Learned something new, Djet ignition Options

[r_towle]

I was fixing a volvo p1800.
This is a 2.0 liter motor with Djet (1973)

the only major difference is the TPS is two circuits instead of three, the rest is the same...the MPS is calibrated for the volvo...but its still an MPS. (the plenum is alot bigger than ours)

So, I was getting a weak and very erratic spark...it would work then it would not...it was driving me crazy.

The final test was this.
Take a spare plug. Using a cable ground the plug and use a plug wire to connect this plug to the coil directly.
With a screw driver, open and close the point (basically the screw driver IS the points in this test...just short out the two sections of the points till it sparks)

So, this was providing me with a random spark...hmmm
I found that the ground lead, or ground strap that ties the advance plates together was faulty..
Even though it looked visually ok...it was weak and somehow broken.
I took it out and pulled on it..its still attached...but its not working correctly.

I happen to have another set of advance plates...plopped those in and everything was fine.

The reason I share is this took me a long time to track down...
It would work, then stop..then run on two cylinders etc.
I checked and replaced everything..relays, FI points, you name it...

It was a lousy ground strap inside the distributor that was at fault..

Rich