new2urq

Hi Gang, I am recently new to ur-q's and the forums, looks like several people have a fair bit of experience with them. I've got an interesting problem with an '84 that I inherited.
Where to start... Car is an 84, engine had to be replaced due front motor mount bosses breaking off the block along with serious lack of compression issues. Before replacement, the ran, but not well.
Entire long block was replaced with that from good running 83. Everything swapped over, the long block, the intake mani, fuel dist, turbo, dist., etc. Everything appears to be correct visually. Timing is correct, car has fuel and spark however, no start. When cranking, it goes for 8-10 secs then fires, but only fires with the accelerator depressed completely. Once the car fires, it only stays alive for 1-2 secs then dies. It will only stay alive if the accel is completely depressed. Cold start is working normally as per book, Fuel pump, accumulator and filter all replaced. I'm thinking vaccum leak but all looks well?
Random thoughts?

AudiSport4000

But, you state the car has fuel and spark, so it should start just fine.

If spark is verified with a timing light or plug pulled, move to fuel. There may be fuel at the top of the fuel distributor, but it may not be getting to the injectors (or not enough). A vac leak would cause a no start issue, or it may run for a few seconds on the CSV spray.

Just my ideas, I could be off.

new2urq

Ok, let's go on the fuel assumption...Is it possible that a vac leak could cause a problem with fuel getting from the f/d to the injectors?

Katman

If extra is is getting into the system after the metering plate, then the metering plate isn't lifting enough (or even at all).

As fuel sparay out of the injectors is proportional to the metering plate lift, vac leaks can be a big problem.

In other words, no meter plate lift, no fuel.

A 'workaround' test for fuel is to apply 12V to the cold start injector ONLY WHEN Cranking (or you will flood the motor), and the fuel pump is 'jumpered' on.

IF you get better action wiht the CSV going, then that is a good clue to sort out fuel and/or air leaks..

new2urq

acti?

Katman

acti = uncompleted though

boxerfan

If not then I would suspect the fuel distributor may be out of adjustment. It doesn't take much to screw it up. On early cars there is a spring clip that can slide up and down and that may have been knocked during the swap over.

If you jump the fuel pump and check the fre play on the sensor plate the3re should be about 1mm of free play iirc. if not then it is time to get a book and set it up correctly. I think it is covered in Bentley (it is for the 5000 for sure so I would assume the typ85 is as well). If those basic and zero settings are not right it won't matter much what is done elsewhere.

That said, like Frank and others have mentioned, the fuel delivered is proportional to the lift of the sensor plate. Any leak after the sensor plate will throw things out of whack. A hole the size of a quarter will cause a car not to start.

new2urq

It stumbled around the block but that was it. The car never really ran right after the swap. I was wondering about the f/d however it was running fine before it was swapped into this chassis. I was also think vac leaks and you mention something the size of a quarter, that _should_ be pretty damn easy to spot. I'm going back into it today, we'll see...

boxerfan

I was saying that it is quite easy to mess up the f/d setting during the swap, especially if it has the spring clip that can get moved or even go missing.

And the vac leaks? A quarter size and it will not run. A slight crack and the a/f is off. A crack that opens under boost and weird 'cut-out' type things are felt.

gmbchef

also, the valve cover vent coupling often will rot underneath where it meets the valve cover.
HTH