Crank no-start 2 days before cruise night :/

[Another MkIII]

So I had just checked my O2 sensor and the car was sitting in my driveway idling, and then it just shut off. I go to restart it, cranks, but won't start. It tries, but it just won't catch. I have checked:
-Checked codes, there were none.
-Checked fuses.
-Had the battery tested. Didn't think that was the problem, but I have seen low voltage do weird things, and its easy enough to eliminate that possibility.
-Checked connections on ignitor, coils and coil pack, and cam sensor. They are old, brittle, but definitely connected.
-Fuel pump does come on, and I am getting 40 PSI according to the gauge on my AFPR.
-Inspected spark plugs to see if they were fouled. Looked perfect.
-When I crank it, the tachometer does jump up to about 400-500 and kind of bounces there. I'm not 100% sure, but I believe that this means the cam sensor is working, correct me if I'm wrong.

I'm out of ideas at this point, I think I covered all the common causes that I have seen, any suggestions? I'm sure I'm overlooking something simple here. Any help is greatly appreciated.
-AM3

 

[roadboy]

could it be cps wiring? it happened to me before, try wiggling it around, once it fires up i zip-tied it so its always steady and its been working fine since.

 

[90mkiiisupra400hp]

I know you said you checked all your fuses but if you were messing with your o2 sensor and it somehow bad wiring grounded out then it could have blown the EFI fuse and you might not have noticed it being blown, it happened to me once so I think its worth checking.

 

[Another MkIII]

I specifically checked the EFI fuse for that reason, but I'll make sure. I've seen too many problems fixed with components that had been checked and were "good", lol.

@roadboy: If the tach is working when I crank it, doesn't that indicate that the CPS is working and the ECU is receiving the signal?
-AM3

 

[roadboy]

my tach was trying to move when i tried to crank it, give it a try, there's no harm in trying.
and dont give up trying to wiggle it once, i had to try at least 4-5 times before it started

 

[lithium14]

I am having the same issue... one question though when you say "wiggle" what part of the CPS wiring are you referring to exactly? where the wires go into the CPS body or the connectors?? I wiggled the shit out of my CPS wiring while a buddy cranked the engine and had no success....

 

[hvyman]

usually right at the connector on both sides and possibly over the valve covers.

Tho its not as common for it to die, but more common for it to just not start when you want it to.

Do you have spark?>
If the tach is moving then the cps is getting a signal.

 

[lithium14]

hmmm I don't mean to hijack the Op's thread, but mine doesn't die... just cranks. I will check tomorrow if the tach moves. Also (prepare for super noob question) how do you test for spark?? (sorry OP, hopefully our issues are the same and we can get it fixed soon)

 

[hvyman]

Pull spark plug reinsert into wire and crank and look at the plug. You will see little blue arc.

 

[lithium14]

oh... =O well then... I shall see tomorrow... but I really don't see how I can just up and lose spark alluva sudden out of the blue for no apparent reason....

 

[hvyman]

Thats usually how it works.

If the engine cranks but doesnt fire. You either dont have spark fuel or air.

 

[Another MkIII]

hmmm I don't mean to hijack the Op's thread, but mine doesn't die... just cranks. I will check tomorrow if the tach moves. Also (prepare for super noob question) how do you test for spark?? (sorry OP, hopefully our issues are the same and we can get it fixed soon)

Mine died, but now it does what yours does, crank, no-start.

I suspect the ground on the head might be bad, its pretty corroded, so I'll be doing that when I have time tomorrow
-AM3

 

[hvyman]

Ecu grounds on intake manifold? Or the ground wire on the head and firewall? The one on the head/firewall wont stop the car from starting.

 

[lithium14]

same... tomorrow is the day... I will have to bring my tools to the body shop... so I'm going to check for spark, ground conditions, clean out the connectors, check for tach movement... and... how do you check for fuel and/or air??

 

[jetjock]

If the MIL comes on with the key the ECU ground is OK. Other grounds, except for the igniter grounding, are not relevant for spark.

If there's spark and fuel pressure it's a simple matter to inject some carb cleaner, fuel, or starting fluid into the brake booster port. Wait 30 seconds or so for it to vaporizes then see if the engine fires up. If it doesn't focus on the injector circuits.

Since you claim the tach flickers the timing belt isn't broken. You won't have spark with a broken belt either. That said the belt can be checked through the oil filler cap. Doesn't mean it hasn't skipped though...

 

[Another MkIII]

Hadn't thought of that. Seems odd that it would skip at idle, but worth checking.
-AM3

 

[jetjock]

Well, you can always check timing.

 

[lithium14]

Ok I'm at the shop right now... my tach moves during cranking so cps is getting signal right??... I pulled the first spark plug and its super dirty, but it fires... not a blue arc but an orange one. I tried spraying carb cleaner into the brake booster port... but I can't get much in there most of it comes right back out.... and when I start it it almost starts... like fires once but that's it... so I'm guessing I'm not getting fuel... how the eff do I fix that while its in the body shop?????

 

[HENRY SIEMON]

Ecu grounds on intake manifold? Or the ground wire on the head and firewall? The one on the head/firewall wont stop the car from starting.

But the injectors grounds on the intake manifold,, its they are bad the car wont start.. two pairs, one brown and the other pair is white.. check it

 

[Another MkIII]

Got it running yesterday, the cam sensor is the issue. After screwing with the wires for a half hour, it finally started. Is there a good way to fix this permanently without replacing the sensor with a new one? It cost like $500... :/
-AM3