Rookie mistakes, I need help!
 

So I changed my spark plugs, fuel filter, distributor rotor, oil, and check head stud torque all in one afternoon. Problem is I didn't try to start to the car even once, until AFTER all of it was done. Now the car won't start, and I don't know which job screwed it up.<p>Is there a priming procedure for a new fuel filter? I let the fuel pump run longer than normal before trying to actually start the car, to let the fuel run back through the whole system. Still no start. How long should I have let it run before trying to start?<p> I could only change out the rotor, not the dizzy cap, because it's on back order and not gonna be here for a while. Is it stupid to put a new rotor in an old cap?<p>So basically, of everything I've done, which would be the most likely reason the car is not starting? Assume I know nothing and don't leave out the most obvious, numbskull reasons. Thanks!

compression fuel and spark -

You messed with two of the three - so work you way backwards... No priming procedure.

Did you remember to attach the coil wire? (I would start by putting the old rotor back in)

Preferable to change both, but it shouldn't be a show stopper.

I would suggest you check each spark plug wire is on the correct plug of the distributor.

Fuel:
pull an injector and place it in a clear container. turn on key and lift air meter plate? Do you have gas spraying from the injector? If yes, move on to spark. If no read next.

lift meter plate with key on until injector spray. It is possible you need to work fuel through the filter and fuel distributor. As soon as the injector sprays - stop! You do not want to hydrolock the cylinders with fuel. you can pull all 6 injectors to verify spray pattern. Once you have fuel try to start the car. Does it start? If yes, congrats. If no, move to spark.


Spark: Did you verify cap is seated on distributor? Did you verify 162435 wiring routing to cylinders? Di you verify that rotor is seated onto distributor shaft? Let's assume you checked these three things.

If so, pull coil wire from distributor cap and ground against coil base with a 1-2mm gap. Then crank car and look for a spark. If spark exists, car should start. If no spark...

Does the CDI whine? A Bosch CDI will whine with key-on.

Next. Check the condition of the green wire from the distributor to the CDI. Does it look brown and heat stressed? If so, you might want to replace. It is possible that you bumped the wire and a signal is not getting to the CDI. You can verify on an oscilloscope if you have one.

You have an SC 3.0 in a '74 chassis (according to your signature). The distributor on a '74 rotates clockwise, while it rotates counterclockwise on a SC 3.0L engine. If you're following the decal in the engine compartment or a repair manual for a '74, then you may have the plug wires routed incorrectly.

I'm betting spark. +1 on the distributor cap. It is easy to get it on wrong. Check all your connections and try again.

I love how people throw out suggestions with such a poor description of the problem to begin with. What does "won't start" mean? Is the engine turning over with the starter? If so, is it firing at all (as in trying to run) or nothing?

How did you "let the fuel pump run longer than normal"? On an SC, you only do that by jumping the fuel pump relay. If you're lifting the sensor plate to run the fuel pump, you're injecting fuel, which, done to an extreme, can contaminate your oil or lock up the engine or do damage.

So, what's going on?

Brian

Lighten up Brian. In any trouble shooting, it is logical to start with "what just changed." He told us that. And I think there are some safe assumptions to make, as well. He knows enough to tackle these jobs, even knows to check the head studs.

"...let the fuel pump run longer than normal" means when turning the key he didn't go direct from off to start, he paused at run for a time for the pump to pressurize the system before he engaged the starter.

Also safe to assume he didn't futz with anything that would prevent it from turning over, so rule that out as a symptom.

Only thing on the fuel side he touched is the filter, not much to screw up there. He did touch a lot of the ignition system's electrical connections. That makes the wires a prime suspect. It follows that he likely got something(s) reconnected wrong.

+1

Sometimes the cap doesnt seat correctly on the distributor. Make sure its clipped on properly.

Sounds like a wire issue to me. If it were a plug installed or gapped wrong, you'd likely have a poor running condition, not a total non-running condition.

The CIS fuel pump doesn't run unless the engine is rolling over enough on the starter to draw air and lift the sensor plate. There is no "paused at run for a time for the pump to pressurize" unless his wiring is altered (which is possible, considering it's an '83 in a '74).

Agree the problem is likely electrical, and re-tracing steps is the logical advice. However, a simple "I turn the key and the starter cranks the engine, but it doesn't fire at all" would be one possible way to better describe the actual problem.

I apologize to any and all if I've come off as harsh.

Brian

Your posts seem to indicate you have a 'no-start' condition (turns over but not even a hint of firing) rather than a 'hard start' or 'intermittent start' condition -- would that be a fair description? If so, you're likely getting zero fuel and/or zero ignition rather than reduced levels of either one.

You also mention that you let fuel pump run a little longer than typical before starting to (e.g., to re-prime the system); did you actually confirm that it's running? Reason I ask is that some folks will pull the fuel pump relay before R&R of fuel filter and either forget to replace it at all, or might not re-seat fully when replaced. Leads to zero fuel.

I'm assuming that -- since dizzy cap not replaced -- plug wires were undisturbed (at the dist. cap end) and are in their original location, so not likely that firing order is off. But since cap was removed, might make sense to pull off and fully re-seat HT coil lead just to make sure you're getting full contact there. No HT lead = no spark.

And, as several others have pointed out, while the mismatch between new rotor and old cap isn't ideal, it should still work unless the distributor cap was reinstalled incorrectly or it has some major fault. I'd suggest you check a couple of items:

a) compare your old rotor to the new unit to verify you've installed an equivalent replacement part (especially the rotor height; if it doesn't reach the carbon 'button' in the middle of the inside of the dizzy cap, you'll get no ignition).

b) carefully examine the dizzy cap -- cracks/carbon tracks will point to ignition issues but generally won't create a 'no-start' condition by themselves. But do check the carbon 'button' in the middle. If it's broken, horribly worn, or -- as I've seen in the past -- no longer has enough spring tension to maintain contact w/the top of the rotor, you'll get no ignition.

c) carefully reinstall the cap, making sure it's fully seated.

FWIW, I re-read a couple of your previous threads, including this one, which appears to have set you on this path to replace filters and ignition components:

http://forums.pelicanparts.com/porsche-911-technical-forum/573890-suddenly-have-bad-stumble-misfire-past-5k-rpm.html

and it seems to me you do have some kind of ignition issue that pre-dates the maintenance work you list at the beginning of this thread. Providing this kind of context helps the rest of us do a better job of offering more useful advice.

HTH

Dale

Yes, this is exactly what is happening.<p>Also, when I replaced the plugs it was one at a time, with only one plug wire off at a time as to not mis-wire them. MY concern about the plugs is one or two or more might have picked up some schmutz on them on the way down the tunnel to be screwed in. I know it's unlikely that would cause a no-start situation, but it still worried me a little.<p>I am at work right now so I can't check how the cap is fitting, but I'll be on it immediately when I get home. Thanks for the advice so far guys.

I vote for rotor being the issue...change that sucker first.

Yes, this is exactly what is happening.

I blindly bought a new fuel relay in preparation for this project(s) but unbeknownst to me, there is no fuel relay on a '74 (ASFIK, all my research seems to back this). If there is, please let me know as I have a new relay sitting on my shelf with nothing to do.

Yeah, the plug wires are all on their proper plugs. I never touched the wires on the dizzy cap. What is the HT lead if I may ask? I've never heard that term or abbreviation.

I will do all these tonight and report back.

Yeah, sorry about that. You guys are like doctors, and I gotta show you my whole chart!!

Thanks for all the great advice guys. I know I've done something boneheaded, I just need this group to tell me what!

I'd reseat the plug wires, with authority.

Doyle]

Check the three connections where the CHT sensor plugs in. It's the white plug on the left side of the engine above and near plug 3. I had a no start issue a month or so ago and all I did was remove spark plug wires. The CHT connection visually looked good, but when I pushed on them and then tried to start, it fired right up.

As mentioned......The Bentley Manual for the SC/3.0 is wrong on the firing order and rotation. It IS the opposite of the 2.7.....

And since I didn't notice the year 911 and engine, you can disregard what I said.

MY rule of thumb is.....check spark, FIRST, got spark, hit it with quick start while turning it over.....no fire, it's fuel related.

My bad. HT = high tension lead = coil wire. Only defense is I'm an old fart, maybe a little sideways from working on old Lucas and Marelli electrics.

Dale