'98 XLT looses all power after about 20 miles

[UKwinsagn]

I'm gonna try to make this short and sweet. Let me start by saying that in the winter this thing runs like a champ. The summer is another story. I have only noticed it on days above 80 degrees but the darn thing will want to drop down to an idle while im goin 70+ on the highway! I can only push the gas pedal down about a half an inch (which usually lets me maintain @ 45mph) which isn't that great. If i give it any more gas than that the rpm's drop to @ 500. If i put it in nuetral and turn the key off -- then restart it, i usually get enough power back to make it up the next hill then it will bog down again. I replaced the fuel pump/filter and the IAT sensor and the plugs/wires are @ 6 mo's old. Fuel pressure in the driveway is a constant 30psi and will go to @ 38psi when i rev it. I checked the MAF and the voltage seemed to be within range and voltage increased slowly as i opened the throttle. Does this motor have a fuel pressure regulator? Because when i go to look it up at Autozone, it says there isnt one on this vehicle. The DTC's all show lean conditions on both banks and a gross evap can leak. Any help or guidance will be greatly appreciated.

 

[safn1949]

I believe the regulator is in the tank on that model.

 

[2000StreetRod]

Return fuel system

I believe your Explorer has the return fuel system (two fuel lines connected to the fuel tank) I think the switch to the returnless fuel system was in 1999. You should have a fuel pressure regulator on the fuel rail. If you idle the engine and disconnect the vacuum line to the fuel pressure regulator the fuel pressure should jump to maximum (more than that for WOT).

Have you checked all of your vacuum lines including the hose that goes to the fuel vapor management valve under the battery and the one that goes to the charcoal canister just behind the fuel tank?

 

[UKwinsagn]

I checked all those lines mentioned and I did find the fuel press regulator. Are you saying that when it does this again to disconnect the vaccum line from the FPR and if performance improves, the fpr is the culprit?

 

[2000StreetRod]

initial post question

The question in your initial post was about whether or not you had a fuel pressure regulator (FPR). My response was to help you locate it which you have accomplished. You also mentioned that your fuel pressure increased from 30 psi at idle to 38 psi at high revs when the vacuum is reduced. One way to check the basic function of the FPR is to disconnect and plug the vacuum line to it. No vacuum should result in a higher fuel pressure than when you rev the engine. If the simple FPR test passes then you probably should look elsewhere for your problem source.

Loss of power in hot weather could be due to an overheating fuel pump, a defective engine coolant temperature sensor, weak ignition, or several other things. Do you have any PCM reported diagnostic trouble codes?