So, I have posted my problem on another forum and I am not getting much response. A couple of weeks ago my fuel pressure began to fluctuate. What happens is that the pressure is fine (19 psi) when I start the truck but it will soon drop to below five PSI. It will return to normal after to sits a while, but the pressure will always fall again. When the pressure begins to fall my Raptor pump begins to whine until it is very noticeable as the pressure approaches five psi and I shut the truck down. I changed the filter twice, checked my lines, changed the overflow valve twice and I still have the same problem. The only thing I can think of is that the Raptor is bad. It has only been on the truck since last June. I do not know if a tear in the diaphragm on the VP would cause this issue. Maybe I am missing something. I have attempted to contact Pureflow several times via email and voice mail (My problem is I work nights and I get off well before they open and I get up after they close) and have yet to hear from them about the pump or warranty. If the pump is done, I would think Pureflow would warranty it or at least tell my it doesn't qualify for warranty. If I have to buy a new pump then that is what I have to do I guess but I don't know if I will buy another Pureflow product due to the lack of customer service that I have received. I suppose my post rant questions are has anyone had this problem with Pureflow other than me? Is there something that I am missing with my pressure problem ? Thanks

sounds like a fuel restriction in the pick-up assembly

Or you got a suction air leak and as the air over comes the Raptor pump its starts to whine loud. Double check the fuel system by pressurizing (1-2 PSI) the fuel tank and have a buddy look for wet spots.

sounds like a fuel restriction in the pick-up assembly

Sorry, I forgot to say that I put a draw straw in right after this all started, because I thought the same thing. If I take off the tank outlet line from the Raptor it will pour fuel like crazy until the tank is empty. As far as the air leak goes, I will check that today. If there was an air leak though wouldn't it do it all the time, not just after it runs for 10 minutes or so?

Have you checked your wiring? Make sure there isn't a ground problem and make sure the power wires are hooked up well. If you are loosing power the pump is going to slow down making less PSI.

Just an update, Pureflow warranted the pump and it ran without an issue until about two weeks ago. The pressure began to fluctuate again, granted not as bad as the prior pump. My neighbor who is a mechanic believes that the pump is seeing voltage spikes from a defective pump relay. I may believe this since they didn’t send a new relay just a new pump. Again, the people at Pureflow do not want to respond to emails and getting them to answer the phone is nearly impossible. I think my pump is again on borrowed time just in time for winter. :banghead:

I am quite frankly sick of this. Anyone run a mechanical pump?

one time last year i had a problem with my airdog. it sounded like it barely was kicking on. come to find out, the battery terminals were awfully corroded. i had wired the airdog's harness to the terminals. after i cleaned them all up, my problem went away completely.even if your terminals are good, check your harness

There is another place ot hook up and prevent this acid issue... Use the postive stud in the PDC for the alternator and find a bolt in the fender well as a ground then you don't have acid/corrosion problems.

There is another place ot hook up and prevent this acid issue... Use the postive stud in the PDC for the alternator and find a bolt in the fender well as a ground then you don't have acid/corrosion problems.

Never wire anything directly to the battery terminals. I find its more pain than its worth as a convenience.

RPM....i see that you live in Arvada,CO..have you thought about going /or calling ats diesel?that is where they are located...home office man!

There is another place ot hook up and prevent this acid issue... Use the postive stud in the PDC for the alternator and find a bolt in the fender well as a ground then you don't have acid/corrosion problems.

Yup, that's how I have it connected. I don't have any dielectric grease on the fittings however. The last time I looked at them they seemed to be fine but I should probably lube them up and take a closer look.

--- Update to the previous post...

RPM....i see that you live in Arvada,CO..have you thought about going /or calling ats diesel?that is where they are located...home office man!

IMO ATS wants way too much for their parts, let alone their labor. I have had some interaction with the owner (Related to my business not his) and I was not impressed. I drive by the ATS Empire all the time, I just choose not to do business there. But that's just me.

I had the same problem you are describing with my airdog. I thought the pump was bad and they sent me a brand new one. Was better for about a week, then same problem came back. I got frustrated and took it to a mechanic. They traced the problem to bad battery cables and corrosion. They replaced the cables and my fuel pressure has been great since.