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Car not starting (Main Relay? Fuel Pump Relay? Others)

Vi3tBoy

Vi3tBoy

Experienced Member
Joined
13 May 2010
Messages
460
Location
Twin Cities MN
So I have been driving my NSX almost everyday since it's been out of winter storage this year. It has a brand new battery only 2 weeks old now. I haven't had any issues what so ever.

So yesterday a friend of mine wants to take pictures of my car. So we head out and drove about 40 mins to a meeting spot. I parked the car and turned it off. Turned it on and off several times to move the car and do several rolling shots. We then get to the last spot and I park the car and shut it down, then needed to adjust the car a bit. Hopped in and it ran for 1 second and died. hmm so i cranked it and it would just sit and crank. Tried several times and in my head right away I thought great main relay? So I let the car sit for 10-15 mins and hopped in and it started right up as usual.

I did some searching on here and it sounds like it could also maybe be a fuel pump relay as well.

So my question is how do I test/check if it really is the main relay or the fuel pump relay, both maybe or could I totally be wrong and it be something else I haven't thought of. I would hate to replace both and it end up not being the issue as well and end up stranded somewhere.

Keep in mind it is a 1991 with 113k miles. I also have a new battery and have been driving it almost daily with lots of starts and shutting off and never had any hiccups until last night.

Thanks Prime.
 
The fuel pump relay serves to by-pass the fuel pump resistor under medium to high engine load conditions (which results in higher voltage to the pump). It doesn't figure into the starting process. The main fuel injection relay has two relays within one enclosure. From what has been reported by others on Prime, it is not the actual relays that fail but the solder joints on the internal circuit board that the relays are mounted on. If you are handy with a soldering iron, you can pry open the relay enclosure and repair these connections without too much effort. Also, if you pry open the enclosure and find that the connections are in good shape, then the main relay is probably not the problem (yes the actual relays can sometimes fail; but, they tend to stay failed and not come back to life). My instinct says that it could be your ignition switch which can definitely go through a working / not working / working period before it fails completely. You said the engine started and then died. Did the engine start when the switch was in the start (III) position and die when you transitioned the key to the run (II) position? If so, then the ignition switch is a strong suspect. If the engine did not die during the transition from the III to II position on the ignition switch, then the switch is probably not your problem. If your car still has the original fuel pump, it is also possible that your fuel pump is in the end of life mode. If the fuel pump had failed to start when you turned the key, the engine could have fired on the residual fuel pressure in the system and then promptly died due to absence of fuel. I have no direct experience with the fuel pump failure mode on the NSX; however, I have had experience with the pumps on the older Bosch D-jet, K-jet, and LH systems. On these systems, the pumps would sometimes start working again on an on again off again basis before dying on a permanent basis. Final failure (on the Bosch pumps) usually occurred within a couple of days of the initial failure to operate. Unfortunately, with everything back to operating on your car, there is no way that I am aware of to test the ignition sw, main relay or the pump to determine if they are in the failure mode. It might be possible to precipitate the failure of the component by going through a number of engine start cycles and then you could get down to testing the individual parts to see what failed. Good luck with it. Its no fun driving around wondering if its going to leave you stranded.
 
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Old Guy said:
The fuel pump relay serves to by-pass the fuel pump resistor under medium to high engine load conditions (which results in higher voltage to the pump). It doesn't figure into the starting process. The main fuel injection relay has two relays within one enclosure. From what has been reported by others on Prime, it is not the actual relays that fail but the solder joints on the internal circuit board that the relays are mounted on. If you are handy with a soldering iron, you can pry open the relay enclosure and repair these connections without too much effort. Also, if you pry open the enclosure and find that the connections are in good shape, then the main relay is probably not the problem (yes the actual relays can sometimes fail; but, they tend to stay failed and not come back to life). My instinct says that it could be your ignition switch which can definitely go through a working / not working / working period before it fails completely. You said the engine started and then died. Did the engine start when the switch was in the start (III) position and die when you transitioned the key to the run (II) position? If so, then the ignition switch is a strong suspect. If the engine did not die during the transition from the III to II position on the ignition switch, then the switch is probably not your problem. If your car still has the original fuel pump, it is also possible that your fuel pump is in the end of life mode. If the fuel pump had failed to start when you turned the key, the engine could have fired on the residual fuel pressure in the system and then promptly died due to absence of fuel. I have no direct experience with the fuel pump failure mode on the NSX; however, I have had experience with the pumps on the older Bosch D-jet, K-jet, and LH systems. On these systems, the pumps would sometimes start working again on an on again off again basis before dying on a permanent basis. Final failure (on the Bosch pumps) usually occurred within a couple of days of the initial failure to operate. Unfortunately, with everything back to operating on your car, there is no way that I am aware of to test the ignition sw, main relay or the pump to determine if they are in the failure mode. It might be possible to precipitate the failure of the component by going through a number of engine start cycles and then you could get down to testing the individual parts to see what failed. Good luck with it. Its no fun driving around wondering if its going to leave you stranded.
Click to expand...

Thank you for your reply. I do not have access to a soldering iron so I decided to order up a new main relay. I figure at this age and miles I might as well.

The engine did not die from the transition as you posted. But I haven't thought about it. Is there ways to really test if the ignition switch is on it's way out?

How often does an oem fuel pump go out? I mean I've had plenty of cars with way higher miles than this and never had fuel pump's going bad. It sounds like I'm getting fuel just fine if the car is running. it's just the actual not starting once that worries me. Ignition switch and main relay sounds more like what it could be is my guess? But I wouldn't be surprised if i was wrong lol.

Mikexike said:
I'd say main relay or maybe ignition switch
Click to expand...

I decided to order a new oem main relay just for the peace of mind and b/c of how common this problem sounds like it is in older Hondas now that i had time to read more into it.

As far as ignition switch wise how often do these go bad?
 
Replacing the main relay with a new one is a good idea. It's not all that expensive, it's often the cause of the problem, and it's easy to remove and replace using only a few metric sockets.
 
like nsxtasy said you only need a philips screwdriver and a 10mm socket and your done.
 
Sometimes the brushes in the ignition switch get worn to the point where your car only starts sometimes...changing it out isn't that expensive.. Fairly worthy of it but the main relay should take care of it.
 
I posted on this last week based on personal experience. I had an intermitent no start and tried all known problems main relay,fuel relay ect. The car finally broke down and I towed it back to my shop. I found the fuel pump resister was the problem. The resistor slows the pump down when less fuel is needed to reduce interior noise. This is not the function of the main relay it is a seperate module located in the engine compartment on passenger side firewall. There is a connector with two wires. I strait wired and bypassed the resistor to verify fix then ordred a new one from acura. The car ran fine without it but you could hear the pump at idle.
 
Mikexike said:
Sometimes the brushes in the ignition switch get worn to the point where your car only starts sometimes...changing it out isn't that expensive.. Fairly worthy of it but the main relay should take care of it.
Click to expand...

More info about the "brushes" I am not familiar with this at all.

With the car getting so old I don't mind doing preventative stuff like this in hopes of not being stranded away from home.

theautoman said:
I posted on this last week based on personal experience. I had an intermitent no start and tried all known problems main relay,fuel relay ect. The car finally broke down and I towed it back to my shop. I found the fuel pump resister was the problem. The resistor slows the pump down when less fuel is needed to reduce interior noise. This is not the function of the main relay it is a seperate module located in the engine compartment on passenger side firewall. There is a connector with two wires. I strait wired and bypassed the resistor to verify fix then ordred a new one from acura. The car ran fine without it but you could hear the pump at idle.
Click to expand...

Do you have the part number for the resistor?


Thanks all
 
The Brushes are inside the ignition switch if you take it apart, its just copper brushes..

Here is the part number for the resistor 16717-PR7-A01

Here is the part number for the ignition switch 35130-SL0-003

If you need any help just give me a call, I work for Niello Acura and i'd gladly help you get these parts for a good price and shipped them. :)

800.472.7278 ask for M2k

Vi3tBoy said:
More info about the "brushes" I am not familiar with this at all.

With the car getting so old I don't mind doing preventative stuff like this in hopes of not being stranded away from home.



Do you have the part number for the resistor?


Thanks all
Click to expand...
 
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You can verify resistor is the problem by jumping the plug. I found mine partially melted and had to replace the connector also.
 
Thanks so much guys.

If the problem still there after the main relay comes in I'll keep moving to the rest of the suggestions.
 
did you fix the issue?? I had a starting issue today. I just backed it out of the garage and tried to move it back in within 2 minutes. Im thinking its not the main relay, because the car wasn't even warm when this happened. Could possibly be a fuel pump relay, im thinking??
 
Does someone have a part number for the ignition switch? Does replacing it mean a new key for the ignition or is it just an electrical part you replace?
 

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