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.

 

[JJMaine]

Where there's a will, there's a way! It actually wasn't hard at all. I just blocked the front of the bed up so it would clear everything and then picked the rear up and set it on the bumper. Had to put the rear axle on jack stands and removed both rear wheels to give the bed room...

I do have a question though. I had a hell of a time getting the locking ring back on, beating it with a hammer and screwdriver lol. Halfway I took the pump back out to try the old gasket to see if that would allow the locking ring more room to turn (it didn't). But when I took the new pump back out I noticed this blue piece had fallen off into my fuel tank. I put it back on but it doesn't have locking tabs like the old (OEM) pump and am worried that it might fall off again..

Also googled the easy way to install those lock rings. I wish I had known that sooner

Picture of the pump showing that blue "piece" that fell out is the old Ford pump but the Bosch pump has the same kind of blue part.

 

[JJMaine]

See how the tabs on the Bosch part sit below the black piece that the tabs would normally slide and lock into?

I'm guessing it can't be that critical or they would have made it lock in

 

[SenorNoob]

These pictures confuse me. What even is that? Some kind of built in reservoir or charcoal canister in the tank?

 

[JJMaine]

Oh I'm not sure, first time doing a fuel pump on a ranger. Mines a 2011 4.0. It connects to the biggest line (maybe 5/8"), I'll have to go look and see where that goes. Maybe that's why they appear to not care if it falls off

 

[JJMaine]

What the hell, the truck is still starting rough after sitting awhile. I hadn't driven it yet but just got back from a bike ride and tried starting it. Stumbling and misfiring until it seemingly builds fuel pressure.

I did notice a crappy line that plugs into my fuel pump but it wasn't leaking. It is dried and cracked around the fitting though. Could that be the cause or is it likely a leaking injector?

 

[JJMaine]

Load up the parts cannon. Maybe if I buy a new set of wheels that'll fix it

 

[JJMaine]

Hooked gauge up and again fuel pressure is 70psi when truck is running but when you turn the key off it drops to 60 instantly and then over the last 2 hours it's crept down to 40psi.

I did notice the fuel line going from the pump to the fuel filter didn't look too great when I had the bed off would this cause it? It wasn't leaking fuel before I changed the pump and it doesn't appear to be leaking now but it surely is dried out, hard and crack at near the fitting.

Wouldn't it have to be leaking fuel to lose pressure? Or could it be letting air in and making it lose pressure?

I stuck my bore scope in there and I don't think it's leaking but hard to tell. I think it is just shiny from when I wiped it off but it's definitely split.

A photo from before I took the old pump out. Definitely not leaking fuel before hand?