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Assistance in Confirming Diagnostic for no-start

2K views 25 replies 4 participants last post by  mrkevinhoang 
#1 ·
Hello. I've spent a few days reading through the forums before posting. I just want to get some ideas if I'm diagnosing this problem correctly.
My 2000 M5 with 170k on it was sitting for about 6 months at 1/4+ tank. I take it out during quarantine for a drive and all is fine. A few days later I take it out for a drive to work (im an essential worker) and it runs fine, but when I leave work, 1/4 tank, the car starts, then dies after 2 seconds. Then everytime I start it, it starts for a second, then dies.
I unplugged both MAF's but the still does not start.
I'm thinking that PDK / black fuel relay in the right side of trunk. I use a paper clip to jump the 12V to fuel pump (bypassing the relay). I dont hear the pump at all and car still wont start.
With the key on 2, and relay in, the fuel power line is about 4v.
I checked some fuses. DME fuse under passenger cabin filter. All 5 fuses are in tact.
I checked the 25A fuse near the relay. It is good.
I also called AAA. they brought me 2 gallons of fuel. ( I thought the gas was stuck on one side of the tank) still no luck. Car now wont start at all now, when before it starts for a second before dying.
I go to the secret menu and I see TNK: 6.8 / 8.5 / 15.3 L.
Fuel filter and pump service history is unknown, I can assume they have not been done in the past 3-5 years.
I have the fuel filter TBInstalled. I dont have the fuel pump yet.

My conclusion is the fuel pump is toast. May I have some feedback on my conclusion before I purchase from FCP. ($223) They have the Delphi brand w / lifetime warranty. Is there anything else I can test?

Thank you!
 
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#17 ·
I've ordered the fuel pump and relay plus clams
I've been reading that the fuel pump is one of those things that will eventually fail. at 170K and little history, I have to assume its either original or replaced a while ago.
I may check fuel pressure, but im almost certain I wont have pressure because I cant even hear the pump.
 
#20 ·
Did the fuel pump, relay, regulator, and filter yesterday. Car fired right up. I ran 12 v to the Old fuel pump and nothing happened. The pump was toast. Fuel filter was bad. The dirty side had black fuel coming out.
by the way, I had the seat off when I fired up the car. The pump is very quiet. It’s a very faint buzz. Def not the same in other cars. I may tear open the old fuel pump to see where it failed. Prob the brushes if I were to guess.
Thanks everyone for the help.
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