stalling all the time

[robert740il]

my 2000 xlt 4.0sohc started to run rough so i replaced maf(2nd one) w/oem reman., car started to act like fuel pump was going out(replaced nov.2010) but after checking pump seems to be ok. fuel pressure test starts and stays(after 5 min.) at 67psi and the tailpipe exhaust liquid is black fluid and clear fluid. the car, after sitting, will crank and not start, then start and die and sometimes just die at a stop light. i just put in a new filter(those clips are fun) so i'm thinking maybe the return line is blocked. any quick way to clear it? or what is up? thanks for your help in the past, you guys are invaluable!!!!!!!

 

[2000StreetRod]

no return line

There is no fuel return line on your 2000. Your fuel pressure is normal. You might try cleaning the IAC valve if you haven't already. Do you have any diagnostic trouble codes? Did the fuel that leaked out when you changed the filter look normal?

 

[robert740il]

since i put the new maf in i have no trouble codes. i was getting "mixture too rich" codes before. when i changed the fuel filter the run out from the filter was black but the gas in the lines was clean. i siphoned out about 8 gal. because i thought i was going to have to drop the tank. that gas was all clear but in the bottom of the bucket it felt like little sand particles were there.

 

[robert740il]

update; even though the check engine light is not on it is throwing out the codes P0172 and P0175. i'll try the iac valve when i get the time. thanks

 

[2000StreetRod]

cold start normal?

Does the engine start and idle normal at cold start but then run rich/rough after warmup? If so, I would suspect the engine coolant temperature sensor.

 

[robert740il]

yes it does. i cleaned the iac sensor today, changed the oil, oil and air filter. drained the rest of the gas and put 5 new gal. in. it is running much better with very little black soot in the exhaust. the exhaust water does kind of smell like anti freeze and i have noticed that my overflow tank is coming up empty every week or so. could these be syptoms of the ECT (engine coolant temp sensor)? if so i will replace it but it seems like a big job removing the upper manifold cover. thanks robert740il

 

[2000StreetRod]

find the leak

If your coolant level drops below the ECT sensor it won't be able to read the engine temperature. The ECT sensor and the temperature sender are in about the same location on the housing.

Does the temperature gauge on the instrument cluster read normal after enough time for the engine to warm up? If not then your coolant level may be too low. I would try to find the coolant leak before swapping out the ECT sensor.

 

[robert740il]

hopefully this will be the last post to this thread. i finally took it to the shop after i fixed a pinhole leak in the hose and was still getting the po171 and po174 codes. the maf that i installed from "rock auto parts" was defective. the mechanic told me to buy only oem parts when it comes to "sensitive" equipment(computers and sensors). i'll see about trying to get a refund since i bought the maf on 1/19/12. anyway my xlt is running fine now. thanks for your considerable help. robert