yes another no start thread.....

[bimmershark]

ok so bit of an odd egg this one...

starts out with me needing to change a front wheel bearing and tie rod assembly...car sat with the front in the air for a week or two...would start and run in that position no issue....didnt have any pre existing start issues..

the day i button it all up and drop it off the stands to take it for a shakedown run and to work to align it it wont start... cranks over all day long have power to everything ... so i know the connector on the top of my fuel pump assembly was not in the best shape..pulled the unit and brought it to work and tested it..one of the prongs was fubar..but put power to the pump and it works..

so i buy a used assembly swap it all over and still nothing..the plug from the car to the unit was in bad shape itself so i cut it off and gave it a new end ... swapped out a few pump relays..still nothing

got a test light ... no power at the pump wires ... so my question is where do i go from here?

car has been pretty reliable for me the past 2 years considering i did little to no maintenance so i cant complain ..but i need to get her going again...along with the issues it had before i got it...she needs loving...as soon as i can get a replacement daily she will be going under the knife as a project e30 truck....just not yet

[Ceeker]

always check your fuses first! might have one blown.

[bmwguy325is]

I say put the back end up on jack stands for a while. Balance the equation kinda thing.

[yert315]

Do you have spark?

[bimmershark]

always check your fuses first! might have one blown.

def the first thing i checked all are good

I say put the back end up on jack stands for a while. Balance the equation kinda thing.

the thought has crossed my mind :shifty

Do you have spark?

yup pulled and tested each wire everything is solid.

even went as far as undoing the fuel line at the pump and cranking it over hoping to see even a drop of gas come out and nothing....

[yert315]

Looks like your pump is shot. Grab one from the yard (get a warranty) and give it a shot.

[bimmershark]

the pump is working , bench tested it... i have no power getting to it ..used a test light right on the pigtail at the pump

[jlevie]

If you have spark, but no power to the fuel pump you could have a fault in:

The fuel pump relay
The fuel pump fuse
The engine wiring harness
The C101 connector
The body harness
The DME

Start checking at the relay with a test light and work back towards the pump.

[bimmershark]

If you have spark, but no power to the fuel pump you could have a fault in:

The fuel pump relay
The fuel pump fuse
The engine wiring harness
The C101 connector
The body harness
The DME

Start checking at the relay with a test light and work back towards the pump.

will do... thanks

[bimmershark]

so update ...no fuel no spark...will crank over all day as long as i give he a fully charged battery ...went over all the connectors to make sure they were tight and snug....also ordered a new cps and a few other bits but it may have been a waste as i swapped it out just now...and still not a fucking thing

quick run down...

no fuel...pump tested good swapped thru like 5 different relays

no spark...plugs are not to old and wires were swapped from a car that had a fresh tune up with in a year or so

replaced the pump housing unit as it had a broken connection on top along with a new pig tail into the harness...and when you give it direct power it kicks on and runs

it was running good when i put it into the air to replace the right front tie rod and wheel bearing..had it running while in the air as i had adjusted my belts and it ran great right after that ...after i got the parts in and dropped it off the jacks went to start it and it would just crank with out actually starting or even sounding like it wanted to start

[jlevie]

If this car has an M20B25 engine...


For the engine to run the following conditions must be met:

Power on DME pins:
27 Start Input
18 Un-switched Power input
37 Power Input from Main Relay

Ground on DME pins 2, 14, 19, 24

Timing data from the CPS on DME pins 47 & 48 from a rotating engine

To have spark power must be present at the coil positive and ground pulses
from the DME's pin 1 must reach the coil negative. Power to the coil is
controlled by the ignition switch via C101. When checking for spark, use the
output lead from the coil to eliminate the distributor, rotor and plug wires.

To have injector firing power must be present at each injector and ground
pulses from the DME's pin 16 (Bank1) and pin 17 (Bank2) must reach the
respective injector bank. Note that the injectors are wired as two banks of
three. With cylinder 1,3,5 being bank 1 and 2,4,6 being bank 2. Power to the
injectors is controlled by the main relay. Injector firing is best checked
with a noid light.

The fuel pump relay must have power on pin 86 (relay coil) from the main relay
output (pin 87) and power on pin 30. The DME will ground pin 85 to turn on the
relay and power the pump(s) via pin 87. Of the above, only the fuel pump power
is fused. So if the there's power at pin 87, but not at the pump, check fuse
11.

The main relay and DME pin 18 receive power from the smaller of the two wires
that connect to the battery's positive terminal. That wire incorporates an
in-line fuse. When the DME is presented with a start signal, it grounds the
main relay pin 85 and furnishes power to the fuel pump relay, injectors, and
DME.

Troubleshooting:

Disconnect the battery and the DME cable. Then:

1) Disconnect the coil negative and check continuity from that connector to
DME pin 1. Also verify that from DME pin 1 to ground is an open circuit.

2) Check the resistance across DME 47 & 48, which should be 500-560 ohms. If
the CPS is dismounted, the resistance can be seen to change from about 500 to
540-560 ohms when a ferrous object is brought to the face of the
sensor. Neither pin should be grounded.

3) Check for continuity from DME 36 to main relay 85 and from DME 3 to fuel
pump relay 85.

Reconnect the coil, remount the CPS (air gap should be 1mm), plug the
relays back in, reconnect the DME, and connect the battery. Then do the
following checks:

1) With the key off, verify that power is present at DME pin 18 and main relay
86 & 30.

2) With the key on, verify that power is present at DME pin 27 and pin
18. Power to pin 18 is from the main relay and there should be power to the
injectors and fuel pump relay.

3) With the key on, verify that no voltage is present at the DME grounds (2,
14, 19, 24).

4) Verify that power is present at the coil positive and at fuel pump relay
pin 30. Those get switched power from the ignition switch via C101.

The engine will start and run (if poorly) with only those connections to the
DME in place. The other signals from Cylinder ID, AFM, temp sensor, etc., are
necessary for proper operation. But they won't prevent the engine from firing.

IMPORTANT:

A power check means seeing a voltage within about a tenth of a volt of what
you measure across the battery terminals, which should be at least 12.6v on a
charged battery.

A continuity check means seeing less that 1 ohm of resistance.

An open circuit means seeing a resistance of at least 100k ohms.

A good quality auto-ranging digital multimeter will make these tests much
easier.