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No power to in-tank fuel pump

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Hefeweizen
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No power to in-tank fuel pump

Post by Hefeweizen » Wed Dec 27, 2017 3:41 am

After my project 6er ran all summer long with a few cut outs he died in the garage last week. There is a very good spark and there is also fuel running but a very weak stream which suggests that there is not enough pressure. Checked the inline fuel pump and that one has 8 Volts at the pump. Car ran with that all summer though. Next one I checked was the in tank pump and there is no power to that one. Following all the way up to the front I discovered that the plug at the distributor cap has issues (see pics). Anyone know where I can find a replacement? [-o<
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Rainer
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Re: No power to in-tank fuel pump

Post by bpoliakoff » Thu Dec 28, 2017 3:13 am

If you have an early, car as evidenced by the picture of the distributor, and I will stand corrected, but the early cars didn't have a pump in the tank. Just the sending unit which was also the feed to the under car fuel pump.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Thu Dec 28, 2017 3:29 am

This one has a M90 engine in it and it does have an in tank pump just like the newer models :(
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by bpoliakoff » Sat Dec 30, 2017 4:03 am

Rainer there is no rhyme or reason with BMW. My car is an 81 euro with M90 but no pump in tank. Just the sending unit.
81 Euro 635 M90 with motronic. Currently under a complete nut and bolt restoration. Pictures at
flickr.com/photos/bertsphotos.

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Hefeweizen
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Sat Dec 30, 2017 3:44 pm

Tell me about it. This car is "special" anyway. The body in itself is a 633 (US) and the previous owner may have wanted to turn it into a Euro. Seems like nothing is the norm on this car and definitely no rhyme or reason.

I fixed the plug and have to attack the relay now.
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by Hefeweizen » Fri Jan 19, 2018 5:15 pm

Now that I have the fuel pressure issue solved with another pump, the car is running. Time to adjust the timing and I noticed that the hoses going into the heater core cover the little window. Any tricks anyone?
Rainer
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Re: No power to in-tank fuel pump

Post by GRNSHRK » Fri Jan 19, 2018 8:35 pm

Rainer, I seem to recall having to stand on your head or something like that, in order to actually "see" the timing marks #-o

Seriously, I can check and see what they have in the "Big Blue Book" over the weekend, but really won't be able to post my findings till Monday next week :(

But as this is your project 6er and it's the dead of winter in CO, hopefully that won't be an issue for you [-o<

Interesting find regarding that little connector with the green wire on the side of the dizzy :shock:

I lost the little wire retaining clip that holds that connector into the dizzy some time last millennium, it has never popped out, but at least I'll know what's up if it does and the car stops running :-k

:mrgreen:
:mrgreen:
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Sat Jan 20, 2018 4:35 am

Thanks Bobbo! Yes, there is no big rush. I drove the car today and it died after about 20 miles. Looks like a fuel problem since it starts right up and runs for a bit and then dies. After waiting a while, it starts up again and then dies. I'll have to investigate the Fuel Pressure tomorrow while it is still summer in Colorado. They predicted winter for Sunday so I better hurry :lol:
Rainer
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Re: No power to in-tank fuel pump

Post by hornhospital » Sat Jan 20, 2018 7:53 am

Do you think there's any chance the in-tank pump (or pickup if it only has one pump) is picking up trash in the tank, shutting off flow. After it sits for a bit the trash falls away and the fuel flows again? I've heard of that but never experienced it. Just a random thought.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"

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Re: No power to in-tank fuel pump

Post by Hefeweizen » Sat Jan 20, 2018 2:09 pm

That was my thought as well. Did not think there was a lot of trash in the tank but you never know. I certainly will investigate today!
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by raykoke » Sun Jan 21, 2018 2:01 am

Hefeweizen wrote:
Sat Jan 20, 2018 2:09 pm
That was my thought as well. Did not think there was a lot of trash in the tank but you never know. I certainly will investigate today!
My tii would do that, due to the tank rusting internally....

Cheers,

Ray
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Hefeweizen
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Tue Jan 23, 2018 4:49 pm

So I checked and discovered that the cables are old (obviously) and the insulation has cracked away. That was after a painful drive where I had some cutting in and out. While I was at it, I replaced part of the return hose and graduated "Basket Weaving 101"! What a PITA!
Rainer
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Re: No power to in-tank fuel pump

Post by GRNSHRK » Wed Jan 24, 2018 8:42 pm

Rainer, finally getting back to you, my apologies for the delay [-X

So, to my surprise, the "Big Blue Book" doesn't actually show how to view the timing marks :shock:

Here's what the manual says, however, along with 2 shots from my 6er, wherein you can see the little window with the pointer on it :-k

The coolant hoses that go to and from the heater core are actually above the window, at least they are on my car :-?

HTH \:D/

:mrgreen:
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:mrgreen:
Bobbo
1980 633 CSi
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2011 F10 528i
2005 E46 330 Ci ZHP Cabrio
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Thu Jan 25, 2018 12:46 pm

Bobbo, thank you so much for your help! I think I have to use my German eyes and look around the hoses?
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by GRNSHRK » Thu Jan 25, 2018 4:18 pm

Rainer, you're more than welcome \:D/

Try using a fixed light source first to find the window and not a timing light, which of course is just going to flash periodically :roll:

But you can see that you have to look "over" the brake vacuum booster, or behind it, but below the heater core coolant hoses :-k

There may be a fuel line in the way as well, but the black "hose" going over the brake vacuum booster in my 6er is actually the positive battery cable from the trunk, so you likely won't have that to deal with [-o<

And just to let you know, I used 2 different flashlights to illuminate that area, in order to even take those photos #-o

:mrgreen:
:mrgreen:
Bobbo
1980 633 CSi
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2011 F10 528i
2005 E46 330 Ci ZHP Cabrio
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Fri Jan 26, 2018 4:00 am

Your efforts are greatly appreciated! I did find the window earlier and that is why I know that the heater hoses are in the way. So far the week was crazy and if it was not the one thing, it was the other. Looking forward to Saturday where I can just move out to the garage!
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by Hefeweizen » Mon Feb 05, 2018 4:17 pm

The wildness with the fuel pumps continues. I don't know if the O2 Sensor has anything to do with it or if this is just the craziest coincidence? The in-tank pump is still not connected right since the pug is all messed up. So I was pretty much driving with just the inline pump (which is pretty noisey). I put in a new O2 Sensor and connected that as well. After driving for a while, the car starts bucking and dies. Waiting 10-15 minutes it starts up and I can drive again. So far I did that driving after I disconnected the O2 Sensor, Another crazy thing, since the plug is all messed up I rewired the in tank pump and connected it. Made sure the polarity is right. The inline pump is considerably quieter but the fuse burns out every time. Thinking that the inline is on its way out?
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by Hefeweizen » Fri Feb 09, 2018 5:32 pm

Can anyone provide info on the inline pump please? Are the assumptions correct in my post above?
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by hornhospital » Fri Feb 09, 2018 11:03 pm

Yes, your outside pump (which is the high pressure pump) is kaput. The description of the car running for 10-15 minutes and then dying, along with the fuel pump fuse blowing, points to a seriously overworked and overheated pump. By the way, the outside pump was never intended to be operated without the low pressure/high volume in-tank pump feeding it. With the high pressure/low volume pump having to act as a lift pump too no doubt contributed to its demise.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'87 325is "Odette"; '93 325is "Elvira"; '95 M3 "Ashlyn"

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Re: No power to in-tank fuel pump

Post by Brucey » Fri Feb 09, 2018 11:47 pm

there may simply not be enough fuel flow to keep the pump cool. Reasons for this include that the in tank pump is not working, or that the filters are clogged. If there is water in the fuel filter this can clog after a short period of running and then unclog by itself whilst the car is standing, enough for another burst of running.

A #1 priority is doing a fuel delivery test as per the manual. IIRC you should get a delivery of 1-2 litres per minute (of water free, bubble free fuel) pushed past the FPR. The car will run with less than this but the fuel pumps will be struggling and may overheat.

Poor fuel delivery will be masked on cars with closed loop fuelling because the system will adjust the injector duration to suit until there just isn't enough pressure to let the engine run.

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Hefeweizen
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Re: No power to in-tank fuel pump

Post by Hefeweizen » Sat Feb 10, 2018 5:29 pm

Thanks Brucey! What baffles me is that when I connect the in-tank pump, the wires get hot and the fuse blows. :-k I'll try today (difficult today since it is winter today in Colorado Springs, next weekend may be summer again) to install my spare in-line pump.
Rainer
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"If you think a good European mechanic is expensive, try a bad one!"

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Re: No power to in-tank fuel pump

Post by Brucey » Sat Feb 10, 2018 9:54 pm

the in-tank pump could be faulty but it could also simply be jammed enough so that the motor is stalled. The motor will probably draw its maximum current at stall, and will soon overheat under those conditions.

Anyway it sounds like you need a good look at it or perhaps to simply get another one. It probably isn't the only thing that is wrong though....

cheers
~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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