12 Valve 2nd Gen Dodge Cummins 94-98 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with P7100 Injection Pumps

GMC cummins 12v swap question

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Old 05-20-2013, 01:36 AM
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Default GMC cummins 12v swap question

i know this is the dodge section, but the chevy guys left me hangin....

intro-- name is jason, truck is 98 gmc k1500 SAS'd w/3link on coils, shackle flip on rear with 14ff disc conversion. (just so you know im not a complete retard) build thread-

98 k1500 coil spring sas.... finally!

now to the goods!

putting a 96 12v cummins into my truck. a question i havent figured out yet, and wouldn't unless i had experience with a 12v. (im poppin my 12v cummins cherry too!)

when i do the swap. do i need to remove my factory MPI (gas) fuel pump from the tank?

reason for question- factory fuel pump runs around 50-60 psi, the flow rate should feed the cummins though. but with the high pressure going to the back of the P7100 injection pump do i run the risk of blowing a seal in the P-pump? is this too much pressure?

what else should i do to the engine before installing it. so far i have
1-retimed fuel injection pump to 16 degrees with a degree wheel
2-fixed killer dowel pin
3-bought gaskets for most of the engine (not the head though) should I?
 
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Old 05-21-2013, 04:06 AM
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cool swap
yes you might need to remove the fuel pump from the tank because the motor has the lift pump.
i'm not sure how much fuel pressure runs through the fuel pump.
i don't think you should worry about the head gasket unless your going to be putting on twin turbo's for example.
 
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Old 05-21-2013, 07:16 AM
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that factory pump would be running way to much pressure to your lift pump. the stock lp wouldnt be able to keep up and would more than likely end up dead heading your injection pump. if you feel the need to run fuel pressure like that your best bet would be to bypass the lift pump all together
 
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Old 05-21-2013, 02:01 PM
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Originally Posted by olsmokey
that factory pump would be running way to much pressure to your lift pump. the stock lp wouldnt be able to keep up and would more than likely end up dead heading your injection pump. if you feel the need to run fuel pressure like that your best bet would be to bypass the lift pump all together
Thats along the lines i was thinkin. but the 60lb pressure directly from the electric pump isnt too much for the injection pump? i know it has a regulator and recirc setup on it. im a little concerned with over killing it though.
 
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