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2002 Turbo Cutting Out

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New to this forum but hope I can ask the experts some questions.



I recently purchased Turbo number 896 but the fun was cut short by an engine cutout at speed, followed by a no-start. After sitting on the roadside for :15 min, I tried the car again and it fired up. This has happened three times recently; each time with the same pattern. 

After reading the Technical Supplement and this board's FAQ on TII fuel delivery, I am thinking that's the culprit. However I wanted to ask the experts.



1)Where is the oil top-off access for the KF piston? Or is it lubricated by the motor?

2) Could this seize and stop fuel?

3) Any recomendations for someone to rebuild the KF?

4) Am I asking the wrong questions?


Thank you



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Welcome to the madness...


I would first check the fuel pressure of your car..




Do you know if the multiple filter screens have been cleaned?  If the fuel tank is grimy,cruddy, then gunk could starve the factory fuel pump above the right rear axle shaft.


The KF pump has a high pressure oil line from the oil filter housing.  You should only need to fill the pump with oil after a rebuild.


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You do need to check the fuel pressure, and leave the gauge hooked up and drive it until you have your misfire, it is very possible you have a fuel pump under the car that is on the way out and stops working when it gets hot. I have had Wes Ingram (Ingram Enterprises) wing@nwlink.com rebuild 4 turbo pumps in the last 5-6 years and they do a great job. He has the flow data from my pumps..

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Thank you for your fast replies!


Jgerock - Am planning to execute your exact recommendation on the fuel filter changes and screen cleaning. The fuel system on my ///M635 really benefitted from the same. Is there a schematic showing all of the filter, pump and screen locations?

Your KF looks a little differnet than mine though the oil filler plug looks to be in the same place. However I am confused about the pump's oil service. The Tech supplement outlines every 8,000 miles the oil be topped off.This seems frequesnt.  I was really thinking the KF pump piston was seizing thus robbing the system of fuel but I guess the only way to find out is to look under the filler screw and verify there is oil present.


Preyupy- The in-line fuel pump is weezing pretty bad. I really hope this is the cause because I would bet a KF rebuild is pricey. Is the Turbo KF resilient and reliable system? Have you ever checked the oil level in your KF? I will start by replacing the "cheap" stuff and work my way up; thanks for Wes' info.


Where do you guys get your parts?


Truly appreciate you both

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See if you can hear the electric fuel pump running if the problem recurs.


But my money is on crud blocking the screen in the tank.


Never heard of the KF pump needing any lubrication service... but I had a tii for only 15 years ;-)


My M635:










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Hi Ray,

The in-line pump starts weezing/squeeling once I turn the key to position 1 and during the no start situation, the in-line pump is still whining. So I ruled out any possible  "fuel relay" related issues (still learning on this car).So that brings me to ask, if the in-line pump was heating up thus causing a loss in fuel pressure, would I still hear it weezing during the no start situation?

I'll check that in-tank screen.


Is your ///M635 Diamant Schwarz oder Schwarz? Most beautiful BMW design IMO.

Edited by m6smitten
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Yeah, check the screen. What usually happens is the tank rusts from the inside, and the flakes, well, they don't float! ;-)


If the pump sound is not consistent it could be due to the partial blockage at the screen(s). Or it could be on its way out. Anyway go find a fuel pressure gauge too. :)


Colour SCHWARZ (086)
Upholstery SCHWARZ LEDER (0159)



Edit: pump rebuilders can be found here: http://web.archive.org/web/20120113082041/http://www.bmw2002faq.com/content/view/66/32/



I didn't see a link from our improved site. I used Precision Automotive Research for mine -- in 1987.


I suggest a wideband afr gauge install before shipping your pump off :)



Edited by ray_koke
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I believe there may be a fine brass screen in the Fuel pump as well if the pump is original- I would check that first. I had the exact running symptoms / problem with my TiSa years ago when dreck (old silicone gasket maker/sealer) would intermittently clog the gas tank output hole.  Flush the tank out. Tell us about the Turbo- share the excitement-?silver?white? where did you get it? Pictures are worth 2002 words.  sincerely,Peter

BTW KF pump rebuilds appx 1100$ when I got mine done.  Hans in Bavaria, NY is the MAN.

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Starting from the rear of the car, your turbo will either have a twist in or bolt in fuel pickup on the large opening of the tank (accessible by removing the right hand trunk board).  Here is a picture of my tank with twist-in fitting opening (note the teeth) and sealing o-ring.  Note the gunk settled at the bottom of the tank.



The bolt-in fuel pickup uses a flat gasket with pre-punched holes.  Make sure to buy a replacement gasket or ring before removing the pickup.  Old gaskets and rings don't seem to work well if reused.

Part number of the sealing ring (twist-in type only)




Here is the first strainer located on the bottom of the pickup.  This one is the first line of defense to the pump.



Moving toward the front of the car, the 18mm fuel hose connects to the inlet of the high pressure fuel pump (under the car) where a conical shaped mesh filter resides. 






The expansion jar/fuel pump mount is located above the RR axle shaft secured to the body with (3) rubber mounts. The jar may rust and leak fuel.


Here is the stock type fuel pump



 Moving to the front of the car, the aluminum fuel filter element (disposable type) is mounted next to the radiator.



The next screen is inside the hex bolt that secures the banjo bolt on the front of the KF pump




The last one (that I know about) is a tiny screen inside the cold start solenoid valve.





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After cleaning all the screens, changing the filter and checking the pressure I would pull out either a graphing multi meter or an oscilloscope and connect in line with power side of the pump wiring (at the fuse should be fine as there aren't any other motors on that circuit) and watch the waveform as the pump operates. There are examples of electric motor waveform viewing online. Let me see if I can find a good one... Be back in a few minutes...

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OK, spent a moment or three to find a decent fuel pump electronic waveform video. In this video the guy connects a waveform viewer to a fuel pump fuse and shows you a pump that has a bad commutator where the amperage current shorts to ground as the pump runs. After replacing the pump he shows a good pattern. There's another thing to look for when watching an electric motor waveform and that's a bad armature shaft and or bad armature bushings. With that you'd see an otherwise normal waveform pattern but the whole would have a wave to it, this wold be the armature wobbling around as it spins. Imagine little waves on the surface with bigger waves rolling through.


A better video. This one with the same amp clamp that I use and a simpler fuse adapter like I use. This user is showing you one bad commutator but if you watch you can see that the pattern here has a wave to it as well.


OK, now that I have you thoroughly confused and thinking that you need super expensive specialized automotive test equipment to view oscilloscope waveforms, you don't.... There are so many inexpensive oscilloscope options these days, the easiest being a USB Oscilloscope converter for your laptop with a low range current probe (I also have a higher range one for charging systems). Here's an excellent website/store to whet your whistle...



Here's the low current probe I use, only $90...



Search eBay for "USB Oscilloscope" to find some that will let you use your laptop as a scope for roughly $75...


Here's a good pattern example. The waves are the electrical pattern of the brushes making contact on the commutator with the motor running.



I couldn't find a good example of a bad armature waveform, but you can imagine a bigger wave rolling the whole pattern of little ones.


Here's a clear example of one of the commutators being bad:



A picture of a bad commutator or two... where either the brushes or commutator were worn enough to make poor contact causing the dip in the waveform. Sometimes, when the car is turned off and the pump happens to stop on the bad part it won't start spinning again until tapped with a hammer... Same can happen with a starter motor. Just don't do it with a modern small case permanent magnet one...



Another way to check the fuel pump oscilloscope waveform patterns would be to take the car to a friendly Automotive Diagnostics Specialist Shop and see if they'll scope the fuel pump for you. I know I would, but so few do and or don't know how....


If I were preparing race cars a scope check of the electric fuel pump would be on my yearly check list... One shop I worked at it was on the service inspection check list. We had to record a picture or other sample of the fuel pump waveform; sometimes we'd get a fuel pump sale out of it.






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Wow! You guys don't mess around.


Tisalover - will get pics soon and thanks for the (Hans) reference.


Jgerock- I pulled the boards and the tank looks brand new but there is no way to know the "gunk" factor until I get in there. I will pull the suction unit, check the screen and replace the gasket. It is the bolt vs the twist version.

Thanks for the back-to-front rundown of the fuel line. Question: is there a torque setting for the banjo bolt?

I'll be ordering parts Monday. And that was a good heads-up about the fuel filler tank. Another thing to pull apart and inspect prior to my parts order. Great reference pics too!


Tjones02- great info and thanks for your time in putting that detailed explanation together. Being familiar with BMW high-pressure fuel pumps and their sounds (the ///M635 has two fuel pumps) I am sure the in-line pump is dying. However I am going to make it an annual service item to check the  pumps on the '02 and the ///M going forward - great tip.

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Oh I meant to say read every jgerock post ;-)


Tom I may be lazy, but if the fuel pressure checked out (after screens were clean) I'd call the pump good :-)


Mr. smitten there are/is a substitute(s) for the tii electric pump which may be somewhat cheaper -- but I forget what it is. I think Mesa Performance may have rebuilt pumps.


Ouch. http://www.mesaperformance.com/web_store/web_store.cgi?page=bmwcat/fuelpump.html&category=yes&cart_id=1883642.1935



To answer a previous question I get my parts from Blunttech.com. Steve stopped including ice cream with every order during the summer months, tho.


... You can use an S38 in-tank pump rather than the M88 one in your ///M635 but you need to swap the pump housing (saved me a few hundred $ years ago) ;-)


Post pics of your car, too!



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