OK Here goes!!!! The wife and I decide to take a nice mountain drive Sunday after my mechanic (Porsche race car certified) gave me a clean bill of health for my '74 2.0 liter. Drove about forty miles through some of the most beautiful country (near ski slopes), and decided to stop for early dinner. Fabulous outdoor dining, temp about 76, several adult beverages, you know!!!! Got back iin the car to leave dead fuel pump

Left car at the only garage in town, daughter came and got us. Next morning, called Nate in Sacramento(THANKS, NATE!!) He overnighted a fuel pump directly to the garage, DUMBASS installed it, and called to tell me it was ready, but it didn't run just right

Long story short, had car towed to my guy (sixty miles), who discovered that DUMBASS had not only kinked the fuel line, but didn't reinstall the fuel filter!!!!!!Who knows what got into my injectors

Update soon!!!!!!!!!





NOW WHAT???

After three weeks in the shop, running down all the FI components electrically, I'm getting no pulse to the fuel injectors. We even tried replacing the computer with a known working one. HELP!!!!!!!!!

Trigger points. Grounds. WTF is "Porsche Race Car Certified"? Never heard of such a title. The Cap'n

Maybe he meant the guy has his DE card for POC/PCA

Ideally you want someone who has a fancy aluminum placard (from Porsche) with lots and lots of certification emblems in it.

There're two relays involved on the relay panel in the engine compartment. #21 is called the "power supply relay". It provides power to the ECU. It also turns on relay #22, which is the fuel pump relay. If #21 croaks, the ECU is out and so is the fuel pump.

My guess is it croaked. If my guess is right, it was your original problem, and your original fuel pump is OK too.

Keep us posted.....

Jim

does the fuel pump give its little burst on key on? That would prove the ecu is alive.

Electically a break in the wires leading to the MPS will stop all pulses to the injectors. Did it get touched during the trouble shooting?

You can learn a lot by making measurements with a multimeter on the ECU cable. I have them written down in my haynes but I think Brad Anders may have them on his site.

http://www.914world.com/bbs2/index.php?showtopic=70441

OK, Here's where we are now.

Fuel pump is delivering good pressure
Engine starts from cold start valve, but dies when that little bit of fuel is used up
Very weak pulse to injectors
Trigger points and wiring are good
Swapped out ECU for a known working one
Wire to MPS is good
All grounds are solid
All relays are good
Multiple grounds at crankcase seam cleaned & replaced

ENGINE WON'T RUN!!!!!

Check Temp Sensor #2 (cylinder head temp sensor) to see if it is internally shorted out.

Have tou pulled a inj. to see if it's pulsing fuel?

remove the coil wire and one by one remove the inj's. and put them in a jar, crank the engine and see if they pulse fuel. With the motor hot or cold, it doesn't matter. this will tell you if there is fuel.

Alway's go to the basics with a prob like this.

A motor needs fuel, spark, and compression to run, simple as that. If it's missing one of those elements, NO GO.

How are you determining that the pulse to the injectors is 'very weak'? Toons right on with the squirt in the jar thing - it will tell you a lot.

I'm really a strong believer in the usefullness of measuring everything possible at the wiring harness of the ECU. That way you can be assured that the all the components are giving (more or less) the correct signal to the ECU.

Given that it will start initially you know that your compression, spark and basic fuel delivery is all good. What you have is a failure in the metering system.

By the way, it is unlikely that the cold start valve is what is giving you that burst at startup. It does not cut in until very low temperatures. When you key on all four injectors get a pulse. If you listen closely you'll hear them. That is what is giving you the start. The injectors also get an enrichment pulse as you move the throttle. What happens if you feather the throttle when you first start it - will it keep trying to run (poorly).

good points, BTW you will see a week signal anyway if you check the elec. pulse at the inj.. It does'nt take much to activate them.

It still sounds like there is a fuel clog somewhere

Given the history of the failure that makes good sense. Perhaps a kinked line on the HP side of the pump that tightens as the fuel pressure builds. Enough pressure for the first bang but pressure drops off immediately.

have you drained the tank and inspected the fuel sock/strainer on the outlet tube with a flashlight?

You said you checked the grounds. Did you verify the injector grounds at the rear center of the engine case? Those grounds are critical to the injectors.

OK, new info!!!

Injectors are squirting, and when the fuel pump pressurizes, engine starts and runs very smooth for a couple of seconds. Any attempt to throttle, and it dies out!

NOW WHAT?

Grasshopper... a be so wise as to SHUT UP and go check all the things everyone said. You are going off half cocked and all that will get you is alot of wasted money on parts you did not need.

First off check the T2 sensor.

Second check all the grounds...again.

Third... how do know that the trigger points are good... did you test them... if you did test them again.

Check the fuel like was suggested.

Check the fuel lines again... how did you verify fuel pressure. If you do not have a gauge on the rail... get one.

THEN... report back.

HHMM, can you tell if the FuelPump stops running after the car starts?

It's not supposed to stop but stranger things have happened. Replace the Fuel pump relay for yits and giggles.

Have you tried starting the car with one of the inj's. pulled to see if they stop pulsing fuel?

Have you checked the MPS to make sure it holds vac.?

when was the last time the fuel system was cleaned, tank and all? Is the fuel filter new?

Is there water in the bottom of the fuel tank?

It sounds like you are running out of fuel for some reason, still maybe a clog or a kink. The car starting is a good sign. Check everything.

Are you doing the work?

Also, check the MPS, both vacuum and electrically.

A rebuilt one in Moab gave up .... luckily I had a spare.

First I would check the CHT.

CHECK SOCK IN FUEL TANK, AS WELL AS FUEL TANK AND FUEL FILTER. SOUNDS LIKE STARVATION DUE TO RESTRICTED FLOW.

since it is running smoothly for a few seconds fuel starvation does start sounding possible. Perhaps leave your fuel pressure guage in line through the start sequence.

Just to confirm the state it is currently in. If you don't touch the throttle it will run for about 2 seconds then die. If you do touch the throttle it will die immediately. Is that correct? Or will it continue to run past the 2 seconds if you leave it alone?

My daughter's VW had the same symptom. Fuel pressure was OK at idle, but as soon as I tried to do anything, like put it in gear (automatic) it died. New fuel pump fixed it. 18 months later, no repeat.

After a long winter, time to revisit this mess!

In-line fuel pressure gauge shows great pressure
All electrical has been checked ( twice )
Fuel tank emptied & cleaned (including screen)

Still won't run!

Please help!!!

check your cht (temp sensor 2) and test out your MPS.

http://members.rennlist.com/pbanders/ for more details

One more time as stated above .... I had a car that would not continue running. Start and die much like you describe. I putzed with it for two weeks...new fuel pump, MPS, etc. I then checked the CHT for correct ohms ... 1st frozen, then room temp, then heated it up (crude methods). Ohms didn't look right.

Changed CHT and car ran like a champ.

Try pulling the air cleaner and holding the butterfly open to see what happens!

Sounds more like an ignition problem to me. I know it's FI, but about half of carb problems are ignition.

Who is doing the work?

Some of the main, possible issues are not being addressed.

Ign. syst. , MPS, CHTS, trigger points ETC.