Buckle up kiddos because there are lots of pieces to this puzzle. I recently took my m20 apart as it needed a head gasket and in the process i basically ended up with a rebuilt engine excluding pistons/crank/block stuff; so, re surfaced head with new oem cam, new springs, a MLS gasket, ARP studs, and all new accessories and hoses. Upon having my head resurfaced my machinist told me the head barley needed resurfacing at all so i used a stock thickness MLS. I got the car running and it was fine for 10+ somewhat spirited drives on backroads as they say to not baby the cam in the early stages of break-in. The car was cold so i was going slow and the car just gently lost power, nothing abrupt, it was as if it lost fuel pressure, i checked the pressure and it was essentially non existent. I assumed i had a bad fuel pump as the car has roughly 200K miles and i suspected it had never been changed. The car sat for a bout a week with the battery unplugged, I swapped the fuel pump/filter and it started up. The car felt like it had a bit more power than before and it was louder however it eventually died after i filled the tank up, it died exactly the same way it did the first time. I then swapped the fuel pump relay with one that i knew worked, the car fired up and i got it off the side of the road, today i went to start it up again and it would not start. I tried several relays and fuse 11 and 12 are not blown. I do not suspect the pre supply pump as i hear the fuel pump can still run the car if your pre sup fails. The car cranks freely but no start or attempt to fire. I also suspect i have a failing ICV as that was one of the few things i did not replace however i doubt that would cause it not to run. Any ideas?
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When it dies, it cranks but does not start? Do you have spark? If no spark, I would suspect Crank Position Sensor. If you have spark, check the in tank fuel pump (pre supply pump). With these old cars, debris in the tank can clog the filter sock. Fuel pressure regulator is also worth checking.2004 525i Manual - 1985 325E Coupe Manual -
Check the fuel pressure. If the pump is running and you still don't have fuel pressure, you have a blockage somewhere.Comment
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tomstin upon further inspection, i see my CPS has part of the insulation cracked open that exposes wire, I will attach a picture to see if you guys think what im seeing would be enough to interfere with the signal telling the car to sent current to the pump. Also yes it cranks with no start.Comment
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If for no other reason that peace of mind, I would replace it. Once oil and debris gets in there you never know what can happen.2004 525i Manual - 1985 325E Coupe ManualComment
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Replace the main relay also, Check your fusible link to the main relay from the battery.
But report back with:
Fuel pressure / Pulse width, Spark, CompressionComment
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