Re: 3126 Injector Failure

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glennbarney@rocketmail.com
Posts: 8
Joined: Thu Nov 17, 2011 9:29 am

Re: 3126 Injector Failure

Post by glennbarney@rocketmail.com »

'Bowhunter,
Looking at your pictures, you are definitely leaking, and not just fuel. You are also leaking air into the system when running. That is why the fuel level is so low in the filter screen. My old filter screen always looked like this as well, and I thought it was normal. Dave Atherton assured me it isn't, and that the screen housing should always be filled with fuel.
The plastic housing also looks yellowed, indicating it is quite old. The plastic can develop micro-cracks as it ages that will also cause air leaks. I would suggest replacing the screen. 
After I replaced my screen, and after multiple purges, it stays full of fuel just like Dave Atherton said it should.
Glenn Barney'97 Continental 4006
'
Keith Bowers
Posts: 218
Joined: Mon Nov 24, 2014 1:55 pm

Re: 3126 Injector Failure

Post by Keith Bowers »

'A little CLARITY about how fuel flow effects a diesel engine.   A diesel ALWAYS run in a 'fuel limited-fuel lean' combustion mode.  Power output is ALWAYS limited by fuel input--whether from reduced throttle position  or fuel filter restriction--- the actual impact on engine combustion/power output is exactly the same--a reduction in power output..   There is no possible 'overheating' condition caused by fuel flow reduction per combustion stroke--regardless of how it is caused
This IS different from a spark ignition engine where all the fuel is already in the combustion chamber before ignition, and a too lean mixture can burn hotter and slower than an ideal mixture.  In a diesel engine, combustion of fuel starts a few milliseconds after injection starts, and continues until injection stops.  There is ALWAYS lots more air available to burn more fuel.  Fuel injection RATE through the injector nozzle is the same--only the duration of injection TIME is shortened or lengthened by changing the throttle position (actually the injector pump setting as the air flow is not changed by throttle position). 
The diesel engine combustion cycle burns the fuel  in a continuous, stationary, constant intensity, flame as fuel is injected. Only if the injector nozzle is defective (not atomizing the fuel but spraying streams of fuel) is the combustion adversely impacted by a shortened injection period (reduced throttle opening.)
In other words, plugged fuel filters can not cause overheating, but will reduce max power output available.
HOWEVER, AIR in the fuel flow TO THE INJECTOR PUMP and INJECTOR WILL CAUSE miss-fire and erratic firing and drastically reduced power output.  The injector pump cannot deliver a steady fuel flow rate (and pressure) to the injectors and the injectors will not deliver a constant fuel flow into the combustion chamber during the injection period---thus resulting in uneven burning and reduced power output. 
Please note that a restricted fuel flow TO the injector pump will cause erratic injection and no injection. 



'
TD
Posts: 767
Joined: Fri May 16, 2014 4:01 am

Re: 3126 Injector Failure

Post by TD »

'Keith,

It's not that simple, especially with the CAT injection system (no injection pump). Air in fuel and to a degree, fuel restriction, cause poor spray pattern (less pressure to atomize the fuel properly) and more importantly, it will delay fuel injection/combustion. This is the equivalent of retarding the timing, which will cause the engine to run hotter, and also cause exhaust gas temps to rise. This condition is magnified at full load, like when our coaches climb steep grades. I would venture to guess that Glenn's lower temps resulted from resolving the combination of both, air in fuel and passive fuel starvation.

John
'95 Safari Serengeti 38ft, 300 Cummins 8.3CTA, Allison
6spd.


On Wed, May 23, 2018 at 12:31 PM, Keith Bowers kebowers47@... [Safarifriends] wrote:


A little CLARITY about how fuel flow effects a diesel engine.   A diesel ALWAYS run in a 'fuel limited-fuel lean' combustion mode.  Power output is ALWAYS limited by fuel input--whether from reduced throttle position  or fuel filter restriction--- the actual impact on engine combustion/power output is exactly the same--a reduction in power output..   There is no possible 'overheating' condition caused by fuel flow reduction per combustion stroke--regardless of how it is caused
This IS different from a spark ignition engine where all the fuel is already in the combustion chamber before ignition, and a too lean mixture can burn hotter and slower than an ideal mixture.  In a diesel engine, combustion of fuel starts a few milliseconds after injection starts, and continues until injection stops.  There is ALWAYS lots more air available to burn more fuel.  Fuel injection RATE through the injector nozzle is the same--only the duration of injection TIME is shortened or lengthened by changing the throttle position (actually the injector pump setting as the air flow is not changed by throttle position). 
The diesel engine combustion cycle burns the fuel  in a continuous, stationary, constant intensity, flame as fuel is injected. Only if the injector nozzle is defective (not atomizing the fuel but spraying streams of fuel) is the combustion adversely impacted by a shortened injection period (reduced throttle opening.)
In other words, plugged fuel filters can not cause overheating, but will reduce max power output available.
HOWEVER, AIR in the fuel flow TO THE INJECTOR PUMP and INJECTOR WILL CAUSE miss-fire and erratic firing and drastically reduced power output.  The injector pump cannot deliver a steady fuel flow rate (and pressure) to the injectors and the injectors will not deliver a constant fuel flow into the combustion chamber during the injection period---thus resulting in uneven burning and reduced power output. 
Please note that a restricted fuel flow TO the injector pump will cause erratic injection and no injection. 




'
bowhunter0608
Posts: 57
Joined: Fri Apr 07, 2017 7:23 am

Re: 3126 Injector Failure

Post by bowhunter0608 »

'I am looking at for now to juts purchase the retro kit, that will take care of the issue so i can get the Coach down top Coburg to get the Windshield fixed. After that. i will consider converting over to the Cat water separator with manual primer or convert to an electric one like some have done. As for now, $90 is what i can afford.
Jerry99 Continental Panther 425 Cat C12'
Keith Bowers
Posts: 218
Joined: Mon Nov 24, 2014 1:55 pm

Re: 3126 Injector Failure

Post by Keith Bowers »

'Delayed fuel injection will reduce power output due to less time force is applied to piston turning crankshaft. However, compressible fuel (dissolved air or actual bubbles in fuel) will also dramatically reduce VOLUME OF FUEL injected per cycle. The delayed start of injection is a contributor, but the decreased volume of fuel per cycle is the main contributor to power reduction. Less fuel injected equals less combustion heat equals less heat the coolant must remove. The detailed analysis is complex and imprecise as it changes with each injection cycle as injected volume varies all over the place--from none to 'nearly normal' . The net average is less injected fuel to burn and lower efficiency in combustion, AND possibly increased exhaust gas temperature (but lower mass) 
It is not worth arguing the finer points of this condition however.  Plugged fuel filters or air in fuel to the injector pump (whether a multi piston pump  a-la-Bendix-or individual oil pressure driven injectors) WILL cause poor or no running.  A MAJOR contributor to diesel injector wear is water and bacteria slime as both cause erosion of the nozzles and the black slime is corrosive and  will plug them also. Blaolck Slime is more prevalent in the Ultra-low-sulfur era as the pristine fuel is a better 'food' with much lower 'toxic stuff' inhibiting slime growth. ULSD approaches the 'purity' of medicinal white oil. It has less than 0.1% of the sulfur #2 Diesel used to have and ZERO phenolic compounds that used to inhibit bacteria growth.
On Wed, May 23, 2018 at 2:52 PM, TD sdjhtm@... [Safarifriends] wrote:
 
Keith,

It's not that simple, especially with the CAT injection system (no injection pump). Air in fuel and to a degree, fuel restriction, cause poor spray pattern (less pressure to atomize the fuel properly) and more importantly, it will delay fuel injection/combustion. This is the equivalent of retarding the timing, which will cause the engine to run hotter, and also cause exhaust gas temps to rise.. This condition is magnified at full load, like when our coaches climb steep grades. I would venture to guess that Glenn's lower temps resulted from resolving the combination of both, air in fuel and passive fuel starvation.

John
'95 Safari Serengeti 38ft, 300 Cummins 8.3CTA, Allison
6spd.



On Wed, May 23, 2018 at 12:31 PM, Keith Bowers kebowers47@... [Safarifriends] wrote:


A little CLARITY about how fuel flow effects a diesel engine.   A diesel ALWAYS run in a 'fuel limited-fuel lean' combustion mode.  Power output is ALWAYS limited by fuel input--whether from reduced throttle position  or fuel filter restriction--- the actual impact on engine combustion/power output is exactly the same--a reduction in power output..   There is no possible 'overheating' condition caused by fuel flow reduction per combustion stroke--regardless of how it is caused
This IS different from a spark ignition engine where all the fuel is already in the combustion chamber before ignition, and a too lean mixture can burn hotter and slower than an ideal mixture.  In a diesel engine, combustion of fuel starts a few milliseconds after injection starts, and continues until injection stops.  There is ALWAYS lots more air available to burn more fuel.  Fuel injection RATE through the injector nozzle is the same--only the duration of injection TIME is shortened or lengthened by changing the throttle position (actually the injector pump setting as the air flow is not changed by throttle position). 
The diesel engine combustion cycle burns the fuel  in a continuous, stationary, constant intensity, flame as fuel is injected. Only if the injector nozzle is defective (not atomizing the fuel but spraying streams of fuel) is the combustion adversely impacted by a shortened injection period (reduced throttle opening.)
In other words, plugged fuel filters can not cause overheating, but will reduce max power output available.
HOWEVER, AIR in the fuel flow TO THE INJECTOR PUMP and INJECTOR WILL CAUSE miss-fire and erratic firing and drastically reduced power output.  The injector pump cannot deliver a steady fuel flow rate (and pressure) to the injectors and the injectors will not deliver a constant fuel flow into the combustion chamber during the injection period---thus resulting in uneven burning and reduced power output. 
Please note that a restricted fuel flow TO the injector pump will cause erratic injection and no injection. 








--
We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm.   -Winston Churchill- '
Bill Edwards
Posts: 418
Joined: Sun Jan 17, 2016 12:59 pm

Re: 3126 Injector Failure

Post by Bill Edwards »

' Makes total sense to me but others questionable sometimes. 
On Wednesday, May 23, 2018, 8:13:03 PM MDT, Keith Bowers kebowers47@... [Safarifriends] wrote:


 
Delayed fuel injection will reduce power output due to less time force is applied to piston turning crankshaft. However, compressible fuel (dissolved air or actual bubbles in fuel) will also dramatically reduce VOLUME OF FUEL injected per cycle. The delayed start of injection is a contributor, but the decreased volume of fuel per cycle is the main contributor to power reduction. Less fuel injected equals less combustion heat equals less heat the coolant must remove. The detailed analysis is complex and imprecise as it changes with each injection cycle as injected volume varies all over the place--from none to 'nearly normal' . The net average is less injected fuel to burn and lower efficiency in combustion, AND possibly increased exhaust gas temperature (but lower mass) 
It is not worth arguing the finer points of this condition however..  Plugged fuel filters or air in fuel to the injector pump (whether a multi piston pump  a-la-Bendix-or individual oil pressure driven injectors) WILL cause poor or no running.  A MAJOR contributor to diesel injector wear is water and bacteria slime as both cause erosion of the nozzles and the black slime is corrosive and  will plug them also. Blaolck Slime is more prevalent in the Ultra-low-sulfur era as the pristine fuel is a better 'food' with much lower 'toxic stuff' inhibiting slime growth. ULSD approaches the 'purity' of medicinal white oil. It has less than 0.1% of the sulfur #2 Diesel used to have and ZERO phenolic compounds that used to inhibit bacteria growth.
On Wed, May 23, 2018 at 2:52 PM, TD sdjhtm@... [Safarifriends] wrote:
 
Keith,

It's not that simple, especially with the CAT injection system (no injection pump). Air in fuel and to a degree, fuel restriction, cause poor spray pattern (less pressure to atomize the fuel properly) and more importantly, it will delay fuel injection/combustion. This is the equivalent of retarding the timing, which will cause the engine to run hotter, and also cause exhaust gas temps to rise.. This condition is magnified at full load, like when our coaches climb steep grades. I would venture to guess that Glenn's lower temps resulted from resolving the combination of both, air in fuel and passive fuel starvation.

John
'95 Safari Serengeti 38ft, 300 Cummins 8.3CTA, Allison
6spd.



On Wed, May 23, 2018 at 12:31 PM, Keith Bowers kebowers47@... [Safarifriends] wrote:


A little CLARITY about how fuel flow effects a diesel engine.   A diesel ALWAYS run in a 'fuel limited-fuel lean' combustion mode.  Power output is ALWAYS limited by fuel input--whether from reduced throttle position  or fuel filter restriction--- the actual impact on engine combustion/power output is exactly the same--a reduction in power output..   There is no possible 'overheating' condition caused by fuel flow reduction per combustion stroke--regardless of how it is caused
This IS different from a spark ignition engine where all the fuel is already in the combustion chamber before ignition, and a too lean mixture can burn hotter and slower than an ideal mixture.  In a diesel engine, combustion of fuel starts a few milliseconds after injection starts, and continues until injection stops.  There is ALWAYS lots more air available to burn more fuel.  Fuel injection RATE through the injector nozzle is the same--only the duration of injection TIME is shortened or lengthened by changing the throttle position (actually the injector pump setting as the air flow is not changed by throttle position). 
The diesel engine combustion cycle burns the fuel  in a continuous, stationary, constant intensity, flame as fuel is injected. Only if the injector nozzle is defective (not atomizing the fuel but spraying streams of fuel) is the combustion adversely impacted by a shortened injection period (reduced throttle opening.)
In other words, plugged fuel filters can not cause overheating, but will reduce max power output available.
HOWEVER, AIR in the fuel flow TO THE INJECTOR PUMP and INJECTOR WILL CAUSE miss-fire and erratic firing and drastically reduced power output.  The injector pump cannot deliver a steady fuel flow rate (and pressure) to the injectors and the injectors will not deliver a constant fuel flow into the combustion chamber during the injection period---thus resulting in uneven burning and reduced power output. 
Please note that a restricted fuel flow TO the injector pump will cause erratic injection and no injection. 










--
We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm.   -Winston Churchill- '
astrnmrtom
Posts: 167
Joined: Thu Oct 31, 2019 8:49 pm

Re: 3126 Injector Failure

Post by astrnmrtom »

'Glenn,
Thanks for that info on the Racor retrofit kit. I put one in my rig last year and wasn't aware of the smaller flow rating. I'll be ordering the larger filter soon. My engine temps rise a little higher than I think they should be under load, and my radiator stack is clean so I wonder if you didn't just solve the puzzle. I'll be real curious to see the temps after installing the proper filter.
The other leakpoint on those systems beside the o-rings is the plastic pre-screen housing itself. The seam at the bottom can crack letting in air and can weep fuel. Mine hasn't cracked yet, but I carry a new one as a spare. With the age of the unit I'm sure its only a matter of time.
Tom Masterson1998 Serengeti 3706300hp Cat, Allison 3060'
Tom and Pris Masterson, w/ Buddy the 18 year old Siamese cat.
1998 Serengeti 3706
300hp Cat 3126, Allison 3060
900 Watts of Solar
17cf, Fisher & Paykel residential Refrigerator
Dragging four telescopes around the US seeking dark skies.
Keith Bowers
Posts: 218
Joined: Mon Nov 24, 2014 1:55 pm

Re: 3126 Injector Failure [4 Attachments]

Post by Keith Bowers »

'Attachments :What is the MAXIMUM fuel consumption rate of the highest horsepower RV engine—say 450 Hp ?    Sent from Mail for Windows 10  From: Safarifriends@yahoogroups.com
Sent: Wednesday, May 23, 2018 1:17 AM
To: Safarifriends@yahoogroups.com
Subject: [Safarifriends] Re: 3126 Injector Failure [4 Attachments]    [Attachment(s) from bowhunter0608@... [Safarifriends] included below]
So, reading this has given me some insight as to my leak issue. I noticed last week that i had a nice fule puddle under my Continental. Looks to me like it is coming from the bottom of the housing, as you can see in the pictures. I googled the Parker Filter number, it comes up as a Racor replacement, however it states it is only 60 gph, not the 90 ,that is recommended. I seen the 700 series retrofit kit from Parker, $91 is not a bad price, however not sure if that is what i need. Right now, i would ,just like to get the leak stopped.      '
Bill Edwards
Posts: 418
Joined: Sun Jan 17, 2016 12:59 pm

Re: 3126 Injector Failure [1 Attachment]

Post by Bill Edwards »

' NO SOME IN THE 600 RANGE!  SMC 505hp in the Beavers and generally 425 but some 455 in the Safari line. I,m guessing but probably still fall under the  90 gallon range, the capacity of the WInn/Racor pre filter units. Really I have no idea
Bill Edwards
On Thursday, May 24, 2018, 10:28:59 AM MDT, Keith Bowers kebowers47@... [Safarifriends] wrote:


  [Attachment(s) from Keith Bowers included below]
What is the MAXIMUM fuel consumption rate of the highest horsepower RV engine—say 450 Hp ?    Sent from Mail for Windows 10  From: Safarifriends@yahoogroups.com
Sent: Wednesday, May 23, 2018 1:17 AM
To: Safarifriends@yahoogroups.com
Subject: [Safarifriends] Re: 3126 Injector Failure [4 Attachments]    [Attachment(s) from bowhunter0608@... [Safarifriends] included below]
So, reading this has given me some insight as to my leak issue. I noticed last week that i had a nice fule puddle under my Continental. Looks to me like it is coming from the bottom of the housing, as you can see in the pictures. I googled the Parker Filter number, it comes up as a Racor replacement, however it states it is only 60 gph, not the 90 ,that is recommended. I seen the 700 series retrofit kit from Parker, $91 is not a bad price, however not sure if that is what i need. Right now, i would ,just like to get the leak stopped.       '
Keith Bowers
Posts: 218
Joined: Mon Nov 24, 2014 1:55 pm

Re: 3126 Injector Failure

Post by Keith Bowers »

'My point is it is unlikely the diesel engines in even the highest HP exceeds 25 GPH, a lot lower than the filter rated flow.
On Thu, May 24, 2018 at 6:04 PM, Bill Edwards billedwardsrs@... [Safarifriends] wrote:
 
NO SOME IN THE 600 RANGE!  SMC 505hp in the Beavers and generally 425 but some 455 in the Safari line. I,m guessing but probably still fall under the  90 gallon range, the capacity of the WInn/Racor pre filter units. Really I have no idea
Bill Edwards
On Thursday, May 24, 2018, 10:28:59 AM MDT, Keith Bowers kebowers47@... [Safarifriends] wrote:

  [Attachment(s) from Keith Bowers included below]
What is the MAXIMUM fuel consumption rate of the highest horsepower RV engine—say 450 Hp ?    Sent from Mail for Windows 10  From: Safarifriends@yahoogroups.com
Sent: Wednesday, May 23, 2018 1:17 AM
To: Safarifriends@yahoogroups.com
Subject: [Safarifriends] Re: 3126 Injector Failure [4 Attachments]    [Attachment(s) from bowhunter0608@... [Safarifriends] included below]
So, reading this has given me some insight as to my leak issue. I noticed last week that i had a nice fule puddle under my Continental. Looks to me like it is coming from the bottom of the housing, as you can see in the pictures. I googled the Parker Filter number, it comes up as a Racor replacement, however it states it is only 60 gph, not the 90 ,that is recommended. I seen the 700 series retrofit kit from Parker, $91 is not a bad price, however not sure if that is what i need. Right now, i would ,just like to get the leak stopped.      

--
We sleep soundly in our beds because rough men stand ready in the night to visit violence on those who would do us harm.   -Winston Churchill- '
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