Setting the fuel pump timing

Hello. I drive a 1980 1.6 Diesel VW Rabbit. I recently replaced the fuel pump. With the old pump, I could keep up with traffic from a stop, accelerating in 45-55 MPH speed zones, no problem…

Not anymore. I also have to keep the cold start knob pulled-out to keep the car from shaking (even in 5th gear after running 10 minutes). Otherwise, it starts almost immediately and the exhaust fumes are smoke-free.

I checked the timing on the pump and got a reading of 0.81, which looks a bit under spec, according to my Bentley manual:

http://photos.ryanandbrooke.bidinger...-2/i-KtTxZ2z/A

So, I adjusted the timing to 0.86 and took it on a test drive. Not any better… I got the same performance and now it takes longer to start (a second or so at most, but still).

Any ideas? Maybe it's not the timing of the fuel pump.Thinking about it logically, if I have to keep the knob pulled-out to prevent the car from shaking, the timing on the pump is set too lean. But then why does it take longer to start now?

I appreciate your help!

Pulling the cold start is advancing the timing 5 degrees.

So I would place the car in time, then take your readings.
I have heard of folks having to set it at 95.

Also are there air bubbles in your clear line?

Thanks Brian. That's good to know. So when I pulled the cold start when it was set to 0.81, that would mean the timing advanced to 0.86 (0.81 +5 degrees = 0.86)? It didn't shake/stutter that way.

Since it didn't shake/stutter at 0.86, I set the timing to  0.86. But strangely, it still shaked/stuttered unless I pulled the cold start (0.86 +5 degrees = 0.91).

I don't get it. Maybe I need to keep advancing it. And maybe my understanding of what 5 degrees means on the dial is wrong.

Nope, no bubbles in the line anymore. Completely clear while the engine is running and after it stops running.

Briano1234 said

Pulling the cold start is advancing the timing 5 degrees.

So I would place the car in time, then take your readings.
I have heard of folks having to set it at 95.

Also are there air bubbles in your clear line?

I suspect that your older newer pump is on its way to the happy hunting ground and that you might want to take your old pump to a rebuilder….

Or do it yourself as the parts are that expensive, and that there are some great how-to's to rebuild it.