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Discussion Starter #1
So I had two bad injectors // I replace them, truck started fine and ran fine for about 2 weeks. Then I replaced the fuel filters, both top and bottom. So now I have a persistent problem.

Symptoms: Truck will start fine on first try, run for about a minute or so and then it will die, and a low pressure warning light in the dashboard will show. I reset the key, and it will start again fine, run for a little while and die. So I keep some pressure on the gas, to raise the RPMs, and when this low pressure problem happens, it stumbles and comes back in about a second, but only if I put some pressure on the gas. Once the engine warms up, this problem goes away and it runs fine without shutting down. I checked the upper fuel filter and lower. I hear some air like leak hiss, but I am not sure from where it is originating from. I've tried many tips and tricks on checking the fuel filters, but still I have this problem.

Could it be from the recent injector replacement work ? and somehow when I replaced the fuel filters, I depressurized the system and revealed the issue ?

Are there any tricks, additives you can add to the oil to seal that up, or how does this work ?

I would like to get it working again, so that I can utilize this truck, otherwise I will have to put it up for Sale.:frown2:
 

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It's not the injector repair that caused the low fuel pressure issue, it's the reverse. Low fuel pressure kills injectors...very quickly so you likely had the pressure issue prior to the injector work. So you have to get to the bottom of this soon before you lose more injectors.

If you haven't already, you need to get a gauge on the fuel system and see exactly what you are dealing with for fuel pressure.

Basically the fuel has to be able to get from the tank to the pump on the frame rail which is also the large primary filter. If it can't, it's an issue with the tank, in tank pickup or line to the pump, (these issues are rare unless you got some really bad debris in your tank). move in to the next component.

The next possibility is the pump on the frame rail, if it is failing or restricted, obviously it can cause low pressure.

Next would be the lines up to the secondary filter and the secondary filter on the engine. Part of this filter assembly is the pressure regulator. Research "Blue spring upgrade". Make sure that has been done to your truck or do it, very important.

Beyond that the fuel is on it's way to the injectors via some tubes connecting the secondary bowl to the cylinder heads were the fuel flows internally to each injector. There are some check valves where the tubes connect to the front of the heads.

Keep up posted, good luck with it!
 

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A low pressure dash light would indicate an oil pressure issue since these trucks do not have a diesel fuel pressure sensor. Check it for codes and post up what you find.
 

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Discussion Starter #4
Thanks Phil / bismic // So I've replaced the fuel pump under the truck on the rail, and also did the blue spring already. I have one of those computers programmed for this truck and no codes, so I am starting to think about the tank. How do you test for the in-tank pickup ? Once in a while I see the fuel gauge level indicator needle jump and go up and down, it will show there is no fuel when there is, it jumps up and down sometimes. So maybe something is going on there ?
 

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sorry to butt in here but just a thought, you ran fine for two weeks until you changed your fuel filters, it sounds to me like your issues could be self inflicted by changing the filters out. Have you made sure you got the oring in properly and it didn't rollon your or tear when installing on the filters? have you checked to see if the lower filter was turned to engage the alignment so it goes in properly and you just didn't just stick it in and tighten it down ?

I know I have done that before and got air in my system and it ran for about 10 minutes then started having issues. I would check everything associate with what you did on the filters because it ran fine before. I suspect its something with those.
 

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Discussion Starter #6
Well, I got the filters from riffraff, and I put on the o-rings correctly and even put some oil on them. I did that many times before, the only thing I can think of, the under the truck filter, the water plug was replaced from the stock to the other one that you can unscrew with your hands, that's it. Could that cause it ?
 

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As mentioned above, you might have an issue with the fuel pump pick-up tube in the fuel tank. It is a pain, but you might want to remove it and inspect.

Also, I would inspect the fuel pressure regulator spring/etc.
 

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Discussion Starter #8
does some kind of a quick test /procedure exists to rule out the pickup in the fuel tank ?

and if so, what is that, any good youtube videos ?

thanks!
 

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Well, I got the filters from riffraff, and I put on the o-rings correctly and even put some oil on them. I did that many times before, the only thing I can think of, the under the truck filter, the water plug was replaced from the stock to the other one that you can unscrew with your hands, that's it. Could that cause it ?
Did you get the riffraff blue spring kit? I had one fail after 3 months. The rubber sealing surface tore causing most of the fuel to pass back to the tank, low pressure with a heavy pull. Went OEM Ford and pressure is fine and holds with the pedal to the floor.

WDP
 

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Discussion Starter #10
I had this problem before the Blue Spring upgrade, that's why I did it, thinking it would help it, but nothing...

Does a quick way exists to isolate the fuel tank to see if that is the culprit ? maybe disconnect the fuel lines and put them into a external fuel container ?
 

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Great idea, use a 5 gallon clearish jug, pull the two lines closest to the tank, use long 1/4 inch tubing, put into the jug and place on the passenger floor. Have a helper watch for bubbles, flow and see if that clears up the pressure problem. Good luck.

WDP
 

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Does fuel level make a difference in how it runs? If so, it would definitely point to a pickup problem.
 

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Discussion Starter #13
Hi WDP - Thanks for the advice, I take it I should drain the fuel tank first ? never done this before...

I hope this is it, it would explain a lot of things...

Ford06 / sometimes the fuel gauge would jump up and down with no reason, sometimes it would show no fuel, when there is fuel, something funky is happening there, might as well isolate for it and keep on drilling, fingers crossed.

Question, if it is the fuel tank, is it recommended to just replace the pickup components and clean it up, or should I at that point, just buy a new tank ? I mean, my truck has 175K miles, this is a recent thing...
 

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My 07 F250 had the same problem. Sometimes it would display that the tank had plenty of gas in it, when in fact it was almost empty, and other times it would read empty when I had gas.

For what it's worth, I was advised to purchase some Diesel Kleen Octane Boost and, maybe it was coincidental, but the problem cleared up.

Could the Sending Unit have been gunked up and did the DK clean it up? Not sure, but it saved me from having to install a new sending unit, at least for now ;-)
 

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Some of the early tanks had a lining that comes apart and causes problems. I didn't make it a point to remember when it stopped as it was changed prior to my trucks manufacture.
 

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dillon134 - did you have the same type of fuel pressure issues as me ?
I've actually never tested/checked my fuel pressure. Everyone talks about the Blue Spring Upgrade and how it is imperative to do it but, I've also heard tons of people discussing issues after the upgrade.

I guess I'm just a gambler by nature... as Dewey Oxberger said in the movie Stripes.
 
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