I've got a 1989 325i.
complete backstory:
The gas tank was dented recently on both sides. When driving home about a week ago I noticed the car was stuttering when I was a little low on gas, and the engine didn't have the high pitch E30 sound, but instead a deeper sound, kind of like a V8 at lower RPM but not quite. Figured filling it up would do the trick, but it didn't.
Within the last 8k miles, I've replaced:
-spark plugs
-wires
-cap & rotor
-timing belt
-a leaky head gasket
so I don't think it's any of those would be the problem. I just tried replaced the fuel filter and got the injectors professionally cleaned (they were filthy). Unfortunately it's still acting up. Hoping maybe it was just bad gas, I drained the tank, pushed out anything left in the lines with a big air compressor, and put 5 fresh gallons in. The gauge reads at halfway (surprise! I lost ~3 gallons of capacity). It does run a little better with all that changed sure, but isn't quite what it used to be.
I'm at the point where the symptoms will be intermittent, sometimes it'll rev up with the highpitched M20 sound and all is well, and sometimes it'll bogdown, sound like a V8 and struggle to accelerate. I noticed it bogging a lot more when going up hills, however steep they may be.
I hooked up a fuel pressure tester, and at idle it's showing ~40-41 PSI. When you open up the throttle it drops to ~36-37PSI. And finally, when you disconnect the vaccum line connected to the fuel pressure regulator, the pressure goes up to ~47PSI.
TLDR
I hooked up a fuel pressure tester, and at idle it's showing ~40-41 PSI. When you open up the throttle it drops to ~36-37PSI. And finally, when you disconnect the vaccum line connected to the fuel pressure regulator, the pressure goes up to ~47PSI.
where I'm at now
Bentley says pressure is supposed to be ~43PSI? I read somewhere else people saying the pressure should be around 35-37PSI at idle and move up to about 42 when the throttle opens? If the second is true my car is doing the exact opposite. Which is the correct pressure?
My theory at this point is with the tank dented, there's more pressure inside the line, but for some reason, it wont send fuel when it's under load (esp on hills). I'm thinking either tank, fuel pump, or fuel pressure regulator needs to be replaced? Maybe the tank and pump need to be replaced? I don't have a jumper wire with a fuse holder, nor an ammeter to test the pump. I'm thinking it's possible the regulator is reading high, but that may be due to the higher pressure from the tank?
Any ideas or input?
complete backstory:
The gas tank was dented recently on both sides. When driving home about a week ago I noticed the car was stuttering when I was a little low on gas, and the engine didn't have the high pitch E30 sound, but instead a deeper sound, kind of like a V8 at lower RPM but not quite. Figured filling it up would do the trick, but it didn't.
Within the last 8k miles, I've replaced:
-spark plugs
-wires
-cap & rotor
-timing belt
-a leaky head gasket
so I don't think it's any of those would be the problem. I just tried replaced the fuel filter and got the injectors professionally cleaned (they were filthy). Unfortunately it's still acting up. Hoping maybe it was just bad gas, I drained the tank, pushed out anything left in the lines with a big air compressor, and put 5 fresh gallons in. The gauge reads at halfway (surprise! I lost ~3 gallons of capacity). It does run a little better with all that changed sure, but isn't quite what it used to be.
I'm at the point where the symptoms will be intermittent, sometimes it'll rev up with the highpitched M20 sound and all is well, and sometimes it'll bogdown, sound like a V8 and struggle to accelerate. I noticed it bogging a lot more when going up hills, however steep they may be.
I hooked up a fuel pressure tester, and at idle it's showing ~40-41 PSI. When you open up the throttle it drops to ~36-37PSI. And finally, when you disconnect the vaccum line connected to the fuel pressure regulator, the pressure goes up to ~47PSI.
TLDR
I hooked up a fuel pressure tester, and at idle it's showing ~40-41 PSI. When you open up the throttle it drops to ~36-37PSI. And finally, when you disconnect the vaccum line connected to the fuel pressure regulator, the pressure goes up to ~47PSI.
where I'm at now
Bentley says pressure is supposed to be ~43PSI? I read somewhere else people saying the pressure should be around 35-37PSI at idle and move up to about 42 when the throttle opens? If the second is true my car is doing the exact opposite. Which is the correct pressure?
My theory at this point is with the tank dented, there's more pressure inside the line, but for some reason, it wont send fuel when it's under load (esp on hills). I'm thinking either tank, fuel pump, or fuel pressure regulator needs to be replaced? Maybe the tank and pump need to be replaced? I don't have a jumper wire with a fuse holder, nor an ammeter to test the pump. I'm thinking it's possible the regulator is reading high, but that may be due to the higher pressure from the tank?
Any ideas or input?
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