2001 7.3 rough idle poor mpg

[greasyF250]

Originally Posted by garretthoehn

HMM, well i ran the buzz test several times, along with cylinder contribution tests, and no codes except for the cylinder 8 contribution test so i have been leaning more and more towards the ipr and or hpop or fuel pump

I randomly get #8 fail the contribution test even with the AD injector.

[garretthoehn]

Well i have bigger problems now, my alternator went out yessterday and i have to glow plugs that are open and the other six have 0.00 ohms of ressistance, so i get to jack with that first.

[garretthoehn]

well i got the alternator and glow plugs done, now back to the crappy mpg and slightly rough idle haha im still thinkin hpop, ipr or fuel pump

[dent-techs]

im sorry if i missed it in the thread somewhere but how many miles are on the injectors? I had a no start/hard start issue with my truck and after going through the whole mess your going through i finally bit the bullet and got 8 stage 1 single shots from swamps and problem solved. You might be lucky if your hard start is just the glow plugs but a real simple way to tell is to plug the truck in over night and if it fires right up then its most likely your injectors. Weak injectors will also cause the rough idle and poor fuel economy. Injectors are almost always the cause of these mysterious problems with the 7.3. The buzz test wont really tell you if the injectors are bad. Its an electrical test meant to tell you if the electrical connectors and or the solenoids on the injectors are hooked up and working properly. If one injector doesnt buzz then theres a disconnection or a complete fault. If some buzz weaker than others its a sign of a weak electrical solenoid and or a faulty injector but it doesnt tell you anything about the health of the hydraulic side and actual fuel portions of the injector as the engine is not actually running during the test. All 8 of my injectors buzzed and buzzed loudly but when we pulled them and did a flow bench test all 8 were weak and 2 where completely garbage. My truck would not start after sitting for 8-12 hours but if plugged in it would fire right up. This had nothing to do with the electrical portion of the injectors and everything to do with the hydraulic side. warm oil is much thinner than cold oil and therefor warmed up the cold stuck injectors. Warm injectors fire off a lot easier than cold ones. The only way to truly test the health of an injector is with a flow bench test.

[garretthoehn]

i have 159000 on it, i am just trying everything before i resort to injectors, and if it is injectors, i will end up getting a set of hybrids, but what were you getting for fuel mileage, and it doesnt matter if its 10 degrees outside or 100 degrees it starts up the same everytime

[garretthoehn]

well i ordered injectors and they should be here by the end of the week, fingers crossed,
so we will see if that fixes all of my issues.