Fuel Distributor Source

[cgifool]

#13 is more like a quarter-turn to release rather than threaded like a screw.

[Layne]

You gotta first remove the level sensor with the 4 little nuts, then use two crossed screwdrivers to 'unscrew' #13. Not even a quarter turn, more like 1/8.

[kevinr1247]

Dug a little deeper today. I went ahead and just dropped the tanks to get at the vents. Lot's of leaking is apparent. Got everything cleaned up.

I also think the part in the list above is wrong...O-Ring for Fuel Sending Unit. This is not the gasket for the fuel level sensor which I thought it was.

All new rubber hoses going in. I just removed the whole fuel filter/pump shabang to get everything cleaned up. That seemed like the easiest thing to do rather than try to replace everything from underneath. Super simple so far.

IMG_2085.jpg

IMG_2086.jpg

[cgifool]

oh nice, I need to do this.. mine looks equally crusty

[kevinr1247]

Well so, I got everything buttoned back and I filled the tank with a couple of gallons. It was sputtering like crazy at it was starting but I could immediately tell it was going to crank. I think it was just purging the system of air.

So I got going and everything was great. I warmed it up, drove it, and let is set for 30 minutes or so. It started right up.

So I took off towards the nearest little twisty road. I haven't put the back seat back in so I was listening to hear any oddities. I did hear what sounded to be a whine but it only lasted for about 10 seconds or so. It was definitely the fuel pump. It went away and it was running great and idling properly. Then I was doing about 45mph down a straight and then it just died. No power, nothing. So had it towed back to my garage.

I'm thinking my new fuel pump failed. Tried to crank is several times, and nothing. So, down the path of diagnosis.

If the fuel pump just quits, will the car just die? The answer is yes.

[320iAman]

I had my quit at a stop light,, I had a new spare fuel pump relay, threw it in bingo started right up.

I then went to town and redesigned the fuel pump circuit, tired of replacing fuel pump relay every couple of years. Fuel pump relay in these cars gets taxed plenty standard design it runs signal voltage and amperage to the Main or lambda relay, runs both Fuel pumps, The Warm up Regulator and Air Auxiliary valve, I rewired this and added a new relay thus the fuel pump relay runs only the fuel pumps and send signal voltage and amperage 100 or so milli amps to two relays, this reduced the load on the fuel pump relay tremendously by many 100's and more ect of %'s.

Too make a long story short the fuel pump relay runs 4 devices and sends signal voltage to one relay, my newer superior design it runs two devices( in tank and external fuel pump) and sends very small signal voltage and amperage to two relays one lambda and one for the WUR and AAV, the load reduction on the work horse fuel pump relay is very large..

I have a post on this in case some legionaries want to up grade, I'm a centurion,,lol.

Randy

[autox320]

I had my quit at a stop light,, I had a new spare fuel pump relay, threw it in bingo started right up.

I then went to town and redesigned the fuel pump circuit, tired of replacing fuel pump relay every couple of years. Fuel pump relay in these cars gets taxed plenty standard design it runs signal voltage and amperage to the Main or lambda relay, runs both Fuel pumps, The Warm up Regulator and Air Auxiliary valve, I rewired this and added a new relay thus the fuel pump relay runs only the fuel pumps and send signal voltage and amperage 100 or so milli amps to two relays, this reduced the load on the fuel pump relay tremendously by many 100's and more ect of %'s.

Too make a long story short the fuel pump relay runs 4 devices and sends signal voltage to one relay, my newer superior design it runs two devices( in tank and external fuel pump) and sends very small signal voltage and amperage to two relays one lambda and one for the WUR and AAV, the load reduction on the work horse fuel pump relay is very large..

I have a post on this in case some legionaries want to up grade, I'm a centurion,,lol.

Randy

I went through this also and posted about it a few times. Basically I could watch the voltage fluctuations and at the time didn't have a wire diagram just traced. Found the lamda relay and 02 was oscillating as it should but somehow the voltage to the fuel pump relay followed. You guessed it the pumps would have varying voltage which was no good. I bypassed the relay and wired the pumps direct feeding battery voltage. It ran great for another season really well actually, till swapped to a 38 weber. Failures on these cars and e30's today is the lift pump/in-tank pump. VDO has gone the way of garbage. Even an oem from BMW paying the cash isn't any better....same crappy pumps. The main high pressure pumps are usually never the issue by design.

Alternate wiring on older 80's car's isn't new but IMO necessary to keep them going in top shape. The wiring gets old and can't carry what it use to. Some fresh copper and reroute is a good idea. Most guys rewire fuel pumps to avoid voltage drop in performance applications. You'd be surprised how much pump output difference there is per volt drop. When running other "vampire" circuits off the same relay well you can imagine what happens.

[kevinr1247]

So I just jumped the relay to see....nothing. I don't hear the fuel pump at all, so I'm thinking faulty fuel pump. Perhaps should have gone with the Bosch. Also, I noticed that the fuel gauge isn't working when I turn the ignition either. When the car quit it was reading at least a 1/4 of a tank which I think is accurate.

Don't know for sure, but I'll keep the thread posted as I learn more.

But overall, the issues that started this whole process seemed to have been solved with replacing all the old braided lines.

More info. It's definitely the fuel pump. This pump...

http://www.ebay.com/itm/Hayg-Orig-In...-/320636928496

...lasted all of 30 minutes.

[SilverPuddle]

I'd do the small things first and check that the circuits are getting power.

My 1982 e21 was not starting and I changed the fuel accumulator and that has resolved my cold and hot starting issues.

Also, you did a very good job of recording the issues.

Welcome aboard the e21 ride.

[epmedia]

So I just jumped the relay to see....nothing. I don't hear the fuel pump at all, so I'm thinking faulty fuel pump. Perhaps should have gone with the Bosch. Also, I noticed that the fuel gauge isn't working when I turn the ignition either. When the car quit it was reading at least a 1/4 of a tank which I think is accurate.

Don't know for sure, but I'll keep the thread posted as I learn more.

But overall, the issues that started this whole process seemed to have been solved with replacing all the old braided lines.

More info. It's definitely the fuel pump. This pump...

http://www.ebay.com/itm/Hayg-Orig-In...-/320636928496

...lasted all of 30 minutes.

You should first inspect, clean and tighten the fuse and fuse holder contacts. And like mentioned; make sure the fuse is getting power. I had to do this once, several years ago.

And just fyi: the copper/brass fuses don't corrode nearly as fast as the silver colored fuses.

[kevinr1247]

You should first inspect, clean and tighten the fuse and fuse holder contacts. And like mentioned; make sure the fuse is getting power. I had to do this once, several years ago.

And just fyi: the copper/brass fuses don't corrode nearly as fast as the silver colored fuses.

Good advice I'd say for those going through this process.

I ended up just pulling the pump, draining the gas out, and hitting it with 12V to see if it would spin. Nothing. I did the same to the old pump which was still functioning when I removed it, and it whirred to life. I did read that if you don't clean the tanks that yo can burn through pumps. Well, I clean the tanks. There was quite a bit of varnish and soot that came out. So I can't imagine that dirty tanks are the culprit. I think it's just a crappy pump. But if I burn through another one, that will tell a different tale I suppose.

[kevinr1247]

I'm slightly worried. I got everything put back in today. The new fuel pump was delivered. The car pretty much fired up right away. All's well there. I ran it for about 20 minutes. Put 3 gallons of gas in it, plus probably another 2 that was already in it.

However I'm wondering if there might be some air getting in. The fuel pump at fairly consistent increments sounds like it's internals are rattling....it's sort of a periodic squirting sound. I thought everything was nice and tight but perhaps not. Or is it a normal sound? I suspect not.

No engine performance issues that I can tell....not sputtering or backfiring. Pretty smooth. If air was getting in I'd think the engine would let me know. Everything seemed to run fine. Wondering if I just hear normal sounds without all the sound deadening and back seat. But I can hear it outside the car too.

Insight always appreciated.

[autox320]

I'm slightly worried. I got everything put back in today. The new fuel pump was delivered. The car pretty much fired up right away. All's well there. I ran it for about 20 minutes. Put 3 gallons of gas in it, plus probably another 2 that was already in it.

However I'm wondering if there might be some air getting in. The fuel pump at fairly consistent increments sounds like it's internals are rattling....it's sort of a periodic squirting sound. I thought everything was nice and tight but perhaps not. Or is it a normal sound? I suspect not.

No engine performance issues that I can tell....not sputtering or backfiring. Pretty smooth. If air was getting in I'd think the engine would let me know. Everything seemed to run fine. Wondering if I just hear normal sounds without all the sound deadening and back seat. But I can hear it outside the car too.

Insight always appreciated.

Man I totally forgot about the old school bar fuses and the copper strip ones are better. Good catch on that. Old quick story why I should of remembered that. Long ago my bro had a 320is before me and was on the side of the road wouldn't run but turned over. Turned out to be the fuel pump fuse fell out of the holder from heat Bent the tabs in and replaced with a copper strip one. Also had one on mine before deleting most of the box.

Anyways to add more on the pump saga. Most dual pump systems when any noises or buzzing from the main pump usually means the in-tank pump is in distress. I'd try a direct wire of the in-tank pump and see if it's just circuit/voltage drop. Even a working in-tank pump may not work enough to feed the main pump the volume it's looking for.

[kevinr1247]

Man I totally forgot about the old school bar fuses and the copper strip ones are better. Good catch on that. Old quick story why I should of remembered that. Long ago my bro had a 320is before me and was on the side of the road wouldn't run but turned over. Turned out to be the fuel pump fuse fell out of the holder from heat Bent the tabs in and replaced with a copper strip one. Also had one on mine before deleting most of the box.

Anyways to add more on the pump saga. Most dual pump systems when any noises or buzzing from the main pump usually means the in-tank pump is in distress. I'd try a direct wire of the in-tank pump and see if it's just circuit/voltage drop. Even a working in-tank pump may not work enough to feed the main pump the volume it's looking for.

Thanks for that. The in tank pump was covered with varnish and a white crusty deposits. I cleaned it off as well as I could so I can see that it might not be feeding correctly. What do you mean "direct wire of the in-tank pump?" Do you mean just wire it directly to 12V instead of the socket plug? Then that will tell me whether or not there's an electrical issue i.e. whether or not power is consistent to the in-tank pump?

[epmedia]

Regarding possibly sucking air bubbles and the in-tank pump:

The in-tank pump has a rubber hose/grommet; if messed up or loose fit, it may allow air bubbles into the fuel system.

Did you inspect this rubber hose/grommet?

And yes, the external fuel pump should not be making random gurgling noises.

[kevinr1247]

Regarding possibly sucking air bubbles and the in-tank pump:

The in-tank pump has a rubber hose/grommet; if messed up or loose fit, it may allow air bubbles into the fuel system.

Did you inspect this rubber hose/grommet?

And yes, the external fuel pump should not be making random gurgling noises.

I did replace the rubber seal around the top of the in-tank pump. I'll double check it's sealed up. A point of clarity....don't know if it's useful, but it seems like the rattling from the pump is on kind of a cadence....so not necessarily random. Would air bubbles in the lines cause the rattle? I'll try to get a recording and post it up.

[epmedia]

I did replace the rubber seal around the top of the in-tank pump. I'll double check it's sealed up. A point of clarity....don't know if it's useful, but it seems like the rattling from the pump is on kind of a cadence....so not necessarily random. Would air bubbles in the lines cause the rattle? I'll try to get a recording and post it up.

A recording would be great.

I thing air bubbles cause just gurgling. If it's rattling, maybe the mounting is not quite proper?

[epmedia]

I was just thinking of something else regarding fuel pump random noises, or as you call it, "noise in cadence"...

I suppose it's possible for this to also occur if the accumulator is severely leaking past it's internals and back into the suction side of the external fuel pump, ie: creating up and down fuel pressures (sort of a 'hunting' behavior).

If you do end up testing the accumulator; there's a procedure in the diy/faq thread. *Wear eye protection too.

[kevinr1247]

I was just thinking of something else regarding fuel pump random noises, or as you call it, "noise in cadence"...

I suppose it's possible for this to also occur if the accumulator is severely leaking past it's internals and back into the suction side of the external fuel pump, ie: creating up and down fuel pressures (sort of a 'hunting' behavior).

If you do end up testing the accumulator; there's a procedure in the diy/faq thread. *Wear eye protection too.

I'm wondering if there is a loose hose. Maybe I didn't tighten all the hose clamps enough. Thought they were all tight. Went ahead and ordered another in-tank pump anyway, the cheaper one <cough>.

[epmedia]

Hmm... that does sound like air. Air from either a hose leak on the suction side of the pump, or even 'possibly' restriction on the suction side of the pump, causing cavitation.

Just for giggles, put a stethoscope on the pump and the accumulator. If you don't have one, you can use a piece of wood or spare hose.

[sbcrockett]

that sounds very similar to what I hear on my 323. random though not quite as frequent as your video. could it be from the intank pump not quite doing it's job as well as it should? for what it's worth, I can't really feel any loss when I'm driving, but then, maybe I'm just used to the feel and I just don't know that my acceleration is sub par?

*I have replaced all the fuel hoses and vent lines back there so I know i'm not sucking air (at least from the hoses)

[epmedia]

that sounds very similar to what I hear on my 323. random though not quite as frequent as your video. could it be from the intank pump not quite doing it's job as well as it should? for what it's worth, I can't really feel any loss when I'm driving, but then, maybe I'm just used to the feel and I just don't know that my acceleration is sub par?

*I have replaced all the fuel hoses and vent lines back there so I know i'm not sucking air (at least from the hoses)

Autox mentioned the in-tank pump possibly causing the external pump to make noise too, which is very plausible.

Very good write up on fuel pump cavitation: What is Cavitation? How to Avoid It.

*cavitation causes pump damage.

[sbcrockett]

thanks Robert. great write up but DAMN i can't stand black background pages. plays funny tricks with the eyes when I return to the forums I had no idea how bad cavitation is, not just for the pumps but how it could lead to lean conditions. I can imagine that CIS fuel systems are even more prone to excessive heat in the pumps, continually running the way they do. they ARE continuous duty, right? meaning that they provide constant PSI and do not change with demand, correct?

[epmedia]

Yes, it's continuous duty, like some more modern FI systems. At engine idle there is more fuel returning to the fuel tank than when the car is being driven. Our fuel pumps work harder than most other FI pumps because higher pressure (and continuous duty), but then again - our pumps are designed to operate at higher pressures so my point on this may be moot. Along with cavitation, a really dirty primary fuel filter or fuel pickup screen can make a fuel pump overheat too. Some pumps have a small mesh filter on the suction side too.

Awhile back my fuel pump got really really hot and turned off all by itself. My fuel tanks were almost empty and I dumped ~gallon of my son's motorcycle E85 into the tank. It was idling for about an hour, then engine died. The pump was too hot to touch. The fuel filter was very very dirty. Replaced fuel filter, the pump cooled and engine ran again. I was a bit nervous about the pump (aftermarket), but I guess it must have (thankfully) a safety 'overheat' switch built-in.

[mxl556]

Just something to add- my intank pump has been dead for probably a decade... Main pump works great and makes no noises except when its really low on gas (starts buzzing, nothing like the noise in the video above). Also, if the fuel level is below 1/4 and I take a hard right I get fuel starvation for a second or two. I know I should replace that intank pump but my point is that external pump should suffice and provide enough fuel for proper running.

Max