2001 honda civic failing to start when hot

Question

my 2001 honda civic is giving me problem:

When starting from cold in the morning, the car starts at one click but when driven for a while with the engine at temperature, if I stop and turn off the ignition when I try to start it again it takes a very long time to start.

When it does start and I drive for a while the car shuts off and the check light come on. I have to leave it for about 5mims for it to start again.

Answer 1

On a first generation Acura Legend (a Honda), this problem is almost always caused by the main relay being old / stuck. You can smack it (located by the fuse panel on the dash), and it'll start.

Answer 2

The symptoms you described have 3 common causes on Honda/Acura vehicles.

First: the "shoulda" disclaimer Reporting the code that drives that check engine light you saw is the most important piece of information you could give us. Without that code everything is blind diagnosis (guesswork) based on a myriad of personal experiences. This is the most inefficient way for you to get your answers. Before attempting to replace parts or diagnose via this thread please go retrieve the code, many parts stores will check it for free.

Common Causes of your symptom

1. Main Relay - The main relay has a responsibility for delivering power to your fuel pump. If you turn the key into the run position without cranking the car you should hear a buzzing sound from the rear of the car as the fuel pump runs until a programmed pressure threshold for the fuel system is achieved. If you hear the fuel pump and the car starts then this is probably not the problem. This part's failure does not typically cause a check engine light.
2. Ignition Module - The ignition module is a compact device located in the engine compartment . Sometimes the manufacturer's construction of this device will allow internal solder points to become brittle and open circuits can occur most commonly when a vehicle is warmed up or external temperatures are extremely hot. Typically the beginning sign of a failing ignition module (igniter) is hard start problems when the car is hot. Eventually it will completely fail. This module's failure will cause a check engine light.
3. Bad Grounds/Connections - This is the most uncommon and most difficult problem source to solve since it involves referencing several logical paths of operation and testing those paths .

That's about all I have from common issues I've encountered for the problem you have reported. The injector leak down response has slight credibility based on some reading I've done, though I've never seen injector leakdown keep a Honda from starting.

Answer 3

When you get into the car, turn the key to on position but do not start the car. While everything is quite, do you hear whirling sound. If you do, that's your fuel pump creating fuel pressure. If you do not hear the pump making the noise, then as up_the_irons pointed out, it could be the relay (@up, is that what you meant by "main relay" or do those civic's have something else?).

Another possible cause is leaky injectors. I had an 89 acura integra (i.e. rebadged honda) and it had both bad relay and bad injectors. Relay was easy to identify. Injectors took me a little while.

But symptoms were kinda what you describe. If the car sits overnight, it would start fine. If I just drove it, it would start fine. But if I left it sitting for few hours it was very hard to start it. Explanation I eventually came across was that injectors leak while engine is off because fuel lines are still pressurized. If you just drove, they haven't leaked enough to flood cylinders. If the car sits for a long time, the gas will drip out past the compression rings into your oil. But at just the right time interval, you end up with flooded cylinders and a car that's really hard to start.

I went to a junk yard, bought another set of injectors, shipped them out to be professionally cleaned/calibrated, then swapped them in and never had tough start problem ever again.

Answer 4

In fuel-injected systems, hot-start problems usually indicate that the fuel line is unable to maintain pressure.

This could be due to a few things related to the fuel supply line, including:

• a leaky fuel injector
• minute cracks in the fuel line which leak fuel when under pressure

The reason why this happens only for hot starts is because the fuel is more likely to vaporize as temperature increases. In order to avoid vaporization problems the fuel lines are expected to be pressurized during a hot start.

However, these are not the only possible causes for hard-starting situations. Anything that could alter the air-fuel ratio can play a role here:

• a faulty mass air flow sensor (MAF)
• a weak fuel pump that isn't delivering sufficient fuel pressure
• a clogged fuel filter that prevents build-up of adequate fuel pressure

I'm reluctant to mention faulty lambda sensors here because they are usually not used by the ECU when starting the engine (open-loop vs closed-loop). However, given the OP mentions that the vehicle doesn't run very well after some time leaves this as a possible reason for the poor running of the vehicle.

To narrow down such issues, the best course of action is to hook up the vehicle to an OBDII scanner and read the vehicle's "pulse". Things like fuel trims, fuel pressure, mass air flow, intake air temperature are usually a good starting point.

Answer 5

Your problem is the coolant temperature sensor. Try unplugging it and if it will start without it the sensor is damaged.

Bad ECT sensors can cause non-starting issues. See honda-tech.com for a conversation about ECT sensors.

...yes a bad ECT can cause hard starting or a no start condition.

If the ECT sensor is bad you can get a new one for around $30.

Answer 6

2002 Honda Civic ES 1.7 Manual Petrol.

It cuts out randomly on unusually hot days. If I wait for a couple of minutes, it starts again. Finally traced it to a faulty TDC Sensor (Camshaft Sensor) failing only when hot. Sensor replaced and now all good. Hope this helps someone.