Okay well there is a problem with the fuel pressure in my 00 cherokee

Symptoms:
takes 2 cranks to start
backfires - causes vacuum line to come off
misfires on random cylinders




The pressure to the fuel when the vehicle is off and on run is about 6 psi but when it is running it is 49 psi


what are potential causes?
-thanks



edit: The engine misfires whenever it is started... i need to rev it in order for it to not misfire.

 

Dude i just had the same problem and it turned out to be my fuel pressure regulator and its located on top of the fuel tank i got a 01 so yours should be in the same place and to check if yours is bad put a fuel gauge on it start it up let it run for a few minutes and shut it off and if the gauge dont hold pressure its the regulator and if it dose its the pump either way the both suck to change. Good luck on your problem.

 

i will have to try it, thanks man!

 

How are you measuring fuel pressure (I assume at the fuel rail) when the engine is OFF? I wouldn't expect to have fuel rail pressure when the engine is off. Now...if you're talking about the fuel pressure immediately dropping to 6 psi after you shut the engine down, it's probably a leaking fuel injector(s) or the check valve(s) in the fuel pump module gone **** up.

49 psi with engine running is good.

Multiple cranks to get the engine to run is a sign that the fuel pressure in the rail has dissipated (see above). You can live with this until you figure out why the pressure is dopping off rapidly (more than likely a fuel pump module check valve).

The backfiring is telling you your too lean... fuel pressure problem? When does it backfire? Sounds like there's a fuel pump module in your near future.

"causes vacuum line to come off". What's this? Sorry, but I laughed at this.

Do you have a CHECK ENGINE light on? If so, is there a trouble code you can tell us about. You can go to O'reilly, Advance, or Idiotzone and they will read your code(s) with their code reader. Let us know.

 

I paid around 90$ for my fuel pressure regulator at autozone but you can find them cheeper if you look around and i bought my fuel pump on ebay 40$ new and its the same one autozone has in stock but they cost way more at the zone i hope it fixes your problem

 

Hope these aren't Airtex products.

 

Why is it a bad product? Because ive had it in my jeep for well over a year and never had a problem with it

 

Im running one also mine came as a assembly from Napa around 100 bucks

 

i put in an airtex fuel assembly on my 2000 and it gave me op's issues,bad or just ****ty made pressure regulator, and im not the only one...

you just put them pump in yeah? your year model is a pump and a seperate regulator?...maybe not as bad as the whole module for the later years

 

I have a code reader and the codes are for the misfires and the vacuum line coming off