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  #1  
Old 01-24-2013, 12:45 PM
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Fuel pressure problem solved '80 300SD

Thanks to Barry12345 and Diesel911 for their help.....
Pressure @ idle = 11 psi but slowly goes back to zero....RPM @ 3000 pressure goes up to near 30 but returns to zero within 12 seconds while RPM remained @ 3000....TANK SCREEN WAS COVERED WITH WHAT LOOKED LIKE MUD.....Installed Stanadyne FM-100 5 micron filter between lift pump and prefilter...pressure now holds @ idle see photo's...

Fuel pressure problem solved  '80 300SD-dscf0002.jpgFuel pressure problem solved  '80 300SD-dscf0006.jpgFuel pressure problem solved  '80 300SD-dscf0003.jpg

Last edited by buch32; 01-24-2013 at 05:24 PM.
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  #2  
Old 01-24-2013, 04:13 PM
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The dual fuel pressure gauges _inside_ the car is kind of cool and frightening at the same time. I am curious where you were measuring. Was it before and after the fuel filter?
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'95 E300D - White, grey interior. (Suffering from stuck/broken glow plugs)

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"Thou shalt not see thy brother's ass or his ox fall down by the way, and hide thyself from them: thou shalt surely help him to lift them up again."
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  #3  
Old 01-24-2013, 04:15 PM
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Quote:
Originally Posted by fdanielson View Post
I am curious where you were measuring. Was it before and after the fuel filter?
Duh. I just looked at your pictures again. Never mind.
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'82 300D - Light Ivory, 2nd Owner (Back in the wind April 2013!)

'95 E300D - White, grey interior. (Suffering from stuck/broken glow plugs)

Deuteronomy 22:4-
"Thou shalt not see thy brother's ass or his ox fall down by the way, and hide thyself from them: thou shalt surely help him to lift them up again."
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  #4  
Old 02-19-2013, 11:13 AM
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Quote:
Originally Posted by buch32 View Post
Thanks to Barry12345 and Diesel911 for their help.....
Pressure @ idle = 11 psi but slowly goes back to zero....RPM @ 3000 pressure goes up to near 30 but returns to zero within 12 seconds while RPM remained @ 3000....TANK SCREEN WAS COVERED WITH WHAT LOOKED LIKE MUD.....Installed Stanadyne FM-100 5 micron filter between lift pump and prefilter...pressure now holds @ idle see photo's...

Attachment 108853Attachment 108851Attachment 108852
Liquid filed gauges installed in glove box....Barry12345 suggestion
Attached Thumbnails
Fuel pressure problem solved  '80 300SD-dscf0027.jpg   Fuel pressure problem solved  '80 300SD-dscf0028.jpg  
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  #5  
Old 02-19-2013, 11:32 AM
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Quote:
Originally Posted by buch32 View Post
Liquid filed gauges installed in glove box....Barry12345 suggestion
Not a good idea long term. Copper capillary tubes will eventually crack from vibration and leak and strand you not to mention the mess. If you must have fuel pressure gauges inside longterm, use elec pressure senders.
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  #6  
Old 02-19-2013, 12:00 PM
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Why would you want fuel pressure gauges in the car after the problem is fixed? I can't see any reason why they would be that necessary.
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  #7  
Old 02-19-2013, 12:11 PM
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The copper fatigue if it becomes an issue should occur in the area of highest vibration. That is closer to the engine in my opinion. Remember that failure of the oil sendors pressure line on the average 616 0r 617 is virtually unheard of.

At this moment I am not sure of the fluid filled tubes composition on the oil pressure gauge. Some have gone 500k or more by now . Supporting the tube in the areas of maximum vibrations also can reduce vibration fatigue problems.

Having the gauges is more important than that extreme possibility in my opinion anyways. I know you have at least one aftermarket gauge in your own system

Plastic feed lines could virtually eliminate any concern if used.. The nice additional bonus of the need for fluid filled mechanical gauges. If an internal gauge leak evolves it will in all probablity be confined to the sealed gauge. Unlike the mechaniucal oil presure gauges.
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  #8  
Old 02-19-2013, 12:32 PM
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Originally Posted by eatont9999 View Post
Why would you want fuel pressure gauges in the car after the problem is fixed? I can't see any reason why they would be that necessary.
They just for starters inform you when the fuel filters should be changed out. Also great early warning indicators of things like the lift pump may be failing or some form of obstruction is forming up in the system somewhere. Greatly aid in troubleshooting issues as well.

Running with low fuel pressure reduces milage. Reduces the quality of the engine idle and increases engine noise especially on the highway.

It is my somewhat unproven belief constant low fuel pressure will take the first cylinders rod bearing out over time. Almost for certain on the 616 four cylinder engines. Less certan on the 617 five cylinder engine but still a probability. There are some reasons the 616 engine is more prone to this.

Pressure gauge installed permanently or not. You should at least know where your fuel pressure in the base of the injection pump is. The upside of this is far greater than the downside. It is still fairly safe to say the vast majority of members at this time have no knowledge if they have even adaquate fuel pressure as these engines will still run seemingly decent at very substandard pressures. In my opinion there is a price to be paid for doing so one way or another.

The high milage expert on our site is not talking much. Still i think the fuel pressure he is running at is beyond what I suspect the recommended maximum pressure is. It is only one of a host of modifications he has done.

I am starting to think what he is doing in this area of boosting the fuel pressure higher is safe but still cannot recommend it without certain tests I would have to do.

At about thirty two miles per gallon at fairly high speeds I thought there was no further room for improving his milage. Yet he was getting 35 or more miles per gallon just awhile ago steadily. Drives a thousand miles a week as well back and forth to work and his observations are reliable in my opinion. He also does not vend cars on ebay. This is one heavy old 617 type engined sled he is doing this with.

I forgot to mention that good pressure increases power as well. So there is absolutly no downside I can think of to actually knowing you have it. Anyways if you have the gauge is it really of better use sittting in your tool box even if just installed in the engine bay? You had to hook it up to use it anyways.

Last edited by barry12345; 02-19-2013 at 12:50 PM.
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  #9  
Old 02-19-2013, 12:35 PM
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Originally Posted by eatont9999 View Post
Why would you want fuel pressure gauges in the car after the problem is fixed? I can't see any reason why they would be that necessary.
The reasons I like the gauges are listed in the 27 page post FUEL PRESSURE RELIEF VALVE ADJUSTMENT... APPRECIATE YOUR QUESTION
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  #10  
Old 02-19-2013, 12:47 PM
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Originally Posted by barry12345 View Post
They just for starters inform you when the fuel filters should be changed out. Also great early warning indicators of things like the lift pump may be failing or some form of obstruction is forming up in the system somewhere. Greatly aid in troubleshooting issues as well.

Running with low fuel pressure reduces milage. Reduces the quality of the engine idle and increases engine noise especially on the highway.

It is my somewhat unproven belief constant low fuel pressure will take the first cylinders rod bearing out over time. Almost for certain on the 616 four cylinder engines. Less certan on the 617 five cylinder engine but still a probability. There are some reasons the 616 engine is more prone to this.

Pressure gauge installed permanently or not. You should at least know where your fuel pressure in the base of the injection pump is. The upside of this is far greater than the downside. It is still fairly safe to say the vast majority of members at this time have no knowledge if they have even adaquate fuel pressure as these engines will still run seemingl decent at very substandard pressures. In my opinion there is a price to be paid for doing so one way or another.

The high milage expert on our site is not talking much. Still i think the fuel pressure he is running at is beyond what I suspect the recommended maximum pressure is. It is only one of a host of modifications he has done.

I am starting to think what he is doing in this area of boosting the fuel pressure higher is safe but still cannot recommend it without certain tests I would have to do.

At about thirty two miles per gallon at fairly high speeds I thought there was no further room for improving his milage. Yet he was getting 35 or more miles per gallon just awhile ago steadily. Drives a thousand miles a week as well back and forth to work and his observations are reliable in my opinion. He also does not vend cars on ebay.

I forgot to mention that good pressure increases power as well. So there is absolutly no downside I can think of to actually knowing you have it.
AFTER I CLEANED THE TANK SCREEN MY PRESSURE WAS STILL BELOW SPEC.
SINCE ADJUSTING THE RELIEF SPRING THE CAR IDLES MUCH BETTER AND HAS MUCH MORE POWER...THANKS AGAIN TO YOU AND DIESEL911
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  #11  
Old 02-19-2013, 01:18 PM
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You could replace the Copper Tube with the Nylon Tubing that is typically used for that purpose.
If you used the Copper Tubing with the compression Fittings the Nylon Tube will directly replace it.
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  #12  
Old 02-19-2013, 02:03 PM
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Originally Posted by Diesel911 View Post
You could replace the Copper Tube with the Nylon Tubing that is typically used for that purpose.
If you used the Copper Tubing with the compression Fittings the Nylon Tube will directly replace it.
I have the Nylon tubing and may change to it before I finalize the project....
Some of my friends and my local parts guys said that copper is much safer than typical tubing...Nylon makes for a much easier installation..
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  #13  
Old 02-19-2013, 02:19 PM
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Originally Posted by buch32 View Post
I have the Nylon tubing and may change to it before I finalize the project....
Some of my friends and my local parts guys said that copper is much safer than typical tubing...Nylon makes for a much easier installation..
Forgot to mention...installed the FM-100 5 micron fuel fliter
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  #14  
Old 02-19-2013, 03:33 PM
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Got a fuel pressure gauge on my Wanderlodge and I like it.
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  #15  
Old 02-19-2013, 11:50 PM
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This gentleman is running close to the top end of the current recommended pressure range. That is known as certainly safe to do.

I think the fuel pressure is implict in the injection pumps profile of the sequential injection point of each element in relationship to each other. If not that then in the volume of fuel flow from each injector being equal.

Good fuel pressure equalises this and is to be expected as bosch the manufacturer of the injection pump always stated at what pressure they wanted the injection pumps calibrated.

Someday someone is going to do a milli volt examination of how much higher the fuel pressure can be taken without upsetting the power balance of the engine.

With low fuel pressure the power balance is off. Loading the first element of the injector pump better than the last one in the string especially is the effect I suspect. Of course the change is progressive right down the line.

Thirty pounds pressure makes a further major differance but without the testing may be tilting the power balance the other way or opposite to what low fuel pressure does.

If testing properly does not indicate this is a problem we should all use still higher pressure. Unfortunatly I feel bosh was well aware of this area but may have designed less than possible results for some reason. Or ran across objectional issues.

The test setup to prove this one way or another is not all that complex as I visualise it. Since these indirect injection engines are not as critical as direct injection engines. There may still be some safe headroom pressure wise.

I know there are people runing thirty pounds base fuel pressure out there for quite a time now but have performed no tests to see what engine effects might be there long term that I am aware of.

So currently unfortunatly I as an individual cannot recomend this practice even though the benifits of doing so are substantial and known to some.

The 616 four cylinder engine especially needs all the power we can safely make it deliver. So at some point hopefully I will do the comprehensive testing that should be done for elevated fuel pressures. Or a better statement is to establish if any risk factors are present by using it.

One of my viewpoints that has never changed since established. . If a person owns a 616 four cylinder engine and does not check their fuel pressure. It may ultimatly cost them the engine. This warning is worth repeating from time to time even if it just saves a few engines.

A good injection pump rebuilder with a variable fuel pressure supply could answer this issue in a very short order. Or if an injection pump is re calabrated at thirty pounds pressure should be totally safe. Testing would decide if the recalibration was a neccesary component of dealing with elevated fuel pressures.

My most recent thoughts are that bosch knew about this and they decided without a permanent fuel pressure gauge installed there would be serious issues down the road. If a injection pump is calabrated at thrty pounds supply presure for example. And an owner is negigent in maintaining a good operating pressure. As has already been proven the case with a lot of of these older models.

The results would have been more catastrophic than they have been. Also bosh had to supply a system at a price. A higher fuel pressure system cost more to produce. Part of the problem right now is the 616 uses a lower pressure output lift pump than the turbo 617 does. Making partial filter obstruction with use more detremental than on the turbo engines.

This leaving fuel filters in service till they really load up is just one of the serious causes of engine failures if the practice is of long standing in my opinion.

Some site members including myself like bargains. If you can get a fuel pressure gauge installed on your car for around twenty dollars. It is one g bargain that is hard to beat.

In one way or another it can pay its cost just in increased fuel milage benifits fairly short term. Many have reported years ago that they observed changing their fuel filter out increased their milage.

Superficially one would expect either higher or simular fuel milage with less available fuel pressure because of a restricting fuel filter. What was not generally realised then is that under low fuel pressure the engines power balance was being distorted. Reducing it's efficiency.

A gauge clearly informs you by dropping fuel pressure that either a filter change is required or something else is going wrong. One of it's real strengths is it's application as an early warning device. This area is worth rehashing in my opinion as it is somewhat signifigant.
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