Help wih fuel system??

[Michiganmadman]

I just bought a 1994 Mazda Navajo. Ran good everything worked fine. Drove it home and ran out of gas. Went to the gas station and brought back gas and filled it. Now it won't start. Turns over good everything sounds good just dosent ignite. Checked the fuel pump and fuel pump relay and they are fine. Was thinking maybe the fuel filter? But could a bad filter stop the truck from even starting? It's not even sputtering. Anything else it could be?

 

[92exp4x4]

Are you sure the pump is working? Did you hear it running in the tank? It will only run for a few seconds after turning the key to on. If the PCM doesn't see engine rotation it will take the ground away from the pump relay.

Do you have fuel pressure at the valve on the fuel rail? The valve looks like a tire valve stem. Normal fuel pressure is about 35-40, if I remember correctly.

Next I would pull codes and see if there is an issue. A bad crank sensor can cause a no-start.

 

[92exp4x4]

Quick, easy test for fuel issue. Turn key to on, spray brake clean into the by-pass hose that goes into the intake tube from oil filler, and short the two big studs of the fender mounted start solenoid to try to start the engine. If it stumbles and tries to run you can rule out ignition as your cause.

 

[natenkiki2004]

short the two big studs of the fender mounted start solenoid to try to start the engine

Doing that will cause a big spark which isn't great to do near the battery. The better option is to jumper the forward stud to the little stud at the top. This will do the same thing your key does and provide a small amount of current (less sparky) to activate the solenoid. I talk about this in one of my 1994 Explorer videos:


Like 92exp4x4 said, make sure the pump is running in the first place. Turn the key to the on position, you should hear a hum from the back. If not, kick or hit the tank a few times while someone cranks the engine.

 

[2stroke]

A quick tip for fuel pressure, is to turn the key, and push the pin in the fuel rail pressure testing port. If fuel sprays out with some pressure, it is working. If not, the pump isn't turning. Either the inertia switch is tripped, the fuse is blown, the relay is bad, the pump itself, or even the wiring.

You can safely jump the solenoid by the battery without issue. Nothing wrong with going to the trigger pin, but its way easier to just put a screwdriver between the lugs. The sparks are the least of your concern, just make sure you are in park (auto) or neutral and brake engaged (manual).

The filter probably wont keep it from not starting at all, but it should be changed every 30k miles or so. If you find fuel pressure, then as was suggested, spray starting fluid or anything flammable into the intake, best would probably be the brake booster line, and turn it over as described (don't forget to turn the key on). If nothing, then you have an ignition problem.