I have a 2003 Ranger 4x4 with the 4.0 engine in it and over the last few weeks I’ve started to have problems with it when it comes to starting it and I’m almost positive it relates to the outside temperature.

When I get in the truck in the morning to go to work (it’s usually around 60 degrees) the truck starts up just fine. But after letting the truck sit for 9 hours at my work and the temperature has gone up into the 80s, when I get in it in the afternoon to go home the truck will crank but after about 4-5 cranks I have to shut the key off and try starting again and it will start. And when it does start when the temperature outside is hot my truck will only idle at around 1000 RPMs when usually the truck idles at around 17-1800 RPMs.

I’m not the most mechanically inclined person in the world but from what I’ve read I’m almost positive it isn’t the fuel pump because the outside temperature shouldn’t affect the fuel pump. Any help on a diagnosis would be greatly appreciated!!

 

How many miles are on this truck / engine?
What's its general state of maintenance / repair? ....good running shape or becoming a beater?
When was the last time you cleaned the MAF sensor?

Does the CEL work? Do you know if the vehicle has any codes?

I'd check (replace) the fuel filter and look for vacuum leaks. The PCV line, both plastic piping and elbows, fail over time.
With the engine running unplug the IAC valve and see if the engine stumbles and possibly dies. A vacuum leak will keep the engine running or even speed up.
Could a failing ECT sensor mess with a "warm weather" restart?

 

The truck has 168,000 miles on it and it’s a fairly good running truck. I’ve had to do some things to it such as replacing the alternator, radiator, and everything to do with the brakes and clutch but overall it’s been a good truck. It didn’t start doing this until maybe about a month ago. The CEL has never came on since I’ve owned the truck which has been around two years.

I may sound like a complete idiot saying this but although the fuel pump shouldn’t be affected by outside temperature could it possibly be a faulty fuel pump relay?

 

I don't know but an aging fuel pump might have its own ideas.
Re the relay: See if there's an identical relay in use and swap them.

 

UPDATE:

So I currently have the truck at my mechanics and he has found out that it’s neither the fuel pump or starter (thought maybe the starter was dragging). But does believe the engine is not getting enough fuel when being started so now we wait to see what he finds!

 

Assuming 2003 Ranger With V6~4.0L~SOHC Engine + 5r55e Tranny + 1354 TCase + ... same DriveTrain as my 2001 SportTrac?
Should ColdIdle ~1000rpm then come down to WarmIdle ~700rpm after 5minutes or so.
At 168kMiles\19years, if not already done, it's overdue for:
~ renewing OilPressurizedTimingTensioners+Plugs+Wires+OxSenso rs+FuelFilter+PCVValve
~ cleaning MAFSensor+ThrottleBody+IACValve+IntakeManifold+EGR Valve
~ checking AirFilterHose+IntakeGaskets+PCVHoses for cracks+leaks
~ renewing Coolant system ThermoStat+Hoses+Fan+FanClutch+SerpBelt+BeltTensio ner
~ renewing Tranny MerconV+Filter
~ renewing TCase MerconLV
~ renewing Differential GearOil
~ AxleLube HubBearings thru ABSSensor holes
~ ...
Also recommend:
~ swapping junk Plastic ThermoStatHousing to an Aluminum version.
~ swapping junk Plastic HeaterCore 2WayBallValve to a Metal 2WayPlugValve.
~ swapping junk PlasticTanked 2CoreRadiator to an AllAluminum 3or4CoreRadiator.
~ Every 5kMiles\6months: renew Engine Oil+Filter.
~ Every 33kMiles\4years: renew Tranny MerconV+Filter, TCase MerconLV, Diff GearOil, Coolant+ThermoStat, PCVValve, AxleLube, FuelFilter.
~ ...
If truck has been reliable for last 2 years, above items should make it last another 100kMiles+.
Click here for detailed info on above items.

 

So another update on the truck. Mechanic ran a fuel pressure test and it showed my truck wasn’t holding any fuel pressure. Checked the fuel filter first and come to find out the fuel filter was clogged up horribly and to his assumption was the same fuel filter that was on the truck when it was first made. So after replacing the fuel filter the truck began to hold fuel pressure much better and assumed that would fix the problem with the truck not wanting to start. But I’ve had the truck back since Monday and it’s still not wanting to start so I guess I’m back to square one

 

Been down this road. Put a pump in that girl, fuel pump that is...

 

Well the trucks going back into the shop middle of next week and that’s probably what I’ll have him check first thing. Because I’ve been trying to avoid having to even mess with the fuel pump because we replaced one on my old 89 ranger before I wrecked it and it was a pain. But I guess good news is if it is the fuel pump I can order one through my work since we sell aftermarket body parts anyways!!

 

Think I’ve tracked down problem to the connector under the tank.

 

After nearly a month the problem has finally been fixed! Upon taking my truck back to the mechanic he found something interesting going on with my truck. When he plugged his computer into it the morning after I took it back and the truck had sit all night, the computer showed the truck was already heated up to nearly 200 degrees. Thus lead to him finding that the coolant sensors in the truck we’re going out therefore was making the trucks computer believe that it was already turned on which was what caused the problem of not wanting to start