My Cherokee ( 2000, 4.0 , 215000 miles) has been losing fuel pressure when I turn it off for a few years now. Used to be one or two key cycles was all I needed to prime it up and it would start like a typical high output 4.0. Meaning - 2 compression cycles and it fires off. Within the last 2 years it's been getting worse to the point I put a momentary switch in the dash to prime the fuel pump to get it to start. And it would barely start.
Fuel pressure once running was 48 psi. Within spec for this year with the return less system.
While all of this was happening , I could hear something in the tank let go and it dribble off fuel back to the tank. This problem started in 2018? when I picked up a branch off-road and broke the fuel output on the regulator. I swapped the regulator to stop the massive fuel leak.
After that , I would get the occasional Renix start ( crank for 40 seconds). Once it got consistent, I would put on another regulator. Rinse, lather,repeat. Problem kinda fixed for a bit.
I ended up swapping 4 or 5 regulators. Dealer ones, cheapies ... They all lasted a month at most.
A few weeks ago, I had it parked on a hill in the yard and went to start it and it cranked very hard on every 6th cylinder. Pulled the plugs and hole 6 was very gassy. Okay ... An injector was leaking and pooling and then it was running down the #6 Intake runner.
Pulled the rail, ran the fuel pump and 2 injectors ( 4,5 ) were leaking. I had someone crank while I watched and they didn't look great.
6 new injectors later ... It still lost most fuel pressure and I had to cycle the key twice to start. An improvement I guess.
Texted a mechanic friend of mine. Aparently there's TWO check valves. One in the regulator and one in the pump.
Bought the most expensive fuel pump I could get for it which was a Carter. Very disappointed because its a $30Airtex with a $50 carter sticker apparently.
Oh well. At least its back to starting like a 4 liter; touch the key and it fires right off!
I wish I had all the money I parts cannoned at regulators...
Fuel pressure once running was 48 psi. Within spec for this year with the return less system.
While all of this was happening , I could hear something in the tank let go and it dribble off fuel back to the tank. This problem started in 2018? when I picked up a branch off-road and broke the fuel output on the regulator. I swapped the regulator to stop the massive fuel leak.
After that , I would get the occasional Renix start ( crank for 40 seconds). Once it got consistent, I would put on another regulator. Rinse, lather,repeat. Problem kinda fixed for a bit.
I ended up swapping 4 or 5 regulators. Dealer ones, cheapies ... They all lasted a month at most.
A few weeks ago, I had it parked on a hill in the yard and went to start it and it cranked very hard on every 6th cylinder. Pulled the plugs and hole 6 was very gassy. Okay ... An injector was leaking and pooling and then it was running down the #6 Intake runner.
Pulled the rail, ran the fuel pump and 2 injectors ( 4,5 ) were leaking. I had someone crank while I watched and they didn't look great.
6 new injectors later ... It still lost most fuel pressure and I had to cycle the key twice to start. An improvement I guess.
Texted a mechanic friend of mine. Aparently there's TWO check valves. One in the regulator and one in the pump.
Bought the most expensive fuel pump I could get for it which was a Carter. Very disappointed because its a $30Airtex with a $50 carter sticker apparently.
Oh well. At least its back to starting like a 4 liter; touch the key and it fires right off!
I wish I had all the money I parts cannoned at regulators...
