A new problem to scratch the old noodle over...

ubercrap · Post by **ubercrap** » Tue Dec 13, 2005 6:06 pm

The 412 wagon has been having a problem while driving at sustained speeds above 55mph. I had been getting some hesitation, and occasional loss of power for a few seconds. I replaced the fuel filter and the car seemed to be OK on a drive of about 25 miles. I thought maybe it was a problem with a clogged filter, but the next time I drove the car, I got up to about 65 miles per hour and about 30 second later, it started to lose power. I pulled over, and let it idle for a bit, and it seemed to be running OK. I decided I had better turn around, but as soon as I was driving at a sustained speed again, the car lost power and died. It was very difficult to get it started, but when I did, it seemed to run fine. On the way back home, it died a couple of more times shortly after I reached highway speeds and was difficult to start. Today, it seemed to start and run just fine around town at low speeds (<40mph). Anybody have any ideas here? I guess the first thing is to test the system pressure and output volume of the fuel pump. I"ve got a fuel pressure gauge on the way. There's also the possibility of the ignition system. From receipts with the car, the points and condensor apparently are fairly new, but this, of course, leaves the coil. It is a Bosch blue unit. I'm probably going to order a Pertronix, as I have no experience with points.

vwbill · Post by **vwbill** » Tue Dec 13, 2005 11:02 pm

Weird! I hate those kinda problems! I think it sounds like a fuel issue or tank breather issue or return line issue? I guess it could be a weak pump but it's weird it does it like a demand issue or build up thing? Sounds like another good Ray question! I wonder if the temp sensor issue could do this also and it is losing ground? Maybe put a meter on that one when it does it and also pull the fuel rail plug(put a hose and jar outside) and see if you are getting fuel! bill

vwfye · Post by **vwfye** » Tue Dec 13, 2005 11:09 pm

i would make sure the fuel pump's pressure is correct. sounds like starvation at full load or that you are pulling crap into the filterscreen in the tank and it takes some time to build up the blockage. after you drive the car and it gets to sit, the silt settles away from the petcock as the vacuum pressure created by the silt reverses.

vwbill · Post by **vwbill** » Tue Dec 13, 2005 11:13 pm

Good point on that sock/crud issue!! It does seem like a starvation issue too! bill

ubercrap · Post by **ubercrap** » Wed Dec 14, 2005 10:44 am

Yes, that does sound like the ticket. The symptoms seemed to me very much like a clogged fuel filter, I just forgot about the "sock" filter in the tank...I wish I had everything ready for a suspension rebuild if I'm going to be disassembling everything to remove the gas tank...

vwaddict · Post by **vwaddict** » Wed Dec 14, 2005 2:45 pm

I've talked about this before. I had the same general problem when I bought my car and it turned out to be the fuel filter on backwards. With the maze of lines by the fuel pump, it's easy to get things bassackwards. Simple but true.

ubercrap · Post by **ubercrap** » Wed Dec 14, 2005 3:21 pm

Man, I hope I didn't do that, but I'll check...

raygreenwood · Post by **raygreenwood** » Wed Dec 14, 2005 4:57 pm

Uh...Yep...I have done it too!

. There is an arrow stamped on most of them. It goes toward the pump. If you happen to have the tank down low...pull the drain plug...unscrew the big bung and pull out the tube assembly...and cut off that dang sock filter. I keep a brand new spare fuel filter in the trunk. There is an integral packed lint filter before the pleated filter in teh stock fuel filter. It performs the same function as the sock filter. If it clogs while driving, get out and change it. Five minutes. Ray

MGVWfan · Post by **MGVWfan** » Wed Dec 14, 2005 6:49 pm

Ah!!! So there really is an advantage to using the square OE style filter over a universal round one, the square one's got a "prefilter" of sorts. Interesting.

ubercrap · Post by **ubercrap** » Wed Dec 14, 2005 7:39 pm

Hmmm...Ray, now that you mention it, I guess tank removal isn't necessary unless I want to clean and seal it...

vwfye · Post by **vwfye** » Wed Dec 14, 2005 11:01 pm

it takes about 15 minutes under the car if the tank is close to empty to fix this issue! how do i know? because i did it when i bought my 74!

raygreenwood · Post by **raygreenwood** » Thu Dec 15, 2005 5:01 am

One thing to check for. All of teh OEM...square gray and square clear colored ones have the pre-filter. There is also a brand that you get at most of theBeck Arnley world parts dealers that has the pre-filter. Those are all made in Israel. There are some cheapies...like at some flaps like Autozone...taht do not. If the filters are real cheap...its worth it to invest and pull one open to make sure there is a lint filter before the pleated filter. Ray

ubercrap · Post by **ubercrap** » Thu Dec 15, 2005 9:18 am

I'll have to take a look. I've been getting filters from bughaus.com and I know one I put on one of the sedans awhile back from them was the made in Israel type, but these newest ones I got were different I believe...I think instead of a molded directional flow arrow, they were just printed.

raygreenwood · Post by **raygreenwood** » Thu Dec 15, 2005 4:37 pm

Yep, if you saw the case in half....what you see on teh inlet side of teh pleated filter will be what looks liek a gray or white matt of what appears to be "felt". It is usually on one side of the parting line and the pleated filter is on the other. Ray

ubercrap · Post by **ubercrap** » Fri Dec 16, 2005 7:28 pm

Well, I had the filter on there correctly. I could see some crud in the inlet side of it already! I decided to try to look at the sock filter, so I drained most of the gasoline through the outlet line, then tried to loosen the drain plug. But, guess what happened? It seems that I broke free whatever the drain plug screws into, not the plug itself!? D'oh! It just seems to turn in there forever now! Dammit. Luckily, I have a really nice extra gas tank, but I hate to lose one this way. Plus, I've got to take everything apart now and I don't have everything ready for the front end rebuild...