2000 ford explorer starter and running problems

[J_C]

If you don't have any data, then you'd put the meter into voltage 20VDC (or nearest higher range) mode, put negative meter lead on any ground (chassis or battery negative terminal) and probe positive lead in the relay sockets to find which one is 12V (or 14.4V, etc, at the battery/charge system voltage) live. When the relay is energized, that will switch that 12V to another contact going out to the fuel pump. The other two used contacts are power to energize the relay and the ground to complete that electromagnet coil inside that trips the relay.

I looked at a wiring diagram for a 2000 but can only assume the wire colors are correct as follows. The relay itself may also have its contacts marked on the side as to their function and/or numbered on the bottom:

Relay pin 1: Red wire, half of coil
Relay pin 2: Light Blue/Orange, other half of coil
Relay pin 3: Light Blue/Orange, power input
Relay pin 4: Not used, there may not even be a contact for it in the relay socket
Relay pin 5: Dark Green/Yellow, power output

I don't know how they have the coil wired. Either one of the two is always live voltage, or one of the two is always grounded, but without the key turned to turn the pump on, you won't have both live voltage and live ground on the coil, but when the fuel pump should be running, first couple seconds with key in aux position or while cranking engine, you should have both live voltage and ground on the coil, then 12V+ on the power output, and at the pump connector plug.

While you can use the multimeter to probe for the power input on the socket contact that corresponds to relay pin 3, but you'd have the relay unplugged and obviously it won't complete the circuit unplugged so there isn't going to be output on the socket contact for pin 5 without the relay plugged in.

If there's power input and coil power and ground, you can presume there will be power output on pin 5 when using a known good relay, and it then follows that you "should" have power on the wire going all the way to the pump connector once the relay is plugged back in, if the circuit is good so far, and then if pump gets power and ground but doesn't spin, it's bad.

Now suppose you had no coil circuit completion, either no power or ground to that part of the relay, then using a jumper wire between the relay socket pin 3 and 5 should turn the pump on if it's good. I mean, odds are only one thing has failed... unless you're cursed.

 

[ccm2001]

That was the first thing I checked

Check wires connectors carefully. I had the same issue

 

[Pudliner8]

Ok so I just checked the other lead in it which is 0 for the other relays and it read 12v is it wired back words from the other two relays even though they have the same connection?

 

[Pudliner8]

Well everything in the power junction box looks to be good but it started raining so I'll have to check the inertia switch tomorrow how do I check that

 

[J_C]

I'm not clear on exactly what you're measuring., where specifically, relay or socket and with relay in or out, and which pin, and with key on, off, accessory, or? Refer back to the pinout i posted last time. Out of pin 3 and 5, one relay contact will read 12V, that is normal. The other won't, until the pump is supposed to be running.

I'm still not so sure this is necessary. If it cranks but won't start you can depress the fuel rail valve to see if it has pressure. If it has a lot and you crank and won't start still, and you press fuel rail valve again and still lots of pressure, your pump is working.

 

[Pudliner8]

There's power to all fuel pump relays but fuel pump isn't priming so fuel isn't gonna run to the engine if the pump isn't priming. How do I check the initial switch it's in the on position now but how do I check to see if power is getting to it?

 

[Pudliner8]

There's power to all fuel pump relays but fuel pump isn't priming so fuel isn't gonna run to the engine if the pump isn't priming. How do I check the initial switch it's in the on position now but how do I check to see if power is getting to it?

 

[J_C]

According to the wiring diagram I see, if the inertia switch has tripped, it should cause a dash "fuel reset switch indicator".

You can probe with a multimeter for 12V between the input lead to the inertia switch and (chassis) ground, when the pump is supposed to be actively pumping, to confirm power is getting to it. You can probe for 12V between the inertia switch output and ground, to confirm it's making a closed circuit (working), though you could instead just do a continuity or resistance test between the input and output pins of the switch to confirm it's working.

However, if the inertia switch trips, it does not reset itself without being pressed, so it is not likely the problem since the vehicle has failed to start but sometimes does start, correct? If it ever starts without having had the switch manually reset, then it did not trip. There is a slim chance that the contacts at the switch, as anywhere else, could be corroded and making intermittent contact, but not likely considering this is an interior component (located at passenger foot well panel, IIRC?) , nowhere near as likely to corrode first unless the vehicle found its way into a lake or otherwise submerged interior.

Anyway, on the wiring diagram I'm looking at, the inertia switch has dark green/yellow input (should read 12V when fuel pump should be on), and pink /black output to fuel pump, which also should read 12V relative to ground when fuel pump should be on. If you are reading 12V on the output, but are not getting pressure at the fuel rail check valve, then either you have a fuel rail clog (fuel filter most likely) or more likely still is it seems to be time to pull the tank off with the assumption that the pump has failed or at least the electrical connection to it.

If you get this far to the point of feeling you need to pull the tank then you can inspect the connection, measure for 12V at the connector when the pump should be running, and even apply 12V direct to the pump motor with a jumper from the battery to see if it works.

I may return to this topic eventually but must take a time-out due to family issues. Good luck!

 

[koda2000]

An inexpensive test light can be used to see if you're getting power (although I prefer a VOM, even an inexpensive one).

Keep in mind, while power is important to run anything, a ground is equally important. Your fuel pump has 2 wires attached to it (12V power and a ground). If either is compromised, the pump will not run.

I've never noticed a "fuel reset" light on any of my dashes. That doesn't mean there isn't such a thing, but I've never heard of one.

The electrical connector to the inertia switch can sometimes become burnt or corroded. Unplug it and check to make the contacts are not burnt or corroded. Also, the fuel pump relay socket has been known to become corroded and can also become loose, making for poor/intermittent contact. Remove the relay and examine the socket's contacts for corrosion. Also you can create better contact with the relay by taking a pair of pliers and tweaking/twisting the relay's contacts slightly. Doing this will make for better contact with the socket.

 

[janolsson]

This sounds to me like the crank position sensor. Crawl under the front of the truck and disconnect it and reconnect it a few times to clean the contacts. Then once back together try to start.

 

[Polardogg]

have you check the fuel injectors or the tbi? they may need to be replace or cleaned, i find that Lucus Oil fuel injector works best or their tune up in a bottle, depending on if you can get it to run to get the cleaner to circulate , i was always was told that there are two things that make a car stall out while running, fuel or electrical, i had same stalling problem with my 98 until i replace the sending unit/fuel pump

 

[koda2000]

Easiest/safest way I've found to test for spark if the crank position sensor is suspected, is to pull off a spark plug wire (whichever one is convenient) using a battery jumper cable connected to the neg side of the battery, clamp an old spark plug on the other end and have someone crank the engine while you watch the spark plug. If no spark, you know you have an electrical problem (crank position senor, it's wiring, coil or PCM). Start with the crank position sensor. If you're seeing a nice white spark you can rule the ignition system off the list and concentrate on the fuel system. Have you tried spraying starting fluid in the throttle body while cranking the engine over? If it stumbles to life briefly you definitely have some sort of fuel delivery problem. If you have fuel, air, spark and timing something has to happen. As your problem has been intermittent, I think we can rule out a jumped timing chain. That only leaves fuel, air or spark. It is pretty easy to determine which one is missing.

This is taking a very long time (almost 2 months now) to resolve this problem. I hope you don't need to drive this vehicle very often. There's no point in anyone giving you any additional advice if you aren't willing (or able) to do some diagnostic testing.

 

[J_C]

^ ? First post date Jan 21st, but yeah it seems like snow or that hassle of dropping the gas tank is an obstacle. If I didn't have a way to test the crank sensor then I'd just bite the bullet and replace it, not that expensive, around $16 at Autozone or might be less on Amazon.

 

[Pudliner8]

Yea it's been like 20 degrees here and windy since the day I posted and the work is outside so I couldn't stay warm enough to even pull the crankshaft position sensor out. I'm gonna work on it as soon as I can but I have another vehicle so it's no big deal just want it fixed bc the other car is on its last leg

 

[koda2000]

^ ? First post date Jan 21st, but yeah it seems like snow or that hassle of dropping the gas tank is an obstacle. If I didn't have a way to test the crank sensor then I'd just bite the bullet and replace it, not that expensive, around $16 at Autozone or might be less on Amazon.

Yeah, says Jan 21 st. I must have been looking at the OP's join date, or maybe I'm thinking of another similar post (there are an awful lot like this) seemed like I've seen this one for more than just a week.

 

[Pudliner8]

I posted it before but got no reply

 

[koda2000]

Ahhh, I knew I remembered reading this thread title before 1/21. The first time was 12/6.





















i

 

[Pudliner8]

update: the tank is dropped and i hot wired the pump to the battery and got nothing so getting a new sender assembly recommendations on sender assembly and where to get it cheap