Am I on the right track?

[asmith]

been awhile since i have been on here. @IdIoit did a great job with the truck and it has been running great. i have been putting it to work and it has not let me down yet.

That said it started doing something strange a couple days ago. when giving it throttle going uphill, the fuel filter light comes on. it doesn't even have to be a big hill. So i figured the filter is getting full. swapped it out today, and it seems to be running better, but I am still getting the same symptoms. Going home I go up a pretty decent grade, 7% for about 3 miles. It hasn't cut out on me yet, but it did surge twice near the top like it was getting air. as soon as i crest the top and cruise down the light goes off, flat ground the light is off.

So my thoughts are my duralift pump is going out and cant keep up with demand on a hill, or there is a partial blockage somewhere in the lines that wont let full flow through. Any other ideas out there? any ideas on how to fix it? I have another new in box pump on hand so I am going to try and swap it in the next day or so. we will see if i can carve out some time.

 

[chillman88]

Very first thing is check all your lines. Mine did the same and it was air intrusion.

How low was the fuel? It's possible air was getting in inside the tank at that grade if you were low on fuel.

 

[IDIoit]

glad to hear its doing good!
one thing im now doing on all my builds is installing a fuel pressure gauge on the outlet side of the filter.
helps with these issues.

have you tried switching tanks when this happens?
and like chillman said, whats the fuel levels?

one thing i have noticed, is that regular rubber fuel line is garbage for these trucks.
its been nearly a year, i would inspect them, if they are hard and brittle, they will start sucking air.
from what i remember, there is a rubber line from the stock lift pump area to the faucet.

good luck! keep us in the loop!

 

[asmith]

Very first thing is check all your lines. Mine did the same and it was air intrusion.

How low was the fuel? It's possible air was getting in inside the tank at that grade if you were low on fuel.

Are you talking return lines?

The tank started around half full and was below a quarter by the time I got home. Did it all day. I am filling up this morning so we will see how it does.


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[asmith]

glad to hear its doing good!
one thing im now doing on all my builds is installing a fuel pressure gauge on the outlet side of the filter.
helps with these issues.

have you tried switching tanks when this happens?
and like chillman said, whats the fuel levels?

one thing i have noticed, is that regular rubber fuel line is garbage for these trucks.
its been nearly a year, i would inspect them, if they are hard and brittle, they will start sucking air.
from what i remember, there is a rubber line from the stock lift pump area to the faucet.

good luck! keep us in the loop!

I will check the rubber line. I can’t run the front tank. Not sure why. Filled it up switched to the front and immediately it started stumbling and died. It is completely full and I just haven’t even messed with it.

I am thinking more and more about going through the whole thing from tank to filter, but I just need to find the time.


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[IDIoit]

return lines are not likely the issue, as you will know by puddles of fuel at the injectors.
most likely on the feed side.

 

[IDIoit]

I will check the rubber line. I can’t run the front tank. Not sure why. Filled it up switched to the front and immediately it started stumbling and died. It is completely full and I just haven’t even messed with it.

I am thinking more and more about going through the whole thing from tank to filter, but I just need to find the time.


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this makes me think fuel switch valve.
a common issue with these, but expensive for the direct replacement.

 

[Clb]

My group buy carrier has -5k on it...
I have cleared the fsv, and lines back to the tanks, and placed filters in between tank and fsv.
On a heavy pull uphill my fuel filter lamp will fire off, does not seem to be weak on fuel.
Still pulls fine, no extra egt's, no stuttering either.
I am leaning twards the 1/8" ports in the pump housing being to small, it should not be an issue as the extra psi should keep the flow up.
Yet it still happens.
I am gunna try the poppet valve on the return side to bump up the stattic psi to the ip.
Hope this helps.

 

[asmith]

this makes me think fuel switch valve.
a common issue with these, but expensive for the direct replacement.

Yeah. The front tank problems happened months ago and I haven’t had any issues just running the back tank til now. But I guess that is another good place to look.
I wouldn’t think the return lines would cause that issue either that’s why I was clarifying with him what lines he meant.


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[asmith]

My group buy carrier has -5k on it...
I have cleared the fsv, and lines back to the tanks, and placed filters in between tank and fsv.
On a heavy pull uphill my fuel filter lamp will fire off, does not seem to be weak on fuel.
Still pulls fine, no extra egt's, no stuttering either.
I am leaning twards the 1/8" ports in the pump housing being to small, it should not be an issue as the extra psi should keep the flow up.
Yet it still happens.
I am gunna try the poppet valve on the return side to bump up the stattic psi to the ip.
Hope this helps.

Interesting. Do you have a bigger IP? Do guys running the bigger pumps have this issue?
My EGTs are fine and it will pull strong for awhile but real close to the top of the biggest grade around here it will surge like it is getting air. I just don’t want this to get worse and cut out completely because then I get stuck on the side of the 101 in 100 degree heat and that is no fun.


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[Clb]

The 93 in my sig line has 48k bone stock miles, only changes are an ats093,3"dp, carrier e pump.
My 88 had a junior and mech pump, never fired the lamp.

The 1 thing I hear you say is
At the top of the grade it will act up...
This AND the lamp are the issue, but now for the concentrated effort of the group to answer it...

 

[chillman88]

Are you talking return lines?

I was talking the lines from the tank simply because it's an easy check. Air can get in smaller places than fuel so if you see something that looks questionable it's worth digging into.

Mine still acts up on the front tank, but I think it's because my hose "pickup" in the tank is too long and likely partly kinked. I'm guessing thats not your problem though because mine was my fault lol

 

[asmith]

I was talking the lines from the tank simply because it's an easy check. Air can get in smaller places than fuel so if you see something that looks questionable it's worth digging into.

Mine still acts up on the front tank, but I think it's because my hose "pickup" in the tank is too long and likely partly kinked. I'm guessing thats not your problem though because mine was my fault lol

Gotcha. That makes more sense.

So I filled up today and going back up the grade it did the same thing. Light came on and several minutes later it surged twice then didn’t do it again. I had gone about 50 miles at this point so it was still pretty full.


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[hesutton]

Do you have a fuel pressure gauge? I run one on both my IDI's. I have the sender in the fuel filer head so I see the pressure the IP is seeing. Certainly sounds like you are starving for fuel (loaded engine for a period of time). Had same symptoms when my Duralift and Holley red failed.

No doubt you want to replace the tank selector valve, I hope that is the only issue, but it may be the lift pump too. I've had great service out of the Duralift on my 6.9 crew cab and crumby service from the one on my F250. I love the fuel pressure gauge in theses trucks. Provides good information. Autometer electric is what I have. Put it where the fuel light switch goes on the filter head.

Heath

 

[asmith]

Do you have a fuel pressure gauge? I run one on both my IDI's. I have the sender in the fuel filer head so I see the pressure the IP is seeing. Certainly sounds like you are starving for fuel (loaded engine for a period of time). Had same symptoms when my Duralift and Holley red failed.

No doubt you want to replace the tank selector valve, I hope that is the only issue, but it may be the lift pump too. I've had great service out of the Duralift on my 6.9 crew cab and crumby service from the one on my F250. I love the fuel pressure gauge in theses trucks. Provides good information. Autometer electric is what I have. Put it where the fuel light switch goes on the filter head.

Heath

Thanks Heath. I do not have a pressure gauge but I will be getting one now.

I haven’t had a ton of time to devote to this, but I did have a chance to inspect all the lines. I didn’t find any wet spots or areas that looked like an issue. I will be able to do more this weekend.

Two questions. Has anybody temporarily bypassed the FSV just to see if that is the issue? I can’t think of that causing any issues but thought I would ask.

The other is how high of a psi can I safely use to blow through the fuel lines back towards the tanks?


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