"Trailer-hitching" bucking problem, Rapid detrioration from running perfectly Options

[boxster914]

Hi everyone

My perfectly running 71 914 1.7 D-jet has deteriorated rapidly this past week.

Early in the week I noticed what felt like a power drop out during a drive. It was very slight and only happened once and I wasn't sure I didn't cause it by unconciously lifting off the gas.

The next drive it happened a few times and was more pronounced. It was then that I knew this wasn't an imagined problem.

On the third drive it was like a bucking bronco, surging and stopping and the engine cut out a few times. It was undriveable.

Today it will start but won't run. The engine cuts out when I try to rev it and the red light comes on.

I've done some searching here but haven't been able to draw any conclusions or come up with an actionable strategy to diagnose the problem. I'm seeing people trace it to spark plug wires, air fuel ratios and bad distributors.

Is there a step-by-step process that you can recommend for me to get to the cause of this? (I'm a newb so I probably will need help with abbreviations like AFR, TPS, etc.)

Here is a video of it's rough idle yesterday when it was still running.

https://youtu.be/n61CP6O8UgM

[wonkipop]

i was just reading back through your thread @boxster914 .

and noticed that you did test the fuel pressure and it was right.
i'm guessing this was just fuel pump running and not engine (since it would not run anyway).

which makes me think of something interesting.
i remember mike, my mechanic saying to me when we recommissioned mine.
we had to test pressure and flow. two separate things.

sounds like despite the filter it built up pressure.
because it wasn't really circulating or using any fuel.
but you had restricted flow. it was a kind of a static pressure it built up?

classic fuel filter problem is the gunk floats off the filter after you switch off.
car will start often and run for a bit.
then the gunk gets sucked back up and jams it again.
you must have had a bit of that going on if it could build up pressure in the injector circuit.

throw a couple of spare fuel filters in your glove box.
might happen again. at least you can save yourself on the side of the road.
assuming you can get at the filter. i'd need to park mine up on a curb in an emergency to get under there.
others suggesting tank might be dirty could be good suggestions.