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Mon Nov 02, 2009 9:49 pm

Hi I'm new here and I am turning to you all to hopefully help with my problem since I CAN NOT figure it out. I have a 1974 Dual Carbed, manual bus with the stock engine. I was driving at full speed on the freeway when suddenly the car started to lose power, no matter how hard I depressed the gas. The only way to describe how strange it was is "deaccelerated". I sat on the side of the freeway and basically waited a few minutes and it started up again and was fine for about twenty feet or so and the same thing happened?! I limped to the exit where luckily there was a Park and Ride to work on it. I figured it just needed a tune-up so I tuned it up, (spark plugs, points, cap, rotor, sp wires,)I changed the entire fuel line and the fuel filter, and it started up great, idled great and drove fantastic all the way home (about 10-15 miles) and for the next couple days, THEN IT HAPPENED AGAIN and when I was only going about 15mph, but had been driving for awhile.
So THEN I figured the after market electric fuel pump possibly had an inferior ground? So I pulled it off, completely cleaned it, tested it, sanded down the ground point to bare metal, and reinstalled it. AGAIN it ran better than ever before, idled better than it had it years, and I drove it around for about 20 minutes when the exact same mystery problem happened.
So PLEASE help me figure out what the heck this could be! I believe it COULD have to do with the engine warming up as it only seems to happen after its been running for awhile or is under a load of some sort, but besides that there is no rhyme or reason to when it happens????
My ideas are these; Is it at all possible there is some sort of large debris in the fuel tank itself and it is periodically blocking the fuel line inside the tank before it gets to the filter? OR ould the rings be bad and as the engine heats up and the oil becomes thinner it loses compression( it smokes slightly but nothing major)? Or am I just grasping at straws?
I would appreciate any and all help as I am out of ideas on how to proceed.
Thank you. Jesse

Mon Nov 02, 2009 9:56 pm

coil breaking down as it gets hot?

Mon Nov 02, 2009 10:01 pm

Sounds exactly like my coil issue - only a problem when hot.

http://www.thesamba.com/vw/forum/viewtopic.php?t=375197&highlight=coil
Skip to the bottom of page 4.

Mon Nov 02, 2009 10:14 pm

Crap in tank = plugged fuel pump =plugged fuel filter = float-bowls full of crap =minimal fuel to motor= poor performance or 15 feet then it will die, and runs like crap I drove mine for an afternoon before it did the same turned out it was two hand's full of varnished gas in the tank floating around...... Clean your tank

Mon Nov 02, 2009 10:35 pm

I'm sorry, what is "coilreaking down mean"? Just bad coil?

Mon Nov 02, 2009 10:52 pm

the coil is doing what EZ Gruv's was doing.

Measure the coil a per the thread and then go for a drive and test it again. i bet the 8Kohm resistance is out of spec when it is hot.

I have copied this from the other thread:

I searched for, of all things, 'testing coil', and came up with this thread:
http://www.thesamba.com/vw/forum/viewtopic.php?t=167305&highlight=testing+coil
Which ultimately says to do this:

Ratwell wrote:
For a stock coil about 3 ohm primary (between terminals 1 and 15) and 8 kohm secondary (terminals 4 and 1).

*Note the engine/coil were still pretty warm at this point; it was shortly after I drove home:
I tested 1 and 15, and got very close to 3 ohm
I tested 4 and 1 (4 being the output to the spark plugs), and got 10.35 kohm - too high!!

Mon Nov 02, 2009 11:06 pm

blockage in fuel tank

worn fuel pump

bad coil

Be sure that the flaps are open when this happens and that the engine is blowing the normal amount of hot air.

Also - the engine is slowing in RPM as the car slows down? Once in awhile someone will decribe the car slowing as a power issue when what has happened is the clutch is slipping.

Tue Nov 03, 2009 7:38 am

I see you mention tune up but don't include a valve adjust in the list of items. When were the valves last adjusted and do you have solids or hydros?

Tue Nov 03, 2009 8:09 am

Sounds like you're describing crap in the fuel tank - except for the warming up factor. Could be coincidence. If you have a fuel sender replacement hole, pull the sunder and look inside with a flashlight. That will tell you very quickly if there is junk in there, or if it's something else.

Tue Nov 03, 2009 9:35 am

Sounds like the same problem mine had. Ended up being a piece of fuel line rubber floating around behind the needle valve in one of the carbs.

Tue Nov 03, 2009 9:45 am

I had a similar issue. I would drive and it would just die. It would start again and do the same thing not too far down the road. I could keep it running but not full power by pumping the gas.

Got it home and just moved the fuel filter to see how much gas was in it while running, it cut off! Ended up finding the Idle Solenoid wire was almost cut through and loosing connection with the vibration. I guess that pumping the gas made the engine shake enough to intermittently keep the connection going for a bit.
Replaced the connector to the Idle Solenoid and it was good to go.

Good luck.

Tue Nov 03, 2009 10:34 am

Put me down for "junk in the fuel". Try replacing the fuel filter and see how long the symptoms take to re-occur.

The other causes listed could all be possible as well, but changing a fuel filter is a cheap way to start.

I had this problem with a bug once. Had to scoot along on the shoulder of the interstate because the junk had clogged my flow to the point where I couldn't go faster than 25 or so.

DJ Roberts

Tue Nov 03, 2009 7:31 pm

personally i think the key here is that it happens after the buis is warmed up and has been running at operatng temp.

Junk in a fuel tank could happen at anyt time.

all the times the OP has described it happenign around the same time frame after driving the bus

So i still think it is the coil, also the coil is easier to test and check and replace (if needed)

Wed Nov 04, 2009 10:57 am

no grease on the distributor cam can also cause the points to walk, screwing up dwell. happened to me, only an issue when hot. added grease to cam, no problems since. (in my case the engine would die at idle when warm, but maybe OPs problem could be less severe or something. easy enough to check dwell anyway)(ALSO happened TWICE to me, after changing points once, sans grease.)

Tue Nov 10, 2009 12:34 am

SO IT WAS THE COIL! Thanks for the help! I wasn't about to drop the engine so I ghetto cleaned the fuel tank, (uscrewed main fuel line connection, drained the tank into a bucket, stuck a hose as far as I could into the tank, and turned it on full blast to try to blow any debris, rust, etc out of it,) well there wasn't any or rust at all so that was good. I cleaned both the idle jets and they were both pretty clean too, so I figured the only other possible scenario, thanks to you guys, was the coil. I pulled the one I had off my project Ghia and cleaned all the connections and it fired right up. Well after 4 days of commuting I think it is safe to say ITS OFFICIALLY FIXED!
Thanks everyone for your input!
Jesse
Next up: Getting the 1974 Ghia Coupe I bought running(after sitting for at least 5 years...wish me luck)

Tue Nov 10, 2009 9:46 am

Yep, that's what we told you 8 days ago.