Questions on my isx 15_continued
11-17-2022, (Subject: Questions on my isx 15_continued ) 
Post: #19
RE: Hello everyone. Code 4691 help
Check the pressure relief valve at the front of the fuel rail. It could be leaking past.


User's Signature: 2015 389 Peterbilt. ISX 550 18speed 3.70 gears
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11-17-2022, (Subject: Questions on my isx 15_continued ) 
Post: #20
RE: Hello everyone. Code 4691 help
I took the big bolt loose at the relief valve and there is no fuel leaking from it when I crank it or when it’s sitting . Shouldn’t there be fuel comimg out of it when I took the bolt out.
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11-17-2022, (Subject: Questions on my isx 15_continued ) 
Post: #21
RE: Hello everyone. Code 4691 help
I took the return fuel line loose no fuel in it.
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11-17-2022, (Subject: Questions on my isx 15_continued ) 
Post: #22
RE: Hello everyone. Code 4691 help
You will need to remove the banjo bolt on the relief valve and then plug the banjo fitting with a bolt and washers or the Cummins tool to prevent the return fuel flow coming back through. Again, Quick serve has all the procedures. The bleed fittings are on the fuel filter housing usually capped with a plastic nub( for lack of better term). Use a screw driver and a cloth to redirect any spray and push the middle of fitting in . You should have some flow with just the lift pump running at key on. But sounds like the mechanical pump is not getting any fuel. 141 psi is usually about what the lift pump provides. Is the solenoid plugged in on the fuel pump housing? How about the inlet screen in the banjo fitting on the fuel supply line to mech pump? Could be plugged.
Were tappets installed correctly…guide pins aligned, if they are not, the tappets won’t ride the cam. This would result in damage. In my experience a leaking injector quill won’t pass enough to not allow any pressure to build.


User's Signature: 2015 389 Peterbilt. ISX 550 18speed 3.70 gears
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11-17-2022, (Subject: Questions on my isx 15_continued ) 
Post: #23
RE: Hello everyone. Code 4691 help
(11-17-2022 )SemiSweet Wrote:  You will need to remove the banjo bolt on the relief valve and then plug the banjo fitting with a bolt and washers or the Cummins tool to prevent the return fuel flow coming back through. Again, Quick serve has all the procedures. The bleed fittings are on the fuel filter housing usually capped with a plastic nub( for lack of better term). Use a screw driver and a cloth to redirect any spray and push the middle of fitting in . You should have some flow with just the lift pump running at key on. But sounds like the mechanical pump is not getting any fuel. 141 psi is usually about what the lift pump provides. Is the solenoid plugged in on the fuel pump housing? How about the inlet screen in the banjo fitting on the fuel supply line to mech pump? Could be plugged.
Were tappets installed correctly…guide pins aligned, if they are not, the tappets won’t ride the cam. This would result in damage. In my experience a leaking injector quill won’t pass enough to not allow any pressure to build.
I took the fuel inlet to the rail and it’s pumping fuel up to the rail . Im gonna do what u said do. It was running before I put the retaining rings in.
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11-17-2022, (Subject: Questions on my isx 15_continued ) 
Post: #24
RE: Hello everyone. Code 4691 help
(11-17-2022 )SemiSweet Wrote:  You will need to remove the banjo bolt on the relief valve and then plug the banjo fitting with a bolt and washers or the Cummins tool to prevent the return fuel flow coming back through. Again, Quick serve has all the procedures. The bleed fittings are on the fuel filter housing usually capped with a plastic nub( for lack of better term). Use a screw driver and a cloth to redirect any spray and push the middle of fitting in . You should have some flow with just the lift pump running at key on. But sounds like the mechanical pump is not getting any fuel. 141 psi is usually about what the lift pump provides. Is the solenoid plugged in on the fuel pump housing? How about the inlet screen in the banjo fitting on the fuel supply line to mech pump? Could be plugged.
Were tappets installed correctly…guide pins aligned, if they are not, the tappets won’t ride the cam. This would result in damage. In my experience a leaking injector quill won’t pass enough to not allow any pressure to build.
I did as you said a bolt on the return line with washers. The bleed from the fuel filter housing was strong. I posted pictures of all 6 injectors and quill tubes in this post . They look ok to me but I could be wrong. Gimme your thoughts
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11-20-2022, (Subject: Questions on my isx 15_continued ) 
Post: #25
Thumbs Down Questions on my isx 15
Gm Rawze and everyone. Im still dealing with no rail pressure . I put new fuel tubes in and torqued them to specs. When I pulled the injectors did they need to be programmed again . I over torqued the fuel tubes so I put 6 new in . Could I have damaged the injectors because it spins over no start no rail pressure. Before I take it to Cummins ? Im a good mechanic just new to the common rail system. Thanks for the help I can post pics of the old tubes if anyone wants to see the tips. Number 1 had a indent in the tip.
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11-20-2022, (Subject: Questions on my isx 15_continued ) 
Post: #26
RE: Questions on my isx 15
(11-20-2022 )Nhramember Wrote:  Gm Rawze and everyone. Im still dealing with no rail pressure . I put new fuel tubes in and torqued them to specs. When I pulled the injectors did they need to be programmed again . I over torqued the fuel tubes so I put 6 new in . Could I have damaged the injectors because it spins over no start no rail pressure. Before I take it to Cummins ? Im a good mechanic just new to the common rail system. Thanks for the help I can post pics of the old tubes if anyone wants to see the tips. Number 1 had a indent in the tip.

PM me your email and esn Ill send you the manual for your situation
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11-20-2022, (Subject: Questions on my isx 15_continued ) 
Post: #27
RE: Questions on my isx 15
(11-20-2022 )RollinCoal Wrote:  
(11-20-2022 )Nhramember Wrote:  Gm Rawze and everyone. Im still dealing with no rail pressure . I put new fuel tubes in and torqued them to specs. When I pulled the injectors did they need to be programmed again . I over torqued the fuel tubes so I put 6 new in . Could I have damaged the injectors because it spins over no start no rail pressure. Before I take it to Cummins ? Im a good mechanic just new to the common rail system. Thanks for the help I can post pics of the old tubes if anyone wants to see the tips. Number 1 had a indent in the tip.

PM me your email and esn Ill send you the manual for your situation
I sent it
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