I'm looking for input here since I seem to be having a problem. I got to walk 1.8 miles today to a parts store to pick up a new fuel pump. Here's a run down of everything that has happened. Most of it I don't think is related to my current issue, but more info is better (unless you get bored of the reading)

Did the in tank mods some time ago, no problems. Did the Riffraff 1st gen FRX. Ran fine for a while then had a hose come apart due to some fittings that he no longer uses. I added some hose clamps and drove around just fine until he got me a 2nd gen replacement. Things were fine for a while and then I noticed my fuel pump cycling on and off repeatedly. Stuck a gauge on it and discovered fuel pressure was maxing out the gauge way over 100 psi and shutting off, then when pressure dropped back down it would cycle back on, over and over and over and over.

Took the fuel bowl apart and discovered a loose part so I ordered a FPR rebuild kit from diesel o-rings. The loose part is the one in the top left corner of this pic


So I rebuild the FPR and the pump quit cycling on and off and started running like it should, but the fuel pressure seemed to hold at 88 psi. I checked here at FTE and found a few others who had been running in that range for some time with no problems so I just left well enough alone.

So I got to thinking (in hindsight trying to outsmart the truck was a bad idea), all that cycling on and off from the way to high fuel pressure could not have been good on the pump. I better replace it before it goes out on me. So I checked all the local parts stores and discovered one carried a Carter replacement pump. Carter is a good name so I went with it. 8 weeks later I got this https://www.ford-trucks.com/forums/1...worthless.html

So I went to the closest parts house and got an airtex pump. Almost 6 months to the day (better than 8 weeks) I got to walk to the parts store when the airtex died. It held 92 psi the whole time. It did act up a couple of weeks ago. At the time I mistook the acting up for a clogged pre-pump filter so I changed the filter in a parking lot. After I did that the truck ran fine for the last 2 weeks. I cut open the old filter and it didn't seem that dirty, but the new one made the truck run better, or so I thought.

I had heck getting the new pump primed with over half a tank of fuel. My new carter (worried a little about that) pump is holding 85 - 88 psi and the truck runs and sounds great. After the ride home I applied voltage to the old "failed" pump and it didn't work. I shook it around a bit and reconnected the test leads again and it came on and pumped 5 gallons of fuel with no problems.

So if you're still reading, here's what I'm thinking. Tomorrow I'll pull apart the FRX and see if I can find a different spring to stick in there and get the fuel pressure down below 70.

Do I need to be worried about something wrong with my pick up or any kind of restriction in the tank? The 2 times it has acted up was at a stop sign or light. Running down the freeway or pulling a trailer it has never given any signs of having a restriction and the fuel pressure has stayed at 92 until it dropped to 0 today.

After having so much trouble getting the pump primed, I'm thinking of adding a helper pump inline just for good measure. If I do, anyone have any positive or negative experiences they care to share?

Any other thoughts or suggestions?

 

Subscribing...I am headed down to the barn now to get you the info on the helper pump I have on mine.

 

Let me know if you have any spare springs for the FPR. I've only been able to find one so far. I've got to do some more digging tomorrow.

 

The pump I have is made by Procomp Electronics(Big Fuel Pump..PC-2801).It comes with a 4psi or a 9 psi spring.I left the 4psi spring in it.
I should have more springs in my parts box.What color you wanting?

 

Subscribing.

Consider adding a vacuum gauge between pump and pre-filter to monitor pre-filter.

 

I don't know. I want to try getting my pressure down to 70 or below. Got any plans tomorrow?

 

My pre-filter is 100 micron so it would take quite a bit to plug it up. Besides, fuel pressure has been all or nothing and it's only dropped to 0 when taking off slowly at idle (red light with cars in front so you can't go fast). On the highway or pulling a trailer I've never seen more than a 2 psi drop from the fuel bowl.

 

I should have the spare springs that came with the frx and stock one. Let me know if you need them. Could you have restriction on the return line? Maybe try blowing that out.

 

[quote=F350-6;11352448]I don't know. I want to try getting my pressure down to 70 or below. Got any plans tomorrow?[/quoI
I have a black and a green spring.I will be here all day,come on over if you want.

 

I did that when I was chasing the original high pressure pump cycling problem. Blew it out with compressed air several times until it bubbled nice and loud in the tank (fuel cap removed).

 

I have a stock fuel pump if that would help you out. Guess you could run a line off the intake of the fuel pump into a 5 gallon bucket. Sounds like a good idea to see if you can get the pressure to change with different springs. Can you see fuel pressure in the cab? There are also a couple of check valves at the heads but not sure how that could cause a problem.

 

I've got the warranty replacement from when my last pump exploded, but for some reason I took it out of my truck and left it in the barn. I'll be carrying that around from now on.

Yes I can see fuel pressure in the cab. I got the sending unit for my scan gauge when it acted up a couple of weeks ago and I thought it might have been a plugged filter.

It just doesn't fit the classic fuel restriction issue since the fuel pressure has either been really high or 0. Unless there's something going on in the tank that's causing the fuel pump to loose it's prime. Voltage has always been there even when fuel pressure was 0, the fuel pump was humming away.

 

Didn't you have a pinched line between the tank and pump at one time? You could rule out the tank by running a line from another source. Just trying to throw out some ideas. Let me know if you need any spare parts I have.

 

Good memory Grant. Yes, when I took my bed off to weld up the broken pieces, I set it back down on the rubber fuel line to my pre-pump filter and pinched it off. That was easily corrected once I found out what I did.

I might drop the tank just for grins to make sure I don't see anything wrong in there. We'll see how the fuel pressure acts with different springs first.

 

You can also compress a spring a bit to lower fuel pressure. On my stock spring I stretched it out a bit to increase it.