2002 XLT exp 4.0 sohc 4x4 idle issue to not starting

[taxman9]

Hello helpful humans -
My wife's explorer, which we had a new fuel pump put on about 6 months ago, was having a hesitation while in idle a couple of weeks ago. It would drop down to 500 rpm and sounded like it was about to die but then would go back to normal idle. Last week I tried to help a neighbor jump their car, which may be entirely unrelated, but since then its had major issues starting. First time it wouldn't start, it would turnover and crank hard but wouldn't pop and start. After 15 minutes of trying every minute or so it started. This has happened every time since and now can't get started at all. I will post a video soon.
Thinking fuel filter (which was said to be done with the pump)?
Starter?
Timing chain?
Spark plug/line?
Hopefully not the pump again!

[taxman9]

https://www.youtube.com/watch?v=uSAG...e_gdata_player

Here is the link. Also no check engine light on.

[shorod]

Do you happen to have a fuel pressure gauge to check for fuel pressure, or a spark tester to determine if you have spark?

If you don't have a fuel pressure gauge you could try spraying some throttle body cleaner in to the intake tube while someone cranks the engine over and see if it starts that way. If so, yeah, it would seam you have a fuel-related issue. That won't however tell you if the problem is due to the fuel system not pressurizing versus injectors not pulsing. If the engine doesn't try to start with the cleaner, then you may have a spark issue. If that's the case, a rather common cause of no spark would be a bad crankshaft position sensor.

Unless someone connected the jumper cables incorrectly, there's not much chance the problem is a result of helping your neighbor out. But that risk is one of the primary reasons I keep a charged jump start pack in each of my vehicles.

-Rod

[taxman9]

Thanks! Couple of questions - where is the intake tube? Second if it was the Crankshaft position sensor wouldn't the check engine light go on?

[shorod]

The intake air tube is the tube that connects the air filter/Mass Air Flow (MAF) sensor to the throttle body (aka "butterfly valve). There should be a few ports on the tube where you can inject some cleaner, or you could even inject it through one of the vacuum ports on the intake.

As for the CKP sensor setting a code if it is bad, nope, I'm not sure I've heard of one yet that failed AND caused a diagnostic code/check engine light.

-Rod

[taxman9]

Rod - thanks again for the feedback. You actually helped me back in November last year when I was trying to diagnose the same type of issue on this car (02 Explorer 4.0 xlt Starting issues). I had went to the store and got an inline spark tester and the CKP to replace. However found that id did have spark on the cylinder and then ended up getting a new fuel pump put on at the shop (in which they blew out a ball joint on the tow!). So I'm thinking I'll get some starting fluid and the inline tester at it to see if we have spark and if I can find any vacuum leaks.

Any potential the fuel pump went out again?

[shorod]

It's certainly possible the fuel pump is at fault again, especially if an inexpensive and/or universal fuel pump was installed. It seems that several folks have had poor luck with non-Motorcraft fuel pumps. It's certainly worth going the starting fluid or throttle body cleaner route to see if the issue is fuel related. And if it seems to be fuel related it would be worth your time to ensure you have power to and through the inertia cutoff switch.

-Rod

[taxman9]

Just got a minute to check it out with some starter fluid. Sprayed some into the air intake tube while my wife turned it over. Started right up and even stayed running....

[taxman9]

Well we got it up to Carmax for an appraisal of a whoping $1200 bucks. Got it back home and again no starting - turns over hard and wants to go a littl ewith the starting fluid but then quickly dies. How do I " "ensure you have power to and through the inertia cutoff switch"?

Whats the normal policy of an autoshop if they replaced a fuel pump (labor, parts, and tax at $800) and the fuelpump goes bad after 7 months?

[shorod]

The inertia cutoff switch is probably on the passenger side kick panel, to the right of where your passenger's feet are intended to rest. If you remove the kick panel you should be able to gain access to the connector at the inertia switch. Using a paperclip or similar, carefully backprobe the connector and use a test light to verify you have power to the switch and power from the switch to the fuel pump. The Dark Green/Yellow wire is the feed to the switch from the fuel pump relay and the Pink/Black wire runs from the switch to the fuel pump. The reason I suggest using a test light is because it will load the circuit somewhat. If there is a high resistance path in the circuit due to corrosion or a mostly broken wire, a high impedance meter will not sufficiently load the circuit to show a reduced ability to supply current. A test light may load the circuit just enough to show a dim light in such situation.

Also, be aware that the fuel pump relay will, by design, only energize the circuit for about 1 second after the ignition key is first turned to the Run position so you'll need to have the test light connected before turning the key to Run. To make a second or subsequent measurements you'll need to cycle the key to Off for 10 seconds, then back to Run to get the fuel pump relay to again momentarily energize the circuit.

-Rod

[taxman9]

Thanks once again - I'm off to the store to get a test light. I assume this is what we're talking about in the picture? What is this switch used for normally? Or better yet what is the Red Button?

[taxman9]

Got the test light and checked the line in to and from the fuel pump relay when turning to run and cranking - both lit up so that tells me it is getting current to and from that switch, right?

[shorod]

Sorry for the delay, I was out of town camping all weekend.

Yep, that's the switch and if your test light is lit in to and out from that switch, the fuel pump is most likely getting power. The switch is just there to shut off the fuel pump in the event of an accident so if there is a fire or severed fuel line, the fuel pump will not feed a fire. In normal operation the switch is not "used" for anything. But it is possible (although unlikely) for that switch to open from a large pothole, etc. where there is no risk for fire. In such a case it's good for the switch to be accessible, even though very few dealers tell owners about the switch and not everyone reads and/or retains the owner's manual section about the switch.

-Rod

[taxman9]

Thanks - it was the fuel pump again. THe shop used AC delco and the part was covered but labor wasn't after 7 months so it was another $200 bucks.

[shorod]

Ouch, bummer that it still cost you $200. And I suppose since the part was covered under warranty they replaced it with another AC Delco? If it goes out again you might consider getting a friend or two over and changing the pump yourself. Considering how often they are replacing these, the mounting hardware probably won't have enough time to rust/seize and make things difficult. You could likely get a replacement Motorcraft for less than the $200 that the shop is changing you to replace these under warranty.

-Rod