nearly what I was expecting. Still a lot of cranking when hot.
Fix #2—Rebult 205T dizzy. Next up, replacing the 009 with the OG 205T distributor. I did this to help a low rpm hesitation, not to fix the start problem. Car pulled much better but idled rougher. No noticeable improvement in starting.
Fix #3—Adjust valves. Worth a shot. Valves were not too out of adjustment and so no noticeable improvement.
Final Fix, #4—Rebuilt 30 PICT-3 Carb. Magic! Car now starts right up every time. Plus the car feels much stronger, smoother, and just much happier. As I mentioned, the H30/31 that I replaced was giving me trouble and running extra rich, so the improvement is probably due to having a decent carb as opposed to switching back to a pure stock carb. But I do like knowing that everything is back exactly the way the VW engineers originally intended. |
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cool karmann collected
Samba Member
Joined: November 23, 2008
Posts: 631
Location: Oxford, U.K.
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| Posted: Wed Oct 15, 2014 1:24 pm Post subject: |
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A most interesting thread. I too have been (lazily) chasing the same hot-start issue for some time now, and I've found 'something' that may or may not have been contributing.
Typically the symptoms were similar to what others have experienced, long drive and it runs fine, stop for anywhere between 4 minutes and half an hour and it was a mega-pig to get restarted. I suspected that fuel was the problem as it's a 1600 dp under an early decklid so doesn't have the big cutout with the rain tray underneath. It's completely stock with all the tin in place, but the oil temps start to climb higher than the exact same set up in my 71 bay window which makes me think that it's probably warmer in the engine bay than it should be. The other thing was that it wasn't a great cold starter either! typically several seconds of cranking before it would unenthusiastically bub-de-dub-de-dub into life. Not ideal.
Anyway, I tried swapping out lots of parts for my 'spares' but to no real avail. I swapped the pump, leads,carb, coil and got nowhere. I had been pondering buying another pertronix ignitor not because I believed that was going to cure it but because it has performed well in my other cars for over 16 years. Whilst looking into this I got thinking about the rotor arm, I must say I hadn't realized that it featured a resistor, but I read a thread about checking it with an ohmeter and thought what the hell. the Bentley book said no more than 10kohm so I measured it and......meter indicated open circuit!
I don't know it this is a significant factor and I won't until the weather dries up and I can do a decent drive with the replacement but I can't see how it could be completely benign either. The spark had to be jumping internally in the arm itself to even start and run at all. No idea how long it's been like this as I didn't expect it to be a problem as it's not that old relatively speaking.
Watch this space for an update.
Ant |
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cool karmann collected
Samba Member
Joined: November 23, 2008
Posts: 631
Location: Oxford, U.K.
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| Posted: Mon Oct 20, 2014 1:00 pm Post subject: |
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What a difference! Car now starts immediately and settles out to a nice idle, took it for a drive today - parked for a short while twice and it started easily both times. Engine is much smoother and more responsive. I checked the failed rotor and it wasa 'BRUCK' branded item that I bought not that many miles ago...Will be avoiding those in the future - I read a few posts claiming parts are sold with the words 'Bruck Germany' printed on them but are in fact manufactured in the far-east.
Anyway I found a genuine Bosch arm inside an oily distributor in my spares pile - almost new from the looks of it, measured 1.1 kohm from the centre to the tip so we'll see how It goes from here but looking good so far.
Ant |
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