Hello,

2002 Ford Ranger 3.0. Had a leaking radiator, kept putting it off. Coming home from work engine overheated on highway. Now the truck only starts with the throttle full open (gas pedal to the floor). Once started the engine idles very rough and usually dies but as long as I give it gas it sounds ok. Plugged in the code reader and had nothing. Pulled the plugs and looked at the top of the pistons everything looks normal. The rubber boot was torn up on the fuel pressure regulator so I replaced it, that did nothing for this problem. I have pictures of the piston heads and plugs if that would help anyone with anything.

 

may have a warped/cracked head..especially if you ran it hot

 

'02 Ranger doesn't have a fuel pressure regulator, it uses a "returnless" system.
It has a Pulse Damper on the fuel rail.


Most common engine issue, after an overheating, is a breach in the head gasket or a cracked head.
The extra heat causes the head and block metal to expand more, this can crush the a cylinder ring on the head gasket.
Top of the cylinder will have the most heat and the metal between the valve seats is a weak point, head often cracks there if overheated too much.

When it starts is the exhaust blowing out white smoke and does the white smoke smell sweet(burning coolant smell).
Did one of the spark plugs look very clean, i.e. "steam cleaned"?

When engine is cold remove rad cap, top up rad with coolant or water.
Start engine
Is coolant overflowing out the rad cap opening?
If so, you have a cylinder leaking pressure into the cooling system, so head gasket or crack issue.

You can do a Glove Test to be sure and to ID which cylinder.


Out side of the cylinder issue an overheating shouldn't effect anything else, i.e. fuel or spark.

On fuel injected engines when you hold the gas pedal down to the floor and then crank the engine the computer will shut off the fuel injectors, so engine should not start until gas pedal is up a bit or your foot is off it.
It is called "clear flooded engine mode" when you do that.

 

Yeah, I understand that the head gasket is probably gone and or the block could be cracked but that has nothing to do with having to hold the gas pedal down on start.

I have doing some more trouble shooting and I think the mass air flow sensor may have magically gone out at the same time this happened.

Or, does anyone know where the ECU gets the eng. temp from to control fuel amount? The Temp control only has one wire so thats not it and I am not that familiar with these engines yet, but I can tell after this I will be a pro.

 

Holding the gas pedal down(opening throttle plate to let more air in), dries out any coolant that may have entered cylinders from bad gasket, so it would explain it.

But no on the MAF sensor, engine will start fine and run without MAF sensor connected, just won't drive well.

On V6 engines the ECT(engine coolant temp) sensor(2-wire) should be located next to the Thermostat housing.
The dash board's temp gauge sender(1-wire) is often right next to it.

On some 3.0ls there might be a metal "T" pipe by the water pump and the ECT sensor will be on it.

This page shows 2000-2005 3.0l ECT sensor next to t-stat housing:
| Repair Guides | Component Locations | Coolant Temperature Sensor | AutoZone.com


For start up Computer only sees 2 gas pedal positions via the TPS(throttle position sensor), under 1 volt(foot off the gas pedal, injectors on) or over 4.5volts(foot to the floor, injectors off).
1/2 throttle would just be like foot off the gas pedal, although it would let more air in to dry out cylinders.
Although unlikely, an injector could be leaking causing a flood effect when engine is off.
After engine is warmed up shut it off then remove intakes air plenum and open throttle plate, if you smell a strong odor of gasoline then fuel is leaking into the warm intake and vaporizing.

I doubt you could crack the block but........??
Heads crack pretty easy.