Engine/Transmission (1998.5 - 2002) Lost 3 MPG with rebuilt vp44 and fass pump

[TFlesner]

I replaced my vp44 pump with a bosch rebuilt unit and a fass pump.

I lost 3 mpg. Highway driving 20 to 17 ( 70 MPH ), city 17 to 14, and towing 12 to 9.

I have 80,000 miles on her, 2500 with an auto.

My fuel pressure is 17 psi and drops to 14 psi on a hard pull.

We just got back from Lake Tahoe and the grade from Carson City to the summit was done with average of 40 MPH pulling a 30' fifth wheel, so I thing the power is OK. My EGT runs around 8,000 to 11,000 degs. pulling and boost up to 28 lb's.

Is there something I can do? I will replace what ever it takes, but I want this truck to get the MPG's back!

 

[ALepley]

First things first what do you have done? Second you mean 1,000 degs? 11,000 is alittle toasty hahaha.

 

[GKruzich]

Wow, those are some serious EGT's!

 

[TFlesner]

Sorry, the EGT is only off a bunch on deg's. I guess I was a due mose on that one,

GOT ME THERE

 

[TFlesner]

I have 4" exhaust, allison 2000 trany, pac brake, three piece exhaust manifold, Edge for milage, K&N air filter, and stock from there. All of this was done before the pump change.

 

[Vaughn MacKenzie]

You might check to see if you have any codes. Maybe there is an issue with the reman unit, for instance if you have a 0216 code it means the timing isn't advancing like it should which would hurt MPG.

You say the power is good, is it about the same as before? Does it sound any different?

On another note, the K&N air filters are not that good, they flow fine but aren't known to be the best filter at stopping dirt.

 

[NIsaacs]

I see you changed to an auto, with 2500 miles accumulated. I would guess this has more to do with your fuel mileage then the fuel pump, unless your previous transmission was an auto also.



Nick

 

[TFlesner]

NIsaacs: The transmission was a stock auto before with issues, converter locking and unlocking, getting hot on long pulls, hard to back up drive-way and more yet. The mileage was about the same after the Allison was installed. Stock transmission rev 2. 21-1 and allison 5. 09-1.

The mileage problem started right after the vp44 was installed.



Vaughn: I will see if there is that code tonight. Is there a way of changing the timing advance?

As for the sound I don't know, I've have gotten use to the sound now.



Thanks, Todd

 

[ESwartzer]

I would check the shaft key on the vp44 and make sure its the correct one and sitting correctly in the keyway. If not the right one, it could any number of issues including poor mileage!

 

[mhenon]

It isn't the FASS as your pressure's fine.

Mike

 

[TFlesner]

How does one tell if he has the right key or if setting correctly?

If I would chose to get another rebuilt pump what would I look for so this MPG problem could be corrected?

 

[fox]

The key has a code on it. It has to match that pump. did you change the key? Is it in right?

 

[TFlesner]

I had someone else put the pump on. I will check it out. It will not be right a way because of the need of the truck.

Thanks very much for the info.

I will tell the guy who did it for me about the need of placement of the key so he can watch for it the next time he does one for someone else.

 

[Chief USA]

If you have already checked for codes and found none, have you tried cleaning or replacing the IAT sensor?



Here is a good review/primer on how to remove, test, and clean the IAT sensor:



Intake Air Temperature Sensor (IAT)

 

[jakprince]

Did you already have the fass pump before or did you install both at the same time?

 

[TFlesner]

I put the on at the same time.

I did order another vp44 pump yesterday. I will keep the old one for a spare with me in the tool box. It will be pickled and ready to go. It will be ready for me or make someone else real happy that they can get going quickly. Yes, I will tell them of the mileage thing.

I will check the key codes and let you all know what happened.

 

[TFlesner]

OK, I put in a new rebuilt vp44 and what I found was the key on the pump I pulled out was in backwards. The mark was to the threads and should be towards the pump. While it was out I did put the new pump in but keeping the old one for back up. The old pump is pickled and ready to go if ever needed (carrying in the tool box).

I will be checking the fuel mileage and letting everyone know what happened. It will be in this post and a new one.

Thanks for all the help, Todd