pgmfi.org

When where you power on your petrol pump so first of all check your power connection.then your pump engine light. don't move any body Working with mobile phone or lighter.don't use any kind of fire related part in pump.pump prime should occur at the same time when power is Applied to the ECU so check engine light

7rrivera7,

To confirm, the only component that you replaced to get an ECU that would not prime the fuel pump is IC17, correct?

If this is the case this is a good thing. I have quite a few ECUs with this problem just laying around.

-kenji

Here is a answer to your question that fuel pump delay also due to some garbage in the fuel that is causing problems for the fuel to pass through it. Check it out.



Sightline Payments Kirk Sanford
dewatangkas

what to check next when I installed an new main capacitor, new ta8903 and new qm3

Good to see these ECUs are getting repaired!

guess, others than Ta8903,what else involved in this issue (CEL not turn OFF)..any others component??

this post is very old, yet I feel compelled to add some info to it. There's one simple way to test TA 8903 and determine if it is the culprit of fuel priming. In fact, I had several cases where the pump did not pump at all. The procedure goes like this: use a heat air gun at 200 Celsius for several seconds to heat-up the TA8903, then quickly power-up the ecu while monitoring IC7 pin 32 (this is the fuel pump pin). It should start low (0 v) and two seconds later go high (5 v). When cold (pump failure present) this pin goes high and stays high all the time power is present. Also you can confirm that RESOUT pin in main processor (pin 21) stays low (0 v) while power is applied. If you heat the TA8903, then pin 21 goes high (5 v) for a split second to reset the CPU as it should (this test is done with a scope or a fast response multimeter). Few minutes after heating the IC, the failure should come back.

Finally if you don't have the spare TA8903 procede like this (it could or could not work):

take the TA8903 out of the board. Use an iron heated to 400 Celsius and put a big blob of solder over the IC and roll it with the iron all over its body for 30 seconds to one minute.
The TA 8903 should come back to life for a longer time. Maybe even enough to use the ECU while you find your spare. You should find a spare IC ASAP, otherwise it will fail again without notice.

BR.

Hello I was the person who originally posted that this IC needed to be replaced to resolve this issue

However...I still have several ECUs that still fail even after replacing this part and I have them stored for when I have time to continue troubleshooting. The schematics do not show any other main components involved other than the ones already listed so if anyone has found a solution to this problem even when replacing TA8903 with a new part (or more than one as I have), please let us know.

along with changing out TA8903 have you tried replacing IC17 and replacing all capacitors with new caps?

also where did you purchase new TA8903's from?

thanks =)

Having similar issues as well.

Still have ECUs with NEW TA8903's and although they fix the problem immediately, they still fail later on after being disconnected from a power source.

Has anyone found a solution? If not, I'm going to have to pull out the scope again...

Excellent thread..!!!

Nice...

I have a PO6 that does not activate the main relay, buying A new TA8903 will fix the problem, or get an other ecu and switch it out?

After some ECU repairs during last year, I wonder if IC17 could be bypassed at all when troubleshooting ECUs with fuel pump activation delay (or CEL staying on etc.)
As far as I know, TA8903SN is "power supervisor" IC and it does not deliver power to CPU at all, only information about power status, most likely triggering NMI or RESET.

Anyone interested?

I would appreciate any information about pinout of main OBD1 CPU (M66207) where NMI or RESET pins are, and some brainstorm about the scenario "interrupt PCB path between IC17 and CPU" and "make some Power Good circuit delivering right voltage to NMI and RESET pins to ensure good bootstrap of CPU".
I imagine Power Good circuit as only a pullup resistor to NMI and slight time delayed log. 1 to RESET (so RESET will be lifted few hundreds of milliseconds after Vcc is applied to ECU).

Update: attached M66207 datasheet. NMI is pin 33, RES is pin 29 - the both in inverted logic, as usual in MCUs. Now we have to analyze logic levels during powerup of good ECU and compare with bad ECU with fuel pump delay. Do anyone have logic analyzer?

Also maybe HOLD (pin 34, P2.4) pin is involved somehow - maybe IC17 holds CPU stopped during powerup? (desperately need the logic analysis of NMI, RES and HOLD )