2001 5.3L Fuel Rail Pressure Leak

[SilverShoe]

I have a 2001 1/2 ton Silverado with 5.3L and it began with somewhat hard starting. It took either a long crank or 2-3 cranks to start. I then noticed that after cranking a few seconds, then turning the key back to the "on" position, then cranking again - the engine would start right up - EVERY time.

 

I put a fuel pressure gauge on the fuel rail and after turning the key to the "on" position (without cranking the engine), the fuel pressure rises to about 45 pounds, then quicky drops down.

 

When doing same test on my neighbor's exact same truck - the pressure holds without dropping (all of this without cranking or starting engine). This is a "Return" type fuel injection system and all indications pointed to the fuel pressure regulator (reportedly a known problem with these engines). I replaced the regulator and problem remained.

 

Some points to add are that when you turn the key to the "on" position (again - not to the crank position), the (externally mounted) fuel pump runs for about 2-3 seconds, then shuts off. I assume this is supposed to happen - to build the fuel pressure to get ready to start the engine but the pump then shuts off - until you actually crank the engine. The problem is that when the pump shuts off, my pressure immediately drops (but my neighbors truck holds the pressure).

 

I assume that if I had dirty/leaking injectors, it would run rough or misfire after starting, but this doesn't happen. It runs great.

 

It seems to me a leak somewhere either in the rail or the return system but where? There's no sign of leaks to the external world.

 

thanks for any ideas

[Gone Again]

I have a 2001 1/2 ton Silverado with 5.3L and it began with somewhat hard starting. It took either a long crank or 2-3 cranks to start. I then noticed that after cranking a few seconds, then turning the key back to the "on" position, then cranking again - the engine would start right up - EVERY time.

 

I put a fuel pressure gauge on the fuel rail and after turning the key to the "on" position (without cranking the engine), the fuel pressure rises to about 45 pounds, then quicky drops down.

 

When doing same test on my neighbor's exact same truck - the pressure holds without dropping (all of this without cranking or starting engine). This is a "Return" type fuel injection system and all indications pointed to the fuel pressure regulator (reportedly a known problem with these engines). I replaced the regulator and problem remained.

 

Some points to add are that when you turn the key to the "on" position (again - not to the crank position), the (externally mounted) fuel pump runs for about 2-3 seconds, then shuts off. I assume this is supposed to happen - to build the fuel pressure to get ready to start the engine but the pump then shuts off - until you actually crank the engine. The problem is that when the pump shuts off, my pressure immediately drops (but my neighbors truck holds the pressure).

 

I assume that if I had dirty/leaking injectors, it would run rough or misfire after starting, but this doesn't happen. It runs great.

 

It seems to me a leak somewhere either in the rail or the return system but where? There's no sign of leaks to the external world.

 

thanks for any ideas

[Gone Again]

I have a 2001 1/2 ton Silverado with 5.3L and it began with somewhat hard starting. It took either a long crank or 2-3 cranks to start. I then noticed that after cranking a few seconds, then turning the key back to the "on" position, then cranking again - the engine would start right up - EVERY time.

 

I put a fuel pressure gauge on the fuel rail and after turning the key to the "on" position (without cranking the engine), the fuel pressure rises to about 45 pounds, then quicky drops down.

 

When doing same test on my neighbor's exact same truck - the pressure holds without dropping (all of this without cranking or starting engine). This is a "Return" type fuel injection system and all indications pointed to the fuel pressure regulator (reportedly a known problem with these engines). I replaced the regulator and problem remained.

 

Some points to add are that when you turn the key to the "on" position (again - not to the crank position), the (externally mounted) fuel pump runs for about 2-3 seconds, then shuts off. I assume this is supposed to happen - to build the fuel pressure to get ready to start the engine but the pump then shuts off - until you actually crank the engine. The problem is that when the pump shuts off, my pressure immediately drops (but my neighbors truck holds the pressure).

 

I assume that if I had dirty/leaking injectors, it would run rough or misfire after starting, but this doesn't happen. It runs great.

 

It seems to me a leak somewhere either in the rail or the return system but where? There's no sign of leaks to the external world.

 

thanks for any ideas

[Gone Again]

aa

I have a 2001 1/2 ton Silverado with 5.3L and it began with somewhat hard starting. It took either a long crank or 2-3 cranks to start. I then noticed that after cranking a few seconds, then turning the key back to the "on" position, then cranking again - the engine would start right up - EVERY time.

I put a fuel pressure gauge on the fuel rail and after turning the key to the "on" position (without cranking the engine), the fuel pressure rises to about 45 pounds, then quicky drops down.

When doing same test on my neighbor's exact same truck - the pressure holds without dropping (all of this without cranking or starting engine). This is a "Return" type fuel injection system and all indications pointed to the fuel pressure regulator (reportedly a known problem with these engines). I replaced the regulator and problem remained.

Some points to add are that when you turn the key to the "on" position (again - not to the crank position), the (externally mounted) fuel pump runs for about 2-3 seconds, then shuts off. I assume this is supposed to happen - to build the fuel pressure to get ready to start the engine but the pump then shuts off - until you actually crank the engine. The problem is that when the pump shuts off, my pressure immediately drops (but my neighbors truck holds the pressure).

I assume that if I had dirty/leaking injectors, it would run rough or misfire after starting, but this doesn't happen. It runs great.

It seems to me a leak somewhere either in the rail or the return system but where? There's no sign of leaks to the external world.

thanks for any ideas

Sounds like a fuel pump problem. The check valve in the pump is not retaining pressure. You'll need a pump.

[wct]

I have a 2001 1/2 ton Silverado with 5.3L and it began with somewhat hard starting. It took either a long crank or 2-3 cranks to start. I then noticed that after cranking a few seconds, then turning the key back to the "on" position, then cranking again - the engine would start right up - EVERY time.

 

I put a fuel pressure gauge on the fuel rail and after turning the key to the "on" position (without cranking the engine), the fuel pressure rises to about 45 pounds, then quicky drops down.

 

When doing same test on my neighbor's exact same truck - the pressure holds without dropping (all of this without cranking or starting engine). This is a "Return" type fuel injection system and all indications pointed to the fuel pressure regulator (reportedly a known problem with these engines). I replaced the regulator and problem remained.

 

Some points to add are that when you turn the key to the "on" position (again - not to the crank position), the (externally mounted) fuel pump runs for about 2-3 seconds, then shuts off. I assume this is supposed to happen - to build the fuel pressure to get ready to start the engine but the pump then shuts off - until you actually crank the engine. The problem is that when the pump shuts off, my pressure immediately drops (but my neighbors truck holds the pressure).

 

I assume that if I had dirty/leaking injectors, it would run rough or misfire after starting, but this doesn't happen. It runs great.

 

It seems to me a leak somewhere either in the rail or the return system but where? There's no sign of leaks to the external world.

 

thanks for any ideas

 

 

 

do you know if the fuel pressure regulator was leaking or was it a (swag). more unlikely it's the fuel pump check valve like previously suggested, But I have seen the small o-ring on the fuel pressure get twisted or pinched so it doesn't seal properly and will leak inertly and you will scratch you head chasing it and can get $$$$, I would recommend quick pull the regulator out and checking the small o-ring then use some sorta vaseline to lube the o-ring if not damage if that is ok I'd replace pump hope this helps you out it's a quick check. note the o-rings may stay in the fuel rail and you may have to use a small pick to remove them and reinstall them on the regulator in order- WCT

[SilverShoe]

do you know if the fuel pressure regulator was leaking or was it a (swag). more unlikely it's the fuel pump check valve like previously suggested, But I have seen the small o-ring on the fuel pressure get twisted or pinched so it doesn't seal properly and will leak inertly and you will scratch you head chasing it and can get $$$$, I would recommend quick pull the regulator out and checking the small o-ring then use some sorta vaseline to lube the o-ring if not damage if that is ok I'd replace pump hope this helps you out it's a quick check. note the o-rings may stay in the fuel rail and you may have to use a small pick to remove them and reinstall them on the regulator in order- WCT

 

 

Yes the small O-ring is in place and lubricated. I pulled the new reg to re-check and verify everything. And then...

 

I haven't found any easy way to check the pump feed pressure to check for leak-back (connecting to the fuel filter or the fuel line just before the regulator) but it was easy to connect a gauge just downstream of the return line. I connected the gauge, turned the key on (pump runs for 2 seconds and shuts off). The pressure came up and held at 58 lbs (same as the rail pressure when engine is runnning).

 

My first thought was that the new pressure reg was bad, but then I connected a 2nd gauge to the rail test port and the pressure was 0. What was happening was the when the pump turned on, the pressure reg let some gas through (fuel pressure peaks above 90 lbs when pump turns on) and then the valve apparently closes as the rail pressure dropped (due to gas leaking back through the fuel pump check valve). The 6" or so of fuel line between the reg and the gauge held its pressure, but not the rest of the system.

 

My question is: do I really need to fix this? I will definitely do it sooner or later, but it appears the only need for the pump check valve is to get that immediate startup when you turn the key. As it is now, I just pause for 2 seconds with the key in the "on" position, crank, and it starts right up.

 

Thanks for your feedback.

[chrias]

I have the exact same problem. I remember reading somewhere that there may be a crack in the clear corrugated tube that goes from the pump to the top of the module feed line.

 

Even if I were to check that I may as well replace the pump considering I'm dropping the tank anyway.