Here we go......

My car will not start when it is hot or warm. It will start when it has been sitting for a few hours. I have spark, the fuel rail has plenty of pressure and I have a brand new high torque starter. I have a new coil, wires, cap, rotor, module, alternator, fuel pump relay, battery and plugs. i even tried using a 1000 CA battery with no luck. The engine just cranks and cranks but it won't start. Now, here is the strange part........as soon as I throw a boost on it from another car, it starts. It fires right up as soon as you turn the key. The starter does seem to spin slightly faster when a boost is applied. Anyone care to make a guess as to what the problem might be? 3 different mechanics have looked at it and have been stumped. When it starts it runs great. Well, aside from the cam surge Thanks guys:hail:

 

Sounds like the starter is getting heat soak. When a started gets too hot from the engine heat it wont start until it cools off. Try getting a heat blanket to put around it or a heat shield. This used to happen to my car and now its fine the heat blanket around my starter works great!..... Erik

 

Thanks for the help. I have a mini starter. Do they become heat soaked as well? I was under the impression that they didn't. I forgot to mention that the car is an '89 GTA with a 5.7L. Thanks

 

Can anyone else help me?

 

Does the engine still turn when it doesn't start or is it completely lifeless?

 

regardless of starters, thats a pretty common problem. just get the heat blanket or a heat shield. Taht should help cure the hot starting woes.

 

If the car cranks ok when its not starting I would look at the ignition. I've had some ignition modules cause a car not to start when its hot when they start to go bad.

 

yeah, definatly sounds like heat soak. aside from a heat shield, i'd check your grounds.

clean the battery terminals, clean the engine ground, and clean the starter connections.

the reason its not starting is because as it gets hotter, its electrical resistance goes up, making it much harder to get the current it needs.

 

Would you guys get off the "heat soak" problem ?????

His starter is obviously SPINNING if his engine cranks forever ! DOH!

When I had TPI I noticed it took a looooooooooooong time for the engine to start and it would crank forever WHEN my coolant temp sender went bad. Might want to check it.... I'd replace it anyway. It's like 5 dollars.

 

Thanks guys. All the connections have been cleaned and new terminals where installed on any that looked bad. All ignition pieces are new within the last few months. I just did the module the other day with no luck. It only used to do it every once and a while before it started getting hot out. The engine cranks fine but when I add the boost, it seems to pick up a little bit. I have verified that I have spark. The engine has around 11:1 compression so i'm sure it's a bitch to spin over but I was told the starter I bought is up to the task.

Blackened, is the sender in the front of the manifold base or the drivers side head?

 

i am sure Blackened meant the coolant tempeture sensor located in the front the the intake manifold. the condition exists only while the engine it hot. the engine turns over and it fails to start. you said it had spark... while the no start conditon exixts? hmm... it's the not module... how old is your pickup coil? if it's old, i would replace it. it's good insurance. are the injectors firing while the conditon exists. if the engine turns over, you have spark, and fuel??? it should start. unless one of the sensors is flaking out on you and is alot of fun to find.

 

The pickup coil was replaced this past January with a new GM piece. My old one looked pretty bad. The injectors are firing. I've pulled some plugs and they've been wet. Which sensor would cause a problem like this if it's going bad? Would replacing the CTS be worth it? Thanks again.

Oh I allmost forgot......I have 24lb injectors from an LT-1 installed. They where installed after I had my chip done so the ECM "thinks" I only have 22lb injectors. Is that relevent? Is it possible that the ECM is providing to much fuel on hot starts? Would turning thge fuel pressure down help?

 

A fellow member had this exact problem a few months back. He checked everything but couldn't figure it out. Finally, he replaced the CTS. Started right up. The CTS had gone bad and was telling the ECM that is was about -40 degrees outside. Needless to say his plugs were a bit soaked. Might as well try the CTS. Its only about $7 and it could do the trick.

 

Well, I just got a new CTS. It was only $20 Canadian so I won't be to pissed when it still won't start

 

To start a hot *carburated* car you have to floor the throttle to purge the over abundance of vapourized fuel so it can start.
What happens if you do the same thing on your TPI car?

 

I believe it sort of does the same thing. It still doesn't start though. Well, i'm gonna go install the CTS now. I'm gonna through some Water Wetter in while i'm at it.

 

Well, I installed the new CTS and it started great for about 2 days and then it started doing the same thing. Everytime someone comes up with a cause or reason for it not starting, when I mention that it starts with a boost, they just say "oh, then I have no idea". This thing is driving me nuts. We just removed my Accel 300+ box and it still does the same nonsense. Could it be my chip? I have the chip burned for 22lb injectors but I have since added 24lb injectors. Could the ECM be flooding the engine out?

 

You could try the chip, but after you installed the sensor, did you reset the ecm? It could be a computer fault?? Good luck finding it.

 

Yeah, the ECM was reset. We checked again today when it acted up and we are getting no fuel. The plugs are bone dry after cranking the engine over......and over and over. The fuel rail is getting pressurised and not leaking down when attempting to start the car. Could the injectors be toast?

 

Acceld,

Your ECM is probably just fine. Since the engine starts and runs well with a boost, the ECM is doing its job when it has the correct voltage and signals.

Something to remember is that the ECM fires the injectors only while the engine is rotating. The ECM determines this by the input from the distributor. The HEI amplifier/switching module gets the firing pulses from the pickup coil, then amplifies and cleans this signal to a square wave DC output to the ECM at a level that the ECM can interpret reliably. Anything that would interrupt these reference pulses would stop fuel delivery, and possibly ignition. However, ignition pulses are acted upon directly by the HEI module, so a marginal signal may provide spark but no fuel (or too much fuel - more on that later). Make sure the electrical connectors at the distributor and ECM are clean and tight.

The pickup coil itself can be sensitive to temperature, and the signal could be diminished or missing when the pickup coil is heated and the insulation is stressed.

The reluctor on the distributor shaft is the device that interrupts the pickup coil magnetic field and creates the small signal pulses. A minute crack in the reluctor can cause signal loss or degradation. This would also be compounded by heat, since the gap at the crack can grow, degrading the signal even further.

Either of these problems might be masked by the use of a booster battery, which would tend to maintain a higher system voltage while cranking. The slightly higher system voltage might be just enough to overcome the poor signal levels and the faster cranking might be enough to generate a slightly stronger pickup coil pulse, which the ECM could interpret and act upon.

Conversely, a low or marginal signal level may cause NO switching of the signal to the ECM or erratic, rapid signal changes which the ECM could interpret as more engine revolutions and would therefore deliver more fuel (since the ECM would think the engine was turning faster).

As a next step, I would verify that the pickup coil is in good condition by measuring resistance and leakage while it is heated. Inspect the insulation for signs of heat damage and cracking. Testing insulation resistance with a megger would verify the insulation strength. Tapping on the coil sharply while testing the overall resistance may help indicate breaks in the windings.

You would need to inspect the reluctor very closely for any small cracks, damage to the peaks on the reluctor ring, and rust, which can cause degradation of the signal. Short of using Magnaflux fluorescent dyes and a black light, you can use a magnifying glass and hope you can see any imperfections.

Of course, all of this relies on the HEI amplifier/switch module doing its job effectively while hot. That requires good connections at the HEI module from the pickup coil. While you're there, make sure the module ground screw is clean and tight. And since you're already there with the meter, check the small capacitor (filter) in the base of the distributor for resistance and breakdown. Capacitors are also sensitive to heating, and can ground out any signal if their insulation is damaged and stressed under heat.

Once you can verify a solid ignition and signal to the ECM, you can proceed with the diagnosis (if necessary).

 

Thanks for the help Vader. Ok, the pickup coil, and reluctor are new. How would I check to see if they are out of spec? I disassembled the distributor and discovered that the pickup coil did not have any grease on it. Should it? How minute would the cracks be in the reluctor if any are present?

Thanks,
Paul

 

Your ignition switch (in the steering colum) might be dirty. Try shooting electrical cleaner in the swithc, let it dry and try to start your car. I went thru all of the same you have, and the problem turned out to be a dirty ignition switch.

 

The engine turns over, it just won't start. Is that the same thing you experienced?

 

My bet:

It's a battery/cable related issue. If you just have to jump the car to get the thing going and before the jump the thing cranks over just fine, it's usually a battery terminal, battery wire, battery feed wire connection problem. ie, you may have a main feed off the battery (not the starter feed, one a bit smaller that feeds EVERYTHING else from the positive terminal). This wire may be suspect and when you jump the other battery directly to the terminal, it fires full 12V to your system and the car starts like it should.

IMO, disconnect and remove all the main feed and ground wires from the battery and from where they lead/connect. Inspect the cables thoroughly, as well as the connections themselves. Yannk on them and check for resistance with an ohmeter. Are they dirty, corroded, rusty? Do the cables feel stiff?

If anything is suspect and/or the big fat part of the cables and/or the smaller positive/ground leads are older, just replace them. When reconnecting the cables, make sure that the connections are free from grime and rust and that they are tight enough.

And do not forget about the GROUND STRAP. remove/inspect/repair that as well.