turns over but won't start???????

[blazey]

wife drove the '91 explorer home today parked in the garage. after two hours she went to leave again and the darn thing will turn over like crazy but won't fire. not sure how to check for fuel pressure on this model, but i am pretty sure i have spark. i pulled all fuses and they are ok, i checked the fuel pump reset switch under the dash on the floor of the passenger side, and it is not tripped. this explorer has never done this before. please i need some help here guys, any suggestions would be greatly appreciated.

thanks

 

[X-1]

Do you smell any fuel when it is being turned over? You can check for pressure at the fuel pressure regulator, it is kinda messy, but it is one way to check the pump, disconnect there, but put a towel over before you pull it off, gas will go everywhere. If you have no pressure than either a circuit or the pump is bad.

 

[Isles4evr]

If you do what exploder-1 says and you have no fuel, pull the fuel pump relay and jumper it with a jumper wire. If the pump then pumps then you have a bad relay, if not, more than likley it is the pump itself.

Chris

 

[TPLYNCH]

When you turn the key to "on", pause and listen for the fuel pump whine before going all the way to start. If you don't hear it, then start w/the relay under the hood. If you do hear it, then check pressure to make sure you don't have a blockage.

 

[woodychitwn]

Before you go tearing things apart, check the relays in the engine compartment. Make sure none of them are burnt out. It happened to me, and I spent weeks trying to track down what ended up being a $6 and 30 second repair.

 

[blazey]

same problem again.

think i might have gotten some water in the tank, got it to start on its own the next morning. when i filled tank i added some HEET and some stp injector cleaner. drove back to work on lunch and the sucker starts buckin like crazy when i accelerate. tach seems to shut off when the buck happens. could be more than water in there. only way i can get it to start now is have someone cover intake with their hand while i crank. then runs till i mess with the accelerator too much and decides to die again. and same problem will not start at that point.
darned if i know. where is fuel pump relay?

 

[TPLYNCH]

Relay is in the black box under the hood. Is near the drivers firewall on my '99.

 

[blazey]

fuel pressure? fuel filter?

how much pressure am i supposed to have? also i have ordered a fuel filter, but i don't know where it is located on a '91 4.0... help help

 

[TPLYNCH]

Fuel filter is under the truck in line with the fuel line. Need a special tool to remove. Not sure the pressure figures, but if memory serves s/b in the 30-40 psi range. Varies between idle and under throttle. Try searching for Replacing Fuel Pressure Regulator and Replacing Fuel Filter for more accurate info on both procedures.