fltdriver

Could be the fuel pressure regulator, pump, clogged filter. Injectors being clogged wouldn't give you low pressure at the rail.

stromius

Ok..thanks! Will see if the regulator has failed. I have just changed the filter so I can eliminate that. I have dual tanks..does that mean a fuel pump in each tank?


Makes sense on the injectors

fltdriver

Yes you have a pump in each tank, the chances both are bad are slim but not impossible. So if it gives the same problem from both tanks then the pump itself is not likely to be bad.

Did you change the fuel filter before or after the problem started? Something I figured out yesterday : If the tank selector is not hooked up/functioning the truck won't start, I was counting dash cluster bulbs and cleaning under the clear plastic cover on the panel, tried to start it and thought I screwed something up. Freaked out for about ten minutes while putting everything back together, thinking the worst, then it magically starts after I hooked the switch back up. That may not relate to you but the idea is that sometimes when we are doing things to the truck we create a problem and have to check everything we've touched.

Aktech

What is engine vac? R all cylinders firing? Pull some plugs and c what color they r.

stromius

Yeah makes sense both wouldn't fail but I should try and isolate on each tank and see if the lean is just one which would indicate one pump is failing... should have thought of that . I returned the pressure gauge already. Isn't there also an high pressure pump between the tanks and the engine. Read that somewhere here.


I changed the fuel filter after. Definitely older. Would explain if P0174 hadn't reappeared but it did the other day. I have also had P0155 and both those codes are Bank 2 (drivers side) and the sensor is new and specs to 4 ohms across the white wires. I will verify voltage today is 5v.

stromius

Changed the plugs trying to fix the issue. They were old but normal.

stromius

Going to try the temp sensor...$10 part. Will check resistance (pole to ground) first but was suggested before fuel pumps to try this first.

stromius

Update:


Got a temp sensor. I tried to test the old one but wasn't able to get any reading. Will retry later.


I retested and am still just getting the P0155 (bank 2, #1) sensor error BUT no lean condition (P0174) on the same bank (2). Good folks at O'Reilly said I could return the one I bought and get a warranty replacement. Not sure its the sensor because I tested it for resistance and got 4.0-4.1 ohmn across the white wires.


Any guesses?

Chris_1

iTrader: (1)

fuel pressure for your truck should be 30 to 45 (45 to 60 is only pre - 95 4.9's).
30 being the bare minimum to make it run, the fuel pressure is not good.
If everything else in the system is Ok it would be likely be pump related, either failing pumps, low voltage, or failing check valves (which are located in the pumps).
Suggest you recheck the pressure and see how long the system will hold that pressure.
i.e. key on engine off you should get your maximum pressure - it should hold that pressure for at least a few minutes. If the pressure bleeds off right away it's a fault in the system - such as back check valve or fuel pressure regulator.
Only 30 psi may or may not be the whole problem - but it is a problem

stromius

I will check the vacuum Line on the FPR and get the tester again from Autozone. How long can I keep the tester on? IE safe to drive around the block to see any changes? Idle only? I put the hose and gauge under the wiper to see so it's pretty secure.