Just read the article from Glacier Diesel about the intank lift pump and sending unit module and why we have fuel delivery problems. Has anyone tried to block off the 8 psi bypass or alter it for more pressure? Seems to me this would be easier and cheaper than aftermarket pumps. Plus the Dealer would not know anything of it when you have it in for warranty or recall issues.

 

One of the reason the bypass is there, is when the fuel tank is really low, it keeps a "reserve" amount of fuel in the chamber (yellow thing) So when the fuel slosh's, it will suck and pump the fuel that's in the yellow tank, untill the pump see's fuel. I'm sure bypasing it will work and you will have higher pressure, but like rich says, one of the reasons it's open is to pump a large volume of fuel and keep sucking through those tiny holes sealed by the rubber one way valve. I'm sure you could try it (I'm not gonna risk that) and see how it does, post results.

On the dealer side. On the outside no, but if something happens and they take your truck apart to inspect, they will find if you tinker with the part. A lot of times they'll warent it, then send the part off to the company for further inspection break down.

See how it works, post and keep others informed of performance and any issues that arive. I dont' know of anybody that's attempted this yet.

I just put my Walbro in, couldn't be happier

 

Are there issues with the in-tank lift pumps? Durability should be fine, and I've not seen any problems with flow/pressure - and my gauge won't drop under 6psi no matter what.

 

Throw a box on there that gives the motor more fuel and you will. I could pull mine down pretty good with the TST on 2/2. I didn't want to go higher than that for fear of damaging it. Stock the pump works great, it's when you pull more fuel you need the increase in fuel.

When you put your box on, you'll see the difference (saw you were gonna get a zilla chip)

 

I can't beleive no one has tried anything with stock tank module. The dealers are looking for a reason to junk your warranty. I think this would be the ticket if done right. I think all you need to do is change the bypass regulator to make it run at more pressure either by changing the spring or blocking the bypass off all together.

 

One of the reasons for that much bypass is to ensure the pump is pulling fuel through the little rubber anti flow back valve (and to keep cool). That's why the engine mounted ones failed, Heat, Vibration, a few reasons. The stock system on the 05's is great, no problems. But with mods you do need more fuel delivery pressure. Just like why upgrade the tranny, turbo, there all good stock but throw mods on them, and you need more.

I'd rather warrent my own stuff than some of the kids at the dealers now adays. We had a ATV once and they said try turning the gas on, (issue with gas problem) and I was like dosent it state in the owners manual while transporting to turn it off, there like well it's only a guide line. It's amazing what they say. I trust my own skills better

 

That little flapper valve is always open when you have fuel in your tank. This unless you are low on fuel and you go on a bit of an incline where the valve will shut and ensure that the pump does not go dry.
As for the 8psi bypass max. Most trucks will idle at 9-10 psi and cruise at 6-9psi and pull down around 4-6 psi under hard excel.
In theory if this bypass was only designed to maintain 8psi then it would do that in all aspects not just idle.
The pump itself is a internally cooled Walbro style pump with a different intake on it. Turns out that Walbro and Federal Mogul are interchangable entities.

My question is what is the real capacity for the stock pump, and how far does it differ from the other pumps?
If one just removed that pump and installed direct inline pump in the tank using the same pick up module would it work?? Of course it would.

 

why couldnt you restrict that outlet with a small valve
that way you could adjust the output PSI

Or am I way off????

 

Hopefully I don't miss anything here...

The flapper is only open when the in-tank pump is running.

The used unit I stipped down would only make 8 psi via the bypass. The spring may have been a little weak. Just what I found upon testing the unit.

The pump is made by VDO.

The stock pump is a high flow low pressure unit. Almost 80 gph free flow but down to 0 by 18 psi dead head.

You can't just remove the stock pump and replace it with a different unit due to the design of the fuel bowl. I wish we could. You can read more about the unit and why here.

Richard

 

what if the output fromn the venturi chamber was routed up above the bypass and into the main fuel line?

that would be a simple cheap mod.

 

The anti drain back valve prevents fuel from going back to tank correct? If so why does your walbro kit have a check ball in the line coming from the stock fuel pump? Is it just more security?

 

The GFS kits come set for 22 psi. The stock bypass would be pushed open and not allow the new pump to achieve desired pressure, hence the check valve. The Comp versions eliminate the stock line all together so that we can up the pressure for the modified CP-3 users.

Richard

 

Thanks knew it had to be something.

I ordered a new tank module today from dealer could not beleive how cheap $200 list. I got it cheaper. They are going to look at it when it comes in before shipping because it sounds to cheap. They even called about it and was told that it is what we are looking for pump and fuel level sender assembly. Should know Tuesday when they get it I wont get my hands on it til late next week. Will probably be calling you agin Richard. Thanks in advance if this works out.