92ToyAuto

Long time lurker, finally have a problem with my truck and was hoping for some advice.

92 Pickup ExCab 3.0 with an automatic

One month ago the timing belt went on it (I guess the previous owners guess of being replaced a ?few? thousand miles ago was a bit off). Anyways, I replace the belt, idlers, water pump and thermostat. Everything is running fine for a few days of commuting (5 miles each way, barely enough to get up to operating temperature).

Come back from a month long business trip, truck runs fine until one day in the Ikea parking lot it stalls. Fairly warm out (high 80s), temperature gauge is in the middle (slightly below). I am driving and apply some gas and it stalls. I coast to the side, it fires right back up, drive around for maybe 1000 feet, stop and go, and it stalls. Had to limp home by letting it cool off then driving a few miles, then stop cool off?.

Symptoms
-Only happens at operating temperature (slightly below middle of gauge). Never happens before.
-Never stalls while going down the freeway
-If it stalls, it immediately fires right back up and idles, drives away fine? sometimes for a few miles, sometimes for a few thousand feet then it stalls again.
-Letting it cool off after it stalls allows it to run until it gets up to operating temperature again.
-After it stalls and it is restarted, turning on the AC (just giving the engine a load) idles up the engine and it stays running. If I put it in drive it keeps running (at least for awhile). If I turn on the headlights, the engine will die quickly.
-When the engine stalls after I turn on the headlights and idling it ?slowly? stalls? the rpms just keep getting lower and pressing on the gas pedal does not change it.
-Starting the engine with the headlights on, works fine. Can even drive down the road for awhile. Turning the headlights on and off and on and off a few times kills it sometimes.

Items checked so far
-Cleaned throttle body
-Checked voltage while engine was stalling (constant 13+ volts).
-Checked main positive lead from battery to fuse box (.15 ohms with engine off and 5.67 with engine on).
-Checked temperature gauge (put piece of cardboard in front of radiator and it got hotter) and pulled cap and measured ~ 180 degrees.
-Checked thermostat and pump (pulled cap and revved engine, got a little geyser)
-Checked for vacuum leaks (just sprayed around and no change in idle)
-Checked timing (10 degrees)

The weirdest part to me is that the engine stalls when the headlights are turned on, not when the AC is turned on, brake lights are turned on, blower motor, put in forward or reverse gear, so it doesn?t seem like it is load related. My guess is either heat related to some component, or a breakdown in the electrical which is just sporadic and related to heat. I have searched the forums but cant find anything related to stalling and electrical, other than posts about the main power cable to the fuse box (which I checked).

I am planning on putting in an OEM thermostat (24 bucks Ouch) instead of the 6 dollar stant I got in it right now, and see if that lowers the operating temperature. However, I feel this is a band aid for the real problem and any suggestions on what to look at next (after I get back from another week away at work) would be really appreciated.

Thanks,
John

TNRabbit

alternator bearings going out? Short in the headlight wiring?

stormin94

Maybe a short, bad(weak) battery, or bad alternator. Or a combination of all of those.

rocket

iTrader: (1)

I really doubt the thermostat has anything to do with it stalling.
Sounds more like a bad alternator, contacts, or a weak ground.
With the recent work you had done, i'd bet it's electrical related... Have you tested the alternator yet?

Bumpin' Yota

Check battery, alternator and ALL electrical connections.

Even with a bad alt the draw from the headlights isnt nearly enough to starve the PCM of voltage. I personally have had my system voltage go in to the 9.10v area and the truck stay running. (The headlights barely work below 10v...lol) Other than the RPM dropping from my HO alternator presenting a pretty good load, there was no change.

The only way I can see this being a bad alt is if your battery is toast too, which it doesnt sound like it is. Ergo - check ALLL electrical connections. You probalby have a short somewhere

92ToyAuto

I will try and do some of the quick tests for the alternator and battery that I found in other posts, and will inspect all the grounds as close as possible.

I kind of doubt the alternator or the battery since when the truck stalls I have had my Fluke on it and the voltage stayed exactly the same while stalling (started to drop a bit once the engine stalled). It definately seems like the battery is at least keeping a charge because after not driving the truck for a month it had a little over 12 volts on it.

It just seems strange that once it starts to stall, there is no recovery. Turning the lights off does not prevent the stall, revving the engine is impossible. Is it possible it is the igniter module heating up and misbehaving intermittently?

shurup

FUEL PUMP!!! Had exactly the same symptoms on my 2005 F250.

95RunnerSR5

when i would turn on my lights my truck would shudder, the cause was a bad connection on my negative battery terminal

TNRabbit

it sounds like something is pulling current away from the ECU, causing it to stall out. I read about this same problem here before, but don't recall what was causing it...maybe the fuel pump as shurup said...

shurup

Check the fuel pressure. See whet it is and then give it some gas manually and see if it changes. Have someone sit inside the truck and ask them to play around with headlights, a/c, put it in drive while holding the blake pedal (hold it really good) and give it some gas (load the engine). Keep monitoring fuel pressure. When the fuel pump is going symptoms won't be all the same all the time. And your headlight thing may just a coinsidence (it adds a little load to the engine).

Bumpin' Yota

i REALLY like the ignition issue....seems oddly familiar for some reason. Look there as well as fuel pressure/fuel pump

92ToyAuto

So I really like the idea that it was starving for fuel, given that it would stumble and then stall, and not just cut out (ignition coil or ignitor normally). So I figured I would look at everything electrically involved with the fuel pump. EFI relay checked good, and when I got to the Circuit Opening Relay I noticed it had a bit of rust. I pried open the cover and sure enough it was filled with rust.

Now I am just trying to find one not from the dealer (90 bucks). I got rock auto for about 40 bucks, so I think I will go with them.

Thanks for all the replied. Once I get the new relay, I will give an update.

some drunk guy

Was this problem ever solved? I have the exact same symptoms!!
New Alternator, New battery, redid all my grounds , checked fuses, swapped AFM, swapped EGR, swapped Ecms's

and mine still dies when I let it warm up and drive for a while, also dies faster when I turn on my headlights, AC etc....

Tom-