starts fine cold , when warm it sometimes has a hard time starting

[gmbroy]

I have a 91 explorer . It starts great when it is cold . When it is warm it sometimes has a really hard time starting . it will sputter really bad . once you get it moving it clears up & runs fine . any help with this would be greatly appreciated

 

[bigbadwolf078]

mine is the same way...any suggestions would help

 

[gmbroy]

As soon as I find out what the problem is I will fill you in I have been just dealing with the problem . It might be the fuel pump leaking back some & letting it get somewhat vapor locked ??? I am at a loss for now . My name is George & I live in orange va . If you should happen to find out anything you holler at me . If you ever need any help just ask & I will try my best to help . I am a maintenance mechanic & was born & raised on a farm . LATER

 

[awood]

Recent experience on the forum here taught me to not forget the basic, simple stuff. If you have any codes, post them here. Make sure the plastic intake is tight and secure with no leaks, even a little pinhole could be a problem. Make sure the throttle body is clean. Make sure the IAC valve is clean. Make sure the air filter is clean. Make sure the MAF has been properly cleaned with the right cleaner. If plugs/wires are in poor condition, replace them. Make sure all your vacuum lines are good, especially at the cluster on the drivers side of the intake.

That said, you could have a fuel pressure regulator leaking, or one or more injectors leaking, but with pressure fuel systems, vapor lock shouldn't be an issue. I've also had issues with the Throttle Position Sensor (TPS) that didn't give a check engine light, but that was a one-time experience.

 

[gmbroy]

I have no codes . I was driving it this weekend & it just shut off . After a few minutes I got it started & it went about a mile then the motor shut off again . After it sat long enough to cool down it started fine & ran like a top . I put a new fuel filter on & it still has a hard time starting after it sets for about 20 min or so . I have put new wires , plugs , vacuum lines ,belts hoses etc. . cleaned the iac , the throttle body , etc.. I am going to change the regulator, then the fuel pump . Will keep everyone posted & thanks for the help .

 

[awood]

Try this thread:
http://www.explorerforum.com/forums/showthread.php?t=394039

The last post suggests swapping the fuel pump relay in the relay box next to the air filter. It's quick, free, and a good try for a fix...

If you swap the relay, it was suggested you swap the fuel pump with the Wide Open Throttle (WOT) relay. Also, this time of year, the A/C relay would work too. They're all the same part number so it doesn't really matter.

As mentioned in the thread, other possibilities for the engine shutting down while driving are a bad fuel pump, bad wiring or connectors, a bad ICM (coil pack), or an unlikely cause is a bad PCM.

If the relay swap doesn't cure the problem, I'd do as the thread suggests, and hook up a fuel pressure gauge and mount it somehow so you can see it while driving. If pressure remains high and the engine still quits, it's not a pump. No use replacing a pump if you don't have to. If you loose pressure, and the engine quits, it could be a pump, relay, or wiring.

 

[gmbroy]

Thank you awood I will give it a try & see what happens . I do appreciate the help .

 

[gmbroy]

Try this thread:
http://www.explorerforum.com/forums/showthread.php?t=394039

The last post suggests swapping the fuel pump relay in the relay box next to the air filter. It's quick, free, and a good try for a fix...

If you swap the relay, it was suggested you swap the fuel pump with the Wide Open Throttle (WOT) relay. Also, this time of year, the A/C relay would work too. They're all the same part number so it doesn't really matter.

As mentioned in the thread, other possibilities for the engine shutting down while driving are a bad fuel pump, bad wiring or connectors, a bad ICM (coil pack), or an unlikely cause is a bad PCM.

If the relay swap doesn't cure the problem, I'd do as the thread suggests, and hook up a fuel pressure gauge and mount it somehow so you can see it while driving. If pressure remains high and the engine still quits, it's not a pump. No use replacing a pump if you don't have to. If you loose pressure, and the engine quits, it could be a pump, relay, or wiring.

I got thinking about your suggestion on how you don't overlook simple things . I drained the coolant which looked horrible & flushed the system . & have not had a problem since BUT the weather has been cooler & I have not ran the a/c . my valve covers is leaking so I am changing them , heater hoses , & new power steering hoses , water pump etc.

 

[gmbroy]

mine is the same way...any suggestions would help

My problem was dirty injectors . Took them out ,removed the screens , soaked them , soaked them again in an ultrasonic cleaner , back flushed them using a home made device to trigger the injector . New screens & O - rings . runs like new . while I was in the area I also replaced both temp. sending units . if you do this I can pretty much guarantee your problem will go away .

 

[FR-425]

It's the temp sensor for the PCM

The one "near" The thermostat housing for the PCM looks like this.

It is a bad Temp sensor.

http://www.rockauto.com/catalog/moreinfo.php?pk=951148&cc=1119631

Been here, done that already.

There are (2) sensors, so make sure you change the one that has a cone on the end of it, next to the thermostat housing.

 

[gmbroy]

It's the temp sensor for the PCM

The one "near" The thermostat housing for the PCM looks like this.

It is a bad Temp sensor.

http://www.rockauto.com/catalog/moreinfo.php?pk=951148&cc=1119631

Been here, done that already.

There are (2) sensors, so make sure you change the one that has a cone on the end of it, next to the thermostat housing.

Well that makes sense . But if you could have seen the stuff that came out of my injectors I think it was time well spent . I thought that sensor could be the cause that's why I changed them while I was in the area . That 3 core rad. is working great .

 

[natenkiki2004]

A lot of Explorers have mileage higher than what Bosch recommends for the injectors (150K if I remember right).

The ECT will foul up (rich) warm idle (thinking your engine's always cold), the IAT will foul up (lean) cold starts (thinking your engine's always warm). That's my theory anyway.

 

[FR-425]

Yep and the other way round.

 

[FR-425]

Mines come'n up on 140K so I'm gather'n the parts to do the top end next year, just for shins and giggles. Still runs perfectly.