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Author Topic: crank no start b5 s4  (Read 475 times)
dilly
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« on: July 05, 2019, 02:09:06 PM »

as the title states, i have a cranking no start condition. no codes etc but i suspect it has to do with fuel delivery.
was pulling out of my driveway and car just shut off. the fuse for the fuel pump is also okay
while cranking, the fuel pump relay clicks on and off until i stop cranking. every few revolutions i get a stutter as if one cylinder is trying to fire. that's it

can't hear the fuel pump prime
so idk if it is the relay or the pump
i dont have a pump or relay at my disposal unless the pump alone is the same as a mk4 vw. so idk what to do
what do you guys think
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IamwhoIam
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« Reply #1 on: July 06, 2019, 04:07:21 AM »

remove the fuel supply line from the fuel rail, have someone crank the car and watch if there's any fuel coming out of it while cranking or not. my money is on the fuel pump, especially if it's a high mileage car. Fuel pump alone is NOT the same as a mk4 VW LOL
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I have no logs because I have a boost gauge (makes things easier)
dilly
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« Reply #2 on: July 06, 2019, 04:40:04 AM »

remove the fuel supply line from the fuel rail, have someone crank the car and watch if there's any fuel coming out of it while cranking or not. my money is on the fuel pump, especially if it's a high mileage car. Fuel pump alone is NOT the same as a mk4 VW LOL
eh didnt know if the actual fuel pump (not the whole assembly just the pump) is the same or not.
but just now i unplugged ecu and battery and rese everything and it fired up. funny because it ran okay for about 45 seconds went to put it in gear and it shut off again yadda yadda.
i changed the ecu back to the original that was in the car and now it runs fine.
so i am assuming the ecu is toast in some way which sucks because now i have to buy another one in order for me to pass inspection. yippee
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dilly
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« Reply #3 on: July 06, 2019, 10:36:07 AM »

welp scratch that
changed the ecu and car ran fine. now it is doing the same thing lol

not really sure what to do from here
the fuel pump relay just clicks away while cranking
« Last Edit: July 06, 2019, 12:29:26 PM by dirtnasty » Logged
dilly
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« Reply #4 on: July 06, 2019, 02:41:58 PM »

UPDATE
if i hold the relay closed manually i get 12v at the pump plug with key on and also while cranking.


what i dont understand is when i leave the ecu and battery out for a bit it starts up. but shortly after dies again and repeat cycle.
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dilly
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« Reply #5 on: July 09, 2019, 08:02:47 PM »

SOLVED
ended up being a bad crank sensor. took the one out of my 2.0 spare jetta and it fired right up and still going strong.
odd to me though cause there were no codes.

does make a little sense though cause when i was watching the rpm value during cranking in vcds, when it stuttered and the relay was going wild the rpm value would quickly drop to zero then back up to 200 something
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