Engine fires, runs, then quits immediately

[Helirich]

Good point. I literally just checked flow with six jars in like, September, so I'm sure it all has to be good in terms of pattern and volume. Even if it wasn't, it would still run, just crappy. I can't even get it to idle right now.

Am I correct in that I can get a baseline CO by pulling an injector, placing it in a jar, jump the RPM relay, then check for spray. Turn the CO screw clockwise (richer) until I get a spray, then back off until it just stops? I already know I'm not flooding because I had all six injectors out when reinstalling the whole fuel injection and I did do a quick RPM relay jump to make sure I was leak-free before putting the injectors back into the ports.

That sounds logical. You could also leave it altogether and just turn it a 1/2 Turn rich and see if it starts. That will probably be too rich and run like crap. But if it runs, you know you found the issue. Then you could turn it 1/8 turn lean at a time till it runs somewhat good. Then you probably need a dwell meter unless you get real lucky. Just make sure you know where your starting point is in case you want to return to square one.

[82DMC12]

...except you shouldn't be showing 12V on the white/yellow wire, ever. You can put 12V on the coil (+) as a test, but don't leave it that way...

Ron, I'm quite confused now. Earlier you said

_____
I know your checked the ballast resistor, but you might do a very simple test to insure the white with yellow (W/Y) wire headed to the coil is getting +12 with the ignition switch in the run position. The car can start from the cranking power provided to the ballast resistor then drop out when the switch returns to the run position.
_____

But I am getting 12V on the white/yellow wire with the key in RUN (key turned two clicks forward) if I take the white/yellow wire off of the coil terminal. In the diagram, white-yellow comes directly from the lower ballast resistor. Maybe my resistor relay is stuck? I will check for 0.5 ohm on both resistors tonight.

Do I have this sorted out in my head now?!?

[Ron]

Hehe.. that wasn't me. Ron versus DMC-Ron.

I'm sure your wires are wrong (because of the capacitor being on the wrong side of the coil and you getting 12V on the white/yellow wire). I can't tell what colors the wires are from the pics to help better.

[82DMC12]

Hehe.. that wasn't me. Ron versus DMC-Ron.

I'm sure your wires are wrong (because of the capacitor being on the wrong side of the coil and you getting 12V on the white/yellow wire). I can't tell what colors the wires are from the pics to help better.

Damn it too many Ron's!

OK let me just start with switching those coil wires around, checking ohms on the resistors, and then we can go from there! If the resistor relay is just a regular relay like most of them in the relay compartment I have a couple spares I can swap it out with to see if that makes a difference. Maybe having these wires reversed for 15 years worked out OK but now something else like the relay or resistor has gone haywire and it's not going to work anymore.

[Ron]

lol!

Try removing all but the white/slate (- side) and a 12V jumper (+ side) on the coil.
This will eliminate the resistor block, relay, etc.

It takes some trial and error, but you can usually get one to idle/rev if you manually work the throttle spool and the air plate together...

[David T]

Very low voltage can also cause it to run badly. Make sure you have at least 12 volts.

[82DMC12]

Very low voltage can also cause it to run badly. Make sure you have at least 12 volts.

Yeah when I first got everything back together and plugged the battery in, my battery was low and needed a charge. I've had it on a trickle now for a couple days and it's fully topped up. Battery is less than a year old and when I tried to start it this morning, no improvement. I'm just going to leave the trickle on it whenever I'm not actively working on the car so I know it's always full until I get the engine running like it should. Obviously the battery will run down if I keep trying to start the car but not getting it to run.

[Azar]

Sounds to me your RPM relay losing signal after you finish cranking and motor is starving for fuel...

[82DMC12]

Hey guys, making some good progress here I think. I pulled my injectors out and put them in mason jars so I could double check volume and pattern. They all look good. While I was at it, I removed the fuel distributor just enough so I was 100% sure the o-ring was still in place and the metering pin is free. I also reached in and checked the roller to make sure it too was moving freely.

Next I started turning my CO screw clockwise to richen the mixture and to my shock I had to turn the thing about 2.5 times to get the injectors to crack open. I then played with it a bit so I could get the sweet spot where the injectors just barely stop dripping after leaning it out. You can kind of tell by the singing sound.

Still not believing this could be possible because I have not touched the screw in years, I hooked up my pressure gauge to reconfirm primary and control pressure. Primary pressure is the same as it's always been at 4.8 bar and control pressure is about 2 bar which makes sense for the ambient temperature in my garage. I know the primary pressure sounds a bit low but that's what it's always read on this gauge so maybe my gauge is not quite calibrated.

Anyway I'm leaving the gauge on for an hour or two so I can monitor rest pressure and make sure I'm not bleeding out.

I'm not one who likes mysteries. I certainly did not turn the screw, and it was a little bit stiff so there's no way that it turned on its own while handling the air meter. The only thing I can think of is I did replace the o-rings on the PPR but my pressures have not changed since doing so.

Can anyone think of a logical reason that would cause the CO to be off that severely after doing a valley dive? I don't really want to go through timing the engine and using the dwell meter if this is a bogus screw position because I'm overlooking something else that needs to be corrected first.

Sent from my Pixel 3a using Tapatalk

[Rich]

Can anyone think of a logical reason that would cause the CO to be off that severely after doing a valley dive? I don't really want to go through timing the engine and using the dwell meter if this is a bogus screw position because I'm overlooking something else that needs to be corrected first.

Yes, the most likely reason is that something in your VOD rebuild left your engine with a decent-size vacuum leak. That would lean out the mixture at any given CO screw setting.

Recommending you run a smoke test to verify/locate any vac leak(s). Ideally you can repair those and then adjust the mixture/CO screw closer to where it used to be. Smart of you to count the adjustment turns to get it running. And smart of you to notice and report that you had to richen the mixture.

So many potential leak points are in play in a VOD job...the Pipe of Agony and its seal, any of the o-rings, vac hoses and components they attach to, the idle speed motor and more.