2.5L ('98-'01) Voltage Issue?

[Theunknownstep123]

1999 2.5 ranger
Getting these reading for PCM relay area, when key is on 11.1 from wire that is only triggered when key is switched to on position. 11.9-12v reading is always on. Everything else in the area and other parts of the vehicle I’ve checked read 12v. Is this a normal reading or am I having a wire/ground issue? I’ve checked and cleaned my grounds.

Vehicle will not crank unless started on starting fluid, where it will run for a few seconds.

 

[Curious Hound]

What is you battery voltage? Those readings are low and may be indicating that your battery is old. If these readings are with engine running, you probably have a charging system problem.

 

[Theunknownstep123]

Battery is normal readings. Vehicle will not start so these are readings with vehicle not running but ignition in on position.

 

[Curious Hound]

What is your definition of "normal"? A brand new battery should readings 12.6volts, possibly 12.8. As the battery ages, it's nominal voltage drops. Your reading of 11.9 - 12 volts indicates an aging battery. Your readings of 11.1 also i dictates a loose or dirty connection somewhere. If you read 12.6 volts at the battery, but 11.9 - 12 volts elsewhere, that also indicates loose or dirty connections. That's why I asked what your battery voltage is.

 

[Mechrick]

The PCM power relay gets 12v applied to the coil side of the relay when the key is in 'run' or 'start'. The other side of the relay coil is always grounded. You can jump across the big terminals in the relay socket to make the pcm run all the time.

Quick/easy method to see if the PCM is getting power and is working is to turn the key on. Check engine light should be on, and when cranking, if a crank signal is present will go off.

When key is on, there should be 12v applied to one side of the fuel injectors, on the red wire(s).

Listen/feel the fuel pump relay when cranking, it should click. Check the inertia switch, it's under the right side of the dash.

Tap on the bottom of the fuel tank when cranking, sometimes you can get the armature of the fuel pump to spin off a bad commutator just enough to make the pump run. I've gotten many tow-ins in the shop that way.

Codes?

 

[Theunknownstep123]

No codes, checked everything over pcm is getting power and registering. Fuel pump working and intertia switch is not flipped. Injectors are getting power. However got around to doing compression test.
Cylinders:
1-165
2-140
3-90
4-155

Could cylinder 3 be the cause of no running unless using starting fluid? Thinking this is a valve problem or something else common with the 2.5? 170k miles on the truck

 

[Mechrick]

Could cylinder 3 be the cause of no running unless using starting fluid?

No. That wouldn't keep it from starting. I would recheck the compression after you get it running and warm. #3 could be the result of washed out rings.

Do you have a fuel pressure gauge?

 

[Theunknownstep123]

I do have a gauge, was getting good pressure and popped in two different fuel pumps to confirm

 

[Mechrick]

good pressure

Were you getting 60-ish psi?

 

[Theunknownstep123]

Yes, getting right around 60 when priming fuel pump and checking

 

[Mechrick]

Try unplugging the Mass Air Sensor, the Engine Coolant Temp Sensor and the Throttle Position Sensor one at a time and see if it runs.

 

[Theunknownstep123]

I’ve tried all of those except the coolant temp sensor, I’ll try that next. I’m thinking it is something with injectors, got a new set coming and will update

 

[Mechrick]

What's the story behind it? Been sitting for a while?

 

[Theunknownstep123]

Been sitting several years, got it from someone’s yard. Was ladies husbands truck before he passed. She said it was running when it got parked.

I’ve replaced fuel pump, cam and crank sensors, cleaned injectors, checked timing, checked relays fuses etc. It would not run at all even with starting fluid before I replaced the crank sensor.

Once replacing crank sensor and fuel pump, filter and injector clean I got it to start and run for about 30 seconds before it bogged down and died and I can now no longer get it to start. Will still start with starting fluid but will not run.

 

[Mechrick]

You might want to pop the fuel filter off and see if it's full of debris.