Back again intrepid 96 3.3 l issue update?

Question

while driving 12 miles into the trip the RPM Went down and i can top at only 15 miles i mean i step on the gas and nothing check engin came on got a code p0171 and 174 i beleive its the O2 bank 1 and bank2. wait for the car to cool off and it will start again. so normally i thought its an issue that happen when the car is hot or reach a certain temp. this morning i connected a fuel pressure gage and it read about 50 psi lfet the car running for about 1 hr waiting for it to happen agian but nothing so i drove the car this time and 30 min later same thing happen looked at the gage and it was reading 14 psi, turn the engine off waited for about 15 min turn it back again and it was reading 50 psi so i was able to drive back home. so i am thinking i need to replace the fuel pump , but i have some question hoping someone can answers: why did the computer didnt give any code relating to the fuel pump unless am not understaing and code 171 and 174 means more than just 02... also and most important , can someone explain to me the logic behind this .. i mean if the fuel pump is bad it should not work period how is it working good at times then bad at another time i guess i am trying to understand what exacly causeing it to behave like that . and not just replacing it whithout understanng? also i guess i wanna make sure its not something else that is causing the fuel to do that if that will be the case then the same thing will happen in the replacement one ,,, could it be a bad connector or wire ?would take it out and cleaning it help or maybe replacing a connector or a wire that gets effected with the heat but then again the car got hot at idle why did not that wire did the same thing its an issue that happen while the car is moving anything i can do to fix it so changing it will not be necessary ? anyone can explaine that to me will be greatly appreciated ,, thanks all in advance

Answer 1

ok i'll try. the o2 sensor codes you are getting could be a lean code meaning the veh. is not getting enough fuel. there are no codes just for the fuel pump. the computer dose not monitor the fuel pump, but if it sees a lean on the o2 sensors then you can expect a fuel pump problem but not all the time. but in your case i would say your fuel is bad. the fuel pump is a electrical motor and just like all electrical motors they do get worn internally just as if a stater goes bad or a alternator. they where out. from what i've seen the brushes where out not allowing the pump to pull enough amps to do its job. i've seen a lot of pumps work good when you first run the car then slowly start loosing pressure. that is due the amount of heat that is created by the pump. the pump starts to get hot and a weak pump is then not able to due its job.  the best thing you can due for a elec. fuel pump is to keep at least 1/4 of feul in the fuel tank at all times. that helps to keep the fuel pump cool and keeps is from bruning up prematurley. hopes this helps.

Answer 2

a fuel pump can be bad and still work,this happens a lot especially on older vehicle,s what happens is as it heats up it turns slower producing less fuel then this causes the engine to starve for fuel ,this is where you get the codes from on one,then when the pump cools down it runs at a higher rate of speed again producing more volume of gas,but the same this can reoccur over and over and as the pump gets worse the vehicle will run worse,eventually it will stop running,but this can go on for a long time,even weeks before the pump will actually burn its self out,just because a pump runs doesn't mean its good,they can on  forever but not put out enough gas to run a vehicle,good luck with it.

Answer 3

The PCM only monitors certain functions, O2 activity, TPS signal, Injector circuits, cam, and crank signal. the fuel pump relay, fan relay etc.  It has no way of telling if the pump itself has low output directly.

It can however tell if the engine is running lean (a symptom of low fuel pressure and/ or volume).It can even compensate for low pressure by increasing the on time of they injector to make up for a loss of fuel volume ( called adaptive  fuel control).

I suspect that your pump has developed a restriction in the primary sock filter on the pickup, or is simply worn and not running at full speed,. The longer it runs (hotter it gets) the less fuel pressure it produces.

You can measure the amperage draw on the fuel pump circuit, and if excessive, this will give you conformation of a worn or defective fuel pump.