No Start Condition

[huesmann]

My 1998 GT has been sitting for a long time. I wanted to move it, so I pulled the battery and charged it up. It ran when parked, but now even with a full battery it won't.

I called to mind the old rule of thumb that a car needs 3 things to run: air, fuel, and spark. I pulled the IACV tube out of the air intake, sprayed some starter fluid into the intake, and stuck the tube back in. Got back in and turned the key. It started, and ran for a few seconds. So it's obviously getting spark and air, but not fuel.

Can't tell if the fuel pump is energizing; I hear something when I turn the key but can't tell where it's coming from.

What's the next easy step in diagnosis? Check power to fuel pump—how? Check fuel pressure—need to rent tester?

TIA!

 

[wmburns]

Confirm IF there's initial key on power at the trunk mounted IFS switch. Best to use a test light that will "load" the circuit. Use a known good ground.

A buddy might be able to help by cycling the key while your head is near the fuel pump.

There's a Schrader test valve on the fuel rail. So it's easy to test for fuel pressure. Even if the only test done is to press in the center part to see if fuel comes out.

If asking for an educated guess:

• Stall gas.
• bad fuel pump
• clogged fuel injectors

I personally wouldn't want to run known stale gas through my car if I could help it.

Sometimes hitting the gas tank with a rubber mallet can free up a stuck fuel pump.

1996+ Crank with no start check list
https://www.allfordmustangs.com/forums/4-6l-tech/336452-1997-mustang-wont-ignite.html

 

[huesmann]

Thanks. I already checked the IFS switch and it doesn't appear to have tripped (pressed on it and it didn't move/click, so I assume it wasn't popped up). What behavior is expected w.r.t. "key on power" there—constant 12V, or a 12V spike when the key is first turned?

Where exactly is the fuel pump located, or where's the best location to listen?

 

[GDawg]

Thanks. I already checked the IFS switch and it doesn't appear to have tripped (pressed on it and it didn't move/click, so I assume it wasn't popped up). What behavior is expected w.r.t. "key on power" there—constant 12V, or a 12V spike when the key is first turned?

Where exactly is the fuel pump located, or where's the best location to listen?

The fuel pump is located inside the gas tank. You should be able to hear it just sitting in the car when you turn the key but don't crank. If not, try listening in the trunk. It needs to be quiet around you when you do this. My '98 sat for years and when I tried to bring it back to life my fuel pump was dead. It had to be replaced. And I'm still dealing with a lean condition that I suspect has to do with semi-clogged fuel injectors.

 

[wmburns]

Thanks. I already checked the IFS switch and it doesn't appear to have tripped (pressed on it and it didn't move/click, so I assume it wasn't popped up). What behavior is expected w.r.t. "key on power" there—constant 12V, or a 12V spike when the key is first turned?

Checking just the IFS switch to see IF it's tripped is missing a major part of the trouble shooting process. What if there's something wrong upstream (Fuse, CCRM, ignition switch, high/low speed relay)? The IFS switch could be perfect but with no power the fuel pump will never run.

Regarding what power should be seen at the IFS switch. That depends upon the model year and engine and fuel system type (return or return-less).

Most return fuel system cars will "pulse" the fuel pump at initial key on to prime the fuel system.

Many V6's will "pulse" the fuel pump.

GT's with a return-less fuel system will have constant power at the IFS switch.

Usually if there's initial key on power at the IFS switch and there's no fuel pressure the odds favor a bad fuel pump.

The 1998 GT should have a return style fuel system with a two speed relay. The PCM will "pulse" or prime the fuel pump at initial key on and then shut off until the motor actually starts.

 

[huesmann]

Ugh. And the tank needs to be dropped to replace the pump, right? Which is now almost full of fuel, and no way to burn it off.

 

[wmburns]

There are ways to force the fuel pump to run. For the 1998 and older all that's needed is to energize the fuel system. Once the fuel filter is disconnected it's quite possible with a short piece of flexible hose attached to the fuel filter and direct into a suitable container.

Either:

• using an ODB2 scanner to "command" the fuel pump to run.
• Inject +12 volts at the trunk mounted IFS switch.
• at the CCRM ground pin #18 LB/O wire.

 

[huesmann]

If the FP could be forced to run that way why would it need to be replaced?