Cold start hesitation

ATHIKER1998

MEMBER
1997 HONDA CIVIC
4 CYL
FWD
MANUAL
166,000 MILES

About one month ago I had a problem with some stuttering on acceleration a couple of minutes after starting the car. After that period of stuttering it runs great with no loss of acceleration. It happens consistently each time I drive. I replaced distributor cap, rotor, wires, plugs and air filter and checked the timing(normal) with no change. I finally replaced the fuel filter and the problem seemed solved.

Unfortunately, last week it started the same behavior again. The fuel pressure is normal during operation and with the fuel pressure regulator vacuum hose disconnected. The only thing I noticed is that the fuel pressure drops after I stop the engine. Within about 5 minutes it is down to almost zero. Could this be causing these symptoms? I imagine fuel pump replacement is the solution. What do you think? Thanks.

5 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi athiker1998,

Thank you for the donation.

The operating pressure is ok so it rules out a faulty fuel pump. It could be the pressure valve in the pump or a faulty pressure regulator.

To test if it is the pressure regulator, pinch the return hose with a clamp and turn ignition switch ON to prime the pressure. If the time required is similar to without pinching the return hose. Then you need to check the fuel pump to rail for pressue leakages.

Sometimes it could be the hose from fuel pump to the mount that is leaking. You would have to remove the fuel pump to inspect.

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Thursday, July 16th, 2009 AT 10:56 AM

ATHIKER1998

MEMBER
2 POSTS

I clamped the return hose and the pressure held. I assume this means that I do not have any fuel leaking through the injectors or leaking out onto the ground. I think the fuel system is fine.

I mistakenly told you that I changed the plugs. I bought new ones(NGK) but when I checked the old ones(Bosch) they looked fine and were properly gapped and should have had another 30000 miles left in them.

I have now changed the plugs and the problem has gone away (at least for now). My new question is: what goes wrong with spark plugs that would cut their life in half? Why did they work most of the time but cause problems in the first few minutes of running? Some aspects of cars are still a mystery.

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Monday, July 20th, 2009 AT 12:07 PM

KHLOW2008

MECHANIC
41,815 POSTS

The heat range of the spark plugs would affect the initial operatons. It could also be due to shorting of the plugs due to lean or rich fuel trims over long periods of use.

For Honda I either use NGK or Nipondenso. Bosch is never my brand to use.

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Tuesday, July 21st, 2009 AT 6:41 PM