engine woes

haze · Post by **haze** » Fri Feb 01, 2002 1:11 pm

Greetings All,
I've got up an AFC fuel injected '74 412 automatic which doesn't run...but wants to.
Everyone keeps asking me why i bought it and telling me to get rid of it, but there is just something about it that precludes me from parting with it.
At this point though, I would like to get some expert advice before i decide to purchase any (more) expensive parts
I am not getting a signal to the injectors. i've not checked the fuel pressure yet, but the pump was replaced and before i replaced the cracked fuel lines, they did indicate some pressure in the system by drizzling gas all over.
What i have done is run through a '76 type 2 AFC FI VW troubleshooting manual which points to ECU. I do have spark and i have gas in the tank. it'll run for a few seconds if you spray ether in the intake. Forgive the length of my ramble, but i'd like to double check my check with you.

operate starter with test light (or meter) hooked to injector connector-no signal.
-->check triggering impulse from coil to terminal 1 of big connector by connecting test light between terminal 1 and ground and operating the starter-light flickers.
-->check ecu ground by checking for voltage (with ignition on) between terminals (10 and 5), (10 and 16), and also (10 and 17) of the big plug. the test light lights for all 3 sets and according to the book, replacing the control unit is in order.

In addition i have replaced the air flow sensor (had a broken door) and double relay with rebuilt/new parts. ...but in writing this i see that i have not checked all the places for voltages at the double relay. will do tonight.
Is there anyone in the MD DC VA area with an AFC 74 412 who would be willing to let me try my ECU with their vehicle?
Any help is greatly appreciated.
Thanks
-Bryan

ray greenwood · Post by **ray greenwood** » Fri Feb 01, 2002 5:23 pm

Hello, chances are rare that it is the ECU. In 23 years, I have only seen one bad one....it got wet. I would bet that you are getting no voltage to the FI system. Also the ground system for the FI is very important. Check all grounds, check all plugs for corrosion. Let us know. Ray

kevin powers · Post by **kevin powers** » Sat Feb 02, 2002 7:35 pm

could this be something as simple as the trigger points in the distributer?

haze · Post by **haze** » Sun Feb 03, 2002 12:43 pm

i've been trying to troubleshoot using a 914 manual i found online here: http://www.pelicanparts.com/914/parts/E ... _AFC-B.jpg
with the cold start valve and thermo switch unplugged, i am showing #4 on the ecu connector(as well as 86 on the dbl relay) continuous to ground. Is that correct? the grounds on the ecu connector #5, #16, and #17 check out ok.
Back into the cold to see if i can verify some more connections.
-Bryan

ray greenwood · Post by **ray greenwood** » Mon Feb 04, 2002 10:06 am

How silly of me. Its usually the first thing I ask...Thanks Kevin. Yes check the trigger points. Without those, you will get no signal. Ray

Bulley · Post by **Bulley** » Thu Mar 21, 2002 1:49 pm

uh-- maybe I'm just used to the later L-jetronic or something, but none of my AFC injected cars had trigger points, only the D-Jetronic did.

Am I missing something?

------------------
Matthew
412@bulley-hewlett.com

Towns can't pave thier way to beauty, or drive their way to prosperity.

haze · Post by **haze** » Thu Mar 21, 2002 1:58 pm

yep, no trigger points here. if the ecu is a robust as people say i think my quest is for the missing ground.

Chris Hobbs · Post by **Chris Hobbs** » Sat Mar 23, 2002 2:33 pm

If you still need help with your easter-egg hunt, I have a spare ECU for a 412, a hard copy of VW's Bosch L-Jetronic workshop manual (it's also available online), and a hard copy of VW's 1976 troubleshooting manual for AFC fuel injection in Type 1s. We have two 412 wagons here. Email me or call 703-771-9470 weekends and evenings.

Chris Hobbs
Leesburg VA

Bulley · Post by **Bulley** » Sun Mar 24, 2002 6:16 pm

Chris--

Can you p-mail me in regard to my "test drive in Eastern NC post? i will be in Bethesda/NoVa Good Friday though Easter Monday with my wife and would GREATLY appeciate some hands-on contact with a 412.

------------------
Matthew
412@bulley-hewlett.com

Towns can't pave thier way to beauty, or drive their way to prosperity.

ray greenwood · Post by **ray greenwood** » Mon Mar 25, 2002 10:23 am

Check basic resistance readings to the terminals at the AFC. Also check resistance to the cylinder head temp sensor...and make sure its grounded. If the fuel pump is running, the main grounds at the centetrline of the case should be checked. They are on a 3 prong ring connector under the center plenum manifold. Make sure the main power relayu that plumbs into the FI harness is giving power at that terminal....with the key on...in all key positions. Ray

rich2481 · Post by **rich2481** » Fri Mar 29, 2002 11:33 pm

you are showing the injector plugs getting signal ( test light flickers on when turning over??) my l-jet had really dirty connectors and I cleaned them and bent the pins alittle to get some spring back in them, started right up

haze · Post by **haze** » Sat Mar 30, 2002 2:44 pm

i have the triggering signal from the coil into the ecu, but there isn't a signal going back out at the injectors.

rich2481 · Post by **rich2481** » Mon Apr 01, 2002 7:22 am

I had dirty, sprung connector pins on mine, cleaned them real good and bent them alittle and cleaned connector on ECU real good, got to looking at all the socket pins and saw alot of them had eased with age, of course do this at your own risk.
good luck

Freq2002 · Post by **Freq2002** » Wed Apr 10, 2002 12:16 am

Ah, memories,... Mostly of spending 2 days under my '71 411 using evey cuss word the Navy taught me,...

Just as a quick check it out type thing I got from a VW factory mechanic: Take the wire off of your temp sensor on the #3 cyl head & ground it to the engine than try turning it over.
This little gem will shut off the injector signal. Something I wish I knew BEFORE I spent those 2 days in the wilds of Oregon,... I grounded it & drove the remaining 300 miles home without a hitch. :/

------------------
Where are we going, & why am I in a handbasket?...

m504specs · Post by **m504specs** » Thu Apr 18, 2002 1:01 am

I am right in the same place. What should I check on the grounds. Resistance?

Sara