Collective brain trust help needed.

Car is a 1971 1.7. Finished my rebuild, now 1911 CC's. (ECU non adjustable)

Car runs a Pertronix Ignition. Distributor was disassembled, cleaned and re-lubed.

Static timed the car and started it, and ran it for about 18 minutes at 2500-3000 rpm to break in the cam and rings. Did my oil change and then it sat for a few weeks.

Started it to finally set the timing and it started running rough, and I can tell it is on 3 cyl, sometimes 4, and spits, coughs etc. I know it isn't timed right and cant time it until it is on 4 cylinders.

Fuel pressure on an inline gauge is at 30 psi.

Pulled #1 and #2 plugs, they are the right color.

Pulled #3 and #4 and they are wet, and have remnants of being the right color from the cam break in.

Checked all the connections, but don't quite know where to start. The trigger points were clean in the distributor when I disassembled it, and it ran right for cam break in.

Cap, rotor, plugs, wires are all new. MPS holds vacuum.

Thoughts on what I am missing here or where would you start digging first.

I thank you in advance.

Can you check for spark at #3 and 4?

All three FI grounds making good contact?

YEs, I checked the 3 prong connector and everything was clipped on there.. I will clean the terminals. Good start point.

It is on the list for sure. I will disable the fuel pump at the relay and test. But based on the wet plugs, I am thinking I am NOT getting spark on those two.

Ok, some progress.

It runs on 4. I brain farted removing the distributor so many times, I switched #3 and #4. I had verified spark first, then looked at the cap and realized the wires were off.

It starts with a turn of the key, cranks a bit slow cause timing is still off but fires easily. Adjusted fuel pressure to 29 psi.

It fires and runs and then dies within a few seconds. If I can get off the key fast enough and work the throttle, it will run and maintain a high rpm, say 2500, but when I release, it will cough and then die. It restarts after resetting the ignition key and giving it a crank.


The cylinder head temp sensor was new from pelican...I verified it is plugged in solid.


Next?

I would suspect a lean condition at cold start. Is the aux air regulator functional and is the cold start valve doing it's thing? Sounds like the csv is working since it runs for a sec. Perhaps try to get the timing closer to where it should be? If it won't idle I suspect it is retarded,. I would plug any vacuum lines going to it for the moment. Just while you are trying to get the timing set and idle going.

Since you bumped it up to a 2.0 you may want to add the inline resister to your cht. You can just make your own, I think it's 220ohms or something like that. You can Google it. Pbanders has the numbers on his djet site. As long as you have the 2.0 injectors, and the resistor, you should be able to tune that mps to your new displacement with an afr and a kit from tangerine racing. Others that have bumped up a 1.7 will know for sure. If it is running lean I would not try to drive it.

I have a spare AAR somewhere, I will clean and test that and swap them out.

Ill take a look at Pbanders and see if I can figure that out.

Anyone have any other ideas while I am digging around?

At this point your issue I believe is a combination of timing and fuel mixture.
Your MPS is not calibrated for the increase in displacement. The Tangerine Racing kit with an AFR meter is necessary for dialing in the correct mixture.
The non adjustable ECU creates an additional problem for idle.
For the timing I would try to adjust it for a smooth idle first.
This takes 2 people to accomplish, with someone turning the key and operating the throttle and someone else turning the distributor.
As the starter is engaged rotate the distributor clockwise and then counter clockwise looking for the sweet spot where the engine fires, keeping the engine running by feathering the throttle keep making very small adjustments to the distributor looking for the smoothest idle, also using the air bypass screw on the throttle body. Because of the displacement increase this will be a lean condition.
You will need to adjust your MPS to correct the fuel mixture, as a bandaid you could try the resistor added to the head temp sensor but you will be guessing at the value.
I believe the resistance is 270 ohms 1/4 watt but this is for a ‘73 2.0 with a 1.7 ECU.
I would not run a new engine in a lean condition.
I think the MPS kit is the way to go.

Additionally don’t worry about the cold start or AAR, you are in California these are not a factor in your climate.

Yeah, not a big issue for cali, but the csv is probably helping you out at the moment. The AAR is better to have than not, you might drive to colder temps someday. It's also a cool and clever device.

You do have 2.0 injectors in there right? The FJ67s?

I will recheck the injector part numbers, I did replace them when I did the rebuild. I believe they are 2.0.

Good advice on the MPS calibration kit, I will look into that as well.

Thank you all for the ideas, I will report back as I tinker.

Your injectors may be to large, you are probably to rich, even at idle. At this point don’t use a resistor as it just make your setup more rich.

Adjusting the air bypass screw will just make the idle higher. D-Jet is very “touchy” when mixing and matching.
Beg borrow or steal an Air Fuel Ratio meter and install the Tangerine kit, a lean air cooled engine will burn up in no time and an overly rich one will wash oil off the cylinder walls and dilute the oil which can damage crank and rod bearings.


New motor, just saying.

Good news. I ordered Tangerine's MPS rebuild kit. While waiting for its arrival, I tested mine for Vacuum. Zilch.

Took it apart (it appears to have been rebuilt before) and take a look at the diaphragm. A total loss.


So Thank you for pointing me in this direction, I think this will be a HUGE step to getting it running. I also appear to have had the wrong Head temp sensor, so I sourced what I believe is the proper one and will install this weekend, hopefully in conjunction with a rebuilt MPS.

Ill keep you posted. Click to view attachment

In your first post you said your “MPS holds vacuum”.

That later changed?

Yeah, I didn't give it long enough when I tested it. After a minute it bled down quick... When I went through Pbanders article like 5 times, I started slowing down and following it closer. I am novice at this part, so learning.

So when I disassembled the sensor, that diaphragm began to crumble in my fingers....

Good find. Make sure you follow Chris's instructions closely on that initial setup of the mps. You got his little screwdriver tool I hope? Also, do you still have your decel? Did 71s come with them? It is important to have that hooked up right to reduce the stress on the mps so it doesn't happen again.

Thank you I intend to. I did order the tool kit as well. 71 did not have a decal valve. Since this engine its 1911, pretty close to 2.0 I ordered the 2.0 spacer for the MPS hopefully to try to minimize it over stressing. I am learning this one step at a time for sure.

Decel would be an easy addition if you wanted to be extra safe. I suspect it isn't really necessary with chris's kit. He may have other opinions. The difference between having it and not is between ~28pounds on lifted throttle and 23 pounds. Not a small difference.