bosch p7100 pump adjustment

Discussion in 'Trucks [ Eighteen Wheelers ]' started by asthesun, Jan 20, 2015.

  1. asthesun

    asthesun Bobtail Member

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    Sep 20, 2014
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    i'll start with the questions in case the hasty want to skip the whys.

    on the back afc housing, (firewall side in my case) there is the pre-boost screw. what direction do i adjust this, in or out, and what does it do?

    on the top of the afc housing, behind the 8mm allen plug is the star wheel. what direction, how much?

    i've heard on other forums something about fuel plate modification, also some place said to remove it entirely. idk what or where that is.

    this is on a 95' international 4800 with dt466 motor. this is a bucket truck, i.e. lots of idle time. i cannot sacrifice any functionality in that respect. my goal is to create additional towing power without the need for any or for very few additional modifications. not for financial reasons, but just because i don't want the hassle of the initial modification or subsequent un-modification in case i sell it and someone doesn't want my changes.

    its an automatic transmission so the problem i have is that between 40mph through about 50mph, it bogs down something serious, to a much higher degree while towing anything, even something very light (2k lbs). i think that it will not even make top speed with a 10k lb load, which is my goal. god forbid you have to slow down during this time and its even worse since you lose whatever boost you have built.

    i've already fiddled slightly with the 2 adjustment screws i mentioned above but my lack of knowledge prevents me from doing too much without more research
     
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  3. dieselfuelonly

    dieselfuelonly Road Train Member

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    Nov 12, 2012
    Chapel Hill, NC
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    I have the same fuel pump on a 12v Cummins in a pickup truck. I've never messed with the "pre-boost screw" you talk about, and honestly it's been so long since I've played with the starwheel I don't remember which direction I moved it in. If I remember correctly adjusting the starwheel will change fueling under lower-boost conditions, so I adjusted mine so it fueled a little harder.

    I wouldn't remove the fuel plate entirely - driving becomes a whole different animal since the plate is no longer there to regulate how much fuel you can dump in.

    I took out my fuel plate and ground it to the #10 profile in the picture below. Along with the above adjustments, the fuel plate, and changing the governor springs, it made that Dodge into a whole new animal.

    [​IMG]

    Mind you, the DT466 is NOT a 12v Cummins so the changes I made to mine might not do you any good. Regardless, be very careful and remember that more fuel = more heat... I'd definitely be installing a pyrometer before you start playing around with the pump. Especially when towing, you might be getting things too hot. Make sure the transmission is up to handling the extra torque as well.
     
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