Started - - Died

[enjr44]

02 Ranger 4.0, Auto, 2wd, 93K.

Back ground. Truck as set for about a week. Put key in and went to run. Let the key set there for about 5 seconds while I check instrument lights. Then turned the key to start and engine started on first hit like normal. And then...

The engine went to 1500 rpm as normal and then immediately dropped to 300 rpm and then died. About two weeks ago, it did something similar. Started on first hit, went to 1500, dropped to about 500; but, that time it immediately went back to 1500 rpm. This time it died. Tried to restart and it acted like it was doing a WOT thing. Tried three times and then quit trying. I had to pickup GD so used another vehicle.

When I got back (about 15 minutes), I did the prime the pump thing. Key off, key on for three seconds, key off. Repeat three times. Fourth time went from off, to run, to start. It started normally on first hit, went to 1500 rpm, held there for some seconds and dropped to 1100 rpm. Everything completely normal. Restarted three times and it was normal each time.

So I need ideas on what us hanging up, sticking or not doing its thing??? My Granddaughter drives this truck a lot and I don't want to/can't leave a 17 year old girl stranded someplace knowing there is something weird going on.

Thanks, Ed

 

[RonD]

Just guessing on available info but reads like a slow fuel leak in pressure part of the system, assuming you don't smell gas anywhere then either an injector or check valve in fuel pump.
You could check the vacuum line on the pulse damper at the end of the fuel rail, not a common issue but vacuum line is there in case it leaks, see if it has fuel or fuel smell

Fuel pressure on '02 should be 65-70psi
System should hold pressure for a few months easy
The 2 second fuel pump run time with key on adds about 15psi, if it was 0psi then it would just start up and die.
Fuel pump does re-start when RPMs are above 500 but engine is also using fuel at that time, so it would struggle to run and once below 500rpms pump would shut off(its a safety thing in case of accident)

The 3 time priming was what lead me to the above.

If possible I would get a test gauge and see if pressure is dropping when engine sits.

 

[enjr44]

Thanks a lot, Ron. But, crud hit the fan this morning, so to speak. It ran great all morning doing this and that around town. When I got home things went down hill in a rush.

I got a fuel pressure tester and hooked it up. There was a lot of pressure and fuel went all over the place while I was installing it. After it was installed there was about 15 pounds of pressure still in the system. Turned the key to run and the pressure went to around 40. Key off and back on it went to 60. Key off and back on it went to 64. All good right!!! Let it sit for a few minutes and it went back down to 60 and seemed to hold there. And that was all I did. Touched nothing but the Schrader valve.

Now here is where it went to crud. I started the truck and it started normally (1200 rpm, good it was warm). Got out of the truck and went to check the pressure, it was dropping fast and when it got down to around 20 the truck, of course, died. Key on, key off a dozen times and the pressure did not increase. Stayed at 20. Swapped the fuel pump relay with the trailer connection relay. No joy! I can hear the relay clicking.

What the heck happened. I can't see as how I did anything that would have stopped the pump!!! It there another fuse in there some place? Could of bleeding the system tripped the cutoff switch (I don't see how, since it pressurized the initially after hooking up the tester)?? I just don't know enough about the system to go forward.....

 

[RonD]

In the passenger footwell up by the top of the carpet, or in the upper kick panel is the inertia switch, inertia switch will cut power to fuel pump in case of a roll-over or sudden stop(accident)
It is a smaller(2x2) plastic box with a reset button on top, fuel pump power passes thru it.
I doubt this is the problem, but what it is good for is to see if power is going to fuel pump.
You can hook up a test light or meter to either terminal and to a ground, you should get 12volts there when key is turned on, for 2 seconds.
If you get the truck to start again then watch the voltage to see if it stays on but fuel pump stops(engine dies), so problem is for sure the pump.
Could be a bad/loose ground but that would be a long shot.

It does read like fuel pump was on it's way out, and now it is out.

Fuel pump power runs like this:

Battery-------Fuel pump fuse---------fuel pump relay------inertia switch------fuel pump----Ground

Fuel pump fuse, there is only 1, is in the engine compartment fuse box

 

[enjr44]

Ron, Thanks again.

OK, I was't very clear earlier. I did check the fuel pump fuse and it was good and I swapped it with another 20 amp fuse. Glad to know there isn't another someplace.

Following your suggestion, I pulled the connector to the inertia switch (its button was down). Ohm checked both wires and got readings (don't remember the readings) on both. I was expecting readings on the pump side and an open on the other; but, not so.

Next, on one of the wires, with the key on I get battery voltage for a couple of seconds and then it drops to 6 volts. Each and every time. The 6 volts sort of has me sort of stumped. I would think it should go the zero?? The other wire nothing when key turned on. Other than the six volts everything check as expected.

But, in any case the pump is getting 12 volts for the first two seconds. But, it does not run (can't hear it and I know what should sound like). So, like you I am guessing the pump died!!! Right then when I was standing there, looking at the fuel pressure.

Not sure if I am going to change the pump myself or take to our local speed shop, troubleshoot and repair (the only people I trust in this town). At 71, I don't do much heavy work anymore.

I'll get back to you all with the fix.

And, thanks again, Ed

 

[Mark_88]

Have you tried simply bi-passing the inertia switch? You can jump it without cutting or anythingl...just use a U shaped wire and jump it...

If that doesn't improve things then it is something else...I had an inertia switch fry on my Tempo and it gave me all kinds of weird things...it wasn't quite dead and every once in a while it would kick out for a bit and it seemed like the fuel pump was dead...

 

[RonD]

The 6 volts is normal when relay is open(off) and key is on.

The Computer monitors fuel pump voltage, so between fuel pump relay and inertia switch there is a splice, that wire goes to the computer, that is where the 6volts is coming from.
If you turn the key off that voltage should go away.

 

[enjr44]

Thanks, Ron, It did go away with the key in off. Like I said I will report back when she is on the road again.
Ed

 

[enjr44]

Have you tried simply bi-passing the inertia switch? You can jump it without cutting or anythingl...just use a U shaped wire and jump it.....

Mark, Thanks for your input.

I didn't jump it; but, I did check voltage on both sides of the switch (in and out) and I get the same voltages (12 then 6). So I am confident that the inertia sw is sound. So there is only two things left. Wiring from the inertia switch to the pump or the pump.

Ed

 

[Mark_88]

Thanks for the feedback Ed...I should say that for some reason...on my Tempo I had to replace the fuel pump no less than 6 times in 14 years...

I called Ford Canada about it after the warranty ran out and they actually replaced the pump free the last time and I didn't have any problems with it after that...lol

 

[enjr44]

Fixed!! It was the pump. Replaced it with a Delphi brand. Had it done, they only charged me for two hours of labor. Over charged me for the pump (full list price); but, hell, they have to make beer money some way. Changed the fuel filter too as it was long over due.

It would have taken me at least two days and would have used up at least a months worth of swear words.

Thanks for all your help in troubleshoots this,
Ed

 

[RonD]

Good work

Thanks for posting the fix

 

[enjr44]

Just a little followup and fyi on the 02's fuel pump. I think that the old pump has been having problems for a couple of years (just lucky it didn't leave me high and dry).

The truck has been cold (over night) starting "funny" for a long time. Sometimes it would start and go to the expected 1500 rpm. But, most of the time it would be around 1000 rpm. Once started and driven and then sitting for a 3 or 4 hours more or less it would always do the 1500 then 1100 rpm thing on start up. It wasn't until I stopped driving it everyday that it started doing the really wild rpm fluctuations on cold start.

After replacing the pump it is back to the normal 1500 then 1100 rpm cold starts.