Hi all! Last weekend took my '02 4.0 on a road trip, all freeway and running at the speed limit of 75-80. After about 2.5 hours of steady driving I noticed some slight engine stumbles and then the engine just shut off, RPMs to zero. Before I could even start to pull to the side it fired back up. A couple minutes later the same cycle repeated, and then again. I slowed down to about 60 and didn't push it too hard; all of this was on a generally uphill climb with AC on. About another 50 miles later on a steep 2-lane it did it again. Pulled off and let it cool for about 15 minutes, then went on to my destination. On the return trip, mostly downhill, I only noticed the stumbles when on inclines, and anticipating the stall I'd turn off the AC and slow down. I later remembered it had done the same thing a few weeks prior, but within a quarter mile of leaving work at the end of the day, flat city driving.

The fuel filter was only a year old, but taking the path of least resistance I replaced it but am still noticing stumbles when I push it hard on the freeway home, again especially on inclines. Fuel pump seems the most likely culprit, but I thought I'd run it past the fine folks here first.

Thanks!

 

Definitely sounds like a fuel delivery issue. Fuel pumps don't always flat out fail, something could have broken or worn itself out on the pickup assembly causing a fuel starvation issue.

 

I assume automatic?
But how did it restart from 0 RPM?

Yes, fuel pump would be my next stop if filter did help

 

Yes, auto, 146k miles, no mods, all stock. Sorry, I should have included those details!
The restart is an odd one, for sure. The tach dropped to zero, but all the electrical components like radio and AC fan stayed on (to the best of my recollection, was a little freaked out!). I was still rolling in gear at 65+ mph and it just fired back up. Pushed on the gas pedal and re-accelerated.

 

While a little odd I might just change the Crank sensor(not cam sensor), Crank shaft position sensor, it is used to time spark and injectors, and also..........tachometer signal

While it is very rare for this sensor to have any problems, it is literally the only sensor that can shut engine off while running or cause a no start
Any other sensor failure will just set a code and might cause rough running, but never a stall

 

Interesting, RonD. Well, it's only a $15 part and looks to be a quick swap-out, both better options than the fuel pump replacement job, so I'll take a run at that and report back. Thanks!

 

Very unlikely to be the problem, but not 0%, and as said, it is not expensive or hard to replace.

Do you remember if the CEL(Check engine light) came on?
It should have if computer was still on

 

No CEL, then or now.

 

Then I might swap out the EEC(PCM) relay, another not expensive part, just to be on the safe side

Owners manuals here: https://www.ranger-forums.com/genera...1-models-3747/

PCM relay is in the engine fuse box, manual has the location


PCM relay closes with key on, it powers the PCM(computer), fuel injectors, and fuel pump relay.
If it opened, then tach would stop as well as fuel injectors and spark, and NO CEL, because computer is OFF

CEL should come on anytime key is on and engine is off, it means computer has booted up and is waiting for crank sensor signal to start spark and fuel flow
Since it didn't come on as RPMs were dropping computer may have been off
I don't think your engine actually dropped to 0 RPMs as tach showed, transmission engagement would have kept engine turning for a bit which is why it "restarted"
But the tach to 0 would indicate computer shutdown or crank sensor

 

One additional data point: I just filled up and checked mileage and only got 16.2 last tank. Have been running high 17s.

 

Meh, still stumbling issues after crank position sensor replaced. Sadly I don't think this is going to be one of those easy fixes. Fuel pump on deck, any last words of advice?

 

So I wanted to close the loop on this topic for anyone else out there with a similar problem, or for anyone removing the bed to replace the fuel pump.

A couple of days before the planned operation I began wire-brushing the underside of the bed bolts and hitting the undersides and tops of them with Blaster. This was an Ohio truck now living in Las Vegas, so I knew the rusty bolts were going to be a real bear. I was able to get to 5 of the 6 bolts; the one hidden behind the fuel tank was unreachable. I also took the suggestion of RonD and replaced the PCM, but unfortunately that didn't resolve the stumbling.

I bought the pump, another T55 Torx (in case I broke one), and a 30" breaker bar. My 16 year old son and I took off the cap and pulled the bed liner, and guess what we found? The forward edge of the bed pan had significant rust, causing it to separate from the front upright bed panel in a number of places, and the one bolt I couldn't get to, behind the driver seat, wasn't connected to bed any longer. So one bolt down, five to go. We applied the impact wrench but none of the 5 budged, so we went at them with the breaker bar. Following the suggestion of several YT videos, once we broke them loose we'd make several turns out, then back them in a bit to free any rust bound up in the nut, rinse with Blaster, and repeat. One eventually snapped, but we got the other 4 out after a long struggle; they don't loosen and spin freely until all 4"+ are almost all the way out. Once out we went over them with the wire brush and applied more Blaster.

Disconnected the taillight plug under the rear bumper, unhooked the filler neck, and then set the bed back on the rear tires and bumper. Cleaned the pump area with the air hose, unhooked the pump lines and wires, tapped loose the pump retaining ring (hammer and wooden dowel - don't need any sparks down here!), and pulled the old pump. The internal filter stayed attached so I didn't have to fish that out of the tank. Cleaned the rim, applied the new seal ring, and pushed in the new pump. And here's what I found to be the most frustrating part of the whole job: getting the retaining ring to thread back on. Too many hands in too small of an area while trying to hold down the springy pump and spin on the ring. Eventually solved that by using a long dowel to press down on the top of the pump from well above while my son got the ring threaded.

Reconnect fuel lines and wiring, reconnect battery, then TEST BEFORE PUTTING THE BED BACK ON! Reassembled in reverse order, and we were able to use the impact to run the bolts back in. I'm eventually going to have to do something about the snapped bolt and the rusted one that's not holding onto the bed, but since I don't do any hauling I think I'm OK with 4 bolts holding it on. No more stumbling, I haven't had any more stalls and restarts, and the MPG is back up over 17, though that probably has more to do with the MAF cleaning and air filter replacement than the pump. About 6 hours start to finish, but we took plenty of breaks during the breaker-bar phase since it was about 100 in Vegas that afternoon. YMMV.

Thanks to all who provided advice.

 

Good work

Thanks for the follow up, I am sure it will help others

 

Glad to hear your issue has subsided.