Home | Contact Us | FAQ | Search & Site Map | Link to Us
Sign In | Join | Other 45 Sites in Network
HomeAnnouncements
Discussion Groups
By Brand
BMWChevroletDodgeFordGMHondaLexusMercedes-BenzNissanPeugeotToyotaVolkswagenOther Brands
By Topic
4x4 CarsRVsDrivingMaintenance & RepairCar AudioCollectible Cars
Country Specific
Australian ForumsUK Forums
ArticlesAuto InsuranceBuyingCars & TechnologyMaintenanceMiscellaneousSafety
DMV Resources
Related Topics
MotorcyclesBoatsMore Topics ...

Car Forum / BMW Cars / January 2008

Tip: Looking for answers? Try searching our database.

'88 325 Fuel delivery problem,..

Thread view: 
Enable EMail Alerts  Start New Thread
Thread rating: 
cosmo - 27 Dec 2007 04:46 GMT
Ok, the stalling problem is now over. The car just cranks and won't
start, so at least it's not an intermittent fault and it's in the
driveway.
I have spark. Fuse 11 is good. I have battery voltage at term 30 and
86 on the main relay. I can light a test lamp at the main relay r/w
wire by turning the key on with the air idle stabilizer valve harness
disconnected. I have voltage at term 30 of the fuel pump relay. If I
pull the FP relay and jump term 30 to 87 I still can't start the car.
This should hot wire the fuel pump, if I'm following things correctly
and jumped the right wires.
With the relay plugged in I test for voltage between term 85 and 86
while turning the key on. I get no voltage- which is a fault condition
but I don't see where the fault is. That's as far as I got today.
What's the next logical thing to try? If I have to test at the
Motronic brain thing behind the glove box I'm disconnecting the main
harness and probing the connectors not the computer, right? You're
really testing the wiring and sensors, not the chip, right?
For those of you joining our program already in progress, this is a
continuation of the "325 dies under way" thread.
1988 325 auto 2.7L, red.
Thanks as always.
Scott Dorsey - 27 Dec 2007 13:55 GMT
>Ok, the stalling problem is now over. The car just cranks and won't
>start, so at least it's not an intermittent fault and it's in the
>driveway.

Excellent!

>I have spark. Fuse 11 is good. I have battery voltage at term 30 and
>86 on the main relay. I can light a test lamp at the main relay r/w
[quoted text clipped - 3 lines]
>This should hot wire the fuel pump, if I'm following things correctly
>and jumped the right wires.

Are you using a high-Z voltmeter, or are you using a test light?  Use
a test light.  Sometimes a broken connection will have just enough leakage
to trigger a modern digital meter but not enough to actually drive a
motor.

An old analogue meter will usually be fine.

>With the relay plugged in I test for voltage between term 85 and 86
>while turning the key on. I get no voltage- which is a fault condition
>but I don't see where the fault is. That's as far as I got today.

This is going to the relay winding?  You don't care about that because
yu KNOW the problem is after the relay, since hotwiring the relay doesn't
solve the problem.

>What's the next logical thing to try? If I have to test at the
>Motronic brain thing behind the glove box I'm disconnecting the main
>harness and probing the connectors not the computer, right? You're
>really testing the wiring and sensors, not the chip, right?

I'd stick a test light right on the fuel pump and make SURE it doesn't
come on.  I bet it does come on, and consequently the problem isn't
electrical.  The output of the computer drives the winding of the relay
that turns on the voltage to the pump.  You know that bypassing the relay
doesn't do any good, so that probably has nothing to do with it.

Unless of course the Motronic ECM isn't getting power either because the
run relay is bad....

Make yourself a test lamp by soldering leads to an indicator bulb.
--scott

Signature

"C'est un Nagra.  C'est suisse, et tres, tres precis."

Bill - 27 Dec 2007 18:06 GMT
cosmo  <puuuurrrh,..> wrote:
>Ok, the stalling problem is now over. The car just cranks and won't
>start, so at least it's not an intermittent fault and it's in the
>driveway.

Excellent!

>I have spark. Fuse 11 is good. I have battery voltage at term 30 and
>86 on the main relay. I can light a test lamp at the main relay r/w
[quoted text clipped - 3 lines]
>This should hot wire the fuel pump, if I'm following things correctly
>and jumped the right wires.

Are you using a high-Z voltmeter, or are you using a test light?  Use
a test light.  Sometimes a broken connection will have just enough leakage
to trigger a modern digital meter but not enough to actually drive a
motor.

An old analogue meter will usually be fine.

>With the relay plugged in I test for voltage between term 85 and 86
>while turning the key on. I get no voltage- which is a fault condition
>but I don't see where the fault is. That's as far as I got today.

This is going to the relay winding?  You don't care about that because
yu KNOW the problem is after the relay, since hotwiring the relay doesn't
solve the problem.

>What's the next logical thing to try? If I have to test at the
>Motronic brain thing behind the glove box I'm disconnecting the main
>harness and probing the connectors not the computer, right? You're
>really testing the wiring and sensors, not the chip, right?

I'd stick a test light right on the fuel pump and make SURE it doesn't
come on.  I bet it does come on, and consequently the problem isn't
electrical.  The output of the computer drives the winding of the relay
that turns on the voltage to the pump.  You know that bypassing the relay
doesn't do any good, so that probably has nothing to do with it.

Unless of course the Motronic ECM isn't getting power either because the
run relay is bad....

Make yourself a test lamp by soldering leads to an indicator bulb.
--scott

--
"C'est un Nagra.  C'est suisse, et tres, tres precis.
-----

Is there any chance of trying another ECU for the car, just to see if it
starts?
It would almost immediately rule it out as a source of the problem and would
take 5 minutes.
I was thinking timing signal issue, too.
Where are you located, country-wise?

Bill in Omaha
'86 535i
Bob Smitter - 27 Dec 2007 18:41 GMT
> Is there any chance of trying another ECU for the car, just to see if it
> starts?
> It would almost immediately rule it out as a source of the problem and
> would
> take 5 minutes.

The OP could do that, but at this point it is almost 100% sure to be the
fuel pump.
In fact, the symptoms from the start have pointed to a fuel pump in my
experience.
Scott Dorsey - 27 Dec 2007 19:03 GMT
>> Is there any chance of trying another ECU for the car, just to see if it
>> starts?
[quoted text clipped - 6 lines]
>In fact, the symptoms from the start have pointed to a fuel pump in my
>experience.

Precisely.  A lamp across the fuel pump wires will tell you for sure.
--scott
Signature

"C'est un Nagra.  C'est suisse, et tres, tres precis."

cosmo - 29 Dec 2007 08:05 GMT
>>> Is there any chance of trying another ECU for the car, just to see if it
>>> starts?
[quoted text clipped - 9 lines]
>Precisely.  A lamp across the fuel pump wires will tell you for sure.
>--scott

It seems the fuel pump is working after all. I pulled the cover and
stuck the hose in a pop bottle. When I crank the engine fuel comes out
a plenty. Still no start. I'm kind of stuck here at this point.
Jack - 29 Dec 2007 09:32 GMT
> It seems the fuel pump is working after all. I pulled the cover and
> stuck the hose in a pop bottle. When I crank the engine fuel comes out
> a plenty. Still no start. I'm kind of stuck here at this point.

I'm not sure what you mean by 'the cover'.
This sounds like you are checking the transfer pump ( the one that's in the
tank).
You need to check the main pump.  (The one in front of the left rear tire)
Disconnect the rubber line from the cold start valve or the firewall end of
the fuel rail.
The Bentley manual also recommends checking the fuel pressure at the fuel
rail.
cosmo - 30 Dec 2007 08:53 GMT
>> It seems the fuel pump is working after all. I pulled the cover and
>> stuck the hose in a pop bottle. When I crank the engine fuel comes out
[quoted text clipped - 3 lines]
>This sounds like you are checking the transfer pump ( the one that's in the
>tank).

That's what has me confused. According to Bentley the 1988 325 has no
separate transfer pump; just a main pump inside the tank, which is
accessed by removing the back seat. However, on my '88 the item under
the oblong cover on the passenger side looks exactly like the picture
of a transfer pump for '84 - '87 models- one fuel outlet, a white two
wire connector (fuel gauge sender) and a black 3 wire connector to
power the pump. Go figure. This looks to be brand new and may be what
was replaced in August- not the main pump as stated in the shop bill.
I will have to get under this thing somehow and try to find the main
pump. There's a round cover on the drivers side which is, I guess, the
tank sender for the second half of the gas tank- just one white
connector with two wires. The plot thickens.

>You need to check the main pump.  (The one in front of the left rear tire)
>Disconnect the rubber line from the cold start valve or the firewall end of
>the fuel rail.
>The Bentley manual also recommends checking the fuel pressure at the fuel
>rail.
Bill - 30 Dec 2007 16:24 GMT
On Sat, 29 Dec 2007 09:32:29 GMT, "Jack" <jack_noble@verizon.net>
wrote:

>> It seems the fuel pump is working after all. I pulled the cover and
>> stuck the hose in a pop bottle. When I crank the engine fuel comes out
[quoted text clipped - 3 lines]
>This sounds like you are checking the transfer pump ( the one that's in the
>tank).

That's what has me confused. According to Bentley the 1988 325 has no
separate transfer pump; just a main pump inside the tank, which is
accessed by removing the back seat. However, on my '88 the item under
the oblong cover on the passenger side looks exactly like the picture
of a transfer pump for '84 - '87 models- one fuel outlet, a white two
wire connector (fuel gauge sender) and a black 3 wire connector to
power the pump. Go figure. This looks to be brand new and may be what
was replaced in August- not the main pump as stated in the shop bill.
I will have to get under this thing somehow and try to find the main
pump. There's a round cover on the drivers side which is, I guess, the
tank sender for the second half of the gas tank- just one white
connector with two wires. The plot thickens.

>You need to check the main pump.  (The one in front of the left rear tire)
>Disconnect the rubber line from the cold start valve or the firewall end of
>the fuel rail.
>The Bentley manual also recommends checking the fuel pressure at the fuel
>rail.
>-----

Crossover year!
My '88 325is had a single pump in the tank, passenger side. The drivers side
tank opening is not for a pump.
The fuel filter is under the car, just forward of the rear wheel on the
drivers side. It may be under a plastic cover.
Prior to 1987 switch to 1988 "model year", there were 2 fuel pumps (like my
'86 535i has). That internal fuel pump
for the Vega is more than enough to get the required fuel pressure at the
fuel rail. Like I said, it can pressurise the system even without the main
external pump on my car. You may check the wiring and connector at the top
of the fuel tank.
Jumper the fuel pump (at the relay, per the Bentley) to run while you check
the connectors at the tank lid.

Bill in Omaha
'86 535i
cosmo - 01 Jan 2008 02:28 GMT
>On Sat, 29 Dec 2007 09:32:29 GMT, "Jack" <jack_noble@verizon.net>
>wrote:
[quoted text clipped - 43 lines]
>Bill in Omaha
>'86 535i

Ok, better weather today,.. Yep, the filter is under a plastic cover
forward of the tank, drivers side. I don't see any other pump. I have
no fuel at the firewall side of the fuel rack. I have no fuel at the
engine end of the filter. If I pull the filter I can pour fuel through
it unoccluded in both directions- at least that's the way it seems to
me. With the filter removed I can pump fuel onto the ground but it
doesn't seem like a constant thick stream. It just comes in spurts.
With the filter removed I can blow through the fuel line from the pump
outlet to where the filter plumbs in. I can blow from the fuel rack
inlet to where the filter plumbs in too. I have to blow pretty hard
but it does pass air. I guess I should pull the pump and check the
sock but it's all supposed to be new. Any idea how to do the current
test with the 3 wire connecter that's fit to the '88 FP? The manual
just gives a procedure for the outboard pump. Thanks again to
everyone- Bill, I'm still trying to download your attachments. I'm
less browser savvy than I used to be.
Bill - 01 Jan 2008 15:40 GMT
Ok, better weather today,.. Yep, the filter is under a plastic cover
forward of the tank, drivers side. I don't see any other pump. I have
no fuel at the firewall side of the fuel rack. I have no fuel at the
engine end of the filter. If I pull the filter I can pour fuel through
it unoccluded in both directions- at least that's the way it seems to
me. With the filter removed I can pump fuel onto the ground but it
doesn't seem like a constant thick stream. It just comes in spurts.
With the filter removed I can blow through the fuel line from the pump
outlet to where the filter plumbs in. I can blow from the fuel rack
inlet to where the filter plumbs in too. I have to blow pretty hard
but it does pass air. I guess I should pull the pump and check the
sock but it's all supposed to be new. Any idea how to do the current
test with the 3 wire connecter that's fit to the '88 FP? The manual
just gives a procedure for the outboard pump. Thanks again to
everyone- Bill, I'm still trying to download your attachments. I'm
less browser savvy than I used to be.
-----

Summary: If your auxilliary fuel pump (in-tank pump) is shot, this is an
inexpensive way to replace it. The mod removes the aux pump assembly from
the fuel tank, dismantles the pump from the assembly, and replaces the pump
with a aux fuel pump from a 1976 Chevy Vega.

Tips: This task will go much smoother and faster for you if you get all the
tools and parts ready before you start. You're installation will be better
if you do. Give yourself plenty of time to work, so you don't feel rushed.

Tools Required:

·       Rachet

·       8mm socket

·       Regular screwdriver

·       Phillips screwdriver

·       Dremel with sanding/grinding disc - or - fine metal file

Optional Tools Recommended:

·       Soldering Iron

·       Solder

·       Soldering paste

Parts Required:

·       Auxilliary (in-tank) fuel pump for a 1976 Chevy Vega (2.2 liter) -
$41.00

·       Cable ties $1.00

·       Two 3/4 inch hose clamps

·       One 1 inch hose clamp

Time Required:

·       30-60 minutes

TEXT ONLY INSTRUCTIONS

1.    Open the trunk, remove the carpet, and remove the 3 screws holding the
cover on to access the auxilliary fuel pump.

2.    Disconnect the two electrical wire harnesses. One is to the fuel pump
assembly (2 pin) and the larger (3 pin) is to the fuel sender unit.

3.    Remove the four nuts and washers securing the fuel sender unit. We
will remove the fuel sender unit to facilitate removal of the fuel pump
assembly. Set the nuts and washers aside for now. You will re-use them.

4.    Slide the sender out until it is barely in, then tilt it to let it
drain. Let it drain for several minutes. The holes on the bottom are very
small. After several minutes, pull it out completely and set it somewhere
dry and clean.

5.    Remove the six fuel pump assembly mounting bolts. Disconnect the two
fuel lines. Save the metal bands that are underneath the hose clamps. You
can throw the old hose clamps away, you should replace them with new ones.

6.    Here's the fuel pump assembly.

7.    Let the fuel completely evaporate from the assembly before starting
this step. When it is completely dry, carefully file off the tops of the two
rivets that are holding the electrical terminals in place. Be careful not to
damage the terminals, since we will re-use them to connect to the new pump.

8.    Here you can see the rivets have been filed off, and the terminals
broken free.

9.    The grounding strap is connected to the assembly with a screw mounted
to a clip nut. Remove the screw and set the screw and the clip nut aside,
along with the grounding strap. We will re-use all these again later.

10.                        Disconnect the fuel pump from the small portion
of rubber hose and set the assembly aside for now.

11.                        Under the old pump is a filter screen piece - on
the bottom is the mounting screw. Remove this screw, then gently wiggle the
screen filter free from the old pump. You can discard the pump now.

12.                        Here's the screen filter.

13.                        Remove the old bit of hose from the assembly. The
new pump should have come with a new replacement piece of hose that you can
use.

14.                        Here's the new pump box.

15.                        The new pump - remove the fuel intake cap.

16.                        Here's the "accessories" that came with the new
pump. We'll need the hose - that's all.

17.                        Attach the new piece of hose to the new pump.

18.                        Attach the new bit of hose (with the new pump)
onto the assembly exactly how the old pump was mounted. I then used some
cable ties to secure it. Reattach the clip nut, grounding strap, and screw
to the assembly. You will need to reattach the screen filter to the bottom
of the pump. You should be able to use the 1 inch hose clamp to secure it to
the bottom of the pump, or use some cable ties to hold it on. You cannot see
the screen filter in this picture, but you can see I've attached it in step
21. Not attaching this screen filter will most surely cause premature
failure of your new vega fuel pump.

19.                        Now we're ready to attach the wires. We need to
make sure we get the polarity correct, since most electrical pumps will run
IN REVERSE if the polarity of the wires is reversed. This would not be
helpful to your fuel situation, and may damage your new pump. In the next
picture (step 20) you can see that the polarity of the terminals on the pump
is labeled on the pump in a very inconspicuous place.

20.                        It was very hard for me to see the polarity
marked on the pump, but here you can see where I found the + mark. The -
mark was in the same place on the opposite side. Obviously, you should wire
the grounding strap to the - side and the black wire that comes down from
the top of the assembly to the + side. When attaching the positive cable, it
may be tight. You shouldn't wire it if it is too tight - it could cause the
cable to break and the pump will then not work. There are three things you
can do (in this order) to get it to reach: 1) push the new bit of hose
farther onto the assembly, thereby decreasing the distance from the cable to
the positive terminal, 2) cut a portion off of the new bit of hose and
reattach the new fuel pump, thereby decreasing the distance and providing
slack, or 3) solder a longer wire and new terminal on to replace the
original wire. - I did both #1 and #2, and had just enough length to connect
it without stressing the wire.

All done. Installation is reverse of removal. Use your new 3/4 inch hose
clamps when reattaching the fuel lines. Then fire it up.
Scott Dorsey - 29 Dec 2007 13:54 GMT
>It seems the fuel pump is working after all. I pulled the cover and
>stuck the hose in a pop bottle. When I crank the engine fuel comes out
>a plenty. Still no start. I'm kind of stuck here at this point.

Good news!  Okay, now measure fuel pressure at the rail.  If fuel is
coming out of the pump but not appearing at the rail, you have a limited
number of things that can be wrong.  These include the regulator and
the filter.

Remember, to run, cars need FAST: Fuel, Air, Spark, and Timing.  You have
verified you have spark, now you need to make sure you have air coming
in, exhaust going out, fuel in the cylinder, and that all this stuff is
happening at the same time.

If you DO have pressure at the rail, pull an injector and see that the
injectors are opening and spraying a nice even burst.  If there is pressure
at the rail, but the injectors aren't opening, it's time to look at the
ECM.
--scott
Signature

"C'est un Nagra.  C'est suisse, et tres, tres precis."

cosmo - 27 Dec 2007 20:08 GMT
>> Is there any chance of trying another ECU for the car, just to see if it
>> starts?
[quoted text clipped - 6 lines]
>In fact, the symptoms from the start have pointed to a fuel pump in my
>experience.

A spare ECU? Are you joking? I can't even find 6 godam spark plugs for
this thing? I live the pacific nw, usa. I will try and find the fuel
pump, which was replace 3 months ago by the previous owner and check
that ooot. tanks again.
Bill - 27 Dec 2007 20:33 GMT
On Thu, 27 Dec 2007 13:41:12 -0500, "Bob Smitter"
<bsmitter@nospamcox.net> wrote:

>"Bill" <wechorba@yahoo.com> wrote:
>
[quoted text clipped - 8 lines]
>In fact, the symptoms from the start have pointed to a fuel pump in my
>experience.

A spare ECU? Are you joking? I can't even find 6 godam spark plugs for
this thing? I live the pacific nw, usa. I will try and find the fuel
pump, which was replace 3 months ago by the previous owner and check
that ooot. tanks again.
-----

I posted earlier that I may have a spare ECU and I may even have a line on
the fuel pump you need.
At this point, if it isn't the fuel pump, and my ECU matches yours, you pay
shipping and I'll loan it for free.
If that fixes the problem, I'll cut you the second best deal you ever
thought on it.

Bill in Omaha
'86 535i
cosmo - 27 Dec 2007 20:04 GMT
>>Ok, the stalling problem is now over. The car just cranks and won't
>>start, so at least it's not an intermittent fault and it's in the
[quoted text clipped - 16 lines]
>
>An old analogue meter will usually be fine.

$35 craftsman digital meter. The manual said use an LED or digital
meter.

>>With the relay plugged in I test for voltage between term 85 and 86
>>while turning the key on. I get no voltage- which is a fault condition
[quoted text clipped - 3 lines]
>yu KNOW the problem is after the relay, since hotwiring the relay doesn't
>solve the problem.

Well I thought it was the "secondary" side of the relay. The circuit
the relay controls- which drives the fuel pump. It sounds like the
book is saying if you have no voltage here the FP relays bad or not
getting battery voltage from the main relay.

>>What's the next logical thing to try? If I have to test at the
>>Motronic brain thing behind the glove box I'm disconnecting the main
[quoted text clipped - 12 lines]
>Make yourself a test lamp by soldering leads to an indicator bulb.
>--scott

thanks again.
Jack - 27 Dec 2007 19:50 GMT
Do the fuel pump delivery test that's in the Bentley manual.

> Ok, the stalling problem is now over. The car just cranks and won't
> start, so at least it's not an intermittent fault and it's in the
[quoted text clipped - 17 lines]
> 1988 325 auto 2.7L, red.
> Thanks as always.
Bill - 27 Dec 2007 20:40 GMT
Contact me at wechorba@yahoo.com. I've got some specific info for you. Lots
of colloected stuff you can use, all on CD.

Bill in Omaha

Ok, the stalling problem is now over. The car just cranks and won't
start, so at least it's not an intermittent fault and it's in the
driveway.
I have spark. Fuse 11 is good. I have battery voltage at term 30 and
86 on the main relay. I can light a test lamp at the main relay r/w
wire by turning the key on with the air idle stabilizer valve harness
disconnected. I have voltage at term 30 of the fuel pump relay. If I
pull the FP relay and jump term 30 to 87 I still can't start the car.
This should hot wire the fuel pump, if I'm following things correctly
and jumped the right wires.
With the relay plugged in I test for voltage between term 85 and 86
while turning the key on. I get no voltage- which is a fault condition
but I don't see where the fault is. That's as far as I got today.
What's the next logical thing to try? If I have to test at the
Motronic brain thing behind the glove box I'm disconnecting the main
harness and probing the connectors not the computer, right? You're
really testing the wiring and sensors, not the chip, right?
For those of you joining our program already in progress, this is a
continuation of the "325 dies under way" thread.
1988 325 auto 2.7L, red.
Thanks as always.
 
Sign In
Join
My Latest Posts
My Monitored Threads
My Blog
My Photo Gallery
My Profile
My Homepage

Start New Thread
Enable EMail Alerts
Rate this Thread



©2010 Advenet LLC   Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.