ranger trouble

[jerry marshall]

Vehicle won't start , Replaced Fuel pump relay , replaced fuel Pressure regulator , Replaced ECM , Low voltage at fuel pump , Will fire up up by squirt gas in Throttle body

 

[Jazzer]

Focus on the low voltage reading. What are you seeing as voltage, and where?

 

[jerry marshall]

6.5 volts at fuel pump

 

[Jazzer]

Take a voltage reading at the inertia switch. It should be located at the top of the carpet/flooring in the passenger side footwell. It's a small plastic box with a push button on top. If you get low voltage there, the problem is between the fuel relay and the inertia switch. If you get good voltage at the inertia switch, the problem is between it and the fuel pump.

There are two wires going into the inertia switch, well one coming in and one going out. If you get 12V+ on one and less on the other,, your inertia switch is bad.

 

[jerry marshall]

thanks for your help ,the voltage is low at inertia switch ,replaced Relay switch , same problem

 

[Jazzer]

Look at the contacts the relay connects to for corrosion. If you see corrosion, electrical contact cleaner can help, or you can use a strip of fine sandpaper taped around the eraser end of a pencil, twisting it to clean the contacts.
If no go, check those contacts for voltage to see if you have a problem in the upstream wiring.
I don’t have a wiring diagram, but if you have low voltage going to the relay, maybe someone here can give you wiring colors and the 12V path.
You’ll get this eventually.

 

[jerry marshall]

Have 12 v to relay ,have 6.9 to inertia switch , ohmed inertia switch checks good but no voltage on both sides of inertia , replaced with another relay , contacts look clean , Once again thanks for your help

 

[Jazzer]

No problem. It looks like you've narrowed it down to the wire path from the relay to the inertia switch. Being as it's 34 y.o. truck, look for bulges or cuts in that wire, it's going to be the color(s) of one of the wires at the inertia switch, coming out of the relay housing.

 

[jerry marshall]

Still no progress checked all wires, have continuity when turn ignition on all relays click then click again . pull relay and run jumper wire in relay block have 10.5 volts at Inertia switch and fuel pump but still won't start , Have fuel to fuel rail , Will attempt to start if spray Gas in Throttle body. is there something that may be affecting Fuel injection system

 

[Jazzer]

When you first turn the key to "on", do you hear the tank pump run for 2-3 seconds?
Are you able to take a gas pressure reading at the schrader valve on the fuel rail?

 

[jerry marshall]

Pump comes on for a couple of seconds , putting out 40 PSI at fuel rail

 

[Jazzer]

That sounds good, except 10.5V is too low, but obviously is working the pump.
Was this vehicle running before? Was there an event prior to its no start condition, such as maintenance performed? Trying to narrow down possibilities.
If it tries to start when you feed it some gas manually and it has 40lb pressure at the rail, you might want to look at the injectors, especially if the truck’s been sitting awhile.

 

[bobbywalter]

since it runs on a squirt...and the pump cycles...most likely injectors are not firing. could be related to the low voltage going to the inertia. make sure there is a solid 12 volts at the injectors.

 

[jerry marshall]

Trucks sets weeks at a time ( BIL truck driver ) ,was at idle and just quit ,really got me baffled , ,I could see one or maybe two injectors being clogged but not all four

 

[Jazzer]

Bobby’s saying you may not have adequate voltage to open injectors’ so you want to make sure you have 12+V there. The ground is provided by the ECM, but you need the power to open the injectors.