Chevy/GMC 6.2L and 6.5L Discussion of Chevy and GMC Trucks with 6.2L and 6.5L Diesel Engines

Now fuel pressure

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  #11  
Old 05-11-2016 | 04:48 PM
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No I havnt hot wired the lift pump. Nor was I holding the petal to the floor while cranking ( I didn't know I needed to) As far as everything else it's good got power to plugs solenoid working I got 6.2 volts leaving Dom which is high according to specs but that could be my old meter. It has bad leads. As far as engine and timing I have no idea. I got the truck from a trusted family friend who said truck ran fine. Son hauled some trash ran out of fuel and just left it sit. I have a good fuel flow at filter and t valve after priming. I got good flow to shut off. But nothing after. Could the problem be in injector pump cause I had fuel to injectors last week but it wasn't 120 psi.
 
  #12  
Old 05-11-2016 | 07:09 PM
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Also what's the best way to hot wire lift pump. I thought about taping into the harness and putting a 3 way toggle switch so I can change it back and forth at Will for future repairs. ( side note I'm planing on a full rebuild next year engine and fuel system.) so the switch would be handy to have but I can't find any elec diagram for how the relay is set up.
 
  #13  
Old 05-11-2016 | 08:04 PM
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Welp I took your advice and held the petal to the floor and got fuel to my injectors. I cycled several times the hooked everything back up. Truck started then died 3 seconds latter It wont even try to start now. So now I'm thinking maybe just air locked or return issue or both. What do you think?
 
  #14  
Old 05-12-2016 | 08:29 AM
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sounds like air in the pump, go under the truck and tap into the pump on the hot wire and just run power to it from a switch or whatever is easiest. Holding the pedal to the floor increases fuel rate which speeds the bleeding process.
 
  #15  
Old 05-12-2016 | 11:15 AM
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Also when you are bleeding a system once it starts it's always best to hold the rpm's up for a bit because it will still be processing air for a bit and it will die if left idling after it's initial fire. a minute or two is normally sufficient, sometimes this is required even after a fuel filter change.
 
  #16  
Old 05-12-2016 | 12:02 PM
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Makes sence it died right after I let off the pedal.
 
  #17  
Old 05-12-2016 | 01:33 PM
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  #18  
Old 05-12-2016 | 07:08 PM
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One thing after another. Went to re prime and noticed something smoking lick crazy on the right side between block and fram after a little investigating I found my ground strap going from block to firewall was hot as fire. I actually got a burn blister from touching it. So all things on hold New strap ordered will resume the fun tomorrow.
 
  #19  
Old 05-13-2016 | 09:12 AM
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You need to finds out why you have current flow that is making the gnd that hot, is it electrical related or just ambient temp from proximity to "hot engine parts", just replacing it if there is a shorted electrical device will just burn out the new one.

There are multiple gnds on these vehicles it is possible one of the main gnds to hi current draw is bad causing trons to do their "normal thing" seek path of least resistance and passing too much current across that braided gnd.

BTW you don't need a special OEM style braided strap on back of the engine they use those for flexibility, heavy gauge automotive wire will do the same thing but because it is insulated you will want to route it away from hot engine parts to keep from melting/burning insulation.

One thing I also do is to add extra gnd between engine & frame get a 3-5' length of battery cable like you find on a card at auto part store with a ring lug at both ends, "polish to bright bare metal" a spot on the block or alternator bracket etc. and another on the frame, liberally apply dielectric or bulb grease to the bared metal spot and the lugs for best contact, with these PCM controlled engines clean gnds all of them are a must.

Since you are new to the 6.5 I HIGHLY RECOMMEND searching interweb for GM service manual or if you can't find one on line, subscribe for a year to alldatadiy.com then you can print off important stuff like schematics etc. and build your own manual, Chiltons/Haynes etc. give the generic info sort of ok but you really need GM specific info
 
  #20  
Old 05-13-2016 | 11:34 AM
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^ all of that, normally start smoking grounds when the starter is going bad.
 



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