93 NSX. Click, No Crank, No Fuel Pump Prime

[Miner]

you mentioned that you opened your ignition switch and it look ok. I suggest conducting the tests in the manual to confirm it is properly functioning.
If you can put the voltmeter on the circuit, are you seeing the 12 volts to the starter when using the key?
Aftermarket alarm installs alway complicate the matter, but with your symptoms consistent with a faulty ign switch, I would make sure it is functioning properly.

 

[AdventureNSX]

you mentioned that you opened your ignition switch and it look ok. I suggest conducting the tests in the manual to confirm it is properly functioning.
If you can put the voltmeter on the circuit, are you seeing the 12 volts to the starter when using the key?
Aftermarket alarm installs alway complicate the matter, but with your symptoms consistent with a faulty ign switch, I would make sure it is functioning properly.

Hello Miner. You are correct. I am running the tests in the manual today.

I ordered a new ignition switch last week, but it still has not arrived. I can return it if need be.

I completely removed the aftermarket Viper Alarm.

 

[Old Guy]

In the photo below....
Is the Clutch Interlock Switch labeled as 'A' or the 'B' ? I'm thinking it is labeled 'A'

It is axiomatic that the clutch interlock switch for the starter circuit - the one that stops you dead in the parking lot when the stopper drops out - is the top switch which is miserable to access.

Since you are 'down there' I suggest that you back probe the blk/yel wire in on the clutch switch connector and connect it to ground. Make sure that the back probe is inserted into the connector plug to make contact with the terminal pin. This jumper to ground will by-pass the security system and you should be able to engage the starter by pressing down on the clutch and turning the key to start. If that is successful, then you know that the starter problem is originating in the security system circuit.

 

[Old Guy]

The Fuel Pump still does not prime.

The fuel pump resistor in the engine bay is OEM & new. The Main Relay is OEM & new.

I connected my continuity tester directly to the Red/Blk wire at the fuel pump connector, and turned the key to start. This caused the continuity tester to show some numbers for the first 2 seconds, but it quickly zeros out before I can see the voltage.

I inspected the wires carefully at the fuel pump resistor and do not see any evidence of heat damage.

I won't have anyone available until Sunday evening who can help me turn the ignition on while I test the fuel pump resistor wires in the engine bay.

I want to unplug the fuel pump connector plug at the rear firewall and run 12V directly to the fuel pump to see if it will run briefly. Do I run power to the blk/red wire and connect - to the blk/silver wire?

When you say "I connected my continuity tester directly to the Red/Blk wire at the fuel pump connector " do you mean you were measuring voltage? If you actually tried to measure continuity at the red/blk wire you will confuse the tester and may render it deceased. I am guessing that you were actually measuring voltage and you are suffering from a tester with a slow A to D sampling rate which is a characteristic of budget testers. The prime pulse only lasts about 2 seconds. If you want to capture a short pulse of voltage with a digital tester you need to fork over > $400 for a tester with a fast sample rate and a peak hold function or find an old school analog meter tester. In this particular case, a simple 12v test light as a voltage checker may work just as well.

Did you do that measurement right at the connector at the tank (access through the back firewall)? If so, that suggests that your fuel pump is dead. You could go back with a test light and repeat the test to confirm that you are getting 12 volts at the fuel pump connector for the two second prime pulse (light illuminates for 2 seconds). Or you can use your tester to measure the resistance of the pump motor. If the resistance is really high or infinite that suggests its dead or an open connection. Or, the gold standard test is as you suggest - you can disconnect the pump and apply 12 volts directly to the pump side of the plug (+ to Blk/red and ground to blk). If the pump doesn't run, its dead or you have a broken connection down into the pump. Either way, the tank is coming out. One of those large 12 volt lantern battery's should have enough jam for a short 2-3 second run.

Both the service manual and the ETS manual say that the pump wires are blk/red and blk. According to the ETS manual, Honda does not use Blk/Sil wires anywhere on the car. Check the wiring - if it really is blk/sil that would be foreign wiring which could lead you in the direction of your problem.. Honda does use blk/wht wiring on the car; but, not in the fuel pump circuit. Check to make sure that you have the correct connector. If the wire really is blk/sil or blk/wht you need to figure out what is going on before you try applying 12v directly to the pump. Applying 12v to the pump is kind of an acid test and if it's not the pump that you are connecting to you could cook something.

 

[AdventureNSX]

It is axiomatic that the clutch interlock switch for the starter circuit - the one that stops you dead in the parking lot when the stopper drops out - is the top switch which is miserable to access.

Since you are 'down there' I suggest that you back probe the blk/yel wire in on the clutch switch connector and connect it to ground. Make sure that the back probe is inserted into the connector plug to make contact with the terminal pin. This jumper to ground will by-pass the security system and you should be able to engage the starter by pressing down on the clutch and turning the key to start. If that is successful, then you know that the starter problem is originating in the security system circuit.

This notorious Clutch Interlock Switch was really unpleasant to work with! Having the driver seat out allowed me to lay on my back and have my face up under the dash. Fitting both arms and a wrench up in there was another story. I hope the engineer(s) who designed this get to experience it first hand in a parking lot.

I did exactly as you advised with the back probe. I quickly isolated the problem to the clutch interlock switch. I also used a jumper to double check if it would work without the switch and it did. Swapped it out with a new part and now the starter engages upon depressing the clutch and turning the key to start.

One problem solved, thanks to Mr Old Guy's guidance.

 

[AdventureNSX]

When you say "I connected my continuity tester directly to the Red/Blk wire at the fuel pump connector " do you mean you were measuring voltage? If you actually tried to measure continuity at the red/blk wire you will confuse the tester and may render it deceased. I am guessing that you were actually measuring voltage and you are suffering from a tester with a slow A to D sampling rate which is a characteristic of budget testers. The prime pulse only lasts about 2 seconds. If you want to capture a short pulse of voltage with a digital tester you need to fork over > $400 for a tester with a fast sample rate and a peak hold function or find an old school analog meter tester. In this particular case, a simple 12v test light as a voltage checker may work just as well.

Did you do that measurement right at the connector at the tank (access through the back firewall)? If so, that suggests that your fuel pump is dead. You could go back with a test light and repeat the test to confirm that you are getting 12 volts at the fuel pump connector for the two second prime pulse (light illuminates for 2 seconds). Or you can use your tester to measure the resistance of the pump motor. If the resistance is really high or infinite that suggests its dead or an open connection. Or, the gold standard test is as you suggest - you can disconnect the pump and apply 12 volts directly to the pump side of the plug (+ to Blk/red and ground to blk). If the pump doesn't run, its dead or you have a broken connection down into the pump. Either way, the tank is coming out. One of those large 12 volt lantern battery's should have enough jam for a short 2-3 second run.

You are correct. I meant to say, I was trying to measure voltage. Kind of embarrassing, lol.

Yes, I did do those measurements directly at the fuel pump connector. I also probed the red/blk with a 12v test light. The LED test light illuminated during the 2 second prime pulse.

Finally, I unplugged the fuel pump plug at the firewall and ran 12 volts directly to the pump (via + to the red/blk wire and - to the blk wire). I used several different batteries, just in case, and the pump remained silent. Yup, the tank will be coming out!!

I'll be ordering some new parts tomorrow...

Denso Electric Fuel Pump 951-0011
Denso Fuel Pump Filter 952-0022
Fuel tank gasket to sending unit.
Beck/Arnley Fuel Filter 043-0977
And will replace all the fuel lines, including the
Fuel joint hose with banjo bolts 17707-SL0-931

If you think I should replace anything else when the tank is out, please let me know.

 

[AdventureNSX]

Both the service manual and the ETS manual say that the pump wires are blk/red and blk. According to the ETS manual, Honda does not use Blk/Sil wires anywhere on the car. Check the wiring - if it really is blk/sil that would be foreign wiring which could lead you in the direction of your problem.. Honda does use blk/wht wiring on the car; but, not in the fuel pump circuit. Check to make sure that you have the correct connector. If the wire really is blk/sil or blk/wht you need to figure out what is going on before you try applying 12v directly to the pump. Applying 12v to the pump is kind of an acid test and if it's not the pump that you are connecting to you could cook something.

Thanks for clarifying and for your kind concern so that I didn't inadvertently fry something important.

I took a photo to show why I mentioned blk/silver. I guess the silver bands mean something different. Do you happen to know what the silver bands mean?

I appreciate ALL your help Sir. I wish I knew your actual name to give you a respectable thank you.

 

[Miner]

This notorious Clutch Interlock Switch was really unpleasant to work with! Having the driver seat out allowed me to lay on my back and have my face up under the dash. Fitting both arms and a wrench up in there was another story. I hope the engineer(s) who designed this get to experience it first hand in a parking lot.

I did exactly as you advised with the back probe. I quickly isolated the problem to the clutch interlock switch. I also used a jumper to double check if it would work without the switch and it did. Swapped it out with a new part and now the starter engages upon depressing the clutch and turning the key to start.

One problem solved, thanks to Mr Old Guy's guidance.

Right on!

The starter circuit is pretty straightforward. Glad you found the “open” that was preventing the starter from working.

 

[LeftyF]

Do we ever get a diagnosis of the fuel pump issue?

 

[Old Guy]

It is good that it appears that you have resolved your non start problem (pending actual confirmation of the fuel pump by its replacement). I must admit that having two completely separate and unrelated systems failing at the same time is not impossible; but, has to be really low probability. I really expected that it was going to be the common system of the aftermarket security system causing failure of the starter and pump circuit. So much for pre conceived notions!

If you have reasonable access to the clutch interlock switch, you might want to consider replacing the matching stopper (a common failure item) while you are cursing the actual switch replacement.

Given the age of the car, the fuel pump failure is not a complete surprise. I have had an OEM Denso pump sitting in my spares box for my 2000 on the expectation that it will fail at some point. Hopefully it will have the good graces to fail at my front door step (like my main EFI relay) rather than some place inconvenient. Rock Auto sells the OEM Denso pump for a nice price.

 

[AdventureNSX]

Do we ever get a diagnosis of the fuel pump issue?

I unplugged the fuel pump plug at the firewall and ran 12 volts directly to the pump (via + to the red/blk wire and - to the blk wire). I used several different batteries, just in case, and the pump remained silent. Fuel pump is dead.

 

[AdventureNSX]

It is good that it appears that you have resolved your non start problem (pending actual confirmation of the fuel pump by its replacement). I must admit that having two completely separate and unrelated systems failing at the same time is not impossible; but, has to be really low probability. I really expected that it was going to be the common system of the aftermarket security system causing failure of the starter and pump circuit. So much for pre conceived notions!

If you have reasonable access to the clutch interlock switch, you might want to consider replacing the matching stopper (a common failure item) while you are cursing the actual switch replacement.

Given the age of the car, the fuel pump failure is not a complete surprise. I have had an OEM Denso pump sitting in my spares box for my 2000 on the expectation that it will fail at some point. Hopefully it will have the good graces to fail at my front door step (like my main EFI relay) rather than some place inconvenient. Rock Auto sells the OEM Denso pump for a nice price.

I agree, very unusual for 2 issues like this to develop nearly at the same time. With that in mind, I too had a nearly certain feeling the issues would have been related to the Viper aftermarket security system. I am rather surprised it wasn't the aforementioned!

I will come back and update this post when the fuel pump has been replaced.

I appreciate you walking me thru this with all the detailed pertinent technical info.

 

[AdventureNSX]

4/11/2024
I'm back with an update on my NSX. In short, the engine cranks, but just turns over and will not start.

Three weeks ago I removed the tank and carefully installed a new Denso fuel pump & new tank filter.

I briefly tested the new fuel pump twice for 1 second (prior to installing it), just to make sure it worked.

***Before starting the engine, I have been waiting for the fuel pump to fully prime, usually 3 times.***

I cracked open the banjo bolts on top of the fuel filter and fresh fuel is present.

I have replaced the following parts, in the following order, one at a time, not all at the same time...

New Clutch Interlock Switch.
New Ignition Switch.
New Denso Fuel pump.
New Denso tank sock filter.
New Main Relay.
New Power Relay.
New Fuel Resistor Relay.
New Fuel Filter.

New Clutch Interlock Switch (no crank issue solved, starter now cranks).

New Ignition Switch. (wires were damaged when original owner had the Viper Alarm installed, so I replaced with a fresh part).

New Denso Fuel pump (fuel pump now primes).

New Fuel Filter (still had original filter, required maintenance due).

I completely & carefully removed the aftermarket Viper Alarm.

I left the gas tank empty the whole time the car sat waiting for the new fuel pump to be installed.

After installing the new fuel pump, I put 10 gallons of fresh high octane non-ethanol fuel in the empty tank.

***Prior to the fuel pump going bad, the car would start easily on the first turn of the key and run & drive without issue.

Edited this post on 7/5/2024 to note, my NSX still will not start. And I removed some dumb questions.

 

[drew]

Stop with the parts cannon, stop ordering and replacing parts. You could be inducing problems and is...bad. Or cause it to be intermittent which is worse.

The NSX is simple in the that you only need a diagnosis plan and not any special tools.

Test for a lack of fuel by spraying something flammable inside the intake boot. Such as starter fluid or brake cleaner. You should get a cough and sputter. if so, start with power to the pimp and work backwards.

Check out South Main Auto on YouTube for "Crank No Start" to get an idea of how to make a diagnosis plan. Probably any Honda of that era with a Crank No Start will be helpful.