Honda Prelude starting problem
Hello My 92 Prelude has 367,999km on the body but still mint. JDM H22a motor has 140,000km.
Car has always started no problem lots of parts have been changed and tested including
-distributer
-tank/pump/filter fuel pressure tested
-has good strong spark
-timing belt is newish but checked timing
-replaced all injectors
-I used a friends ECM and still none

BUT

IF I UNPLUG THE FUEL PUMP AND CRANK THE ENGINE A FEW TIMES THEN PLUG IT BACK IN IT STARTS...

BUT IF ITS COLD OUT NONE SO I PUT A BLOCK HEATER IN AND IT ALWAYS STARTS
ANY BODY GOT ANY IDEAS PLEASE ANYTHING...

Oh you when I am driving it all seem perfectly fine...

Test/replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependent resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot.

Yea, we had a 1998 or 1999 Honda Prelude. It was a pleasure to have, but when we started having problems with it wanting to start. Then found out that it needed a new starter and spark plugs. It was all going to cost close to $2000. With a baby on the way and buying a house. We decided to trade it in for a new car. So my guess, it's probably the starter and new spark plugs. So be prepare for the repair costs.

Quote:

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Originally Posted by TxGreaseMonkey

Test/replace the Engine Coolant Temperature (ECT) Sensor, which affects fuel injector pulse width. The ECT Sensor is a temperature dependant resistor (thermistor), whose resistance decreases as the engine coolant temperature increases. It provides a richer mixture when cold, leaner mixture when hot.

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I have replaced all three of the sensors relating to coolant temp.

Quote:

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Originally Posted by tiny4me76

Yea, we had a 1998 or 1999 Honda Prelude. It was a pleasure to have, but when we started having problems with it wanting to start. Then found out that it needed a new starter and spark plugs. It was all going to cost close to $2000. With a baby on the way and buying a house. We decided to trade it in for a new car. So my guess, it's probably the starter and new spark plugs. So be prepare for the repair costs.

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Yea I am a mechanic I have done all the basics, I have spent way more then $2000 at cost,
And money is no issue. Not to mention it cranks hard and fast, and has new starter, alt, battery and cables, plugs, wires, cap, rotor, distributer, coil, injectors, fuel tank, pump, level sending unit, filter, IAC valve, ignition wiring, coolant, T.P. and oil pressure sensors.
There's lots more I can't remember but if think of it mention it I'll Try ANYTHING!!

Perform K-Test on the ECM.

K-Test? I have swapped the ECM for a couple of days, my buddy had no problems and mine still only started when warm. I have done a compression test on all 4 cylinders (135-150psi) and fuel pressure tests with and without vacuum. (28-35psi) I Thought maybe warped head, worn valves or rings. But now I think there must be a commonly replaced valve or relay that I've over looked, not to mention the car training I got is more useful on newer cars with 1000's of engine codes and sensors of all types, Not good old fashion basics.

Does the CEL always come on and go out after 2 seconds, when the ignition switch is turned to ON?

yes it does and I have had random codes over time and fix those, the OBD1 system works.

There is a chance that the fuel pressure regulator may be leaking fuel back through the vacuum line, which would allow excess fuel during the initial start-up.
You may also have an issue with the Idle-up control valve not functioning properly.
But, why all the parts changed? They all tested bad?

Well I'm a Mechanic so I get parts cheap and work 55+ hour weeks @ 40/hr if the part is cheaper then the testing time or results vary I don't waist time plus I have another prelude to use parts from that runs and works fine not to mention some of the parts were bad i.e.. Engine light, and the fact that the body has near 400,000
so stuff that didn't come with the new engine is old. I also thought just replacing all the common Honda problems would eventually fix it.
But I'm waiting on the "thermo valve" is this what you mean? And I have done fuel pressure tests on the pump alone, and on the test port on the fuel rail with and without vacuum didn't see a leak out the vacuum line? But over night pressure went down so I replace all injectors figured they were leaking in to head causing it to flood before I started it first thing in the morning. Because the pump alone did not loose pressure. And another weird thing to try to work in to this equation is cold the car can always be jump started??
and many people have told me to give up and move on But I won't so keep shooting your ideas some one will get it.
Thanks
Cryptauto

Quote:

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Originally Posted by CaptainRich

There is a chance that the fuel pressure regulator may be leaking fuel back through the vacuum line, which would allow excess fuel during the initial start-up.
You may also have an issue with the Idle-up control valve not functioning properly.
But, why all the parts changed? They all tested bad?

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Well I'm a Mechanic so I get parts cheap and work 55+ hour weeks @ 40/hr if the part is cheaper then the testing time or results vary I don't waist time plus I have another prelude to use parts from that runs and works fine not to mention some of the parts were bad i.e.. Engine light, and the fact that the body has near 400,000
so stuff that didn't come with the new engine is old. I also thought just replacing all the common Honda problems would eventually fix it.
But I'm waiting on the "thermo valve" is this what you mean? And I have done fuel pressure tests on the pump alone, and on the test port on the fuel rail with and without vacuum didn't see a leak out the vacuum line? But over night pressure went down so I replace all injectors figured they were leaking in to head causing it to flood before I started it first thing in the morning. Because the pump alone did not loose pressure. And another weird thing to try to work in to this equation is cold the car can always be jump started??
and many people have told me to give up and move on But I won't so keep shooting your ideas some one will get it.
Thanks
Cryptauto

Is the MAP Sensor good and have you checked for leaks? This is the key sensor on these cars.

Quote:

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Originally Posted by TxGreaseMonkey

Is the MAP Sensor good and have you checked for leaks? This is the key sensor on these cars.

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I did another vacuum test today @ idle 20ip steady dropped to zero for a second when quick revved and then maintained 20ip checked all individual vacuum components for leaks nothing still...

I hope by now you have this fixed but did you check the ignition switch?