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Fuel pressure loss


Well-Known Member
March 20, 2012
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City, State
Year, Model & Trim Level
'03 Sport Trac XLT (RWD)
Hey All, having an issue on first start of the day. Even after an hour sometimes. Getting worse as the months go by. It takes 2-3 attempts to start. When I prime the fuel pump 2-3 times first(KOEO), it starts no problem. No drive-ability issues.

I finally got around to hooking the fuel pressure gauge up. Here's what I found. KOEO jumps right up to 60+psi then quickly drops to approx30psi then slowly to 8psi and holds there. Runs steady at64psi. Turn key off after running-drops just the same.

IIRC, is this because there is a check valve in the fuel pump assembly that went bad? If so, I guess it's time to order a new assembly. Or, leaky injectors?Seems to much of a drop though and no initial high idle at start up. I couldn't locate a fuel pressure regulator. Is there one? Any other checks I should do before ordering a new assembly?
Anyway, just looking for direction for my next step. I believe I will be fine and not breakdown until I can fix this. Correct?? ...I'm not too concerned with doing a fuel volume test at this point. I don't know the spec for it anyway. I would do a current ramp test on the pump but I don't own a scope. Not too concerned with that either. It runs fine. No sputtering or loss of power. I cant read the fuel trims either. Decent scanner is on the X-Mas list.

Here's a video I did doing the check. (Pardon when I say PVC. I meant PCV.) It's unbearably hot outside today and it's my first video EVER. I was a little nervous. I'm not much of a talker in general. Especially to myself:)

Youtube video:(sorry it's about 8min): https://www.youtube.com/watch?v=TZoPEFpw7F4

Fuel assembly thinking of getting from rockauto: AIRTEX Part # E2444M $169 5-pin connector according to my wiring diagram. I Hope that's correct.

I cant afford the Motorcraft:( and it's not so clear in the description which one is correct. Guess I can call. There is also Spectra. I've used there rads many times before without issue. But, not so sure of their pumps. If someone can convince me to hold off and save for the Motorcraft unit.(double the $) I will do so.

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After some reading. I learned the fuel pressure regulator is in the tank. But, I also learned there is a fuel pressure damper on the back end of the other fuel rail opposite of the schrader valve test port.(where I couldn't see) I'm not worried about the damper. I would expect to have seen fluctuations on the needle or other issues if that were suspect.
Also, apparently, yes there's a check valve in the tank. Looks like it's time to replace the unit. Not looking forward to this one.
I'll start reading up on removal while I'm saving up.

Fuel damper can leak internally like an fuel pressure regulator mounted on the fuel rail. Please refer to other forum site in which I wrote an reply.

Great stuff Mic! I will definitely inspect and test the damper before moving forward. Thanks!

Update: a week after this post, I dumped 1/2+ a can of Seafoam and premium gas in the tank and went out and did a few WOT's and over the next few days. Believe it or not, I have not had any issues since. Starts right up every try. No more having to prime the fuel pump a few times before starting. I have not hooked my fuel pressure gauge back up. But, I see no reason to at this point. I usually use Techron every few months. But Seafoam is what I had on hand. I think just the WOT's may have cleared the check valve. Who knows. All is good:thumbsup:

2l2u-9h307-db airtex e2348m

My 2002 also required turning the ignition key 3 or 4 times to prime the fuel system. In my case the problem was indeed the fuel pump assembly. 2002 & 2003 (built after 30/04/2002) have a problem with fuel draining back to the tank. Mine was built 07/2002. I bought my '02 back in late February 2015. Seller said his mechanic changed the fuel pump and didn't understand why it was still doing this problem. I decided to change the fuel pump after doing my own research. As it turns out the pump was never changed. I bought an Airtex E2348M and replaced it early June 2015. It has been starting and running flawlessly so far. I love that I no longer need to prime the fuel system and I can actually use the remote start feature on my Viper alarm.