Well the poor old 535 and her

[Bill R.]

new fuel pump that i had gotten off of ebay weren't quite right....
Since i installed it ,the tank,filter and injectors, I was having the usual hot start problem with 3 trys to start it when hot soaked...

I checked the fuel pump pressure and it was good but instantly went to zero,when shut off, I thought to myself it could be the fuel pump check valve, or the fuel pressure regulator letting fuel drain past, or a number of leaking injectors. So i deadheaded the pump by pinching off the return line from the regulator and briefly cranked the engine, gauge shot up above 70 and then when i stopped cranking instantly went to zero
That pretty much confirmed it. So i installed the bmw retrofit check valve kit 16 14 9 068 988..... pretty cheap from Patrick at bma, less than 10 bucks. Nice kit ,comes with checkvalve, fuel line, hose insulator, hose crimp clamps and plastic nut covers to get rid of sharp edges on the pump cover.

[Bill R.]

After running it for a good while getting it good and hot, shut engine down and waited 45 minutes with the pressure gauge hooked up... Pressure guage only dropped to here





new fuel pump that i had gotten off of ebay weren't quite right....
Since it installed it ,the tank,filter and injectors, I was having the usual hot start problem with 3 trys to start it when hot soaked...

I checked the fuel pump pressure and it was good but instantly went to zero,when shut off, I thought to myself it could be the fuel pump check valve, or the fuel pressure regulator letting fuel drain past, or a number of leaking injectors. So i deadheaded the pump by pinching off the return line from the regulator and briefly cranked the engine, gauge shot up above 70 and then when i stopped cranking instantly went to zero
That pretty much confirmed it. So i installed the bmw retrofit check valve kit 16 14 9 068 988..... pretty cheap from Patrick at bma, less than 10 bucks. Nice kit ,comes with checkvalve, fuel line, hose insulator, hose crimp clamps and plastic nut covers to get rid of sharp edges on the pump cover.

[shogun]

Thanks a lot Bill. Nice pics, I needed that too for my website and there are offten question about that, and will borough that and mention your name, if you agree.

My collection so far
http://i230.photobucket.com/albums/ee23/IBHenry01/black%20e30%20vert/IMGA0609.jpg
here non-BMW http://members.cox.net/zmuff/crop%20check%20valve%20done.jpg

installation pics E30
http://www.bimmerboard.com/forums/posts/496880/

When yo talk to Patrick at BMA, tell him the pic does not work.

Used with the search there with the part number, 16149068988 CHECK VALVE KIT

[Claude]

....
Since i installed it ,the tank,filter and injectors, I was having the usual hot start problem with 3 trys to start it when hot soaked... .

Q1) Why a bad gas check valve is this hard starting problem source only when engine hot, not also when it's cold ?

Q2) Does this check valve kit add a second check valve in serie with the pump, why not just replace the existing one ?

Glad to see that it solve the problem easily and cheap.

[Bill R.]

Q1) Why a bad gas check valve is this hard starting problem source only when engine hot, not also when it's cold ?

Q2) Does this check valve kit add a second check valve in serie with the pump, why not just replace the existing one ?

Glad to see that it solve the problem easily and cheap.

When hot, the fuel will boil in the fuel rail by the injectors creating an air lock or vapor lock when you have it under pressure it raises the boiling point and also gives it no place to go. On a cold start the fuel is denser and the pump fairly rapidly gets to the injectors , but it still starts faster with a good check valve.

Q2, it takes less than 5 minutes to install the check valve start to finish and doesn't hurt to have 2 in series, its a lot more trouble to pull the fuel pump out of the tank to replace the check valve. This was a cheap 88.00 ebay pump so for less than 10 more it works fine now.

[Claude]

When hot, the fuel will boil in the fuel rail by the injectors creating an air lock or vapor lock when you have it under pressure it raises the boiling point and also gives it no place to go. On a cold start the fuel is denser and the pump fairly rapidly gets to the injectors , but it still starts faster with a good check valve.

Q2, it takes less than 5 minutes to install the check valve start to finish and doesn't hurt to have 2 in series, its a lot more trouble to pull the fuel pump out of the tank to replace the check valve. This was a cheap 88.00 ebay pump so for less than 10 more it works fine now.

Thanks for your explanations Bill. Another one: When we purchase a new full pump does it come equip with a new check valve on it or do we have to order it separately ?

[Bill R.]

Thanks for your explanations Bill. Another one: When we purchase a new full pump does it come equip with a new check valve on it or do we have to order it separately ?

The check valve is condsidered an integral part of the pump, it comes with it built in more or less.

[angusbn]

Bill R,

How exactly did you hook up the check valve. From the picture I can't see now you tapped into the send line?

[Bill R.]

Bill R,

How exactly did you hook up the check valve. From the picture I can't see now you tapped into the send line?

I added arrows and text to the picture , it should be obvious now.

[Bill R.]

Erich, next time i order from bma i can check for you if you want. How many would you like? I can check my local dealer also, I have to pick up some e46 parts from them in the next couple of days anyway.

[shogun]

Easy to remember about the connections on the tank: The outside pipe connection is always from the fuel tank to the fuel rail in engine room, the more inside (center on the lid) connection is always the return line from engine room to tank, no matter if there are 1 or 2 pumps like on my E32 750, outside = sending line out of tank to engine room. And the check valve has an arrow for the flow of the fuel, so 'basically' you cannot make anything wrong.


question to the experts for a friend who also owns a E32 750 with M70 engine: I put some pressure gauges in my fuel lines to make sure I have correct pressures left and right. The fuel pressure holds steady after the car is switched off for several hours,
overnite, however, the pressures appear to have leaked down to about zero, on both sides...750IL 1990 (9/89)
-----------------------------------------------------------------
Is there any general instructions how long the pressure should hold, or a time curve with max permissible drop in pressure?

Edit: found it:
Notes on fuel pressure check (reference pressure: intake manifold pressure)
Feature of this version with intake manifold pressure: The connection for the vacuum hose of the fuel pressure regulator is located in the intake manifold after the throttle.
Test precondition:
The correct fuel pressure regulator is fitted.
- Using the EPC, check whether the fuel pressure regulator suitable for the car is fitted:
Connect test adapter,
refer to 13 31 029.
Description of operation: fuel pressure regulator
Depending on requirements, the fuel pressure regulator regulates a low or high fuel pressure. This requirement is set with the help of the pressure regulator.
Depending on the engine's operating state, less or more fuel is needed:
- at idle speed, less fuel
- at full load, considerably more fuel.
The injection rate is precision-adjusted by means of the injection time; the injection time is controlled by the DME.
The partial vacuum in the intake manifold serves as engine load information for pressure regulation. The diaphragm of the pressure regulator is actuated with this partial vacuum.
A partial vacuum builds up in the intake manifold during idling operation or in overrun mode. Depending on the partial vacuum value, the fuel pressure decreases starting out from the nominal value. The nominal value is stamped in the fuel pressure regulator housing.
At full load, the partial vacuum in the intake manifold is approximately equal to zero. The fuel pressure regulator regulates the fuel pressure to the nominal value stamped in the housing.
Description of operation: fuel pump
The control function of the fuel pressure regulator must be ensured in all operating states. The fuel pump must therefore always be able to generate a higher fuel pressure than the pressure regulated by the pressure regulator.
Description of operation: fuel return line
When the engine is at a standstill and the ignition key is in position 0, the fuel return line after the pressure regulator is at zero pressure.
Description of operation: pressure retaining function
The pressure regulator closes when the engine is at a standstill and the ignition key is in position 0. The fuel pressure in the delivery line is retained over an extended period. A non-return valve closes in the fuel pump. These measures help to retain the fuel pressure in the fuel system. Extended starting times are thus avoided.
Complaint: drive characteristic faults, lack of power
- Run engine at idle speed and measure fuel pressure.
- In order to simulate "full load" state: ne Disconnect vacuum hose from fuel pressure regulator and measure fuel pressure.
The measured value must increase by 0.4 to 0.7 bar depending on the engine. Note down measured value.
- If the measured value does not increase: Replace vacuum hose and measure fuel pressure again
- If the measured value still does not increase: Replace pressure regulator
- Measure fuel pressure again and note down measured value.
- Compare the measured value with the nominal value stamped in the pressure regulator housing.
If the specified measured value is still not achieved, you must carry out the following checks depending on the measured value.
If the measured value is less than the nominal value - 0.2 bar:
- The cross-sections in the fuel feed line are contracted or the fuel filter is clogged,
or
- the fuel pump voltage supply is not O.K., e.g. due to high contact resistance (corrosion) in the plug connection between wiring harness and fuel pump
If the measured value is greater than the nominal value + 0.2 bar:
- Switch off engine and then observe measured value.
- If the measured value drops to the nominal value, the cross-sections in the fuel return line are contracted or clogged.
- Check the fuel lines for kinks.
If no kinks are visible:
- Replace return lines.
If the measured value remains too high, the pressure regulator is most probably faulty.
Caution!
With less likelihood, the return line may be completely blocked. When the pressure regulator is removed, fuel could escape under pressure!
- As a precaution, have a cleaning cloth ready and collect and dispose of any escaping fuel.
- Replace the return line but not the pressure regulator.
Complaint: starting problems
- Run engine briefly at idle speed and switch off.
- Note measuring value when engine is stationary.
- Read off measured value again after approx. 20 to 30 minutes with engine stopped.
The special tool 13 3 010 (hose clip) is needed for the following check.
If the measured value has dropped by more than 0.5 bar:
- Start engine and wait briefly for a stable pressure increase.
- Switch off the engine and immediately pinch off the delivery line just before the pressure gauge with the special tool 13 3 010.
- Note down measured value.
- Read off measured value again after approx. 20 to 30 minutes with engine stopped.
If the measured value has now dropped by less than 0.5 bar, the following faults may be present:
- Fault in delivery lines
- Fault in in-tank delivery hose
- Faulty pressure-holding non-return valve in fuel pump
Check components. Replace faulty components.
If the measured value has again dropped by more than 0.5 bar:
- Replace pressure regulator
Note:
- All the fuel hoses and hose clips which were detached within the framework of the checks must be replaced.
- Fault messages may be stored in the fault memory of the DME control unit if the vehicle is operated in the intervening period. The fault messages "Incorrect lambda control" or "Lambda control at stop" must be cleared after the check is completed:
Interrogate fault memory of DME control unit. Check stored fault messages. Rectify faults. Now clear the fault memory.

13 64 582 Checking injector valves for leaks and cleaning, Special tools required: · 13 6 200, · 13 6 205, · 13 6 206, · 13 6 207

Injector valves removed. Mark sequence of injector valves relative to cylinders on each injector valve. Caution! Observe country-specific safety regulations when handling fuels and cleaning agents.

Check injector valves for leaks: Clip fuel injectors into special tool 13 6 205 . Connect special tool 13 6 206 to the injector valves. To catch remaining fuel, wrap fuel injectors in clean cleaning cloth. Connect special tool 13 6 206 to a 12 V car battery. This removes the remaining fuel from the injector valves. Connect special tool 13 6 205 to compressed air connection of max. 5 bar. Residual fuel is now blown out of the injector valves.
Caution! Carry out leak test only after remaining fuel has been blown out of injector valves.
Separate special tool 13 6 206 from the injector valves. Install injector valves with special tool 13 6 205 in a container with hot water (60 ... 80° C). Adjust air pressure at connection ① on special tool 13 6 205 to max. 3 bar (motorsport models max. 5 bar).
Note volume of air emerging. Permitted volume of air emerging: 2 air bubbles per injector valve within a 15 second period. Note injector valves with larger volumes of air emerging. Injector valves with larger amounts of air emerging must be cleaned. Remove fuel injectors from water and dry thoroughly with compressed air.
Clean injector valves: Install injector valves in special tool 13 6 205 . Connect special tool 13 6 206 to injector valves and to a 12 V car battery. Use ultrasonic cleaning unit 13 6 200 to clean injector valves. Read operating instructions before operating ultrasonic cleaning unit.

Attach injector valves to special tool 13 6 200 with special tool 13 6 205 . Fill special tool 13 6 200 with cleaning concentrate 13 6 207 as specified by manufacturer. Perform cleaning procedure as specified by manufacturer. Repeat leak test on cleaned injector valves.
Caution! Do not carry out leak test in cleaning concentrate but rather in a water bath. Only replace injector valves from which volume of air emerging exceeds the permitted limit of 2 bubbles within a 15 second period. Caution! Install cleaned injector valves immediately in engine and run engine. This flushes out any remaining cleaning concentrate thereby preventing injector valve corrosion. Due to the risk of corrosion, cleaned injector valves can no longer be stored.

From spagetticoder when it was still working

now I got my check valves send from someone from USA, but still do not need them. Believe it or not, the fuel pumps in my E32 750iL from 11/1988 are still the first ones and still run without problems. Of course, the total miles are not that impressive, now I have 164.000 km on the clock = abt. 100 k miles. Anyway, new Bosch fuel pumps are in my parts shelf for day X.but I want to see how much life the old ones still have.

[Bill R.]

Glad to see you got them, based on your mileage i would guess you pumps will last at least 4 more years. Do you run
a methanol /ethanol gas mix in japan for pollution like we do here. That 10% ethanol seems to contribute to the death of a lot of
fuel pumps here.

[shogun]

that just started some years ago here with the methanol mix. Japan began testing E3 (3% ethanol and 97% gasoline) and ETBE (ethyl tertiary butyl ether) in 2007. Now we have E10
copied:
Infrastructure and Vehicles

Japan started to offer E3 at two gasoline stations, one in Sakai City and the other in Daito City, in October 2007. E3 is also offered in Osaka but is limited to about 100 cars registered in advance with the local government. Japan is gradually increasing the number of E3-supplying gas stations to sell the product to the general public in 2008. There are about 50 stations in the Tokyo metropolitan area offering ETBE blended gasoline. Their number is expected to reach 100 during 2008, increasing to 1,000 nationwide in 2009 (Asia Times 2007).

Trade

Japan imports ethanol (mostly from Brazil and China) to supply its beverage, chemical, and pharmaceutical industries. Brazil has the world's largest ethanol export potential, and it is seen by Japan as its major source of the alternative fuel. Last year, the governments of Japan and Brazil set up a study group on trading in the fuel. It is expected that large amounts of fuel ethanol will be imported from Brazil in the coming years (Ohmy News International 2007).

The problem is that Japan does not have enough agricultural land to grow the raw material, even cattle feed soy beans, corn etc are imported from outside the country

http://eneken.ieej.or.jp/en/data/pdf/451.pdf

For the use of ethanol-blended gasoline as conventional gasoline for vehicles, JAMA recommends a blending ratio of maximum 10% (E10). Similarly, JAMA does not recommend the use of ethanol-blended gasoline of more than 10% ethanol content except for vehicles specially designed so or for flexible-fuel vehicles.
Green Car Congress: Japan Automakers Support B5, E10 as Baseline Biofuel Blends, Recommend Specifications to ASEAN Countries (http://www.greencarcongress.com/2010/02/jama-biofuel-20100228.html)

[John B.]

Still on the original pumps in my 90 535i with 190K & going on 8 years of E10 fuel.

[v8csl]

Bill,

I installed the check valve retrofit kit today in hopes of curing hot start problems on my '95 525i and had fuel spraying out from the rubber fuel line (off the regulator/fuel rail assembly) along with a rough idle. I removed the check valve and the problem went away. Idle is steady again, car drives fine. Any idea on what caused this? Bad FPR? Clogged return line? Hard starting trumps a torched car any day!

Thanks!

Reg

[Tiger]

Your fuel injector(s) are leaking. I had my fuel injectors cleaned and they told me one of my fuel injector was leaking... after the cleaning, the injectors are good again.

I had a mild hard start problem. This also affect the emission test and engine smoothness.

I pulled all fuel injectors out and sent it to a fuel injector rebuilding specialist. Don't bother with fuel injector cleaners that goes in fuel tank or those shops that hooks up some sort of IV to the engine. Get the job done right... that including new seals, new internal fuel filter (inside the injector) and the powerful machine they use to test, clean and benchmark yoru fuel injector performance.

You will notice on the test that your fuel injectors are all different spec before and after cleaning... they are all identical spec test result.

One note... install the injectors once you got it back. Do not wait. Do not buy used injectors online unless you will send them to injector cleaning shop... do not trust anyone else to clean injectors or so called cleaned injectors unless you trust that seller.

Otherwise you risk buying a bad leaking injector that will hydrolock your engine. However, it will not immediately hydrolock your engine... you will notice super rich fuel exhaust smell.... IMMEDIATELY SHUT DOWN AND REMOVE INJECTORS... DO NOT RESTART ENGINE FOR the rest of the day or pull spark plugs out and turn engine over to eject any fuel.

Don't ask how I know... lol. Bad expensive lesson.

[v8csl]

Thanks for the input. In any case, it's time for an Inspection II - I'll look into getting the injectors pulled and cleaned as well.

--Reg

[Bill R.]

Its sounds like you installed the kit wrong and were blocking off the return line with the check valve. The pump pressure would then skyrocket since the pressure regulator wouldn't or couldn't regulate the pressure. The rough idle would be caused by excess fuel pressure at the injectors

[v8csl]

I hooked it up based on the fuel pump supply/return hose orientation diagrammed in Bentley. Also observed the fuel flow direction arrow etched on the retrofit kit. I'll try it again this weekend and report back. It is very possible it's a self-inflicted wound ;) Thanks for the feedback!

[v8csl]

I swapped the check valve to the inner pipe - the one that Bentley marked as the return pipe and it fired up, idled smoothly, and revved cleanly. No more leaks. The PO must have cross-fitted the fuel pump's internal hoses (suction hose to return pipe and return hose to supply pipe). Best of all, it eliminated my hot-start issue - starts with one crank. Score another one (M50TU) for the check valve kit!

[genphreak]

I put a brand new pump in the wagon recently and think the check valve is needed as well as the hard start issue has changed from an intermittent no start condition due to no pressure, to one of boiling fuel in the lines (which is worse on hot days).

[v8csl]

It's amazing how a simple piece of kit can make such a difference to the ownership experience... Vacuum hoses are next.

[genphreak]

It's amazing how a simple piece of kit can make such a difference to the ownership experience... Vacuum hoses are next.Yes indeed. I put the same replacement pump in the other 525 and there are no hard start issues at all...

[shogun]

still same old original pumps and working, now around 175000 km. I will leave the old pumps in till they are dead, want to see when this happens. Have new pumps, filters etc all on stock , so no problem, and as the car has 2 fuel pumps and can run in limpmode with 1 side and one bank, I can take the risk and will not be stranded somewhere (hopefully) when 1 pump breaks.Did not put much more mileage on it, still under 180kkm.

For Kibokojoe
notes on fuel pressure check - reference pressure intake manifold pressure M30. Feature of this version with intake manifold pressure: The connection for the vacuum hose of the fuel pressure regulator is located in the intake manifold after the throttle.
Test precondition: The correct fuel pressure regulator is fitted. Using the EPC, check whether the fuel pressure regulator suitable for the car is fitted: Connect test adapter,refer to 13 31 029. Description of operation: fuel pressure regulator
Depending on requirements, the fuel pressure regulator regulates a low or high fuel pressure. This requirement is set with the help of the pressure regulator.
Depending on the engine's operating state, less or more fuel is needed:
- at idle speed, less fuel
- at full load, considerably more fuel.
The injection rate is precision-adjusted by means of the injection time; the injection time is controlled by the DME. The partial vacuum in the intake manifold serves as engine load information for pressure regulation. The diaphragm of the pressure regulator is actuated with this partial vacuum. A partial vacuum builds up in the intake manifold during idling operation or in overrun mode. Depending on the partial vacuum value, the fuel pressure decreases starting out from the nominal value. The nominal value is stamped in the fuel pressure regulator housing.
At full load, the partial vacuum in the intake manifold is approximately equal to zero. The fuel pressure regulator regulates the fuel pressure to the nominal value stamped in the housing. Description of operation: fuel pump: The control function of the fuel pressure regulator must be ensured in all operating states. The fuel pump must therefore always be able to generate a higher fuel pressure than the pressure regulated by the pressure regulator. Description of operation: fuel return line: When the engine is at a standstill and the ignition key is in position 0, the fuel return line after the pressure regulator is at zero pressure. Description of operation: pressure retaining function: The pressure regulator closes when the engine is at a standstill and the ignition key is in position 0. The fuel pressure in the delivery line is retained over an extended period. A non-return valve closes in the fuel pump. These measures help to retain the fuel pressure in the fuel system. Extended starting times are thus avoided.
Complaint: drive characteristic faults, lack of power
- Run engine at idle speed and measure fuel pressure. In order to simulate "full load" state:Disconnect vacuum hose from fuel pressure regulator and measure fuel pressure. The measured value must increase by 0.4 to 0.7 bar depending on the engine. Note down measured value. If the measured value does not increase: Replace vacuum hose and measure fuel pressure again. If the measured value still does not increase:Replace pressure regulator. Measure fuel pressure again and note down measured value. Compare the measured value with the nominal value stamped in the pressure regulator housing. If the specified measured value is still not achieved, you must carry out the following checks depending on the measured value. If the measured value is less than the nominal value - 0.2 bar: The cross-sections in the fuel feed line are contracted or the fuel filter is clogged,or the fuel pump voltage supply is not O.K., e.g. due to high contact resistance (corrosion) in the plug connection between wiring harness and fuel pump. If the measured value is greater than the nominal value + 0.2 bar: - Switch off engine and then observe measured value. If the measured value drops to the nominal value, the cross-sections in the fuel return line are contracted or clogged. Check the fuel lines for kinks. If no kinks are visible: - Replace return lines. If the measured value remains too high, the pressure regulator is most probably faulty.
Caution! With less likelihood, the return line may be completely blocked. When the pressure regulator is removed, fuel could escape under pressure! As a precaution, have a cleaning cloth ready and collect and dispose of any escaping fuel. Replace the return line but not the pressure regulator. Complaint: starting problems: Run engine briefly at idle speed and switch off. Note measuring value when engine is stationary. Read off measured value again after approx. 20 to 30 minutes with engine stopped. The special tool 13 3 010 (hose clip) is needed for the following check. If the measured value has dropped by more than 0.5 bar: Start engine and wait briefly for a stable pressure increase. Switch off the engine and immediately pinch off the delivery line just before the pressure gauge with the special tool 13 3 010. Note down measured value.
- Read off measured value again after approx. 20 to 30 minutes with engine stopped. If the measured value has now dropped by less than 0.5 bar, the following faults may be present: - Fault in delivery lines: Fault in in-tank delivery hose. Faulty pressure-holding non-return valve in fuel pump.Check components. Replace faulty components. If the measured value has again dropped by more than 0.5 bar: - Replace pressure regulator. Note: - All the fuel hoses and hose clips which were detached within the framework of the checks must be replaced. Fault messages may be stored in the fault memory of the DME control unit if the vehicle is operated in the intervening period. The fault messages "Incorrect lambda control" or "Lambda control at stop" must be cleared after the check is completed: Interrogate fault memory of DME control unit. Check stored fault messages. Rectify faults. Now clear the fault memory. http://www.meeknet.co.uk/e38/Fuel-rail-pressure.pdf
http://workshop-manuals.com/bmw/5_series_e34/535i_m30_sal/2_repair_instructions/13__fuel_system_(m30)/31__fuel_pump_with_drive_and_line/1_ra__notes_on_fuel_pressure_check_(reference_pres sure__intake_manifold_pressure)/

[Kibokojoe]

Shogun, is there a check valve kit available anymore?

[shogun]

The original one from BMW is no longer available, that means 16149068988 CHECK VALVE KIT = check valve, hose and the foam insulation as shown here
http://www.bimmernut.com/forum/attachment.php?attachmentid=6558&stc=1&d=1234132939
I still have 2 on stock new which once someone bought for me from BMA.
But the check valves you can buy easy from aftermarket, they come in various designs from plastic to alu, steel and with various pipe diameters
Just google for Fuel Non Return One Way Check Valve or look at Ebay, they have plenty.