P0172 on 2003 dodge Ram 1500 3.7L 6 cylinder
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I have noticed that there is no easy way to check the fuel pressure. My fuel rail does not have a Schrader fitting for testing. Is there any other easy way to check the fuel pressure? The fuel pump is not original, but it is an aftermarket.
I have done extensive work and refrigeration and I know I can obtain a piercing valve that would pierce through copper tubing, the piercing valve is probably strong enough to pierce through the fuel rail, has anyone ever tried this? My fear is that the gas would eat the gaskets inside the piercing valve and cause a catastrophic failure under the hood. The idea of cutting the fuel line to put a T in it, does not seem very feasible to me either. A new fuel rail is about $300, that is a very expensive test.
I have done extensive work and refrigeration and I know I can obtain a piercing valve that would pierce through copper tubing, the piercing valve is probably strong enough to pierce through the fuel rail, has anyone ever tried this? My fear is that the gas would eat the gaskets inside the piercing valve and cause a catastrophic failure under the hood. The idea of cutting the fuel line to put a T in it, does not seem very feasible to me either. A new fuel rail is about $300, that is a very expensive test.
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Good question Heyyou, and my understanding is it does not. The PCM assumes fuel pressure and commands fuel injectors based on O2 input. This is the discussion on the Mitchell system link you have given previously:
https://www.kolhosniki.ru/mitchell&m...02008103100000
"The fuel feedback system will maintain a stoiciometric fuel/air mixture, 14.7:1, by modifying the injector pulse width according to the oxygen content of the exhaust gas. The PCM makes short term and long term fuel corrections to maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. Short term fuel correction is based on upstream O2 sensor output and is designed for quick engine response."
https://www.kolhosniki.ru/mitchell&m...02008103100000
"The fuel feedback system will maintain a stoiciometric fuel/air mixture, 14.7:1, by modifying the injector pulse width according to the oxygen content of the exhaust gas. The PCM makes short term and long term fuel corrections to maintain stoiciometric fuel/air ratio for best catalytic converter efficiency. Short term fuel correction is based on upstream O2 sensor output and is designed for quick engine response."
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Side note: When I worked in refrigeration, I had asked the company to add schrader valves behind every check valve so the field engineers can easily test the superheat. I was told no because it added to much cost per check valve ($4 per check valve, typically 6 check valves) on a $1,400,000.00 unit.......... Are you kidding me corporate America??????
Ok, back to business.... I can order the Delphi pump form the online store for $120, if that is an easy way to eliminate that issue. I don't remember how long it took me to replace the last pump, but, I remember having to lift the truck high off the ground to get it out. At least now I have a garage to work in (last time I did it in the driveway in the hot sun....
I see the fuel filter looks like a "pad". is that part of the Fuel pump or is that mounted separately? Does it come with the fuel pump housing?
again, a million thanks for all the help.
Ok, back to business.... I can order the Delphi pump form the online store for $120, if that is an easy way to eliminate that issue. I don't remember how long it took me to replace the last pump, but, I remember having to lift the truck high off the ground to get it out. At least now I have a garage to work in (last time I did it in the driveway in the hot sun....
I see the fuel filter looks like a "pad". is that part of the Fuel pump or is that mounted separately? Does it come with the fuel pump housing?
again, a million thanks for all the help.
Last edited by guzman200; 10-21-2021 at 11:01 AM.
#26
You can certainly install a fuel pump, but I don't think we are there yet. You've already put in a fuel pump and I would hate to see you put in a new one unnecessarily.
Is your fuel rail fed by a flexible fuel line? The kind with the pinch connector? There should be a flexible rubber line with connections on each end somewhere. Maybe some pictures of your fuel connections? You need to find a run of flex hose that you can replace with a fuel pressure gauge.
You mention sluggish acceleration, how does the engine run under hard acceleration? PCM ignores O2 sensor data when you floor it.
I'm trying to figure out why you would get a rich code (0172) but have lean plugs and symptoms. Maybe low fuel pressure, or maybe cat is not burning exhaust and PCM thinks you're rich so it compensates.
When you replaced the fuel pump, did you replace the fuel pressure regulator? I'm not recommending you do this yet.
Follow the fuel line from the gas tank to the engine and see if you can see any kinks.
Is your fuel rail fed by a flexible fuel line? The kind with the pinch connector? There should be a flexible rubber line with connections on each end somewhere. Maybe some pictures of your fuel connections? You need to find a run of flex hose that you can replace with a fuel pressure gauge.
You mention sluggish acceleration, how does the engine run under hard acceleration? PCM ignores O2 sensor data when you floor it.
I'm trying to figure out why you would get a rich code (0172) but have lean plugs and symptoms. Maybe low fuel pressure, or maybe cat is not burning exhaust and PCM thinks you're rich so it compensates.
When you replaced the fuel pump, did you replace the fuel pressure regulator? I'm not recommending you do this yet.
Follow the fuel line from the gas tank to the engine and see if you can see any kinks.
#27
Maybe I was not clear, I replaced the fuel pump assembly a few years ago with an aftermarket fuel pump from the online store. I was just thinking it would be easier to replace the fuel pump assembly than check the fuel pressure as there is no easy way to verify fuel pressure without destructive testing (piercing the fuel rail, or cutting the fuel line). Why doesn't someone make a fuel testing kit with the locking connectors (sorry, I do not know the name of the connector). You would think if the OEMs do not put a schrader fitting in, there would be a company taking advantage of this to make a fitting and make money, I would pay $50 to not piece the fuel rail and I am sure somebody can make it (maybe even on a 3D printer) for $2.
In the picture below is my fuel line to fuel rail connector. I removed the brake booster vacuum line for clarity of the picture.
In the picture below is my fuel line to fuel rail connector. I removed the brake booster vacuum line for clarity of the picture.
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