Hi guys. I tried to read through the other posts to get my answer but I don't seem to find exactly what I am looking for. I have been having multiple problems with my truck and RonD helped me out on another issue which I greatly appreciate. I replaced the alternator today because I was getting very low (12.1) volts when under load with the fog lights on and the blower on high. I was also getting 14.7 volts under normal operation when the engine was hot. Now with a new alternator in I am getting a constant 14.45 all the time. I believe it should be around 13.6 in park and at idle and about 750 RPMs. My warm idle is around 1000 which I know isn't right. I cleaned the IAC but maybe it is still bad? I also tried RonD's test by unplugging the IAC when it is running and the idle drops to about 700 and then about 500 with all lights on and blower on high. What tells the regulator to lower the warm voltage level? Could it have something to do with the IAC misbehaving? I got a brand new Interstate 590 CCA and I don't want to cook it before I get a chance to even use it. Thanks and have a Merry Christmas!

 

I would test voltages at alternator with key off

Test battery voltage first, say it is 12.8volts
Test B+ voltage, stud and nut terminal on the back of the alternator, should also be 12.8v
Use battery as ground and then test using alternators case as ground
Should be same 12.8v at B+ either way

Pull off 3 wire connector on alternator, test Yellow/white wire the same way, should also have 12.8v

In simple terms a voltage regulator works by voltage "back pressure" from the Battery and vehicle electrics.
After starting the battery is drained, so "back pressure" is less, voltage regulator increases alternators output voltage to above 14v
As voltage "back pressure" increases, battery gets recharged, voltage regulator decreases alternator output voltage to under 14v.

As you turn on lights, fan, radio, "back pressure" drops and voltage regulator increases alternator output to compensate for it.

As RPMs increase alternator amps increase so voltage regulator reduces increased output to match existing "back pressure" in the system.


I would also test your Volt Meter, on 9volt battery and maybe another vehicles battery, make sure you are basing concerns on real numbers

 

Thanks RonD. I have a nice Fluke multimeter and it seems to be right on. Grounded to the battery terminal or alternator casing I get 12.6 volts at the nut and the white/yellow wire as I should. Bad news is it got to 16F here last night in Minnesota and the truck doesn't even think about firing. Just cranks over, plenty of cranking juice from the new battery. I had the intake manifold gaskets replaced because they were leaky, thought I had the problem licked. Also new plugs and wires. Multiple problems are fun!

 

I checked the voltage at the fuel pump relay for the heck of it. 12.6 volts on one of the terminals with the car off and then 12.6 with the ignition on. I pushed the schroeder valve in while cold and almost no fuel came out. I did the trick of turning the ignition on and off 8 times to pressurize the fuel and it started up. While started there was tons of fuel pressure at the schroeder valve. It is like the fuel is leaking back into the tank although I am getting terrible mileage so it could be leaking elsewhere. I don't smell any gas though nor do I see anything on the ground.

 

Happy Holiday

2000 Ranger(all 1998 and up) would have a Returnless fuel system, so no FPR to leak pressure.

Since it didn't start first time I doubt an injector is leaking, it would have fired at least once, from Key On fuel leaking into that cylinder

So fuel pressure is most likely being lost by a bad check valve inside the fuel pump.
Not a big deal for now, just cycle key on and off 3 times and it should start right up.
Not a sign pump is failing, but check valve is in the pump so whole pump needs to be replaced.

At the end of the fuel rail on passenger side is the Pulse Damper, it has vacuum hose attached, check that vacuum hose for fuel, it is possible damper is leaking, not at all common but not impossible either
If leaking, pressure would drop with engine off, and MPG would go down

 

Thanks Ron and Merry Christmas to you. It was about 12 degrees in my garage this morning. I turned the key on and off 8 times and it started up right away. Going to leave it out today and when I get home it should be around -5 and I will see if I can get it to fire. Going out right now to check on the damper. My last fuel load came out to exactly 13 MPG with no towing,. I did have it idling a lot and some of that was before the intake manifold gaskets were done but that is still really bad. Thanks again!

 

Cold weather = lower MPG , but should only drop maybe 1 MPG

Idling is 0 MPG so will bring down the average for sure, but like you said that's a pretty big drop.

And no "new" tires?
larger diameter tires cause a false lower MPG because odometer is reporting less miles than actually traveled

 

Good morning Ron. Is the pulse damper in the front left as I am looking from the front? It has a braided line that comes off of it? It has been below zero here in MN and it won't start. When I turn the key on I hear a multi-toned noise that seems to be from under the hood where I would normally hear the fuel pump hum. I get no fuel pressure at the schrader valve no matter how many times I turn it off and on. The inertia switch is in the down/plunged position, I clicked it on and off a couple times to make sure. Tires are crap but I have not changed them out and they are the correct size. I was getting 20MPG on the highway over the summer. No issues last winter at all. Thanks for the help.

 

No, the braided line is the Fuel IN line
Pulse damper should have a regular black vacuum hose

With no Pressure then pump is not working.
You should hear a HUMMMM....from gas tank, back of the cab, for 2 seconds each time key is turned on, it is not quiet, quite loud if you are listening for it

In the engine bay there would only be clicks from relays closing with key on.

If you know where inertia switch is then you can use a volt meter to see if fuel pump relay and fuse are working and OK
Ground the meter
Put meters red probe on either wire on the inertia switch
Turn key on
You should see 12volts for 2 seconds, then it will drop to 5 to 8 volts
This would mean wiring and relay is good, fuel pump has failed
If no 12volts then fuel pump fuse or fuel pump relay(both in engine fuse box) has failed

Just FYI, the 5 to 8 volts at inertia switch with key on is from the computer's Fuel Pump Power monitor circuit, there is no AMPs just volts, so can't power fuel pump itself

 

I get the 12 volts at the inertia switch wires for just a second and then it goes to 6.6 so that seems correct. I can hear the relays click in the electrical box. When I turn the key on I hear a strange sounds that changes pitches a number of times where I used to hear the fuel pump run. And for the life of me I can't find the damper. I see the braided line running into what I THINK is the damper but you are telling me that is my fuel input line? Also, is there way to engage the fuel pump at the relay box? And lastly, can the fuel pump misbehave because of the cold? I can't get the thing in my garage to warm it up unfortunately.

 

Update time. I put a jumper from pin 3 to 5 on the fuel pump relay socket and I can get it to turn on and it starts up right away. I can hear the pump run of course. When I put the relay back and turn the key on I get the pump to turn on intermittently. While warm sometimes it comes on ten times in a row, sometimes it doesn't come on at all and sometimes it starts to come on and then stops before the two second cycle completeion. What the hell? I swapped out the relay with others in the box that are the same and it doesn't matter, it still works SOMETIMES. If I put the relay in after I get it started it stays running just fine. I have no idea if this means anything but I get 450 OHMS from battery ground to pin 2 of the fuel pump relay socket. That seems strange.

 

Not sure what "pin 2" is

The FP Relay's coil is grounded by the computer, so has no ground directly.
An automotive relay's coil uses pins 85 and 86, there is no polarity, if one pin has 12v and the other is grounded then relay closes, which connects pins 30 and 87
Image here: https://www.12voltplanet.co.uk/user/...ng_diagram.png
Ford sends FP relay's coil 12v with key on, then computer controls Ground to close relay for 2 seconds "key on" or ground it full time, RPMs above 400

Some relays have 5 pins, 87A is the 5th, unused in most applications, 87A is connected to 30 when relay is "open", coil not powered
Image here: http://www.rowand.net/shop/tech/imag...iringGuide.jpg

If you jumper 87 and 30 slots in base then FP should come on, key on or off wouldn't matter.
One of these slot may be making intermittent contact with relay's pins, so works with wider wire but not thinner pins.


If you ever wondered why relay terminals are oddly numbered it comes from old "standard" terminal designations, "30" was a connection to Battery +, not just for relay but any device in a car
85 and 86 were the 2 ends of a copper wire winding, usually a relays coil
87 was an INPUT or output of a relay

85 and 86 are interchangeable, +/-
30 and 87 are also interchangeable for power, i.e. 30 can be the 12v from battery and 87 the Device being powered, or 87 can be from battery and 30 the device being powered, works either way

 

I was talking about the second terminal on the relay itself. Does it hurt anything to jumper those two connections? That wire got really hot and it was pretty thick gauge. I will check for the bad connections. If they are bad makes me wonder if the previous owner may have had some trouble and was pulling relays in and out. Ran perfect for 18 months I owned it until now. Now I just need to fix the high idle and the high voltage. Can they be related? I checked the set screw for the throttle body plate and it doesn't look like it has been touched or moved.

 

You only Jumper it with Key OFF, because only the Fuel Pump fuse slot will have 12volts then.
When key is ON then there would be 2 slots with 12v, coil power from PCM relay is active, and that wire would get HOT because its only made to carry 5 amps at most.

Once you KNOW which slot is the fuel pump fuse power then you can turn the key on

12v from fuse would be slot 87 or 30, look at the diagrams, very easy to ID, as said 2nd terminal doesn't help

 

Thanks Ron, I really appreciate the help. I got it started today at 1 degree here in MN. I swapped the jumper wire for the relay really fast and it stayed running. Going to try and start tomorrow when it is -14 here. Won't fix my electrical issues but will test to see if intake gasket replacement did its job.

 

Another update. Saturday morn it got to -14 and it was -8 when I started it. Sunday -14 and today -14. I got it running all three times with either jumpering the fuel pump on temporarily or turning the key on and off a few times to build fuel pressure. Seems as though the intake gasket repair has worked as far as air/fuel mixture is concerned. I also played around with the set screw for the idle. It does not seem to matter where it is set, the hot idle still runs around 950. I wonder if that IAC is just partially misbehaving but not totally broken? Also, are the connections for the relay box known to go bad? I bent the coil pins on the pump relay inward slightly and today it primed 4 times without issue and without having to jumper the pump. Lastly, please let me know if this is correct: Pin 30 gets connected to pin 87 after the coil between 85 and 86 is energized. Thanks for the help!

 

I noticed the yellow connection sockets are new or a different color than the one holding the fuel pump relay. Wondering if maybe they were replaced at some point in time? It has been really cold here and I can see how these pins and connections could misbehave in the extreme cold.