This is a repost. I used a bad title on the last one.
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Hi. I'm 76, but still do all my own vehicle work except for frame and major body work. I've repaired diesels, lots of small engines, and more normally-aspirated trucks and cars than I can count. But I'm in fairly unfamiliar territory with a port-injected engine. I have an 02 Ranger Edge (my farm truck) with the 3.0 V6, 144K miles. It runs like a top, with no major leaks or problems... until yesterday on the way back from a medical visit.

1) it was 97F outside temp, and yesterday was the first time in many months that I had been running the AC. The fluids and pressures were all good (all analog gauges). The coolant temp was smack in the middle of 'normal'. I was running 60 on an open country road with LOTS of traffic both ways.
2) about six miles from home, the engine suddenly QUIT at highway speed (all dash lights came on). It didn't sag then die, it just 'snapped off', like I'd turned off the key. I flipped it into neutral, cruised onto the grass, and stopped in a safe location. My first thought was 'ignition failure', because of the suddeness of the failure. But I didn't have any tools with me.
3) The engine would still crank, but no start.
4) After about ten minutes sitting, it started. I drove with almost zero power for about five hundred yards, and it died again.
5) I have tow coverage, so I called for a tow. The guy came, towed me the five miles to home, and put the truck in my barn. It had been sitting turned off for over an hour and a half.
6) I cranked it up, and it ran FINE. Good idle, good power, everything. NO DTCs on my (proper) code reader.

Given the heat, if this had been a normally-aspirated engine, I'd have immediately declared "VAPOR LOCK"... except this is port-injected.

One other little symptom might be related. For the last year and a half, if I start it HOT after about 1/2 hour of sitting, the idle drops below 500, and it'll stall. I can drive 'two-footed' for about five minutes (one on the brake, one on the gas), and it heals itself. This was present before I changed the fuel pump (yeah... pulled the bed) about six months ago. No change in that symptom. I changed the pump because it died.

Oh... and it's painted Red... so that might be the real problem. <grin>

Anybody else seen this?
This morning, I'm about to check fuel pressure from the tank pump while it's running (maybe that darned fuel filter under the driver?). Anything else?
Thanks,
Lloyd

 

Maybe I have a clue. There are conditions where an overheat condition may be sensed, even if the temperature gauge reads properly. Some models in this range go into 'limp home' mode when they sense overheat, and some just shut down. The fact that it was a blistering hot day, I was running AC wide-open, and it ran fine after cooling off completely tend to point to that.

I've had a very slow coolant leak from the front seal of the pump that I haven't bothered to repair, because I only have to add about a quart every 1000 miles or so. But I checked the sump/overflow, and it was empty, and the radiator was down to about 1/4" over the tubes. So there probably was vapor in the cooling system. Hmmmmm.... It's still running fine, good compression, no sign of smoke or vapor from the exhaust, and it's not blowing any bubbles back into the overflow container.

Has anyone heard of that combination of stuff causing a shutdown at speed? I just learned that there are both a gauge sensor near the thermostat, and an engine temperature sensor for the PCM on the back end of the head. Hmmmm....

LS

 

Welp... found two issues. The radiator cap is releasing at 10psi, and it's a 16psi cap. The top gasket on the cap is leaking some, and the overflow hose is leaking at both ends where it goes on the barbs, and there's not enough length to cut and re-attach it.

Basically, when it expands in the radiator, it's just blowing coolant (prematurely) out through the leaks onto the ground, instead of pushing it into the reservoir. So when it contracts again, there's less to retrieve each time, until there's nothing.

Both cheap. I hope that solves it.

L

 

I just put a new cap on, and fit a new reservoir hose with clamps. I drove the vehicle 30 miles, 50 one way, and 60 the other, without any overheat or loss of coolant. We'll see. Maybe the PCM was smart enough to save my head from warping! 'Still 'burping' the system a little, but most of the air seems to be out of it, now. It went down in the neck of the filler about 1/2" this last time, but not below the top of the radiator housing.

LS