What causes fuel pressure to drop overnight?
There may be an injector that is not closing completely, the check valve in the fuel pump assembly could be bad, or the pressure regulator on the rail could be leaking- either to the fuel return line or the vacuum line.
Can a fuel pump go bad overnight?
yes, they will go bad overnight, one day fine, the next day, nothing, look at the fuel window to see if there is fuel in it, no point in crank and crank and crank, if it won’t start..
How long should a fuel system hold pressure?
For the specification we must consult service-data, but the system should hold some pressure for about five-minutes. In the example above, from a late-nineties model Jeep, it should hold at least 30 PSI for five-minutes. If the system maintains the pressure, a third test is in order.
What happens when the fuel pump goes out on a Toyota 4Runner?
There are physical signs that you can feel when your 4Runner’s fuel pump is going out. Before taking anything apart, check to see if your engine’s computer has any trouble codes saved in it. The engine may throw a P0087 trouble code. This trouble code detects that the fuel rail/system pressure is too low.
What does a bad fuel pump sound like?
A priming fuel pump sounds like a high-pitched whine for a few seconds and can be heard with a sharp engine right after the ignition key is turned, but before the starter is engaged. The symptoms of a bad fuel pump match a lot of other common problems that can occur in the Toyota 4Runner.
Do you need to do a fuel pressure test?
This test is only necessary if other pressure tests indicate lower than normal fuel pressure. CAUTION: Perform this test only long enough to determine if pressure rises above minimum specification; risk exists of blowing coupler hose off of pump. This test is only necessary if other pressure tests indicate lower than normal fuel pressure.