Why do I have high fuel pressure...

steve meltzer · #1 (**permalink**) 03-02-2017, 10:40 PM

Got out to the car this PM and despite kicking on the e-pump the pressure never got to be more than 3-4 PSI, the car started but died about 100' later. Couldn't restart and pressure remained at 3 with or without the e-pump. Cranked OK, but would never fire. I needed to get home, so my wife took me, leaving the car parked at work. Tomorrow I'll see if I have spark or fuel or whatever I can determine. Could the mechanical pump fail in such away that the e-pump can't bring fuel to the rail? Or, is this just another problem before I start cussing, swearing and throwing dangerous objects? thanx s

patrickt · #2 (**permalink**) 03-03-2017, 05:43 AM

Quote:

Originally Posted by steve meltzer

Got out to the car this PM and despite kicking on the e-pump the pressure never got to be more than 3-4 PSI, the car started but died about 100' later. Couldn't restart and pressure remained at 3 with or without the e-pump. Cranked OK, but would never fire. I needed to get home, so my wife took me, leaving the car parked at work. Tomorrow I'll see if I have spark or fuel or whatever I can determine. Could the mechanical pump fail in such away that the e-pump can't bring fuel to the rail? Or, is this just another problem before I start cussing, swearing and throwing dangerous objects? thanx s

Well look on the bright side. A no-start/no-run condition is a heckuva lot easier to figure out than an intermittent, car still runs, but misbehaves condition. Even if the car starts, I would not drive her home -- 1) you could stall on the highway, which is a danger; and 2) there's a small chance that the loss of fuel pressure is the result of "internal bleeding" in to the oil pan. I don't think that's happening, but I'm not going to risk your engine on it. Put her on a flatbed and get 'er home. Then we'll figure it out.

steve meltzer · #3 (**permalink**) 03-03-2017, 06:05 AM

Not a fuel cell. Stock from Kirkham. Thanx for the advice. More later. s

patrickt · #4 (**permalink**) 03-03-2017, 09:17 AM

Yeah, just to be on the extra-safe side, check your dipstick to see if the oil level is unusually high, or if it looks funny, or if it smells like gas. Having owned her for 15 years, you know what it normally looks like on the end of the stick.

steve meltzer · #5 (**permalink**) 03-03-2017, 09:40 AM

thanx. BTW, could a failed mechanical pump, ,plumbed the way mine is, cause a low pressure, even tho' the e-pump seems to be working OK? Am I making sense? s

patrickt · #6 (**permalink**) 03-03-2017, 10:07 AM

Quote:

Originally Posted by steve meltzer

thanx. BTW, could a failed mechanical pump, ,plumbed the way mine is, cause a low pressure, even tho' the e-pump seems to be working OK? Am I making sense? s

Without it leaking, I'm going to say "No." Here's why: Think of your home's water pressure, which is usually around 80psi. So, if you put a pressure gauge on the end of your garden hose, with the hose not running, it will show 80psi. If you stab a really skinny, hollow swizzle stick in to the side of the hose, and put a gauge on the end of the swizzle stick, it will read 80psi as well. Obviously the flow out of the swizzle stick end would be much less than the flow out of the hose end, but the pressure will be identical throughout, provided there is no flow anywhere. When you turn your electric fuel pump on, and the car is not running, after a few seconds the pressure will be identical throughout the fuel system unless 1) there is a complete clog (in which case the pressure after the clog will be zero); or 2) there is a leak somewhere down the line that is reducing the pressure. In our swizzle stick example, a small crack in the swizzle stick will create a larger pressure drop at the end of the stick than the identical crack would cause in the hose itself, because of the volume of flow is much greater in the bigger hose. So, what this means is that if your electric fuel pump is really putting out, through its regulator, 6psi and the pressure on the far end of your fuel line run, at the fuel pressure gauge, reads 3psi, and the car is not running, then there must be a leak somewhere.

steve meltzer · #7 (**permalink**) 03-03-2017, 01:07 PM

OK, got out to the car at lunch....fuel pouring out the secondary vent tube with pump on...flooding everything within 10 miles. I assume it 's a stuck float and hope to fix it over the weekend. Did have the presence of mind to bring a rubber hammer, but a few wacks on the bowl only made me look an idiot in a parking garage full of fuel injected SUVs. s