Engine/Transmission (1994 - 1998) Injection pump wear

[McLaughlin]

Does the fuel mileage of trucks using the P7100 injection pumps go down as they wear? Just curious if anyone has replaced an older injection pump and noticed a significant increase in fuel mileage.

 

[Vaughn MacKenzie]

It would stand to reason that they would lose MPG, because of increased amount of fuel leaking by the plunger during injection which results in somewhat deteriorated fuel plume. I would think the wear would have to be significant before it has a real affect on fuel economy, ie a pump with a lot of miles or one that's seen too much poor fuel. I had my 215 pump tuned up at 370k miles and one plunger was leaking down, which was corrected quite well by lapping the plunger bore.

 

[PKozlowski]

I just had my injector pump replaced last Thursday.

I was getting 9mpg average. With the new one I'm getting 19. 3mpg!

So I'm going to say ya, they wear and the mpg goes way down.

 

[Ahopper]

PKozlowski

: i think he is asking if the p7100 pumps where out. your truck is the 24v so its a little different i know the lift pumps go out on them is that what went out on yours?

 

[PKozlowski]

No my injection pump went crazy one day so they replaced it and the lift pump.

Still has no power to speak of though. When I step on the gas it doesn't

really accellerate like it use to.

 

[McLaughlin]

It would stand to reason that they would lose MPG, because of increased amount of fuel leaking by the plunger during injection which results in somewhat deteriorated fuel plume. I would think the wear would have to be significant before it has a real affect on fuel economy, ie a pump with a lot of miles or one that's seen too much poor fuel. I had my 215 pump tuned up at 370k miles and one plunger was leaking down, which was corrected quite well by lapping the plunger bore.

Thats sort of what I'm thinking. My daughter's 96 with a #4 fuel plate gets between 22 and 30 depending on the elevation and terrain. I'm only getting 16-17. My injection pump has about 195K on it while hers only has about 30K (was replaced).

 

[MAleksandrowicz]

No my injection pump went crazy one day so they replaced it and the lift pump.

Still has no power to speak of though. When I step on the gas it doesn't

really accellerate like it use to.

01' 6 speed is a High Output. Maybe they replaced your vp44 with a 235hp version?

 

[pwerwagn]

Maybe they replaced your vp44 with a 235hp version?

Dont the SO trucks actually have a larger VP44 than the HO trucks??

 

[Dr.Bob]

PKozlowski you better get yourself a new pump like a fass or your going to burn up your new injection pump.