Low fuel pressure until truck starts?

[JJMaine]

My 2011 Ranger has been having rough starting and the odd misfire code. I just hooked up a pressure gauge and when turning the key on I got little pressure but when the truck starts it jumps up to 65psi.

Also, if I cycle the key the fuel pressure goes up about 10psi with each key cycle. This explains why the truck starts rough sometimes but runs perfectly after. I just want to confirm that it is the fuel pump before I spend the money on a new one and an entire day changing it. Anything else it could be? My battery is good at 12.4v (good not great). Truck has a new OEM fuel pump relay as well (not sure if that could cause the issue?) Thanks!

 

[mr_manny]

Sounds like your pressure drops down to zero after it's been sitting awhile.
Since you already have a gauge, it would be good to recognize how quickly your pressure is dropping.

I don't know if it's the same on later rangers, but zero fuel pressure on earlier models:
FPR
Fuel Pump
Leaky injector
Leak in your fuel/return line.

 

[bills4065]

Your check valve in the fuel pump may be bleeding off all the fuel after shut down. I would put a gage on after shut down and see how quick the pressure bleeds off.

 

[mikkelstuff]

Not sure if the same but my 2002 Ranger was doing similar. I was told the problem was a faulty FPR. Rather than change that out, I installed a check valve, suitable for gasoline, in the metal portion of the fuel line under and near the engine which solved the starting problem. The one I used:

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

 

[JJMaine]

Thanks guys, I'll have to try leaving the gauge connected to see how quick it bleeds down. Sounds like it is most likely the fuel pump since isn't the FPR in/on the fuel pump?

Good idea on the check valve but I'd rather just replace the pump. My luck I'd put the check valve on and a week later the pump itself will quit lol

 

[JJMaine]

How difficult is it to move the bed back far enough by yourself? I wish I had an overhead area so I could use straps and just lift the bed off far enough to change the pump.

 

[SenorNoob]

I know it's been done. Usually just tilt back or to the passenger side. I've also seen people jack up and stack 4x4s under the bed to give em just enough room to work.

 

[JJMaine]

Ahh that's a good idea just lift it up and put blocks under it. I always overthink everything. Thanks guys. I ordered a Bosch pump from Rock Auto. Hopefully that lasts as good as OEM.