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Help needed - car not starting


Parry_10
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Just completed my na-tt conversion car started up fine ran for 5-10 mins then cut out and wouldnt fire up again it was just cranking over, i thought maybe ran out of fuel so went to get some came back 15 mins later put fuel in and it fired up was running for few mins then cut out again and wont start again.. Ive done the 12v fuel pump ecu mod so its not that, when i turn my ignition on i cant hear the fuel pump and ive just fitted a walboro fuel pump- chris

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lol funny, its just weird because when i put more fuel in it 15 mins later it fired up again then cut out and wouldnt start again, then i come out hours later and it still doesnt start so it doesnt really make any sense, tried disconnecting and reconnecting the battery etc didnt make a difference:(

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The fuel pump won't run if you just turn the ignition on. The first time you key on after a period it will run briefly then it won't run again until you are cranking the engine. If you want to check the pump is working bridge the FP and +B terminals in the diagnostic connector under the bonnet with a wire and then turn the ignition on - the pump should then run continuously.

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Depends how you did it. The correct way is using a relay so that switches with the FP wire in which case the pump will run at 12V all the time it is running rather than switching between 9V and 12V as needed (which is pretty pointless actually). If you have bodged it without using the FP wire I would undo it before you find yourself upside down in a ditch with the fuel pump still running and pouring fuel everwhere because it hasn't switched off with the engine!

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the car wont start if the fuel pump isnt priming,

 

have you installed the fuel pump the same time as you did the conversion?

 

as someone mentioned, it will only prime/make the noise each time the engine has been cranked.

 

get the fuel pump to prime 1st as it sounds like there your problem is, then remove the fuel pipe in the engine bay to check its getting there

 

 

i went thro all this shit when i did a conversion on my 300zx, went NA to TT, woundt start. my problem was the injector connections on the loom were all cloggy, but i went thro all the step by step things,

 

fuel, fuel pump, fuel filter, fuel pump ECU, check if fuel is being sent thro the rail, check the ECU is working the njectors with a NOID light,

 

im sure youl get there, just process of ilimination

Edited by Lude (see edit history)
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If you have done the 12v mod with it perma-wired you should be able to hear the fuel going through the rail with the ignition on II, can you hear anything? Also remove the metal fuel tank cover in the boot and listen for the motor, it should be audible even if the tank is full.

 

If you don't hear anything then look to your 12v mod or a pump/pump ECU issue. Have you changed the pump? Also, try the port bridge Simon mentioned earlier in the thread and see if that kick starts the fuel pump.

 

There's lots more things that can be checked, but if you can respond to the above for a start it should give some next steps.

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Yeh i fitted a brand new walboro fuel pump just before i started the engine for the first time, i can hear the fuel going through the rail i just cant hear the pump at all, it was fine before i changed it/did the na-tt conversion i was running the na with the 12v mod and it was fine, i will try the FP and +b bridge in the diag port tomorrow

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If you have done the 12v mod with it perma-wired you should be able to hear the fuel going through the rail with the ignition on II, can you hear anything? Also remove the metal fuel tank cover in the boot and listen for the motor, it should be audible even if the tank is full.

 

If you don't hear anything then look to your 12v mod or a pump/pump ECU issue. Have you changed the pump? Also, try the port bridge Simon mentioned earlier in the thread and see if that kick starts the fuel pump.

 

There's lots more things that can be checked, but if you can respond to the above for a start it should give some next steps.

 

Does the 12v mod not by-pass the ECU?

 

We had exactly the same issue with Suprash's car a year or 2 ago, went through everything trying to find the problem. He had done the 12v mod, (which personally I think is pointless..), went through the entrire loom all the way to the ECU. I'll be buggered if I can remember what it was though.. Gav may know as he had the loom diagram. Off the top of my head I seem to recall some sort of connector or something above the nearside rear wheel arch area. Could be wrong but it was something there that was causing the problem. (P.S, i'm not talking about the ECU by the boot light, it was something further forward but still in the boot)

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Yeh i fitted a brand new walboro fuel pump just before i started the engine for the first time, i can hear the fuel going through the rail i just cant hear the pump at all, it was fine before i changed it/did the na-tt conversion i was running the na with the 12v mod and it was fine, i will try the FP and +b bridge in the diag port tomorrow

 

Don't do that for long.. It'll get very hot very quick!

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If you can hear the fuel going through the rail the pump is working :)

 

Just a couple more things to check tomorrow:

- Ensure the white clip on the main ECU looms are fully down and locked (just above the ECU)

- Check the sock filter on the fuel pump is not pressed against the bottom of the fuel pan in the tank, it should rest just above it

 

However, if the fuel is circulating it is likely another issue, so best to get checking all the plugs are fully seated. Did you change the fuel pump ECU for a TT one?

 

Also, as mentioned, get rid of the 12v mod, it's completely pointless at even BPU levels not to mention extremely dangerous.

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