Running Rich when HOT??

[MEXEXP]

I have a problem with My Explorer when it gets past the half way thru the temperature gauge it starts to run Rich and it's smells like gas around it and I almost see the fuel gauge go down on every stop and go light. Is there a problem? I have checked the codes and nothing comes out, I know it's 105F outside but is it normal to run rich when it's hot?

Thanks for any help you can give me.

 

[Alec]

Without more information it's hard to tell what's bad.

Could be:
MAS (mass airflow sensor)
O2s
FPR (fuel pressure regulator)
as the most likely off the top of my head.

 

[MEXEXP]

Thanks

but could some of this parts you are mentioning be bad or malfunctioning and not throw any codes?

And the problem is only when the gauge get's past half way the temperature gauge when is under the half way mark everything is normal.

Thanks for your help.

 

[Alec]

How high does the temp gauge get?

 

[MEXEXP]

Not much...

about 5/8 the range of the the gauge, consider that is very hot outside and with the A/C on.

 

[Glacier991]

You say it is running rich. How do you know this? WAY rich will throw an O2 code... are you sure you are not LEAKING fuel when something gets hot ?

 

[MEXEXP]

Maybe thats it

I haven't tought of that maybe that's the high smell of gas I get when the motor is hot, and from where can It possibly leak because it's probably vapor because it doesn't leak any gas on the floor.

And another thing how can you check for a vapor fuel leak????

Thanks

 

[Bwana Bob]

I haven't tought of that maybe that's the high smell of gas I get when the motor is hot, and from where can It possibly leak because it's probably vapor because it doesn't leak any gas on the floor.

And another thing how can you check for a vapor fuel leak????

Thanks

Two things to checK:

Sometimes when the fuel pressure regulator fails it will leak gas back through the vacuum line into the intake manifold.

Also, in the fuel vapor vent line from the tank there is a short rubber hose connecting two sections of steel piping. There could be a vapor leak here (I'm currently troubleshooting that area myself). The hose connection is inside the frame rail, by the driver's side door, just aft of the fuel filter. I'm not sure if there is another rubber hose further back. I need to trace out the vapor line.

Bob

 

[Bwana Bob]

I haven't tought of that maybe that's the high smell of gas I get when the motor is hot, and from where can It possibly leak because it's probably vapor because it doesn't leak any gas on the floor.

And another thing how can you check for a vapor fuel leak????

Thanks

I paln to check for a vapor leak this weekend, because I smell gas when I shut down the engine and get out of the truck. Here's what I plan to do:

Put some soapy water on the vent hose connection. Disconnect the vent line from the charcoal canister and connect an air pump or big plastic syringe to the vent line. Pump some air into the vent line and look for soap bubbles on the hose connection.


Bob

 

[V8BoatBuilder]

Definitley look into the FPR. I had a car that ran great cold, would barely run hot, turned out to be the FPR diaphragm. A failed FPR wouldn't throw a direct code.

 

[MEXEXP]

Question on the FPR

Other than dumping the fuel on the vacuum lines is there a way to check the FPR, because the explorer left me stranded yesterday and was fuel related but there wasn't any fuel on the vacuum lines, like they say when it goes bad.

 

[MrShorty]

Hook a fuel pressure gauge to the fuel rail and see what's going on.

 

[MEXEXP]

Will Do That

Will do that on the weekend, what's the correct pressure?

 

[MrShorty]

With the pump running: 35-45 psig.
With the pump off: should stay within 3 psi of running value over 5-10 minutes.
Pressure should stay within that range as engine RPM increases.

 

[cjbarron5]

o2 sensors?????????????? coolant temp switch for the computer ?????????these all affect your fuel quantity along with the obvious fuel pump and fpr

 

[performancenut]

Try removing the FPR vacuum hose and see if fuel drains out the end. Fuel discharge from the vacuum hose is a good indicator of a bad fuel pressure regulator. I question whether the high temperatures outside may be causing fuel vaporizing in conjunction with a malfunctioning fuel system. If the fuel pump is overheating, it may contribute to the problem.
Alternatively, a problem with the vapor management system could be a cause or even a clogged catalytic converter issue worsened by the heat.
You might try putting the stock air box back on; the universal K&N conical filter is going to draw it's air supply from the hot engine compartment on top of the high ambient temperature.

 

[MEXEXP]

Stranded...

I took out the vaccum hose out of the FPR and nothing came out, yesterday the explorer left me stranded on the side of the road, probably is the pump because when you checked for pressure on the valve on the side of the intake it didn't came out with pressure only a few drops, but what troubles me is that I can still hear the pump, I bypassed the relay for the pump to always stay on and it didn't fire. I have good spark, If you click on and off the key to charge the injectors a few times in a row you could barely start it but right after it dies, the problem is the fuel but exactly don't know what.

 

[performancenut]

Sounds like a need for a new fuel pump.