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Muamer

Mack 2003 E7 engine hard start

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Hello there everyone I am having some trouble with my mack E7 engine with jake brakes 2003 470hp the truck just had a rebuild done but having problems with the fuel system starts up fine but found issue at the fuel return valve on the block once the truck starts a lot of diesel comes out of the return, the injectors have been done and re conditioned would anyone know what else could be causing so much diesel to return thanks 

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Perfectly normal for a large portion of the rails unused fuel to be returned to tank.

The fuel rail supplying the EUP’s is very similar to an “open center” hydraulic system. Constant pump volume flows through center and is consumed as needed. 

Up here the drawn fuel tank gets warmed in the winter by hot return fuel. There is enough return flow volume to argue the transfer fuel pump is part of the right side engine cooling system and the aluminum tank is a functional heat sink.

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Define your "hard starting". If it has to crank for 5 seconds or so before firing off then your camshaft position sensor could be failing or has enough buildup to screw up the reading. It's on the front of the timing cover, in front of the camshaft! 

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Any codes? Is your engine malfunction light in working order? That'd be the lightning bolt on the dash.

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So look at it this way we couldn't get it going until I removed the return line on the side of the block and put my finger over the fitting to try and restrict the high volume of diesel coming out while cranking that's when it then started 

Ran like crap after that but kept running and kept flowing high amounts of diesel out of fitting thanks 

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Yes the lightning bolt is there but I wouldn't have a clue what the codes are do not have a code reader 

 

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39 minutes ago, Muamer said:

Yes the lightning bolt is there but I wouldn't have a clue what the codes are do not have a code reader 

 

you can use the speed control switches to get it to flash/blink.  Then count the flashes and post the codes.  there is two flash/blinks per code so if it was the engine timing sensor that threw the code it would be (Blink Blink Blink---Blink Blink) 3-2 on a V-Mac III

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13 hours ago, Muamer said:

So look at it this way we couldn't get it going until I removed the return line on the side of the block and put my finger over the fitting to try and restrict the high volume of diesel coming out while cranking that's when it then started 

Ran like crap after that but kept running and kept flowing high amounts of diesel out of fitting thanks 

That’s an important piece of missing information. Replace the fitting your putting your finger over. That fitting is the fuel pressure regulator and there’s a good chance it’s stuck open and creating insufficient pressure. The fitting is a simple, non-adjustable, spring & ball, restriction valve.

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With engine off, key on you need to hold the set/decel button til the lightning bolt starts doing stuff. Count the flashes, it'll be a 2 digit code. When that code is done spitting out, hit set/decel again to draw another code. Each code request gives you one code. This method will only pull "active" (current) faults. You need a computer to pull stored, inactive faults. Post the list of codes you pull here, and some of us have the book and can tell you what the codes mean!

And start by replacing the fuel regulator as well! And next time don't leave out pertinent information!

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Mine will read the code with the truck running.

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