GT won't start, cranks but doesn't turn over

[Chythar]

This is kinda weird, I didn't see anything exactly like it when searching. I went off to run an errand last week, engine started fine. But when I tried to restart the engine to go home it wouldn't start. It would crank, but when the engine seemed like it was about to turn over the voltage meter would drop suddenly and the car would stop cranking. No popping, no clicking, nothing. It's hard to describe, but it seems like something had just shorted to ground. If I let the key go, the voltage returns to normal. I eventually had to get towed to my mechanic.

After sitting overnight, they tried to start it and it started right away. So I've got some component overheating. I haven't gotten there to check codes yet, but I wanted to run this all by you guys first.

One weird thing. On the trip out (before the car wouldn't start), something weird happened. While driving, the engine sorta stuttered. It didn't try to die, the gas pedal had no effect on the situation. It felt like something was holding the engine back, or like the engine was struggling to move. It reminded me of when I was setting my timing - I had forgotten to put the spout connector back in, and the car ran like a dog. This stutter felt like the spout connector was being connected & disconnected rapidly, or something like that. After a few seconds, the stutter went away and the engine was back to normal. No check engine light at any time.

After searching for this issue, I'm guessing either the PIP sensor or the TFI module. The stutter makes me think it's the TFI. Any ideas?

 

[cbarr300]

get a set of noid lights and hook it up to an injector harness. Crank it over when it's doing it's no start thing and see if you have pulsing. If it pulses, I'd look towards the coil or the ignition module overheating.

If it's not flashing, I'd look towards the PIP sensor (hall effect) inside the dizzy.

Also, I'd check your battery voltage. I don't think it has anything to do with your current problem...but, a low voltage can throw things off somewhat. Also check to make sure your grounds are in good shape.

 

[BlownFiveLiter]

A bad engine ground will cause that also.

 

[HISSIN50]

I like the bad battery or bad cable/connection idea of Matt's. The connection is borderline when cold but becomes resistive when hot. This can lead to a no-crank situation (though your voltmeter dropping like it did suggests a bad battery over a cable. I'd look into it). A batteyr can have ok potential (voltage) but crap its pants when hit with a large draw.

It could also be a starter that's on the outs (resistve and causing a massive draw when hot).

For the studder, I like Clay's idea. If it becomes more regular, I like to run a magnet around the dizzy bowl (ferrous material suggests PIP failure and possibly dizzy bushing failure, which took otu the PIP in the first place). I also douche the dizzy bowl with electrical contact cleaner.

:OT: Clay, did you get that issue worked out finally? PM me with the goods if you did. I'm curious.

 

[ford302redneck]

I had the bad ground problem. Try that first.

 

[xkuntrycowboyx]

I'm interested in this... my mustang does this in the summer or when its warm and i've driven it a while. i shut it off and run in somewhere and i come back out and it gets 3/4 through the crank about to start and cuts everything.
-i've also noticed i have to crank alot longer than i used to, to get it to start ...
i've checked grounds and connections at battery, all good and new batt. if i wait like 10 or 15 then try again it barely gets it but starts just before it seems like it's going to cut out again. ....very annoyin when in a hurry. i have to leave it run pull the keys and lock it to run in somewhere... (not hijacking but the longer cranks i was leaning to fuel pump breaking down because i run the tank 1/4 tank or less makin it work harder to maintain pressure in the tank ..right? anyways ... possibly starter? and how would i load test the starter and what numbers should it be at or not at?
i know this is alot but i feel its along his same lines and could answer a question he might have if he was to slide under to the starter with a meter
...thanks for any help

 

[Chythar]

**** UPDATE ****

No one gets a cookie this time, 'cause no one guessed it. Unfortunately, I need a good smackdown for not checking something this simple. It was the cap and rotor, they were badly corroded; so bad there was cross-firing under the cap. The cap & rotor is such a simple thing to check, I should have known better. And it's such a simple thing that I bet most of you figured, "he must have checked them, I won't mention it". The engine runs much better now, my rough idle has smoothed out and I've got a lot more SOTP power.

I'm looking on the bright side, my mechanic found a bad transmission leak, so bad I was down 4 quarts That would explain the transmission trouble I was having.... One replaced pan gasket and the AODE shifts like new. I never saw any leaks, no dribbles and no blinking Overdrive light (happens when you get a transmission error code). I would never have known about the low fluid level if I hadn't brought the car in. Money well spent.