1st Generation Dodge Cummins 89-93 Discussion of 12 Valve 5.9 Liter Dodge Cummins Diesels with Rotary Injection Pumps

Star screw

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Old Jun 30, 2009 | 10:07 AM
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Default Star screw

Is that the fuel screw or smoke screw? I just pulled the cap off and noticed its the star wheel I believe yall talk about, but unsure of what it does.
 
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Old Jun 30, 2009 | 10:26 AM
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Yeah that is the star wheel. With your DennyT pin I would leave it at the stock setting. What it does is adjust the pre load on the spring that controls the diaphragm for the fuel pin. By screwing the star wheel in there is less pre load and it takes less boost to push down the fuel pin allowing the pump to get to full power faster. The down side to this is you get full fuel with less boost so smoke and EGT's increase. I actually have my star wheel up pretty far from stock or the truck is a pain on the road. Start with it in the stock position and see how the truck runs.

The fuel screw is on the rear of the pump
 
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Old Jun 30, 2009 | 02:09 PM
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On the rear of the pump would be towards the firewall correct?

Thanks for telling me what that does im glad I didn't mess with it. Been driving it quite a bit sence I put the fuel pin in and it has great amount of power over factory and nice puff of smoke when taking off hard. EGT's have stayed the same.
 
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Old Jun 30, 2009 | 03:06 PM
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yes it would be. It probably has a plastic or rubber cap over it and a tamper proof collar on it. I wish I could get ahold of a bone stock truck to do a good write up on pump tweaking. Make sure you read the warnings on runaway before messing with it. I would hate to see you scatter your engine.
 
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Old Jun 30, 2009 | 10:16 PM
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Ya im probley not going to mess with it, I need to keep reliablity as high as possilbe and be able to drive and tow with her.

Thanks for the help.
 
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Old Jun 30, 2009 | 10:30 PM
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Tune by your EGT's. If you can load the trailer and do what you need with out you temps getting above 1250* Pre-Turbo to do go ahead and give it a little more fuel. These pumps are CRAZY easy to adjust so you can turn it in and out and keep playing with it till your happy.
 
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Old Jul 1, 2009 | 02:20 PM
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Ya I need to get my new miliatry's on the mud truck and load her on the trailer and check out what my gauges read.
 
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