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Not main relay,fuel pump resistor,ignition switch,fuel pressure fine,what else?
- Thread starter sjones
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If it is cranking but doesn't start, you can consider trying this: turn your key to the on position making sure you hear the fuel pump prime completely. Then turn it off without cranking, then back to on position and let prime.
Do this 3 or 4 times, then try to start. What this is doing is testing the fuel pump by fully priming the fuel. Although it is rare for our fuel pumps to go bad, it can happen.
Does the car run fine after it starts? Are you getting any CEL's?
Good luck
Do this 3 or 4 times, then try to start. What this is doing is testing the fuel pump by fully priming the fuel. Although it is rare for our fuel pumps to go bad, it can happen.
Does the car run fine after it starts? Are you getting any CEL's?
Good luck
What exactly is the car doing when you turn the key to start? did you hear a single click? more info. please
CEL = check engine light. Sure does sound like classic main relay symptoms. Did you replace the main relay yet? If not, how did you rule that out as being the culprit.
If you have already replaced the main relay, my money would be on the fuel pump. The fuel pump has to work hardest to get the car started, that is why the car would run fine once started up.
good luck
If you have already replaced the main relay, my money would be on the fuel pump. The fuel pump has to work hardest to get the car started, that is why the car would run fine once started up.
good luck
Year of vehicle?
Modifications (list all)?
Recent maintenance?
CEL Code?
DanO
Modifications (list all)?
Recent maintenance?
CEL Code?
DanO
Year of vehicle? 91
Modifications (list all)? no mods, completely stock
Recent maintenance? no recent maintenance aside from replacing main relay along & the fuel pump resistor. 90K maintenance will be done next month.
CEL Code? no check engine lights. I'll have to get back to you on getting any codes read.
Modifications (list all)? no mods, completely stock
Recent maintenance? no recent maintenance aside from replacing main relay along & the fuel pump resistor. 90K maintenance will be done next month.
CEL Code? no check engine lights. I'll have to get back to you on getting any codes read.
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this also happends to me at the wrong time (when im in a hurry)
i turn the key to the on position, listen for the pump. Then i turn it back off and do it once again. Then the car starts.
gil
by the way, how much is the main relay and where is it located.
thanks
i turn the key to the on position, listen for the pump. Then i turn it back off and do it once again. Then the car starts.
gil
by the way, how much is the main relay and where is it located.
thanks
Yellow Rose
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The fuel pump has to work hardest to get the car started, that is why the car would run fine once started up.
Huh? The fuel pump exerts the same amount of "work" regardless if the engine is first started or is at steady-state cruise conditions or is at 8000 RPM.
Please explain yourself.
EDIT - better explanation below.
Huh? The fuel pump exerts the same amount of "work" regardless if the engine is first started or is at steady-state cruise conditions or is at 8000 RPM.
Please explain yourself.
EDIT - better explanation below.
Last edited:
Yellow Rose
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by the way, how much is the main relay and where is it located.
$53.....behind the long interior panel behind the seats.
$53.....behind the long interior panel behind the seats.
Yellow Rose
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Something Else To Think About
The ignitor module.....about the size of a deck-of-cards, located on top of the intake manifold.
The ignitor module.....about the size of a deck-of-cards, located on top of the intake manifold.
This is not what I was told. I have a friend who is a good mechanic and when he was repairing my neighbor's car (had the same symptoms as the original poster, car would run fine once started but had a hard time starting) he said the fuel pump works hard to prime the engine vs normal idle. He replaced the fuel pump and now works fine.AndyVecsey said:
You're saying this is false? That would mean to fuel pump supplies the same amount of fuel at idle vs WOT. Don't mean to get off topic, but would like to know. I'm not a fuel pump expert by no means.
Yellow Rose
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Fuel Pump
.....he said the fuel pump works hard to prime the engine vs normal idle......You're saying this is false? That would mean the fuel pump supplies the same amount of fuel at idle vs WOT.
A centrifugal pump, such as the NSX fuel pump, requires less input power to spin the shaft at “dead head” conditions vs at flowing conditions. The term “dead head” is an industry term which indicates that the pump is spinning but no flow is being delivered. This would be the case when you prime the fuel system - you are building pressure in the fuel rails, but because the injectors are not injecting, there is no fuel flow.
For a constant shaft speed, the pump flowrate is fixed. If the pump is delivering more fuel than what is needed, excess is diverted back to the tank via the fuel pressure regulator. If the pump is delivering less fuel than what is needed, the fuel pump resistor is bypassed and the motor voltage increase, which results in a faster spinning pump, which results in more gasoline.
.....he said the fuel pump works hard to prime the engine vs normal idle......You're saying this is false? That would mean the fuel pump supplies the same amount of fuel at idle vs WOT.
A centrifugal pump, such as the NSX fuel pump, requires less input power to spin the shaft at “dead head” conditions vs at flowing conditions. The term “dead head” is an industry term which indicates that the pump is spinning but no flow is being delivered. This would be the case when you prime the fuel system - you are building pressure in the fuel rails, but because the injectors are not injecting, there is no fuel flow.
For a constant shaft speed, the pump flowrate is fixed. If the pump is delivering more fuel than what is needed, excess is diverted back to the tank via the fuel pressure regulator. If the pump is delivering less fuel than what is needed, the fuel pump resistor is bypassed and the motor voltage increase, which results in a faster spinning pump, which results in more gasoline.
Re: Fuel Pump
Or more precisely, at 4,800 RPM the ECU signals the Main Relay to bypass the Fuel Pump Resistor Circuit and therefore the fuel pump sees more voltage. I do not believe that the ECU knows anything about fuel pressure.
DanO
AndyVecsey said:
Or more precisely, at 4,800 RPM the ECU signals the Main Relay to bypass the Fuel Pump Resistor Circuit and therefore the fuel pump sees more voltage. I do not believe that the ECU knows anything about fuel pressure.
DanO
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I may have the answer if your having the same problem I had. Basically i would get in the car turn the key and CLICK. that was it, sometimes after a few tries it would start right up like nothing happened. After checking for all over I found this was the problem. I checked to make sure the starter was getting power and it was only getting 9v, which seems to not be enough to start the car. So i checked for a power draw, it turned out the clock was drawing power, so i pulled the fuse. I have a gel battery in the car so i should be able to just charge it up and the alternator should hold charge. However the battery terminal was loose, so the car was fine but the battery never got power back. So i stuck a piece of metal in between the battery terminal and battery clamp thing and it that fixed. Sorry this was so long, but hopefully thats your problem because its an easy fix, just wanted to warn you it may not start if your battery is drained. Good luck, let me know if that helped
mike
mike
Yellow Rose
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Battery Connection
I had the same problem as demon81 described. About two weeks ago, I cleaned the outside of the positive battery cable with Diet Coke (excellent source of carbonic acid) and an old toothbrush. Last week I started the car and it acted as if the battery was drained. Got home, removed the positive cable and noticed there was still residual corrosion between the inside of the cable connector and the battery post. Sharing some of my bourbon-n-coke with the car cleaned up the nasty corrosion and we are happy. Not sure if we are happy because of the clean battery cable or the slight buzz.
I had the same problem as demon81 described. About two weeks ago, I cleaned the outside of the positive battery cable with Diet Coke (excellent source of carbonic acid) and an old toothbrush. Last week I started the car and it acted as if the battery was drained. Got home, removed the positive cable and noticed there was still residual corrosion between the inside of the cable connector and the battery post. Sharing some of my bourbon-n-coke with the car cleaned up the nasty corrosion and we are happy. Not sure if we are happy because of the clean battery cable or the slight buzz.
92gpwnsx said:
There is a small relay behind the drivers seat, I jumped the 2 gold conectors.
It runs a little rich as the fuel pump is running on high all the time.
I replaced the Main realy, secondary relay, fuel pup resistor, and ignition switch.
It turned out I had a bad ECU that was shorting out, I replaced it and all is good now.
