Fuel pressure sensor 1974 VW 412

jasminqv@msn.com · Post by **jasminqv@msn.com** » Fri May 22, 2009 10:21 pm

While we were fixing the master clutch the car sat for two years while we tried to locate parts. We got the car running, the clutch works but now it's running rough and blowing white smoke. Our mechanic changed the points, cleaned the gas, put in a new condensor and thinks the problem is our fuel pressure sensor. He is not sure, but he believes it's the next logical thing.

Once again we are searching. This time for part # 02801000043. We understand the Porsche 914 also used this part. We found several d tronics for a Type III, but the L tronics are more difficult to find.

Any suggestions. Please Help!

raygreenwood · Post by **raygreenwood** » Tue May 26, 2009 5:59 am

You mean...."fuel pressure regulator"...don't you? there is no fuel pressure sensor on any car ever built....that I know of.

Also....there is no "next logical step". He may very well be right as regulators go bad when they sit still (rust)....but that is NOT how to diagnose VW fuel injection.
If he does not know the test.....has not tested the pressure....or does not have the gauge to apply to the car to test it...find another mechanic. All this one will do is break things and cost you money. He is guessing.

Where are you located? The regulators are not too hard to find...though they can be a bit pricey sometimes. Ray

wildthings · Post by **wildthings** » Tue May 26, 2009 12:28 pm

The L-jet fuel pressure regulator is shared with 1972 and later buses, and many other vehicles. It is readily available, if not from a local source, then from dozens of internet sources like Bus Boys, Bus Depot, or German Supply.

Doing a full diagnostic is not hard and takes little time. The test can all be found in various manuals for 411/412 and '72 and later Bay Window Buses. (Some of the info is slightly different, but the way it is presented in the Vanagon edition of the Bentley is the easiest to understand to me.)

jasminqv@msn.com · Post by **jasminqv@msn.com** » Fri May 29, 2009 1:41 pm

Thanks for the advice, it's very appreciated. I spoke to the mechanic and the car is running, but rough. The Temp head sensor was disconnected and when they connected it, the car ran even worse.

The odd thing is the part #0280100043 came out of the car. We looked it up on the internet and it belongs to a porsche 914 and costs over $1000.00.

I'm taking the car home. The problem is finding someone who knows how to work on the thing. I live in Eugene OR (a big VW town) and we've exhausted all the VW mechanics in town. It's a shame because the car really is in excellent condition and all origional.

This weekend is a big VW show in Woodburn OR., and we were hoping to trailer the car up there to find parts or someone who can help us. Keep you posted!

wildthings · Post by **wildthings** » Fri May 29, 2009 11:25 pm

With a hot engine you should be able to ground out the wire running to the TSII sensor and have the engine run well. I am not sure what could cause white smoke on an aircooled engine. I have heard that loose valve guides will, but that doesn't sound at all like your problem.

If you haven't done it yet add some FI cleaner to your gas. This should clean out any crud in the injectors. If the previous owner was driving the car with the TSII sensor disconnected it must have been running way lean. I wonder if the AFM has been messed with.

Bill K. · Post by **Bill K.** » Sat May 30, 2009 8:43 am

jasminqv@msn.com wrote:The odd thing is the part #0280100043 came out of the car. We looked it up on the internet and it belongs to a porsche 914 and costs over $1000.00.

You are working with the MPS, not the FPR. If this car has a MPS, it is not L-Jet, it's D-Jet. Let's get straight what you are working with before moving forward. A 74 412 will have L-Jet stock... Is the air filter square (L-Jet) or round (D-Jet)?

herr_sparky · Post by **herr_sparky** » Sat May 30, 2009 10:26 am

did you try Springfield German Import? there used to be a cranky old German there that would work on my 412... i think for this very problem, a faulty MPS...i have several spares if you need one

raygreenwood · Post by **raygreenwood** » Mon Jun 01, 2009 9:05 am

Bill K is correct. You need to find out what injection system this car has.
(1) It should be L-jet if it is a 1974
(2) The 02801000043 is a 1973 to 1976 pressure sensor from a D_JETRONIC....(not L-jetronic) Porsche 914. It will also work ......with adjustment in 1971-1973 411 and 412.

Also...it has nothing directly to do with fuel pressure regulation.

Your mechanic sucks and has no business whatsoever working on this car.

Also...you cannot run or drive without the cylinder head temperature sensor connected....and reading the proper resistance.

Wildthings is correct that connecting the wire for the CHT directly to ground may help you start....but also leaves the system very lean. Do not do it for very long.

Also.....

...just trying to get people to quit using the damn sensor 1 and 2 terminology. That was a very stupid VW only....terminology thing that changed over the years...and invariably messes people up and leads to a multi-post waste of time conversation concerning what year you have and what your ECU number is and....blah, blah blah etc.

Call it what it is and does....like every other user of Bosch injection and fuel injection in general. It is either a CHT (cylinder head temperature sensor...plugged into the head).....or its an ATS (ambient air temperature sensor plugged into the manifold).

. Ray