Yes. I know. Another low fuel pressure thread. 🤷♂️
Pertinent truck specs:
2005 F250, Colt stage 1 cam, Atlas 40, blue spring upgrade (not OEM, but only ~ 5000 miles old). Stock turbo and stock injectors.
Cleaned HFCM and installed new filters <1000 miles ago.
Recently I noticed my fuel pressure dropping when I really feed 'er the onions. Idle pressure holds about 58-60, cruising is around 55, drops to 48-50 going up a hill. That seems low, but not alarming, until I decide to have some fun and put my foot into it, and then it drops into the 30s. I think I even saw it dip below 30 at one point, but I immediately let off, because, you know, I like my injectors the way they are. Pressure measured with a gauge coming straight off the HFCM shows 70psi.
I'm leaning toward probably the pump, but I wanted to be sure, so I've done some bench testing and in-truck testing. First bench test was to see if the HFCM was sucking air, second was testing max pressure, and the third was back in the truck pulling from the tank, checking for air as well. You can see it better in these videos I took.
The only thing I didn't do in these videos was to check for air with the module installed normally, with the return lines hooked up. I can do that too, if anybody thinks it's necessary. Your input is appreciated. I thought about replacing the whole HFCM, but after my bench tests, it doesn't look to be bad.
Pertinent truck specs:
2005 F250, Colt stage 1 cam, Atlas 40, blue spring upgrade (not OEM, but only ~ 5000 miles old). Stock turbo and stock injectors.
Cleaned HFCM and installed new filters <1000 miles ago.
Recently I noticed my fuel pressure dropping when I really feed 'er the onions. Idle pressure holds about 58-60, cruising is around 55, drops to 48-50 going up a hill. That seems low, but not alarming, until I decide to have some fun and put my foot into it, and then it drops into the 30s. I think I even saw it dip below 30 at one point, but I immediately let off, because, you know, I like my injectors the way they are. Pressure measured with a gauge coming straight off the HFCM shows 70psi.
I'm leaning toward probably the pump, but I wanted to be sure, so I've done some bench testing and in-truck testing. First bench test was to see if the HFCM was sucking air, second was testing max pressure, and the third was back in the truck pulling from the tank, checking for air as well. You can see it better in these videos I took.
The only thing I didn't do in these videos was to check for air with the module installed normally, with the return lines hooked up. I can do that too, if anybody thinks it's necessary. Your input is appreciated. I thought about replacing the whole HFCM, but after my bench tests, it doesn't look to be bad.