Hard starting when hot

I am stumped. My car (2003 Hyundai Accent 1.6l 5 speed) has trouble starting when hot.

Sometimes it starts just fine first try. Other times it turns over just fine but won't fire...

If I push start the car, it fires right up immediatly.

The starter doesn't seem to be an issue. It doesn't sound any different than it did when I bought the car, but I won't rule that out.

Anyone have any ideas about what could be causing this???

If this was an older car with a distributor, I'd suggest that the timing may be a tad too advanced. No idea on a 2003 car if that is even applicable. Other than that, it could be a fuel issue. Do modern cars ever suffer from vapor lock?

What do you mean by hot? When the engine is hot or it is hot outside? Is your AC on? What is the temperature outside? I don't know if that has a distributor or not, but my guess would be coil pack.

93 octane gas go back to 87

my '95 Impreza showed some of the same symptoms ... I found that if I turned the key on and waited 'til the fuel pump quit cycling then turned it the rest of the way ... presto ... immediate start where before it was hit-or-miss when hot

YMMV

T.J. wrote: If this was an older car with a distributor, I'd suggest that the timing may be a tad too advanced. No idea on a 2003 car if that is even applicable. Other than that, it could be a fuel issue. Do modern cars ever suffer from vapor lock?

According to what I have read on the ArpaNet, or whatever the kids call it today... Vapour lock can still be an issue with modern cars.

N Sperlo wrote: What do you mean by hot? When the engine is hot or it is hot outside? Is your AC on? What is the temperature outside? I don't know if that has a distributor or not, but my guess would be coil pack.

Hot outside and hot engine. AC off. No distributor. Outside Temp in the 90's with high humidity.

I just find it weird that a push start fires it up immediately. Every time.

wbjones wrote: my '95 Impreza showed some of the same symptoms ... I found that if I turned the key on and waited 'til the fuel pump quit cycling then turned it the rest of the way ... presto ... immediate start where before it was hit-or-miss when hot YMMV

I will give this a this a shot!!! And report back my results...

Anyone here know how to diagnose what my underlying problem may be???

Your starter may be dying.

Heat will affect a starter motor. If it's getting tired, heat soak will make the solenoid weak.

I've -never- seen a car that actually had a vapor lock problem, I seriously doubt it could even happen with the pressures and flow rates in a modern EFI fuel system.

4g63t wrote: 93 octane gas go back to 87

No 93 in my car just cheap assed 87. Although thanks for the reply. Anything that helps me rule out, or rule in a possible cause is appreciated.

Trans_Maro wrote: Your starter may be dying. Heat will affect a starter motor. If it's getting tired, heat soak will make the solenoid weak. I've -never- seen a car that actually had a vapor lock problem, I seriously doubt it could even happen with the pressures and flow rates in a modern EFI fuel system.

If my starter is a problem. In your opinion. Could it be Diagnosed by ether putting a heat shield around it (even temporary). Or by cooling it (in the event of a no start) with cold water? Or cooling it in some way??

Trans_Maro wrote: I've -never- seen a car that actually had a vapor lock problem, I seriously doubt it could even happen with the pressures and flow rates in a modern EFI fuel system.

I've had 2 cars that suffered from vapor locking problems ... but as you point out about EFI .. both of them were carburetor models ... '51 Plymouth and a '62 Jag Mk X

Strange, I wonder where my earlier post went.

Your starter will require more current when it's hot, have you checked, cleaned and tightened your battery terminal connections?

As for the '51 Plymouth and '62 Jag. Those cars probably wouldn't have a return line in the fuel system. That tank return seems to have eliminated vapor locking in cars.

Shawn

Trans_Maro wrote: As for the '51 Plymouth and '62 Jag. Those cars probably wouldn't have a return line in the fuel system. That tank return seems to have eliminated vapor locking in cars. Shawn

you are correct ... all I was doing was raising my post count without totally hi-jacking the OP's original post

If the car had a rotary engine, I would suggest that your fuel injectors are leaking fuel into the engine, resulting in a flooded condition on hot restarts. Might apply to your Hyundai, who knows?

When I got my Escort, it was flooding due to some bad sensors, but it took a petal to the floor and about 20 seconds of cranking to get her started, so I doubt its flooding. The Escort should have a very similar ignition system. I can imagine a bad PCV valve may cause this problem or the IACV if the engine is warm.... Anyone else with me on this one?

When was the last time you checked your ignition parts?

Trans_Maro Your starter will require more current when it's hot, have you checked, cleaned and tightened your battery terminal connections? As for the '51 Plymouth and '62 Jag. Those cars probably wouldn't have a return line in the fuel system. That tank return seems to have eliminated vapor locking in cars. Shawn

Tried it out. Cleaned and retightened battery and alternator post. It did make a noticable difference! But not out of the woods yet.

1988RedT2 If the car had a rotary engine, I would suggest that your fuel injectors are leaking fuel into the engine, resulting in a flooded condition on hot restarts. Might apply to your Hyundai, who knows?

In my initial search about this problem others did mention this as a possible cause on non rotary engines. Next fillup I'm going to splurge and give the car a dose of the good injector cleaner.

N Sperlo When I got my Escort, it was flooding due to some bad sensors, but it took a petal to the floor and about 20 seconds of cranking to get her started, so I doubt its flooding. The Escort should have a very similar ignition system. I can imagine a bad PCV valve may cause this problem or the IACV if the engine is warm.... Anyone else with me on this one?

I did change the PCV valve a few weeks prior to the problem. Maybe I got a bad part.

JtspellS When was the last time you checked your ignition parts?

I changed the sparkplugs recently and checked the resistance through the plugwires. Although I have yet to check the coil pack.

wbjones my '95 Impreza showed some of the same symptoms ... I found that if I turned the key on and waited 'til the fuel pump quit cycling then turned it the rest of the way ... presto ... immediate start where before it was hit-or-miss when hot YMMV

I tried the method wbjones mentioned above. It actually worked. It actually worked really well. Although I still want to get to the root of the problem.

Heat will also affect the battery.

Some vehicles even have a heat sensor for it.

I don't see how a pressurized fuel system can have vapor lock. Kids today don't even know what vapor lock is.

Also, check the coolant and intake air sensors.

drsmooth wrote:

Trans_Maro Your starter will require more current when it's hot, have you checked, cleaned and tightened your battery terminal connections? As for the '51 Plymouth and '62 Jag. Those cars probably wouldn't have a return line in the fuel system. That tank return seems to have eliminated vapor locking in cars. Shawn

Tried it out. Cleaned and retightened battery and alternator post. It did make a noticable difference! But not out of the woods yet.

1988RedT2 If the car had a rotary engine, I would suggest that your fuel injectors are leaking fuel into the engine, resulting in a flooded condition on hot restarts. Might apply to your Hyundai, who knows?

In my initial search about this problem others did mention this as a possible cause on non rotary engines. Next fillup I'm going to splurge and give the car a dose of the good injector cleaner.

N Sperlo When I got my Escort, it was flooding due to some bad sensors, but it took a petal to the floor and about 20 seconds of cranking to get her started, so I doubt its flooding. The Escort should have a very similar ignition system. I can imagine a bad PCV valve may cause this problem or the IACV if the engine is warm.... Anyone else with me on this one?

I did change the PCV valve a few weeks prior to the problem. Maybe I got a bad part.

JtspellS When was the last time you checked your ignition parts?

I changed the sparkplugs recently and checked the resistance through the plugwires. Although I have yet to check the coil pack.

wbjones my '95 Impreza showed some of the same symptoms ... I found that if I turned the key on and waited 'til the fuel pump quit cycling then turned it the rest of the way ... presto ... immediate start where before it was hit-or-miss when hot YMMV

I tried the method wbjones mentioned above. It actually worked. It actually worked really well. Although I still want to get to the root of the problem.

I can't tell you why it works ... just that in my case ( and now yours) it seems to do the trick ...

wbjones wrote:

drsmooth wrote: wbjones my '95 Impreza showed some of the same symptoms ... I found that if I turned the key on and waited 'til the fuel pump quit cycling then turned it the rest of the way ... presto ... immediate start where before it was hit-or-miss when hot YMMV

I tried the method wbjones mentioned above. It actually worked. It actually worked really well. Although I still want to get to the root of the problem

I can't tell you why it works ... just that in my case ( and now yours) it seems to do the trick ...

Sounds like the fuel in the lines is draing back into the tank and you need to let the pump refill the lines. My Focus has a check valve built into the top of the pump to prevent drainback. Don't know where it might be located on your cars.

I can't get past the "If I push start the car, it fires right up immediatly. " statement. Makes me think the ignition switch or associated circuitry is bad. Loses power to the ignition/ecu/fuel pump/whatever when going from "on" to "start". Next time it does it, try to start it with a remote start button wired in (or just jumper, if you can) with the ignition switch in the "on" position and see what happens.

I would agree with Hal on the fuel draining back. I had an S10 with a similar issue that I fixed with a check valve from Mcmaster-Carr installed between the fuel tank and engine.

Next time its warm try this: turn the key to run and wait about 30 seconds. Should force the fuel pump to cycle enough to get fuel back up to the injectors.

I suspect the reason push starting works is that it gives the fuel pump enough time to reprime the fuel system before you try firing the engine.

A fuel pressure gauge would be real helpful in diagnosing the problem.

Joe

Thanks for all the help in this thread. Problem solved.

One of the theories in this thread was a leaky injector flooding a cylinder. This must have been the cause.

This could be why a push start, started the car everytime. When the starter is used the fuel injectors increase flow to assist in normal starting. Which would make the flooding even worse.

A push start does not have the extra flow through the injectors which would help a already flooded car start. Kind of like putting your foot to the floor on a flooded carbureted car.

At my last fill up I added Lucas fuel injector cleaner to the tank. After 1/8th of a tank the problem was gone.

iceracer wrote: I don't see how a pressurized fuel system can have vapor lock. Kids today don't even know what vapor lock is.

BWAHAHA that is so true.