Engine/Transmission (1998.5 - 2002) fuel pressure gauge ='s more power???

[TPlasek]

Please don't flame me on this observation I made this evening, but I find this to be very odd. I hooked up an ISSPro Egt and boost gauge last weekend. I have had the mechanical ISSPro fuel pressure line just laying in the engine compartment. Today, I purchase a 1 foot Freon has with a ball valve and hooked it to the schrader valve at the VP44. (14psi idle 8psi WOT pump with 2k miles on it) But, this isn't what I found interesting.



I only bled the air out of the line after the 1 foot freon hose. I left the remainder 5 ft of hose with air to act as a "pulse" dampener, to hopefully eliminate gauge noise, prolong the life of the gauge, and hopefully keep the spillover valve from opening and slamming shut constantly in the lift pump.



I wish I had numbers to prove it, but the truck runs much better now Especially at the low end. It builds RPM's much quicker and it blows MUCH more smoke. I used to only be able to make 28psi of boost and now I can make 34psi. How could this be possible? One more test I did, I raced my friends PowerStroke from a full stop. We have raced many times and do to his auto he always just barely gets me. Well not this evening, I had about 2 car lengths on him.



I have a couple of questions to help me figure this out.

1. Does the fuel have a constant flow through the VP44 or does it pulsate(move fluid then stop then move again) each time the VP44 (lift) vane passes the intake, thus causing the relief valve in the lift pump to open and close constantly leading to its' failure???

2. Since fuel (in this case) is not compressible and air is, could the air be acting as a cushion for the moving fluid, giving it a place to go (compressing the air) and not physically stopping the mass of the moving fluid and then requiring energy to restart it and get it moving again???

3. Do most people bleed their fuel pressure gauges or leave air in them???

4. Think maybe I could have wiggled some wire on the EZ while running the fuel line thus causing it to work better???



Any help/info would be greatly appreciated.

ps. it is more then just a little improvement(even my wife noticed )

 

[Breck]

TPlasek,



I'm going to be hooking up a fuel pressure guage real soon... I'll see if that makes any difference on my set up?



V/R



Breck

 

[Steve Campbell]

Sounds like your 5' of air charged fuel line....

... is acting like a pressure tank. I could see it evening out the flow to the VP44 somewhat , but 6 more lbs of boost???? That is a lot!!! If what you have discovered is actually the case, there will be a lot of CTD's with "pressure tanks" installed by weeks end. Oo.

 

[fj40charles]

Don't have a clue. Maybe it is less drag on the transmission... ;-)



Did you install the 275's yet?



Charles

 

[curatchko]

Can you explain how your hoses are setup again? You lost me.

 

[TPlasek]

Hoses are set up as this:



Schrader valve at VP44 still has valve in it. I attached a 12" section of freon charge hose to this. I purchased a premium grade hose from a local A/C store. At the end of this 12" of hose, the hose has a ball valve built in(attached from the factory) to the hose and on that ball valve it has another an-6 fitting just like what is on the VP44. I then attached my 5 ft of 3/8 wire braid from this point all the way, through the firewall, up the dash, and to the gauge.



I played around with it some more this morning on my way to work. Actually, with closer inspection, it is making 32psi not 34psi. Still 4 more lbs. I am going to take the hose off this evening and play with it some more.



No 275's yet FJ40Charles. They are still on the work bench. I want to figure out what is going on here before I through in another variable. This is about the gain I was expecting from the injectors. I still wander if I somehow inadvertently messed with the EZ connections somehow.

 

[Steve Campbell]

Tplasek...

The more I think about this, the more I think you might be on to something. As fast as sending units go out when hooked directly to the VP44 banjo, lots of pressure fluctuations are happening there. If you have some sort of pressurized fuel reservoir with a big enough line to accommodate the volume needed, those pressure peaks and lows should be evened out. With just an EZ, 34 lbs of boost is a lot.



Keep us informed of any changes in boost pressure.

 

[15w40]

I agree that limiting the fuel pulsations can only help with the lift pump and maybe power also. Here is something I found to do exactly that. It is a tank that is pressurized with fuel and can supply fuel when the VP44 is using more than the lift pump can supply. It would also damp the pulsations and keep pressure up for those burnouts.



#ad




A link to the web page is: http://www.capa.com.au/capa_fuel.htm



I have been using a poly bottle for the last 6K miles to do the same thing as the surge tank. What I have found is that the air in the bottle will eventually dissolve into the diesel fuel and air has to be added about every 2000 miles. I am also worried that the bottle may leak with high underhood temperatures. But the pulsations are greatly reduced. I have not seen any great increase in power but my clutch has been slipping for a while so I will not dispute a claim of power increase. My goal is to prolong the life of the lift pump and injector pump.

 

[Steve Campbell]

Tplasek....

... I slept on it again. Try unhooking the fuel guage and see if the extra boost goes away. Then you (we) will know if this is purley circumstantial or actual.



15-40... Did you notice any change in fuel mileage? Sorry to hear your clutch is slipping with what looks like a stock truck from your signature.

 

[illflem]

First off I'd beware of the freon hose, it may not be compatible with diesel. No need to bleed air from the hose, it will fill with fuel on it's own rather fast. As for your new found power, you sure you didn't accidentally unplug a sensor wire during installation?