1995 Explorer Sometimes Cranks But Won't Start

[MichelleM]

1995 Explorer Sometimes Cranks But Won't Start / Loss of Power on Hills

Trying to diagnose the prob w/ my 1995 4.0 Explorer.

At random intervals, it will crank and crank but won't start. If I leave it alone and come back 30 minutes later, it will start. This seems to happen, so far, on warmer days and/or when the car has been driven and then restarted (like quick trip to the grocery store). But not always.

That's obviously the big problem, here's more details about it in case they help:

I had a CEL about 6 mos ago and replaced the EGR sensor, that resolved the CEL.

It seems to run rich (smelly exhaust) and has since I got it about a year ago.

Going up hills on the freeway it does this thing that gotten worse over the past year. It will seem like it's skipping or missing, for just as second. If I accelerate or decelerate it will go away, but with my foot on the gas maintaining a normal freeway speed up a hill, it gets these "flat" spots in the engine sound.

When it's hot outside it will sometimes idle rough and seem like it's going to die at stoplights, but it never actually has died while running.

All gauges are always good, no CEL on now either.

Despite all that, the power seems OK for a 20 year old V6.

I've pulled codes and got a 543, Fuel pump monitor circuit shows no power - Power / Fuel Pump Circuits.

I checked the fuel pressure tonight and it's about 28psi while running. When I turn the car off it rises to about 32. Minor fluctuations while revving the engine (drops to 26, back to 28).

Of course, I haven't been able to replicate the no-start in about 3 weeks so I have no idea what those numbers are when it won't start.

Since I can't duplicate the problem I'm at a loss for where to go next. I want to be certain it's the fuel pump before I dump a bunch on $ into having it replaced.

Any ideas / tips on how I can narrow it down further to see what's causing the intermittent no-start?

Thanks in advance!

 

[lobo411]

Here's a thread on code 543:

http://www.explorerforum.com/forums/showthread.php?t=171110

How many miles and what engine (OHV or SOHC)?

 

[MichelleM]

It has about 160,000 miles and is an OHV according to the VIN.

I did read that thread and a few others on the 543 code and most ended up having different solutions. Being new to all this, it didn't give me any clear place to start with. Add to that it hasn't done it in a couple of weeks and I'm stumped.

 

[jester1023]

The next time your Ex does this, raise the hood and rap your knuckles on top of the buss fuse/relay box near the brake master cylinder. Do this with the key on, but not trying to crank. You will probably hear a click and the fuel pump will power up. Then you can start it right up. I call it the Fonzie treatment. It is actually a common problem the 2nd gens develop with the wiring to the pump relay. The wire connection coming into the relay block becomes loose or corroded and won't complete the electrical path as needed. There is probably a fix for this, but it's so intermittent and infrequent, I just bump the fender with the side of my fist and say "eh!" then comb my pompadour back and drive away.

 

[MichelleM]

Still haven't been able to replicate the no-start, but today was the first time I've taken it on a longer drive in several weeks and it was bad news...

Up steep hills at freeway speeds, I'm experiencing a complete loss of power. It decelerates, can't keep up with the 65mph, even seemed like it was shaking a little. It's seemed "sputtery."

On flat ground and on hills at city street speeds it's ok. It's ok at freeway speeds on flat terrain or even moderate hills.

This problem on hills has existed sorta and seemed to be getting worse slowly since I got the truck a year ago, but today was the worst ever, by a lot. A dramatic decline in performance and a little scary.

I hope I make it home tonight! Gotta travel those same hills back home after Thanksgiving dinner.

Does this point to anything specific now?

 

[drdoom]

How long since fuel filter replacement?

 

[koda2000]

have the o2 sensors ever been replaced? if you stick your finger inside the exhaust pipe does it come out black and sooty? if the o2 sensors are bad it would explain your running rich and lack of power. it might also explain the no start when warm/hot if the engine is flooding. unheated (2-wire) o2 sensors have a lifespan of about 50k-60k. heated 02 sensors (4-wire) should be replaced at around 100k-120k. i'm not sure which type a '95 has. how many miles on your truck?

 

[MichelleM]

It has 160k miles.

The fuel filter hasn't been replaced since I've owned the truck (1 year). I don't know when/if it was replaced prior. I don't know if the O2 sensors have ever been replaced either.

I stuck my finger in the exhaust pipe and it was clean, there was a bit of grey residue if I rubbed really hard but not much.

The drive home last night was totally uneventful. Power was fine up hills. The speed of traffic was slower overall on this drive, so I don't know if it would continue to lose power and hesitate at a higher speed.

 

[MichelleM]

Replaced the fuel filter today for good measure.

This vid was a big help and the Sharpie cap worked just fine: https://www.youtube.com/watch?v=hkZRSMGqQ0E

I took it for a test spin afterwards, and it had some hesitation on a freeway onramp that gave it trouble yesterday, but didn't seem as bad. Then traffic crawled to a halt so I couldn't test it out more.

It idled MUCH smoother, took off from a stop smoother, etc. though.

I'll have to wait until I get up to big hill country again to really test it out.