750 M70 also runs with one fuel pump

[shogun]

got to read this one, I tried to help a 750 owner on RF, here the excerpts: need help diagnosing limp mode
1993 750iL (prod. 12/1992) increasingly went into limp mode over about a 15 minute span, starting out intermittent and ending up full time limp (low power, runs rough, etc.)

0) Reading the codes with the Peake shows only O2 sensor (for both banks).

1) Disconnecting the right MAF had no effect, meaning it still starts and runs rough. Disconnecting the left MAF and she won't start.

2) Putting a timing light on the right coil wire shows intermittent pulses at idle and no pulses at all above about 1K rpm. Checking the left coil wire shows strong consistent pulses.

3) Both distributor caps, rotors, wires all check good. Both coils have correct resistance on primary and secondary sides.

4) Both crankshaft sensors have correct resistance (540 ohms).

Assuming one bank of the V12 (right side?) is not running, I tried swapping some parts to isolate the issue.
- swapped MAFs and #1 above still holds true.
- swapped throttle bodies and #1 above still holds true.

My gut tells me this is a sensor somewhere, but what to check next?
Thanks!
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Sorry, this is NOT limp mode Update:
I know this because if I put the shifter in '3', it starts in 1st gear, then shifts later to 2nd as it accelerates, and finally up to 3rd gear. My understanding is that limp mode starts and stays in 3rd gear. I swapped the DME connectors and the problem doesn't change.
I'll check the voltages on the MAF connectors next.
Any suggestions would be strictly followed and greatly appreciated!
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no fuel pressure at left bank
Forget the mention in the original post of intermittent spark on the right bank. I double-checked and it is fine. That was my bad timing light connection to the right bank's coil wire.

I put the timing light on each of the 12 plug wires and there is voltage for spark, so I'm ruling out the ignition system for now.
I pulled off the left bank's fuel line where it meets the fuel rail and started the engine. Not a drop of fuel came out. It must be the fuel pump, relay, filter, etc., right?
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time to check the fuel pump, relay, fuse, etc.
Thanks to Sean and Johan's site, I'll be probing further for the source of the lack of fuel pressure on the left bank. Stay tuned...
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Found: bad fuel pump #2
After disconnecting the electrical connector to the fuel pumps/sending unit from the trunk, I checked resistance between pin 4 and pin 5 (fuel pump #1) and showed just less than 2 ohms. Checking resistance between pin 4 and pin 6 (fuel pump #2) showed an open circuit!
I'm considering installing a Y-connector where the two fuel feed lines meet the fuel rails so that the one good fuel pump will drive both fuel rails. Than should let me drive the car, as long as I'm not racing it, until both (yes, both!) new fuel pumps arrive. Anyone thinking I'm crazy to try this should let me know why.
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good idea with the Y-connection
I believe one pump will be enough to pump enough fuel as long as you do not drive full throttle. Original the capacity is laid out per pump for 875 ccm/30 seconds at 3 bar, so theoretical that would be >100 liters per hour!Per pump of course.
You can also try to install these cheaper pumps from TrePerformace, they are claiming to pump our 255 l/h. I have asked someone to take the dimensions. Of course most of it goes back with the return line.
Read this here http://www.bimmerboard.com/forums/posts/696070/
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gasoline insulates! I'm laughing at myself right now, because I just realized why the electrical connectors to the fuel pumps sitting inside the fuel tank immersed in gasoline don't short out. Gasoline, being an oil, is an insulator. Though I could see if you got a lot of water in the tank and the fuel level was just right, the fuses would pop...
Just use 1 pump then

Good find, Shogun. I was wondering about after market fuel pumps too.

That TREperformance fuel pump has more than enough power to push fuel through both fuel lines in the 750iL. I would just use one pump and a Y-connector inside the fuel tank.

Of course, you would lose that nice feature of being able to drive home on one cylinder bank when one of the two fuel pumps goes bad (like I was able to do).

According to their website, the current price of the BMW 255 LPH fuel pump is $69.99. They are right down the street from me! Let me know if you want any information on it, such as dimensions in cm, and I'll go there and measure it.
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1 pump works just fine, thank you
Bought a nice Y-connector for $2.99 at Kragen Auto. Connected the double ends to the fuel rails and connected the single end to the right side fuel line (the one connected to the remaining good fuel pump); all using some short sections of new fuel hose.

Capped off the left side fuel line using an extra vacuum cap from when I replaced the ones on the throttle bodies; fit perfect.

After warming it up I found some open road and did some hard acceleration and she behaved just fine, no lurching or sluggishness.

I won't leave it this way for long. The plan is to get a couple TrePerformance fuel pumps and retrofit them in the plastic holder in the fuel tank. I'll report on the when it's done.

He is now going to install the TrePerformance fuel pumps and hopefully will give me some feedback
http://treperformance.com/

[nateb603]

thanks for this post. Does anyone know the part number for the pump or where to get it for said 69.99?

[tornacious]

I just got back from TrePerformance where I purchased two of their TRE-340 fuel pumps. These may not be the correct ones. They have several part numbers with varying sizes. Unfortunately, I didn't have an old pump with me so I bought these because they were smaller and came with a sleeve. I'll be working on the 750iL this Saturday, so I'll post whether these fit or I had to exchange them for a different model. Hopefully I'll take a few pictures along the way and share those as well.

[shogun]

nate, they have 4 different models or better to say kits. When you go to the TrePerformance website you can see it. That they offer for BMW
http://treperformance.com/c-66145-fu...pumps-tre.html
But there is no E32 750 listed, so not sure which pack/kit is best.
About 2 years ago I sent them an email if their pump fits on the 750, the detailed answer was one word, "no". Maybe that guy had a bad day.
Here is a very detailed instruction for a 540. I have asked acet for the dimensions for that pump and he has given it to me, I also mentioned the original pump size and tech data
http://forums.bimmerforums.com/forum....php?t=1245212

Maybe you contact them again. The only point is if they fit into the insert
http://bmwe32.masscom.net/sean750/fu...t/Fuelpump.htm
in case they are smaller than the original Bosch pump, no porblem, a rubber sleeve will help, capacity is more than enough there.
M70 pumps/each: operating pressure: 3 bar
conveying capacity at 12 V: 1.7 litre per minute = 102 liters/60 minutes/1 hour
conveying capacity under counter pressure: 875 ccm/30 seconds
= 105 liters/60 minutes/1 hour
power consumption: 5.5 Amp.

There are some other samples of pumps used
A Korean Hyundai pump
http://www.bimmerboard.com/forums/posts/500482


GOSS from Australia
http://www.bimmerboard.com/forums/posts/663869
http://stores.shop.ebay.com.au/Ultra....c0.m14&_pgn=2

[nateb603]

I just got back from TrePerformance where I purchased two of their TRE-340 fuel pumps. These may not be the correct ones. They have several part numbers with varying sizes. Unfortunately, I didn't have an old pump with me so I bought these because they were smaller and came with a sleeve. I'll be working on the 750iL this Saturday, so I'll post whether these fit or I had to exchange them for a different model. Hopefully I'll take a few pictures along the way and share those as well.

pics/diy would be great!

[StoyanG]

well the only thing I don't like about this job is using plug'n'play connectors because they can always make a spark an you know the results after this.
So everything would be better if soldering the two wires to the pump directly.
You see that the original parts don't have any connectors in the reservour itself, everything is soldered and bolted.
So have this in mind.

[shogun]

pics/diy would be great!

have you not seen the bimmerforums link I posted above, there are plenty of pics when acet installs the pump to the E34 540.
That is enough, also the dimensions he has shown. Check it.

StoyanG
a spark inside the filled tank will not make an explosion. to make an explosion you need the right mixture of air and fuel vapour, but not in 100% fuel.

[tornacious]

I installed the TrePerformance TRE-340 fuel pumps in my 750iL. It was a simple job and total working time was about two hours. I took my time and made photos along the way. See the 60 photos here:
http://s898.photobucket.com/albums/a...01993%20750iL/

When I went to TrePerformance, Nick showed me the different models they have. Like a dummy I didn't bring an old pump to compare, but I did bring pictures I printed from a few websites of the Bosche replacement pumps and that's how we selected the TRE-340. I told him after the job was done I would give him the information about my installation so he could maybe add the E32 to his application list. I think I'll bring one of my old pumps with me when I go back for that!

I referred to the Bentley manual a few times (for the pinout of the 6-pin connector). I used this article from Sean and Johan's wonderful website as a guide.
http://bmwe32.masscom.net/sean750/fu...t/Fuelpump.htm

The new pumps are 1.5 inches in diameter (versus 1.683 inches on the original pumps) and about 0.5 inches shorter, but they fit perfectly after slipping on the supplied rubber sleeves. I cut off the original wire terminals and soldered the new cable wires on. Both the original and new pumps clearly had markings for the '+' and '-' terminals. In the pictures there is a crude schematic showing where the wires connect to the 6-pin connector. Notice that the wires on the '-' terminals actually connect together.

The original hose clamps have to be destroyed to remove them. If you grab the metal stub with a large pair of pliers and twist, they come apart easily. It took a few aggravated attempts and some swear words to figure this out.

Although only one pump was bad, I replaced both because these were the originals (150k miles). The fuel tank was half full, leaving the level below the release tabs for the assembly in the tank. So I didn't even have to put my hands in gas. A little fuel came out of the fuel return line when disconnected, but none came out of the two lines that feed the fuel filters. It wasn't messy at all.

The new pickup filters were too long to fit in the cavity where the fuel pump assembly mounts inside the tank, but I just bent them around the edge and tucked them under the plastic bracket (you'll see in the pictures). Everything else went very smoothly.

Those pumps are very quiet. After I was done and started the car to check for leaks I couldn't even hear the pumps running, and that was with my ear right next to the 6-pin connector with the access panel removed. To hear them I had to shut off the engine and jumper them at the fuel pump relay sockets and be VERY quiet.

In terms of overall satisfaction, this is one of the best repairs I've done on this car so far. For anyone with an E32 V12, I highly recommend this replacement. It was cheap (comparatively), easy, gives good performance, and there was plenty of space to work - what a concept! Note: I have no affiliation with TrePerformance.

[shogun]

That is great news, and special thanks for the pics and the detailed write up. Please let us know when you show Nick of TrePerformance the original Bosch pump if he still recommends to use the 340 set as best solution.

OEM pump is 69493 Bosch
Capacitywise it is almost the same like the M30 pump, the fuel pressure for the M30 and M70 engine is 3 bar, the M60 engine needs 3.5 Bar.
M70 pumps/each:
operating pressure: 3 bar
conveying capacity at 12 V: 1.7 liter per minute=102/60 minutes

conveying capacity under counter pressure: 875 ccm/30 seconds
==105 liters/60 minutes/1 hour
power consumption: 5.5 Amp.

I have some original ones here, the BMW part number is 16141179710
(made in Czech Republic according to the box).

Just measured
diameter at the metallic part 43 mm,
length of the metallic part 95 mm

total length from bottom to the top of the nut where the cable comes: 118 mm
total lenght from bottom of plastic part/connector to top of the connecting stud for the fuel hose 146 mm

[tornacious]

Nick at TrePerformance emailed me the following:

"For the dimensions of the pumps they are all the same, 1.5" wide without the sleeve, and 4.75" from tip to tip, and about 4" from the bottom to the top of the case. The TRE-342 is the one which would work best when reusing the original filter."

[shogun]

Great! Thanks a lot for that info, appreciate very much. TRE -342 then. Do you have any idea what is the difference between 340 and 342? Probably some of the accessories for fitting? i assume the capacity is the same?
anyyone else is using Tre-performance on the 750? Which one did you use? 342 or 340? As far as I understand the pumps are always the same, but the accessories like fittings are different for various cars.

[shogun]

I am especially interested in the installation of the plastic pre-fuel filter at the bottom of the fuel pumps. That is a plastic strainer with 2 connections for the 2 pumps as shown here, Strainer 16141179703 $50-60 going price + only for the E32 750.
http://bmwe32.masscom.net/sean750/fu...mpAssembly.jpg
http://bmwe32.masscom.net/sean750/fu...rFromAbove.jpg
http://bmwe32.masscom.net/sean750/fu...Underneath.jpg

Can the original filter be used ot the cheapo aftermarket filters which often come with aftermarket fuel pumps?

[mitch23]

For aussies, i had a 525i which i take it takes the same sort of fuel pump, bought mine from bursons, cost me $90 bucks, local dealer wanted $900, just matched up the size and it was plug and play more or less, they are actually made to fit the older ford falcons i believe, brand is "goss" from memory, i can pull recipts if anyone needs me too.

[shogun]

We tested for more than 2 years now with E36 fuel pumps, my buddy installed them in his Alpina B12 E32, another one in an E31 850, both work nicely. The E36 fuel pumps have very similar diameters and length as the M70 fuel pumps, capacity seems to be o.k., as even used in E36 M3 3.2 liter engines.

I found a site by Bosch AUS, basically for all cars the data, see link below, I only list here what is of interested for E32 + other BMW and what I found in the long list http://apps.bosch.com.au/AAExtranet_...pflowrates.PDF
The data are:
Part No. Vehicle L/H CC3/30s Pressure (bar) Voltage Loc

0 580 453 011 BMW 750i "M70" 87-150L/H 780-1650cc3/30s 3.0 bar
0 580 453 002 BMW 45 2.5 J7
0 580 453 020 BMW 5 & 6 cyl. (Forbidden)
0 580 453 021 BMW 520i / 525i 102-170 850-1420 3.5 J10
0 580 453 040 BMW 525i (Series not produced) 102-170 850-1420 3.5 J10
0 580 453 067 BMW 730i, 740i J12
0 580 453 422 BMW 1.6 4cyl. / 1.8 4cyl. 95 3.0 J16
0 580 453 439 BMW E36/5 115 3.5 J16
0 580 464 013 BMW L-jetronic 120-200 1000-1670 3.0 K10
0 580 464 032 EPK3 BMW 100-157 830-1560 3.0 K13
0 580 464 048 EKP3BMW 100-175 830-1560 3.0 K15
0 580 960 013 BMW K-jetronic 80 0.3 K21

from Fuel Pump Flow Rates, From Microfiche KE-26. As there is mentioned microfiche, the list might be a bit older as microfiches are nowadays no longer used. Updated numbers for fuel pumps and other Bosch parts you will find on the Bosch vehicle parts finder https://www.boschautoparts.com/auto

[shogun]

I can confirm the E36 pumps work fine, still installed and running perfect. I took some more measurements of size of the original Bosch fuel pumps, when I replaced my original Bosch ones made in 1988 last December, they lasted really long:
In case someone does not want to invest that much for a good quality Bosch fuel pump, the cheapo China made E36 and E34 fuel pumps also work (lifetime I do not know, also the check valve inside the pump might die earlier, see here
http://www.bimmernut.com/forum/showt...ight=fuel+pump

They just must have the correct dimensions to fit into the fuel pump unit, As both M70 pumps clip into the unit and the bottom part of the unit has an extra cut out for the inlet tube of the pump and all that goes into the plastic container/bracket fixed at the bottom of the fuel tank. The tube dimension is also important so that the original dual pre-filter fits = 1 filter with 2 connections for both pumps. So if you want to buy the cheapo pumps, here are the details of the original Bosch pump I removed:
body diameter 43.5mm
body length 94.00m (without the attached tubes and the part for the wire connection = metal body only)
total length of body from end to end of the connection pipes 146.5mm
length of inlet/suction pipe at the bottom 15.2mm, outer diameter of bottom pipe 12.0mm
outlet pipe at top outer dia. 6.2mm, at the top of that pipe a small enlargement to dia. 8.9mm (to keep the fuel hose tight), Length of outlet pipe 20.0mm
New up to date part number for M70 pumps is: 16141179710
replacement procedure http://bmwe32.masscom.net/sean750/fu...t/Fuelpump.htm

Bosch 0 580 453 010 was written on the old pump.

And just for fun I also compared the weight of the original pump from Bosch = 475 gramms, and a new cheapo chinese made I have here which fits for the M70, that is 315 gramms