The thing I most like about 914World, is that there always seems to be somebody that has "Been There, Done That".

This evening, I was making adjustments to the timing on my stock 72, with 1.7ltr D-Jet. I somehow got it to the point that it was backfiring during deceleration, so needed to fix before it took a 20 mile ride to the shop that is going to help me get everything dialed in. I had just finished getting everything back together after having the heads rebuilt.

I loosened the distributor, and was rotating to get it to 27', per spec, with the
RPMs at 3500, when all of a sudden it backfired, and shot a flame out the tailpipe.
Now I cannot seem to get it to catch and start. What I have done so far to try and get it back to spec.-
1. Checked the Points with a feeler guage, .016" when on a cam peak. Dwell was at 48' when I checked the day before running at 1200 rpm.
2. Checked that the wire coming off the coil, is sparking to ground.
3. Lined up timing marks to TDC on impeller, and used a Circuit Tester to Static Time the Distributor. I used the template from Pelican, to verify the markings.
4. Verified that the Connector for the Contact Points in the Distributor is seated.
5. Fuel pump still comes on and runs for a few seconds when the ignition is turned on.

Based on everything I have read, this should allow it to at least start, again. Any suggestions on what I am missing? Did I create another problem when it backfired? Hopefully it is something simple that I am overlooking. Just need to get it running again so I can get it to a pro.

Thanks in advance!

What are the symptoms now when you try to turn the motor over? Starts but dies? Never starts? Starts, idles so horribly bad and dies on its own?

Smell lots of gas when cranking?

Maybe you blew a relay...check the box in the left side of the engine compartment.

Thanks for the reply. I just turns over. No firing, Never Starts. Yes, the smell of gas. Going to pull the plugs to tomorrow and confirm the flooding.

Check your ground wire on the distributor points plate to make sure it's not come loose. That will cause your car to not start in that manner. Jon

That happened to me with very similar symptoms.

I may be wrong, but if you are using the TDC mark, your timing will be too far retarded, which will cause it to backfire from the exhaust. Try setting the static timing with the 27 degree mark and see if that makes a difference.

You are wrong. The 27 degree mark is for use at 3500 RPM, when the centrifugal advance is all in. Timing for zero RPM (no centrifugal advance) is much closer to TDC. Static timing to TDC should be close enough for the engine to start.

I would look for unplugged wires of any kind. I had a similar problem and tore my hair out for a while over a no-start after doing something to the ignition. Turned out I had bumped the CHT sensor plug and it had gotten un-plugged, so the engine was actually getting too much fuel to run!

Next, I would check to see if I actually do have spark or not. Use an extra spark plug, and tape it so the outer electrode or the threaded part is touching a ground like the crankcase or heads. Hook it up to a plug wire. Look to see if there is spark while the starter is cranking. That verifies if there is spark at all. If not, troubleshoot that. If so, your problem is something else.

--DD

I agree.
This comes as a BTDT thing.

YOU touched something.
Look at all the wiring....
Rotor back in place?
Plug wires?
Coil wire?
Points wire?
CHT and TPS plugs, the whole gammit of plugs...

Most likely its near where you worked.
Just be patient and check all the wires...

Sounds like you have fuel, and possibly spark..

Rich

Problem Fixed! Thanks to everyone for your suggestions. I decided to pull the distributor and start over, by taking it apart and cleaning, resetting everything.
In putting it back into the engine, I believe that I must have installed it 180 out
the previous try. This time, it started right up. To be positive, I checked the
valves again, verified dwell, and adjusted timing to 27' at 3500 rpm.

Only issue that I have now, it that I am occasionally getting a backfire when I downshift while coming to a stop. Any ideas on how to sort out that issue?
It is running a Bursch exhaust.

Possible exhaust leak somewhere?

I thought backfire on downshift was timing is a little too advanced? Maybe you are closer to 28' @3500?

Is it backfire or a gurgle?

What fuel system are you running?

Exhaust backfires are typically leaks in the exhaust, or to much fuel.

Stock D-Jet for fuel system. Tomorrow, I am going to back off of on the timing, and see if that will address the situation. The gurgling, is coming out the tailpipe.
It is not a single backfire, but popping on deceleration under load.

Bursch does that, at least mine did.

Timing is really not variable....set it right, leave it alone.
What fuel pressure do you have?
Decel valve still hooked up?
Vacuum advance still working?

Had time today to change out the Bursch for the Stock 1.7ltr. Muffler. Problem solved! Can definately tell the difference in the restriction on the stock muffler.
I plan on going back and looking at all my settings, as now the idle seems to be a little low with the stock set up.

Thanks to everyone for your advice! Making solid progress.

Not to hijack your thread but,,,,,,,
How do you check vacuum advance ??

Thanks

You pull a vacuum on the canister, and make sure that the vacuum will hold, and that the arm moves with the vacuum.

Update-
After much sorting, many of the issues are solved. The Timing issue was finally resolved, once it was determined that I had the wrong Rotor in the Distributor. Somehow, I was sold a Rotor with a very wide blade, that once replaced, allowed for a successful timing of the motor. The backfiring was solved by getting a CO2 meter on the exhaust, and increasing the mixture at the ECU, to fix the lean condition. (The previous owner had adjusted the mixture all the way counter clockwise, since the MPS diaphram had failed.) This also allowed the idle to be set properly. It looked like everything was solved......now a new problem.

This is a stock 1972 1.7ltr. with D-Jet. All the pieces are there, with everything connected. It starts fine cold, and idles at 2000rpm, until the AAR heats up, then
it settles down to 900rpm. Once I drive it a couple of miles, and it heats up, then it will not automatically drop down to 900rpm when I come to a stop. It rests at 2000rpm. It will then only drop back to 900rpm, after slowly droping rpms over a couple of minutes, or if might drop back down, it I rev it quickly, by tapping the gas peddle.

Am I right to think that it has something to do with the Vacuum Canister at the Distributor, and associated plates? Or could it be the Deceleration Valve? AAR?
Since it can sometimes drop right back to 900rpm, by tapping the gas peddle,
something is sticking, or not being moved as is should in the Distributor, Right?
Going to start the process of isolate and eliminate in the morning.

Thanks for everyones input and advice.

Same issue here was a dirty advance plate, or binding advance plate.
A screw too long holding down the points can do this.
Some of the screws for a distributor are longer than others.
You want the short one for the points....or it touches the lower advance plate.


Also, your TPS could be affecting that idle issue.

Before you go to far, look at the throttle system, return spring, and gas pedal spring.

The spring at the throttle body could be old, messed up, missing etc.
The pedal actually has spring steel in the part that bolts to the floor...l
It's part of the return spring power/system.

Turning the nob on the ECU only affects idle mixture. Nothing under load. Any adjustments under load have to be adjusted at the MPS (not a procedure for the faint at heart and probably not to be done with the right tools/measurement gauges).

Try disconnecting the decel valve and plugging off the connections with vacuum caps. I had this issue after fixing my AAR and disconnecting the decel valve was the issue. I now run without decel valve hooked up.

Thanks to everyone for your advice and comments. I believe I have located the problems. Just to be safe, I checked just about everything, including removing the Distributor, and cleaning the advance plates(checking for proper screws). It turns out that the AAR was not closing all the way, and the Temperature and Load Sensitive Temperature Pre-Heating System on the Oil Bath Air Cleaner was leaking. After isolating both of those systems, the Idle dropped back to normal. Working on Reconditioning the AAR, and hooking everything back up. Seems the problem is solved. Nice to know that many of the troubles with Fuel Injetion can be solved with simple isolation testing. Keeping my fingers crossed.