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Kugelfischer flushing - where's the fuel going?


BarrettN

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Ok, having determined that the rest of my 74 tii fuel system is going to need replacing, I decided to try flushing the fuel side of my kugelfischer pump. Blocking off one of the two inlets, and having removed the internals of the pressure relief valve I was thinking that I could just run some carb cleaner into it, let it set, and then flush it out with more cleaner. I'm using clear tubing, so I can easily see the fluid level - and as I squirt carb cleaner in, the level drops down. Not immediately, but in less than a minute. 

 

From what I know the fuel side of the pump should be building up to 28 psi, so I've been assuming that the fuel side of the pump is sealed, otherwise how else can it be pressurized?

 

This wasn't a question of just not putting enough liquid in to fill it, it's going somewhere. If it's leaking external to the pump it's doing it in such a way that I'm not seeing it. I'm going to have to study the cut away drawings of the pump to figure it out if there's a path that fuel can take to the oil side of the pump. I'm suspecting that my oil sump might be a mix of oil and carb cleaner now. 

 

Anyone else experience something like this? Or is there something I've not taken into account or misunderstood that changes my conclusions? 

 

Thanks, 

 

Barrett 

Koboldtopf - '67 1600-2

Einhorn - '74 tii

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The K-Fisch pump is a small 4-inline piston engine, by the time fuel gets to the pump it should be cleaned by the filters and not need to be flushed. If you have indeed put carb cleaner though the oil passage, better change that oil before starting the car. 

Andrew Wilson
Vern- 1973 2002tii, https://www.bmw2002faq.com/blogs/blog/304-andrew-wilsons-vern-restoration/ 
Veronika- 1968 1600 Cabriolet, Athena- 1973 3.0 CSi,  Rodney- 1988 M5, The M3- 1997 M3,

The Unicorn- 2007 X3, Julia- 2007 Z4 Coupe, Ophelia- 2014 X3, Herman- 1914 KisselKar 4-40

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I'm familiar with the fuel filters one a tii - for example I've removed and cleaned the mesh filter of the banjo bolt on the fuel inlet.

 

Given my car appears to have not been run in about ten years, and based on the condition of the rest of the fuel system, my concern is that while the fuel that entered it those 10 years ago may have been clean, that it may have turned to varnish and other desirable gunk in the interim. And who knows if it attracted any moisture and (heaven forbid) caused any rust inside the pump? It sure did inside the fuel tank - my hope is that being that the pump is more of a sealed unit that the fuel tank that it's not the same.

 

I've not run anything through the oil passages of the kugelfischer pump, only the fuel inlet (I blocked off the line that goes to the CSV, and removed the internals of the pressure relief valve (I did that to clean it, left it that way so that the carb cleaner could flow through the pump without needing to be under pressure.)

 

Agreed, the kuglefischer is similar to a small piston engine - I wouldn't expect fuel in a regular piston engine to disappear not knowing where it has gone either.  

Koboldtopf - '67 1600-2

Einhorn - '74 tii

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11 minutes ago, BarrettN said:

my hope is that being that the pump is more of a sealed unit that the fuel tank that it's not the same.

 

Did you reconnect the hose at the pressure relief valve?  I understand that you removed the guts of the valve, so fuel will pass through the KF unobstructed and return to the fuel tank.

 

Does that answer your question as to where the carb cleaner is going?

73 Inka Tii #2762958

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I didn't reconnect the outlet to the return line, I just had a short section of transparent hose on each end of the pump, turned up to make a "U" shape with the pump at the bottom of the U. So essentially the pump was isolated. As I sprayed cleaner into the inlet line I could see the cleaner level in the output tube rise, the inlet level would rise a bit slower. When I stopped spraying after about 30 seconds an air bubble would work its way up the inlet tube and the level would drop and drop. 

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Koboldtopf - '67 1600-2

Einhorn - '74 tii

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We've seen many dormant tiis brought back to life without the need to run cleaner through the KF.  Not a bad idea, but maybe not necessary.

 

Have you read these:
 

https://www.bmw2002faq.com/articles.html/technical-articles/engine-and-drivetrain/recipe-for-sorting-out-fuel-delivery-problems-in-a-tii-r229/

 

http://www.2002tii.org/kb/59

 

You could try loosening the fuel delivery valves to confirm that fuel is being pumped to the injectors.  With the valves loosened there will be leakage when you turn over the engine.  If there is no leakage, the suction valve(s) may be seized.  

 

Note:  I have seen ONE fuel delivery valve that was defective and blocking passage of fuel to its injector.  There is a chance, I guess, that yours are clogged with old fuel turned to varnish.

73 Inka Tii #2762958

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8 minutes ago, BarrettN said:

When I stopped spraying after about 30 seconds an air bubble would work its way up the inlet tube and the level would drop and drop. 

 

Are the injector lines disconnected?  

 

I can't see fuel (cleaner) getting into the oil passages, but I can see it seeping past the suction valves toward the injectors.  Strange.  

 

More expert advice needed. 

73 Inka Tii #2762958

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My 74 tii power plant was stored and not started for 18 years, I pulled the tank and flushed it clean, ran fresh fuel to the filter, replaced it, then attempted a start. Had leakage at the fuel delivery valves, replaced O rings and it fired and ran. If you need a clean but dented tank and good pump I can help.

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I've read that article by the Hack Mechanic and the one where he pulls the head also. I have downloaded the pump manual and the video as well, but all this, while very helpful with respect to stating what to do, doesn't help me to understand why the fuel side of the pump, which I understand should pressurize to 28 psi, would be allowing the carb cleaner to go anywhere. if the system was pressurized I could see it maybe leaking out an injector, but the system as it is now is just gravity fed, so there's no force to make the fluid go up the injector lines - the liquid height in the output line never gets that high.

 

The injector lines are connected and tight - and I don't see anything weeping past the o-rings for the fuel delivery valves. The volume of carb cleaner disappearing is non-trivial.

 

I have a second kugelfischer pump that I can experiment with, I think that may be my next step.

To cap it off, the diesel injector pop tester I bought seems to show all the injectors opening at a very low pressure, so I'm now questioning my test methodology on that as well. I was so hoping to be able to hook up the injectors I have and potentially come across some in the high 490+ psi, none are anywhere close to that.

Edited by BarrettN
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Koboldtopf - '67 1600-2

Einhorn - '74 tii

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22 minutes ago, BarrettN said:

I have and potentially come across some in the high 490+ psi, none are anywhere close to that.

 

I've found that most decent injectors open between 360 and 400 psi.  A lot open between 300 and 350, while only a few between 400 and 425.   None I've tested opened near 500.  IMHO I believe it's a function of age.

73 Inka Tii #2762958

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If you have your inlet tube and outlet tube for fuel hooked up, you can see the cleaner going in and coming out, correct?   There is only 2 places for the fuel cleaner to go to other than your tubes, internally leaking into the oil passage or to the injectors where it can only go past the pistons into the oil     Check and see if your oil is smelling of fuel cleaner or pull a plug and make sure that it is not wet     Ultimately the only other place it could end up is back into the oil 

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1 minute ago, stephers said:

If you have your inlet tube and outlet tube for fuel hooked up, you can see the cleaner going in and coming out, correct?   There is only 2 places for the fuel cleaner to go to other than your tubes, internally leaking into the oil passage or to the injectors where it can only go past the pistons into the oil     Check and see if your oil is smelling of fuel cleaner or pull a plug and make sure that it is not wet     Ultimately the only other place it could end up is back into the oil 

That's pretty much the conclusion I'd come to as well - I don't see gravity being enough force to cause it to go up the injector tubes and out the injectors, so draining the oil is probably the next step. 

Koboldtopf - '67 1600-2

Einhorn - '74 tii

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You could also disconnect the 2 oil lines ( pressure and return ) and see if the cleaner is coming out of either  Those are the only 2 places for fuel to get into the engine from the actual pump itself.   If both of those are dry, well, then you have an interesting situation   Gravity feed into the pump will not / should not push fuel up thru the suction jets, you need a some pressure to do that , could also remove the inj line connection at the pump and remove the fittings ( only ) and see if any thing comes from there but doubt it very much

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1 hour ago, BarrettN said:

That's pretty much the conclusion I'd come to as well - I don't see gravity being enough force to cause it to go up the injector tubes and out the injectors, so draining the oil is probably the next step. 

Assuming the tii injection pump is similar in design concept to an Alfa SPICA pump, those four little gasoline pistons have tight tolerance fits, but not so tight to prevent a thin solvent to pass by into the fuel injection pump crankcase, especially if the pump has some normal wear. And guess wear the FI pump crankcase gets its lubrication? From your engine oil (at least that's what happens in an Alfa w/SPICA FI). Gas in Oil is a common issue for worn SPICA pumps. Check your oil.

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On 3/2/2020 at 1:17 PM, stephers said:

You could also disconnect the 2 oil lines ( pressure and return ) and see if the cleaner is coming out of either  Those are the only 2 places for fuel to get into the engine from the actual pump itself.   If both of those are dry, well, then you have an interesting situation   Gravity feed into the pump will not / should not push fuel up thru the suction jets, you need a some pressure to do that , could also remove the inj line connection at the pump and remove the fittings ( only ) and see if any thing comes from there but doubt it very much

Good suggestion - I need to check those oil lines as it is. I may be delayed in getting some of this done, my floor jack decided to die, rebuilding it has turned out to be non-trivial as there are a couple of parts where the torque exceeds 500 ft/lbs! Hopefully I get it finished off soon and back to this.

Koboldtopf - '67 1600-2

Einhorn - '74 tii

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