Starting Problems

[SilverSN95]

Here is my problem,

When the car is hot, after running for 20+ minutes and given a little time to heat soak it doesn't always want to fire back up. It only ever has this starting problem when hot. This problem isn't consistant though. Today was a good example. I ran it for 30 minutes, semi hard and parked it for 20 minutes. When I went back in to fire it up it wouldn't. If I turn the key to the on position I hear the pump come on for a few seconds then stop. When I go to crank the engine it cranks but will not start. It seems to crank over just fine. Then after about the 10th attempt, and 10 minutes later it cranks and fires like there is nothing wrong.

Sometimes when it is hot it will crank but when it fires it seems slow to do so. Sometimes it just won't until it has cooled down. Today was strange in that is seemed like it just wouldn't but then all of a sudden it started normally. I have been having this problem along with it stalling for now reason if idling for extended periods of time. During the winter I would fire it up and let it idle for 20minutes in the garage and sometimes it would stop running with no indicated problems. No stumbling or anything, it would just stop. When this happened it wouldn't start again until it cooled down.

I changed out the ignition module late last year and also changed the fuel pump last month in hopes of stopping this from happening to no use.

Anyone have any suggestions?

[Capri306]

Assuming that your ignition module is functioning and the fuel pump is good, if I were to take a stab in the dark, it'd be at the coolant temperature or mass air flow sensor(s).

You're going to need to do some more troubleshooting to nail this, though. "It just shuts off" or "doesn't start" isn't enough to really diagnose. You need to check and see whether you're not getting ignition (spark), fuel, or both, when it dies AND when it will not start. I'm not going to make any more bets until it's established whether it's an ignition- or air/fuel-related problem. There are simply too many variables.

[USMC302]

Have you tried pulling codes?

[mustangII460]

Who's TFI did you put in?

[SilverSN95]

Are there simple ways to check for fuel and spark? This problem is not consistant either. I've never had the problem when the engine is cold or has been cooling off for a few hours. Only when hot and then it isn't all the time.

The ignition module was changed with a Ford part from the dealer, not an aftermarket part.

As for codes, I did the check last fall and I think I got a 35 (can't remember anymore). I believe it was EGR related though.

Just in case anybody asks, the fuel filter was changed approx 10,000kms ago along with the plugs, cap, rotor and wires.

One other point, not sure if it means anything but the coolant gauge has always run on the cold side (O in NORMAL). It has never made it to R no matter how hard I drive it or how hot a day it is.

I also get spark knock when it is hot and I go WOT. I run premium fuel to stop it from happening.

[mustangII460]

Pull a plug wire and put a screw driver in the boot, hold the metal shaft of the driver (close) to a ground (header.) While cranking it should throw an arc across the driver to the ground. Keep your hand on the handle.

Fuel, crank the car and push in on the schrader valve. It should spurt some gas from it. Looks like a valve stem on the fuel rail. A gauge would be better.

*Check your TPS voltage. If its too high it tells the ECM your motors flooding, The ECM will cut off your fuel.

When its running does it have surging idle or cut off for no reason?

[SilverSN95]

Originally Posted by mustangII460

Pull a plug wire and put a screw driver in the boot, hold the metal shaft of the driver (close) to a ground (header.) While cranking it should throw an arc across the driver to the ground. Keep your hand on the handle.

Fuel, crank the car and push in on the schrader valve. It should spurt some gas from it. Looks like a valve stem on the fuel rail. A gauge would be better.

*Check your TPS voltage. If its too high it tells the ECM your motors flooding, The ECM will cut off your fuel.

When its running does it have surging idle or cut off for no reason?

I'll try the the spark check tomorrow after work.

As for fuel, your comments reminded me that I did check fuel pressure from the schrader valve last fall. it showed 38psi at idle, but when I cracked open the throttle the fuel pressure dropped to 30psi I believe. I can check again but I don't think that is the problem.

How do I check the TPS voltage? Sorry, I have not really done too much underhood on this car so I might ask some basic questions. What range should it be at?

When it idles it is pretty smooth, for a 5.0. The idle is steady. But for some reason it will just stop, no stumbling or anything. I could be sitting at a light looking at the tach running 600rpm or so and then it just drops right off. It doesn't do it consistantly either but it only does it when it is hot.

[mustangII460]

Heres an awsome website on TPS.

CLICK HERE

Bookmark it.

[PKRWUD]

Sounds like the module to me. When the engine is cold, start the engine and let it idle. Use a hair dryer, set to low, and blow hot air on the module. If the engine stalls within 5 minutes, replace the module. If it doesn't stall, shut it off for 1 minute, and try to restart. If it cranks, but won't fire, replace the module.

[SilverSN95]

Problem solved....the hard way!!

Well, looks like my car couldn't wait for me to figure it out and decided to stop running all together. I was driving down the highway a few days ago and she just quit on me and would not fire back up. It was a hot day (90F) which didn't help. So I got it towed to the dealership and let them fix it. Turns out it was the ignition module and pick-up. I told the dealership that the module was changed a year ago but the mechanic said that you never just change the module. He said a bad pick-up will fry an ignition module. He seems to think that has been the main problem all along. I hope this helps anybody who has a similar problem in the future.