fuel pump issue

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DaYouper
Posts: 59
Joined: Thu Sep 23, 2010 1:55 pm
Location: Upper Michigan

fuel pump issue

Post by DaYouper »

so on final phase of auto to 5sp conversion, 1981 633csi, 43K original miles, drove it onto lift, been almost 2 yrs not started. Have jumped necessary wires at auto plug in, engine started on "starting fluid spray" but getting no fuel to engine. Have "jumped" relay, hear intank pump running, relay shows power while cranking, ran 12v directly to external fuel pump and in tank pump will run, I do not hear or feel and noise or vibbration from external pump. I am guessing it is not working/pumping fuel, as none is getting to engine fuel rail. any other thoughts? I prob will order fuel pump tomorr but looking if anyone has input on anything I might be missing?
1961 Borgward Coupe
1981 633csi 43K miles
1998 M-Roadster
1968 1600-02
DaYouper
Posts: 59
Joined: Thu Sep 23, 2010 1:55 pm
Location: Upper Michigan

Re: fuel pump issue

Post by DaYouper »

try again, 12V direct to external fuel pump, nothing, the old "tap" on it with handle end of screwdriver and YIPPIE!, she starts buzzing, and pumping fuel, guess I woke her up from a long long nap. Car starts, just need to disconnect and re position gas pedal linkage at firewall so to get full throttle, then drive her off the lift and into heated front garage to finish up interior under dash and center console
happy,happy, happy, nice birthday present for me today!!!
1961 Borgward Coupe
1981 633csi 43K miles
1998 M-Roadster
1968 1600-02
plip1953
Posts: 400
Joined: Mon Aug 13, 2018 4:15 pm
Location: Leeds

Re: fuel pump issue

Post by plip1953 »

It's soooo satisfying when you get a result like that!

Just picking up on something else you mentioned - do E24s routinely have an in tank pump as well as the external one. I'd always assumed not, but happy to have it confirmed otherwise.
Phil
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1988 Highline 635 CSi
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hornhospital
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Re: fuel pump issue

Post by hornhospital »

MOST E24s have a low pressure high volume in-tank pump, and a high pressure low volume pump outside the tank. I'm not sure about the last couple years production. There were many changes between 1986 and 1989.

It takes a little work, but the system can be converted to a single in-tank pump. A Walbro pump (#450?) can replace both pumps. I've done that on my two E30s and it works great.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
plip1953
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Re: fuel pump issue

Post by plip1953 »

hornhospital wrote: Sat Jan 11, 2020 2:35 am MOST E24s have a low pressure high volume in-tank pump, and a high pressure low volume pump outside the tank. I'm not sure about the last couple years production. There were many changes between 1986 and 1989.

It takes a little work, but the system can be converted to a single in-tank pump. A Walbro pump (#450?) can replace both pumps. I've done that on my two E30s and it works great.
Thanks, that's interesting. I just checked on Real OEM and for my particular (UK '88 Highline) it seems it has just a single external pump (ie what I thought), but I also see references to cars for other markets around the world also having a "pre-supply pump", which I assume will be in the tank.

When you switched to single in-tank Walbros did you have to make other adjustments eg re fuel pressure regulation?
Phil
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hornhospital
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Re: fuel pump issue

Post by hornhospital »

Negative. Plug and play. Works a treat!
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
ron
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Re: fuel pump issue

Post by ron »

Check out #7. All Highlines have it.

https://www.realoem.com/bmw/enUS/showpa ... Id=16_0030

Take the cover off the tank. #10.

https://www.realoem.com/bmw/enUS/showpa ... Id=51_1673
They are ALWAYS rustier than you thought!!!!!!
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plip1953
Posts: 400
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Location: Leeds

Re: fuel pump issue

Post by plip1953 »

ron wrote: Sun Jan 12, 2020 8:52 am Check out #7. All Highlines have it.

https://www.realoem.com/bmw/enUS/showpa ... Id=16_0030

Take the cover off the tank. #10.

https://www.realoem.com/bmw/enUS/showpa ... Id=51_1673
Ok, thanks for that. I only looked at sub-group 16.15 "Fuel feed" rather than both that and 16.05 "Fuel Tank".
Phil
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1988 Highline 635 CSi
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