97 2.3L Hestitates/Stalls

[chilsam]

turn signal effect

rmmber that the relay thros out an on off circuit to the pump!

 

[runningslow]

No. I have not checked fuel pressure, yet.

When I drove last night with the pump relay jumped (pump always on) I still had some troubles. It only bucked and never tried to stall. When I pulled over and put the relay back, it was worse, but not much. It did stall a few times, though.

I wonder if it drove better with the relay jumped, because the PCM was never able to cut off the fuel pump when it tried to stall.

Anyway, that leads me to suspect the fuel pump, but I don't want to throw money at it unless I'm sure.

Can someone tell me where the grounding point for the fuel pump is?

 

[runningslow]

I just rented the Fuel Pressure test kit from Autozone. Hopefully, I will be checking it tonight. What am I looking for? ALLDATA says 35-40 psi.

 

[runningslow]

I finally got around to running the test yesterday, only to discover that the Ford Schrader valve adapter was missing from the kit. Back to Autozone today....

EDIT: Ok. I finally ran the test. The gauge would show a steady 40-42psi at idle. It would rise slightly with the throttle, but settle back around 40. When it would try to stall, the pressure would increase to 45-50. If it hit 50, the truck stalled out.

Thoughts??

 

[runningslow]

Anybody? I'm stumped. I'm suspecting the PCM, but I don't want to throw money at it unless I'm sure.

 

[runningslow]

I truly hate intermittent problems. Let's summarize:

I've got a '97 2.3L 2WD 5spd with about ~250k on the clock.

On my morning commute with outside temps in the mid 60s, all is well and usually no problems.

In the afternoon with outside temps in the upper 80s, it'll idle at about 800 rpm, then it seems to want to stall (rpms drop) then it surges to about 2000 and eventually settles back to about 800. it actually stalled on me a few times when stopped. It will also stall on me in traffic at highway speeds, or any speed for that matter.

While moving it feels like the engine stops firing for a moment and then kicks back in. Sometimes its just once, others it'll happen in rapid succession and it bucks. The truck runs beautifully in between incidents. I tried swapping the coil packs, which did not do anything. On a '97 2.3L, the ignition control module is integrated in the PCM.

A few times now, I've had the fuel pump relay click and chatter and the truck wouldn't start. When I jumped the relay, the truck would start, but still try to die.

When I finally rented the tester from AutoZone, I found that the fuel pressure sits around 40psi when running and goes up to about 45-50psi when it starts bucking. If it managed to hit 50 it stalled. After the test, I'm pretty sure the fuel pump is fine.

The only codes I was able to pull were P1443 & P0420, which have not come back since I installed a new Magnaflow cat, replaced the O2 sensors and replace the purge valve assembly this past week.

Possibly related: the speedometer has been flaky. Usually it sits at 0-20 mph while I'm cruising at highway speeds. If I let off the gas, the needle will rise. When accelerating, the needle drops to 0. Its been doing this for a few years. I've tried replacing the VSS, gauge cluster, etc... The only thing that seemed to help was cleaning up some of the grounds, but the problem would come back.

Anyway, I'm looking for help. I'm suspecting the PCM.

 

[Mark_88]

Hmmm...symptoms are exactly what my Tempo would give when the in-tank pump was going south...except for one time...turned out to be the inertia switch...but I found that out after an incredible $2,000 engine/fuel pump/transmission replacement...

The inertia switch was fried but it was actually working...when it quit the pumps would shut off and I'd coast off the highway...thinking it was the fuel pump (which opening the gas tank cap and letting pressure out seemed to help on hot days)...

Anyway...could be the PCM...but check the inertia switch just to eliminate that...they are usually up under the dash on the passenger side...you can actually by-pass them the same way as the clutch interlock...might be worth a try...

 

[runningslow]

Mark, you may be onto something there....

Last week, when it the truck wouldn't start and I first noticed the clicking relay limped to AutoZone for a replacement fuel pump relay (which didn't make a difference), one of the guys at the store reset the inertia switch. The truck ran great until I drove it about 100 yards to a gas station. The issues came back when I tried to start it again, so I just thought it was a coincidence.

Just now as I went for lunch, I reset the switch again and drove around without incident, except for one small little hiccup (which may or may not have been related). I'll try to bypass it later to see if that's truly the culprit.

How do I do that? The switch has three wires.

EDIT. Nevermind, I found a wiring diagram.

 

[Mark_88]

That would be good if it turns out to be the problem...if you cut any wires make sure you leave them long as possible...forgot what the switch looked like...apparently three wires involved and not just a clip...one source says dark green/yellow and pink/black wire need to be jumped...

 

[runningslow]

That would be good if it turns out to be the problem...if you cut any wires make sure you leave them long as possible...forgot what the switch looked like...apparently three wires involved and not just a clip...one source says dark green/yellow and pink/black wire need to be jumped...

That's what I figured out from the diagram, but its nice to have some confirmation! The third wire goes to a warning light on the gauge cluster. When the switch is tripped, the power gets diverted to the light, instead of the fuel pump.

I hope its something this simple. *fingers crossed*

 

[Mark_88]

Crossing eyes...lol

From your silence it appears it either wasn't the problem or you are out busting the speed limits with your new found power...hope it's the later...but at least you eliminated one more possible source...

Perseverance...it pays sometimes...

 

[runningslow]

Crossing eyes...lol

From your silence it appears it either wasn't the problem or you are out busting the speed limits with your new found power...hope it's the later...but at least you eliminated one more possible source...

Perseverance...it pays sometimes...

Sorry, I didn't have time to post after I got home from work. I went right back out with the wife.

Sadly, that was not the problem. But, as you say, I eliminated one possible problem.

I think I may venture out to a few junkyards tomorrow in search of a new (used) PCM. I know I have to find another one from a 4 cylinder/5 speed, but does it have to be a 97? Would a 96 work?

I could probably pull a fuel pump, too...

 

[Mark_88]

Dang! Not sure about what years are compatible but if you have a part number you may be able to cross reference it with a dealership...don't have to buy theirs, just find out if the parts are interchangeable...I do it all the time with my engine because some parts work with a wide variety of model years...

Someone on here may know for sure, but if they don't chime in just call up or visit a local Ford dealership and ask them to check the replacement part and ask them if it applies to different years...takes quite a bit of the guess work out of finding a suitable one in the junkyard...

 

[Kenneth S]

As far as Rangers go I think they are year specific (I'm not 100% sure on that). Don't rule out a 1997 Mazda B2300 (same truck)

 

[chilsam]

auto

Sorry, I didn't have time to post after I got home from work. I went right back out with the wife.

Sadly, that was not the problem. But, as you say, I eliminated one possible problem.

I think I may venture out to a few junkyards tomorrow in search of a new (used) PCM. I know I have to find another one from a 4 cylinder/5 speed, but does it have to be a 97? Would a 96 work?

I could probably pull a fuel pump, too...

We run a 91 auto 4.0 ecu on our 89 4.0 5 speed "X 2.9" with no probs just can't use manual on a automatic.