Bosch 3pin question

[upwardr]

I'm having trouble getting the 911 to run. On the Bosch 3 pin I have 2spade connectors on the bottom of the box, 1 you can see in the front and 1 that is slightly behind the visible one. Do both of these connectors have wires and if so which is which?
I have spark at the cap and have fuel delivery but all I get is very loud backfires in the muffler. So loud I went to check get my eardrum checked out.

Fuel pressure is only 2 1/2 lbs

This car was running before 2yrs out for painting, and have cleaned and sealed tank and new fuel.

Any suggestions

[T77911S]

sounds like it is not the CD unit.
you did not say the year. CIS/ carbs/ mechanical injection??

make sure plug wires are in the correct order/dist not in 180 degrees out.

CIS:
if it has been sitting, fuel pressures/ (cold) need to be checked and make sure the plunger in the fiel dist is not stuck.
check fuse 18

[upwardr]

It's a71 that has been converted to webers. Car was running and no engine work was done. I don't remember why the 2 single wires were not connected, maybe they were never connected.

[47silver]

1 wire is power
1 wire gies to the points
1 wire goes to the coil. Check out the wiring diagrams here for wire colors

[upwardr]

The 3 wires at the back on the bottom were Ok they have not been off its the 2 single spade connectors at the front I am not sure off. I have 5 total connections

[E Sully]

Those should be the ground connections, D.

[gamin]

Sounds like distributor/timing related. Fuel pressure should be 3.5-4.0. The CD box is giving you spark just not at the right time, thus the backfire, actually afterfire.

[upwardr]

Yes Gary that's what it appears. I have a spark tester that goes into the cap and you insert the lead from the spark plug. When I turned the engine over I got a light indicating seems good, right?

I cranked the engine without touching pedel and it sort of ran, probably 1 or 2 cylinders only. When I open throttle I can see gas squirt down the carbs. It's pissing me off.

Any suggestions?

Could I be getting spark but not enough? Can the CDI be functioning but not well enough? Coil is weak? Is that possible?
maybe time to call the experts.

Thanks

[timmy2]

Your CDI Harness should have a terminal that attaches to the terminals sticking out of the box. (Braided wire for Ground)
Just like the one beside the 3 pin connector in this partial picture of a new '73 CDI harness.

[47silver]

It really sounds like a timing distributor problem.
go back to basics,,
1. put your motor to #1 top dead center
2. remove your distributor.
3. adjust the points while the distributor is out.
4. check the vacuum advance on the distributor.
5. replace the distributor making sure the rotor is lined up to the #1 cylinder at #1 TDC.
6. install the distributor.
7. recheck all spark plug wires and the firing order. if you moved any spark plug wires, this could be your culprit. check again.
8. verify that the cdi is wiring properly.
9.. turn the key on, the cdi should buzz..
10. start the car.
11. it will run, then put it in time.

[upwardr]

I don't remember seeing that wire (single spade) in my harness. Will check it Wednesday.

[timmy2]

You need a ground from the coil and points.
Perhaps it is grounded elsewhere. There are actually 2 ground wires in one connector in the picture shown, perhaps your '71 has 2 wires coming from the CDI harness that need to be grounded.

[upwardr]

So it kind of ran on two cylinders today and I checked a couple of plugs with the light tester. Flashed but not too bright. I had a couuple of older plugs so in they went and
Bingo!!!

It ran so so.

Tracked down new plugs and good as gold, after 3 years it's music to me. Now I just want to sit in the garage and listen to it run.

Thanks for all the help with this.