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Common rail injection


IH OAK
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My brother just asked me "What is 'common rail'?" I said "I'm not quite sure"

Can someone explain what exactly it is...Is that where the pump in the tank/lift pump make the injection psi???

I've forgotten already

(He wants to diesel swap a subaru forrester)

Thanks!

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Common rail engine, Has 1 high pressure pump which supplies fuel to a common rail which feed the injectors. There are 2 different types of fuel injection, #1 fired electronically by the flywheel/cam position sensors and the Engine Computer Unit/throttle position. #2 engines which use the cam shaft for timing of fuel injection, the ECU/throttle position determines the amount of fuel. Some of the newer advanced fuel systems inject fuel at 28,000+ psi in small pulses to reduce emissions. 

Guys on here far smarter then I can explain it better

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3 minutes ago, 806 man said:

Common rail engine, Has 1 high pressure pump which supplies fuel to a common rail which feed the injectors. There are 2 different types of fuel injection, #1 fired electronically by the flywheel/cam position sensors and the Engine Computer Unit/throttle position. #2 engines which use the cam shaft for timing of fuel injection, the ECU/throttle position determines the amount of fuel. Some of the newer advanced fuel systems inject fuel at 28,000+ psi in small pulses to reduce emissions. 

Guys on here far smarter then I can explain it better

So is the high pressure pump at the tank or on the engine??

I've heard rumors of extremely high pressure pumps at the tank??

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2 minutes ago, IH OAK said:

So is the high pressure pump at the tank or on the engine??

I've heard rumors of extremely high pressure pumps at the tank??

Engine as far as I know. Maybe some hot rod pull tractors setup that way ?

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For me with an '07 5.9, the pump is at the engine feeding the common rail, the lift pump is builtt into the tank, the problem there was if the tank unit failed the hi pressure pump would destroy itself, there are two different pumps that I know of in the 2000s, with the 6.7 I don't know of the later versions.

My remedy for failure was installing a FASS system which has higher lift pressure (16-18 psi) over the stock pressures and if one of these show failure it can be changed quite easily, also if you go to utube and type in your query there are a few 3-5 minute vignettes.

 

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All I have seen are engine mounted.

It's not a new system. Detroit diesel and Cummins has used camshaft operated common rail systems for well over 70 years.

Here's a video 

Thx-Ace 

 

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I didnt know either so i asked the wife...she told me its what happens when im being lazy.

No really im learning a lot here. Thanks for posting.

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Cummins PT, Cat EUI, MUI, HEUI injectors are not a common rail fuel system. They create working injection pressure in the injector.

Common rail systems as stated above use an engine driven pump to build pressure that is available to all injectors at all times via the "common rail", the injectors then open/close electronically. Common rail systems generally can vary the injection pressure at the rail, and can attain stupid high pressure... imagine 30,000 PSI.

The advantage of common rail is that injection timing is independent of mechanical timing. It is more precise and allows multiple injections on each firing stroke. Instead of one shot of fuel, they can inject several small shots effectively giving cleaner, lower temperature burn. In the case of some newer engines that have a DPF, regeneration is achieved by giving a small shot of fuel while the exhaust valve is open - eliminating the need for additional afterburn equipment.

A good portion of common rail fuel systems have a tank mounted or inline low pressure fuel delivery system. These usually contain a constant bleed valve or orifice to remove air. It is imperative that no oxygen is present when the HPP pressurizes the fuel to the extreme pressures.  

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15 minutes ago, Cattech said:

Cummins PT, Cat EUI, MUI, HEUI injectors are not a common rail fuel system. They create working injection pressure in the injector.

Common rail systems as stated above use an engine driven pump to build pressure that is available to all injectors at all times via the "common rail", the injectors then open/close electronically. Common rail systems generally can vary the injection pressure at the rail, and can attain stupid high pressure... imagine 30,000 PSI.

The advantage of common rail is that injection timing is independent of mechanical timing. It is more precise and allows multiple injections on each firing stroke. Instead of one shot of fuel, they can inject several small shots effectively giving cleaner, lower temperature burn. In the case of some newer engines that have a DPF, regeneration is achieved by giving a small shot of fuel while the exhaust valve is open - eliminating the need for additional afterburn equipment.

A good portion of common rail fuel systems have a tank mounted or inline low pressure fuel delivery system. These usually contain a constant bleed valve or orifice to remove air. It is imperative that no oxygen is present when the HPP pressurizes the fuel to the extreme pressures.  

The problem with lower temperature burn is it leads to carbon packing in the rings and dirtier air back thru the egr. Pittsburgh Power carries a fuel catalyst that increases burn temp and length eliminating 70% more of the carbon in the cylinder keeping dpf cleaner much longer and eliminating lots of emissions problems.

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46 minutes ago, jass1660 said:

The problem with lower temperature burn is it leads to carbon packing in the rings and dirtier air back thru the egr. Pittsburgh Power carries a fuel catalyst that increases burn temp and length eliminating 70% more of the carbon in the cylinder keeping dpf cleaner much longer and eliminating lots of emissions problems.

Thank the EPA. Higher burn temps are what causes Nox. Had Nox not been an issue, we wouldn't need a DPF as engines had nearly eliminated particulate matter before emissions standards.

That's also why SCR using DEF is superior, burn properly and then eliminate the NOX.

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1 hour ago, Cattech said:

Cummins PT, Cat EUI, MUI, HEUI injectors are not a common rail fuel system. They create working injection pressure in the injector.

Common rail systems as stated above use an engine driven pump to build pressure that is available to all injectors at all times via the "common rail", the injectors then open/close electronically. Common rail systems generally can vary the injection pressure at the rail, and can attain stupid high pressure... imagine 30,000 PSI.

The advantage of common rail is that injection timing is independent of mechanical timing. It is more precise and allows multiple injections on each firing stroke. Instead of one shot of fuel, they can inject several small shots effectively giving cleaner, lower temperature burn. In the case of some newer engines that have a DPF, regeneration is achieved by giving a small shot of fuel while the exhaust valve is open - eliminating the need for additional afterburn equipment.

A good portion of common rail fuel systems have a tank mounted or inline low pressure fuel delivery system. These usually contain a constant bleed valve or orifice to remove air. It is imperative that no oxygen is present when the HPP pressurizes the fuel to the extreme pressures.  

My concrete buddy called last night wondering how much return flow a JD or other common rail setup has. His question was they blend no 1 and no 2 fuel. On older engines and Cummins m11 or those types they return a lot of fuel so once fuel has warmed it won’t gel as easily. Do you know how much say a cat system returns?

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11 minutes ago, dale560 said:

My concrete buddy called last night wondering how much return flow a JD or other common rail setup has. His question was they blend no 1 and no 2 fuel. On older engines and Cummins m11 or those types they return a lot of fuel so once fuel has warmed it won’t gel as easily. Do you know how much say a cat system returns?

For the most part, common rail systems return very little fuel and what does return doesn't pass through anything warm.

Go back to a unit injector system, such as a Cat 3406E, tons of fuel is returned and it flows through a passage in the cylinder head, meaning it comes back to the tank much warmer than it left.

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1 minute ago, Cattech said:

For the most part, common rail systems return very little fuel and what does return doesn't pass through anything warm.

Go back to a unit injector system, such as a Cat 3406E, tons of fuel is returned and it flows through a passage in the cylinder head, meaning it comes back to the tank much warmer than it left.

That is what I told him last night I didn’t think it did a lot. Just couldn’t remember the exact routing of fuel return on his JD 6068 in a payloader. He has a few cat payloader, case  and a JD. As you mention the Cat  ,Cummins and others return a fair amount. Even the old IH engines 06 through 66 return to tank above and nestled in so some heat from engine transfers up.

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5 minutes ago, Cattech said:

Go back to a unit injector system, such as a Cat 3406E, tons of fuel is returned and it flows through a passage in the cylinder head,

I was always told 60 gallons an hour are returned on 3406E and C15 cats

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1 hour ago, Cattech said:

Thank the EPA. Higher burn temps are what causes Nox. Had Nox not been an issue, we wouldn't need a DPF as engines had nearly eliminated particulate matter before emissions standards.

That's also why SCR using DEF is superior, burn properly and then eliminate the NOX.

Us diesel emissions are so far behind Europe.  I heard 30 to 40 percent egr. Worked on some power strokes, the 6.7 piezo injectors worked quite well had from what I heard 5 squirts per injection cycle. I didn't like the dpf regen. The rear two cylinders injected on the ex stroke but some if the diesel made it past the rings into the oil. Ford  TSB said to change the oil if you have more than a gallon of dilution  and  a service wrighter said start with 2 qt low.

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We see fuel dilution quite often these days, mainly in the smaller engines and winter months - more idle time and the cold air.

These emissions systems just aren't built for winter climates. I see machines go thousands of trouble free hrs when they're primarily summer workers. Take one that runs more in winter and treated like a pre-emissions machine, or doesn't get worked hard enough, and the problems never stop.

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Sorry for the misinformation.  I considered the early mechanical and modern systems both common rail.  After looking closer there are more differences than I realized. 

The reliability of the electric common rail systems seems to be much lower than the mechanical systems. 

Thx-Ace

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55 minutes ago, Cattech said:

We see fuel dilution quite often these days, mainly in the smaller engines and winter months - more idle time and the cold air.

These emissions systems just aren't built for winter climates. I see machines go thousands of trouble free hrs when they're primarily summer workers. Take one that runs more in winter and treated like a pre-emissions machine, or doesn't get worked hard enough, and the problems never stop.

Yes they just had trouble in town with one of their dump trucks. New used 2013 freight liner with dd13 Detroit. They don’t get taken out of town so it wouldn’t regenerate. After a few hours they figured out how to force a regen idling. 

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What is your fuel return statement? Is that a common circulation of your fuel? Tank to engine, engine return to tank? How is that done on a stock system? When I was reading up on FASS it was a selling point of fuel return and constant cleaning of your fuel, especially any water particulates, I also went with a sump in the tank bottom instead of having a drop tube from the top so I wouldn’t have the 1/4 tank quandary when driving and the scavenging would keep the tank cleaner, I think.🤔 

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45 minutes ago, Dasnake said:

What is your fuel return statement? Is that a common circulation of your fuel? Tank to engine, engine return to tank? How is that done on a stock system? When I was reading up on FASS it was a selling point of fuel return and constant cleaning of your fuel, especially any water particulates, I also went with a sump in the tank bottom instead of having a drop tube from the top so I wouldn’t have the 1/4 tank quandary when driving and the scavenging would keep the tank cleaner, I think.🤔 

Exactly. Here in cold climates extremely cold climates. You can get by blending Winter and good clean summer fuel. Most stations sell a 50/50 treated winter blend. If you are really worried a few stations carry straight No 1 winter fuel. If you farm and ranch and stay close to home you can blend your own fuel maybe 70/30 for a high return rate engine and 50/50 for a less return. The high return engines will actually melt the snow on a fuel tank in milder weather.

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7 hours ago, Cattech said:

Common rail systems as stated above use an engine driven pump to build pressure that is available to all injectors at all times via the "common rail", the injectors then open/close electronically. Common rail systems generally can vary the injection pressure at the rail, and can attain stupid high pressure... imagine 30,000 PSI.

So were IH pumps like the "A"'s on the way to common rail?

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A little off topic but why would anyone blend fuel on their own?  It just seems like a lot of work unless they have multiple bulk tanks or have the fuel supplier blend it for them.  We either have dyed or undyed number 1.  Our fuel supplier will put additives in for winter etc at time of delivery if requested.

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I don’t know an answer to your query but I reread dales, and I wonder if his second paragraph explains a want or need to mix, the only mix I would ever do is additives to keep the fuel healthy just like I do with gasoline, but if you have multi vehicles and find you need different mixes to run each I guess that’s a reason, for me the only close scenario is my bike with an early 80s engine that was born to leaded fuel and I have to add additional stuff to raise my octane rating. Just a thought.

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