I think the fuel pump might be in its way out, but not sure. The wife started having problems with the truck starting, it woukd turnover but never fire or start. If you cycle the key a few times, it'll finally start. Got a gauge to check the fuel pressure and when the truck runs, it's at 60psi. When you cycle the ignition, pressure will either read 0 or 50 psi. Do you think it could be a bad ground or bad sensor or regulator, or am I in for a fuel pump replacement? Truck has about 75k miles. TIA

It's a 4.7l v8.

44-54 PSI is within the FSM range when the truck is running..

Is it running rougher than usual?

So you're saying when you do a key on, engine off, you get 50 PSI sometimes, and then zero other times?

You can check the relays and make sure they're ok, but usually if a pump is dying you get low fuel pressure, rough running and a P0174/174 (lean fuel trims)

No codes yet, and as far as rough running, when the truck does start, it'll drop in RPM's for a brief second a few times at startup, and when it does, fuel pressure drops to 40 psi. This is at cold startup, so I'm not sure if it's fuel pump related or just cold start related.

Correct, when you cycle the ignition on, but do not attempt to crank, sometimes the gauge reads 0 psi, and when it starts, it will read 50 psi before you finally crank to start it.

As far as relays, I pulled what I think to be the right relay under the hood and replaced it with one from a different spot, and didn't notice any change.

Looking at fuel pumps on rock auto, and there are quite a few to choose from, so which one do I pick if I do indeed need a fuel pump?

$186 https://www.rockauto.com/catalog/moreinfo.php?pk=6424851&cc=1447845&jnid=351&jpid=0
$214 https://www.rockauto.com/catalog/moreinfo.php?pk=5929446&cc=1447845&jnid=351&jpid=1
$295 https://www.rockauto.com/catalog/moreinfo.php?pk=4938444&cc=1447845&jnid=351&jpid=2
$312 https://www.rockauto.com/catalog/moreinfo.php?pk=6427254&cc=1447845&jnid=351&jpid=3
$619 https://www.rockauto.com/catalog/moreinfo.php?pk=5970198&cc=1447845&jnid=351&jpid=4
$658 https://www.rockauto.com/catalog/moreinfo.php?pk=4839915&cc=1447845&jnid=351&jpid=5

Id go with Mopar or Carter.

Not sure why there are so many Mopar choices but my guess is that this has something to do with the Flex Fuel set up.

When I was returning the fuel pressure gauge to the auto part store, I told them I was going to buy the fuel pump from Rock Auto because it was much cheaper. The auto parts guy said Rock Auto sells products that either just passed or just failed QC. Is there any validity to that?

Not true, they typically offer 3 grades of products. One of which that meets a particular set of standards that a insurance company may require.

Do you realize how much part stores markup their products?

quote:

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When I was returning the fuel pressure gauge to the auto part store, I told them I was going to buy the fuel pump from Rock Auto because it was much cheaper. The auto parts guy said Rock Auto sells products that either just passed or just failed QC. Is there any validity to that?

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I LOL'd.

Everything they sell has a warranty on it from the manufacturer.

If you dont buy from Rock Auto, Amazon is ok too.

I typically try to still support the auto parts stores, because you never know when something will fail, and you cant wait 2 days for Amazon or Rock auto to ship you brake pads, alternator etc if your car is out of service.

That's what I figured. It didn't make sense that they would sell a product that doesn't meet specs.

This fuel pump issue is driving me a little nuts. It seemed like it was really on it's way out, but now, all I have to do is cycle the key twice, pump the gas pedal 3 times and it'll start no problem. Wonder if the fuel pressure regulator or possible bad gas is causing the problem. Once the truck starts, it runs just fine and the fuel pressure is 60 PSI.

Most of the big auto part brick and mortars will price match Rock Auto

Advance Auto

Finally got around to replacing the fuel pump, and to no avail, still have the same problem. When you cycle the key, some times the fuel pump will run to pressurize the system, and other times, the fuel pump won't kick on. I'm kind of lost on where to look next. Switched all of the relays around and it doesn't make a difference. Bad PCM or another sensor somewhere else?

I'd start with the ignition switch.

Looks like there might be a TIPM issue and even a class action lawsuit and recall, but not for the trucks.

http://verticalvisions.com/TIPM_solutions.php

http://absoluteraleigh.com/tipm-repair/

Finally got the wife's truck fixed. Turned out it was the TIPM and used http://arspeedometer.com/ out of Tulsa to replace the relay that was causing the problem.

Ah yes I didnt even think about this.

I had a T/C Minivan come to my door with the same issue.

Glad to hear there are places that offer a repair service now.