She won't start.

[69XSN]

91 nsx, manual transmission. Ok, I have gas, she ran fine yesterday, jumped in this afternoon and she won't start. The engine cranks but won't come to life. Also i've noticed that even though the engine is cranking the tachometer did not move. Help, please anyone.

 

[69XSN]

Also can anyone please tell me where the clock fuse or fuse for resetting the ECU is located on a 91 model.

 

[Zishan]

Main Relay, part EZ-1010 I think. Do a search, it will turn up tons of results....

Good luck,

 

[69XSN]

Thanks very much sir, it seem that you are correct it was the main relay, the car started after i tapped on it a couple times. thanks again.

 

[Larry Bastanza]

If you open up the main relay, you can resolder the cracked solder joints, it will work for another 10 years.

HTH,
LarryB

 

[Zishan]

If you open up the main relay, you can resolder the cracked solder joints, it will work for another 10 years.

HTH,
LarryB

Larry, you are right. And it'll save you $60 bucks! :smile:

I felt really helpful, until Larry chimed in! j/k

 

[KooLaid]

Is this also related to the engine cranking over for about 2-3 seconds to start on occasion instead of the usual, crank and fire?

 

[davidf]

Could be cam sensor. Mines leaking now. I know it's behind a cam gear but is it a costly job labor wise? I'm not one to wait until it's broke to fix it. Cost anyone?

 

[Sulley]

Make sure you fix or replace it.
Just because it starts when you tap it doesn't mean it will start the next time.
Mine failed completely when it went.
Sulley

 

[Larry Bastanza]

Could be cam sensor. Mines leaking now. I know it's behind a cam gear but is it a costly job labor wise? I'm not one to wait until it's broke to fix it. Cost anyone?

They all leak, actually this is the potting material getting heated and getting soft. I would not do a preventative on this unless you are doing the timing belt, or for some other reason you are in there. It is quite a bit of work to get to it, as much as a complete T/Belt replacement. This would be at least in the $800+ range by itself, which again, I would not recommend, unless it actually failed. Personally, I have not replaced one yet.

HTH,
LarryB

 

[Elite]

Speaking of cam angle sensor, I'm leaning toward that on my car. I have replaced the main relay, swapped out a known good ecu, swapped in a known good igniter, checked all associated wires for continuity, checked all resistances the manual asks for, I have fuel when cranking, but have absolutely no spark. Anyone have any other ideas?

 

[sojusoulja]

another issue with hard starts could be attributed to a faulty or bad coolent temp sensor

 

[davidf]

They all leak, actually this is the potting material getting heated and getting soft. I would not do a preventative on this unless you are doing the timing belt, or for some other reason you are in there. It is quite a bit of work to get to it, as much as a complete T/Belt replacement. This would be at least in the $800+ range by itself, which again, I would not recommend, unless it actually failed. Personally, I have not replaced one yet.

HTH,
LarryB

Thanks larry. TB was done last year so I guess it'll be put off awhile.:smile:

 

[dlynes]

Thanks very much sir, it seem that you are correct it was the main relay, the car started after i tapped on it a couple times. thanks again.

had the same problem earlier this yr. replaced main relay and started right up!!

 

[Jett]

You need to either replace or repair the main relay.

If you decide to repair it, it has sort of a "hand-in-glove" design. Remove one end and the electronic components (hand) slide out of the black outer casing (glove). The electronic components are soldered onto a circuit board. Flip the board over and the solder points on the back are are clearly visible. Typically, the cause of the failure is small cracks which develop in the solder points themselves, which cause an open circuit when the car goes over bumps or otherwise vibrates a little, opening the cracks and preventing current flow. Examine the solder points closely, looking for small hairline cracks. To correct these, take a soldering iron and melt the solder joints until they are liquid, being careful not to let the solder run or drip, then allow them to reset. When you have done them all and are satisfied with the results, reassemble and reinstall the main relay.

I feel that is safer for the typical do-it-yourselfer just to melt and reset the old solder joints, rather than completely resoldering them, as it takes a bit of skill to solder properly from scratch if you are inexperienced. If you are skilled and experienced with a soldering iron you might consider removing and resoldering them completely, but it is not necessary.

Or you could have it resoldered at an electronics shop. When my main relay went bad, I drove the car to a television repair shop and removed the main relay in the parking lot. I was fortunate to show up at a time when the technician had a hot soldering iron out. I was probably in and out in 15 minutes, and they didn't even charge me. The technician heated and reset the cracked solder points, and the main relay has been trouble-free for 5 years now.

Here is a picture of the main relay, with part number...

http://www.nsxprime.com/forums/attachment.php?attachmentid=33662&d=1179120990

 

[69XSN]

You guys are so great, feels like i'm part of a family. I took the relay apart and saw where it was cracked. Thanks a million guys for helping me diagnose my problem and saving some cash. I would gladly donate the money but my supra needs a new engine :biggrin: . Thanks again guys, prime's the greatest.

 

[soloracer951]

Is this also related to the engine cranking over for about 2-3 seconds to start on occasion instead of the usual, crank and fire?

Mine is doing the same thing. Anyone know the answer as to why?

 

[Zishan]

Age my friend, age.

 

[soloracer951]

Age? Of what specifically? My compression numbers were very good as were my leakdown numbers. So what is aging and causing this problem?

 

[Zishan]

I'm no expert, but the Main Relay seems to be a part that will eventually fail. I believe the connections inside maybe weak, and that with the usage and age, the connections begin to deteriorate, eventually breaking.

Again, I'm no expert, but that's my unofficial prognosis. :smile:

 

[Larry Bastanza]

Speaking of cam angle sensor, I'm leaning toward that on my car. I have replaced the main relay, swapped out a known good ecu, swapped in a known good igniter, checked all associated wires for continuity, checked all resistances the manual asks for, I have fuel when cranking, but have absolutely no spark. Anyone have any other ideas?

I would install the test jumper and check for an OBD code. You should get one it the crank angle sensor has failed.

HTH,
LarryB

 

[Elite]

I would install the test jumper and check for an OBD code. You should get one it the crank angle sensor has failed.

HTH,
LarryB

I'll do that, it is much easier then swapping the sensor out. :tongue: Thanks

 

[jrehner]

I read this post and had the same symptoms and also tapped on the main relay box and it would start up but that was only coincidental for me as the problem turned out to be the ignition switch instead. I was told that if u turn the ignition key full on and it operates not only the starter but ALSO the engine then the problem is the ignition switch and that's what it was in my case (but I have a spare main relay now).

 

[DDozier]

I am adding this for the bennifit of others with an AEM ECU, the simptoms for the the Main Relay Failure are the same, car either will or wont start, and no fuel pump voltage. The AEM ECU will not allow you to connect or you will get a message that reads "multiple varification errors, please power ECU then try to connect". Basically one side of the main relay powers the ECU and the other side is for fuel and other key on power devices.

I did the solder fix and have had no other issus, I would advise reloading your last .CAL file only after you have fixed the relay and verified the connection to the ECU for more than 5 min. Then start the car. My .cal had some data errors in it and the car idled like crap, I loaded my last known good .CAL and everything went back to normal.

Dave

 

[britlude]

i did the main relay on mine, tho the solder joints looked good, the problem was under the surface skin... when heated with an iron, the solder flowed away from the pin, with no tinning to it at all. It looks like over time the solder flux corrodes the pin effectively insulating it from the solder but leaving a nice looking solder 'joint' over the top of the pin!

so, even if it looks fine, resolder it anyway!!!