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Well, after spending the better part of two weeks trying to absorb all I can from this site, I have a question.
Last week, my VP44 died. I replaced it and at the same time changed the stock lift pump to a FASS DDRP and put in a new filter. I did about 145 highway miles the next day and it ran incredibly well.
Then the day after that, I went to work in heavy start/stop traffic. About 17 miles into my trip, it started running rough and missing. It got progressively worse and barely got me to work (total 25 miles). I had codes P0122, P0251 and P0252.
To make a long story short, I pulled the connectors off the VP44 and the APPS, hosed them down with contact cleaner, blew them out, reconnected, reset the APPS and cleared the codes.
That seemed to fix everything until I was on my way home. About 17 miles into the trip, again in start/stop traffic, it did the same thing. This time, I had P0251,
P0216 and P0252. By this time, the VP44 & FASS have a total of 162 miles on them. I pulled the connector again, reconnected without doing anything to it and started the truck. Again, it worked fine. Unfortunately, this was more than an hour after it stopped, so I don't know if it got better because it cooled off or because I pulled the connector.
Anyway, I put a gauge package in today (ISSPRO EGT, boost & electric fuel pressure) and took a test drive. Fuel pressure was initially 14 - 15 psi at idle and dropped to 5 - 6 on normal acceleration. On heavy accel, it was dropping to as low as 2 psi and very slow to come back up
. My test drive was about 8 miles total and toward the end, the pressure wouldn't come back above 10. Idling in my driveway, it was about 9. Outside temp, for what it's worth is about 56°.
Any ideas? I'm wondering if I have a problem in the power supply to the FASS now.
Last week, my VP44 died. I replaced it and at the same time changed the stock lift pump to a FASS DDRP and put in a new filter. I did about 145 highway miles the next day and it ran incredibly well.
Then the day after that, I went to work in heavy start/stop traffic. About 17 miles into my trip, it started running rough and missing. It got progressively worse and barely got me to work (total 25 miles). I had codes P0122, P0251 and P0252.
To make a long story short, I pulled the connectors off the VP44 and the APPS, hosed them down with contact cleaner, blew them out, reconnected, reset the APPS and cleared the codes.
That seemed to fix everything until I was on my way home. About 17 miles into the trip, again in start/stop traffic, it did the same thing. This time, I had P0251,
P0216 and P0252. By this time, the VP44 & FASS have a total of 162 miles on them. I pulled the connector again, reconnected without doing anything to it and started the truck. Again, it worked fine. Unfortunately, this was more than an hour after it stopped, so I don't know if it got better because it cooled off or because I pulled the connector.
Anyway, I put a gauge package in today (ISSPRO EGT, boost & electric fuel pressure) and took a test drive. Fuel pressure was initially 14 - 15 psi at idle and dropped to 5 - 6 on normal acceleration. On heavy accel, it was dropping to as low as 2 psi and very slow to come back up

Any ideas? I'm wondering if I have a problem in the power supply to the FASS now.