My "New" Airtex fuel pump...... A question

After all the fuel pressure problems I've had, I thought a new pump would solve them...

All this week, the pressure would immediately come up to 70PSI and hold there, for about 3-5 minutes. It would then drop sharply, depending on how much pressure I had on the go pedal. I figured my new fuel filter might already be clogged, but hadn't changed it yet.

I installed a post-pump filter this evening and had to mount it horizontally. That kept me from being able to fill it with fuel, before spinning it on. I decided to try just pushing the air through the system, and back to the tank. I temporarily have my fuel pump wired to a relay, so it gets power directly from the driver's side battery. I bypassed the relay and just let the pump run for a while. Using the OBS fuel pressure regulator allows me to hear the air, when it goes through the regulator.. Kinda cool sounding..

When I first hooked up the pump (With the truck off) It sounded nice and fast. The pressure built up and I eventually heard the air going through the regulator. After about 4 minutes, the pump started slowing down. The pressure also dropped to 65PSI. The longer it was running, the slower it got. It did keep maintaining the 65PSI though.

I'm wondering if there is a design flaw with the pump, or if it's supposed to do that. I know it wasn't my W85 fuel, since I filled up with D2 this morning.. The check valve part of the pump is still working, as evidenced by the bath of diesel I got, then I pulled the line from the pump outlet.

I'm kind of at a loss on this one.. If the pump were still wired to the factory harness, I might think it was a voltage issue. Since I'm wired directly to the battery, that rules voltage issues out.

Anyone have any ideas?

honestly, we get bad Airtex pumps out of the box all the time.

Even worse for us, as most of what we install are in-tank pumps in gasser cars..

Motorcraft is the way to go.

Thanks John...

Finally figured out and it wasn't the pump, or the regulator. I replaced everything from the tank to the heads, with the exception of the fuel bowl. Since the regulator had a plugged port readily available, I put a barbed fitting in it and Tee'd off the supply line from the pump. I now have 55PSI at idle and no less than 45PSI at WOT (On my 80hp tune) I haven't tried it with the stock tune yet..

I have an upgrade planned, for the supply lines to the heads.. I used 1/4" steel line originally and plan on upgrading to 5/16" and deleting the fuel bowl. Depending on how things go in the winter, I may add a 12V fuel heater.

Are you saying you were running your fuel at 70PSI? Is that a little high for an OBS? I think you said you had an OBS. I figured 60 lbs at idle was max? I might be wrong, just confirming. I've done my own e-fuel system so any info on pressure would help. I also run the Airtex pump.

I had several airtex (Advanced Auto) pumps on my OBS. Never had an issue other than running cold veggie through them. After I killed the last one, I stopped running veggie in the truck until I could get more heat in my system.

70psi is excessive. 60psi is all you need - anything above that is just extra wear on the pump.

Sam

On a stock system 70 is not excessive especially on a stock system. In fact I would run 75 given the fuel starvation issues of a stock system. But even with 65psi being fine it does not make it a satisfactory reason for pressure dropping from 70-65 for no reason. I would not want to run a pump continuously at its max psi. These pumps should be able to hold 80 psi +

The OEM bosch pumps are rated for 100 PSI have check valve in the outlet fitting and thermal overload and the flow rate is very even from 0-100 psi where most pumps tend to drop off significantly with pressure increases.

Airtex pump are made in china
Bosch in Europe and USA.


Is it possible the issue is your regulator and the sound difference of the pump is the fact the reg is changing the amount its bypassing thus changing the load on the pump.

I woudl also pick up a fuel gauge and see whats going on while driving and doing some hard pulls.

I work at AutoZone part time and we sell Airtex. I have sold a few to OBS guys and they haven't had an issue.

For the most part Airtex is decent. They carry warranty, and seem to work well. I am an honest guy and I know from working at a parts store what is safe to buy aftermarket and what is not. I will tell the customer my opinion on things also.

On some vehicles we have Airtex fuel pumps come back all the time for issues, but that hasn't been true for PSD's at the store I work at.

If you are worried about the pump just bring it back under warranty. They carry a 1 year warranty at least.