...so when you get 9.5v from the ecu, is this making it all the way to the fuel pump connector? Doesn't really matter at the moment what leaves the ECU if it's not making it all the way to the pump.
tlr ecu fuel pump logic and circuit ?
hey guys got a 98 that will not cycle the fuel pump. initially the tos was gone (5 volts all the time) so i replaced it and now the bike will run only if the fuel pump relay is jumped. I checked for voltage on the wire going to the ecu but as the ecu cycles the pump for 3 seconds the voltage is only 9.5 but i have 12.5 at the battery. I know usually this is where the manual says replace ecu. but i would like to delve a little deeper into it. the po could not get the bike to run due to the tos being bad so i got the bike cheap. he also got another ecu. but unfortunately the one he got will not cycle the pump also. i tested it and only get 1.5 volts going to ground threw the ecu. so i am assuming this one it toast to. has anyone been into the ecu and know what controls the fuel pump? I am curious if it is just a transistor that could be replaced. my plan is to open the ecu that he had gotten to try and make the bike run as i think the pump logic or circut is bad in that one anyway. Any input be great. oh ya i did check the anti theft 100 omn resistor and it seems to be ok and the green plug at the head stock is in good shape.
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its 9.5 volts threw the ecu, as it controls the ground side of the relay as the ecu could not handle the draw of the pump. the pump is fed hot from the battery threw a relay controlled by the ecu. so what is happening at the ecu is does really matter.
Where are you measuring the above highlighted voltages?hey guys got a 98 that will not cycle the fuel pump. ....and now the bike will run only if the fuel pump relay is jumped. I checked for voltage on the wire going to the ecu but as the ecu cycles the pump for 3 seconds the voltage is only 9.5 but i have 12.5 at the battery. .....also got another ecu. but unfortunately the one he got will not cycle the pump also. i tested it and only get 1.5 volts going to ground threw the ecu. so i am assuming this one it toast to. .....
If both measurements are from the "low" side of the fuel pump relay coil (yellow/blue wire), then the 1.5V is likely a good ECM. The other one (9.5V) could be bad, or it could be merely flakey wiring (more likely).
The ECM fuel pump relay drive circuits have been known to fail, but it is not a common failure. There is an internal transistor that sinks the relay coil current, but I haven't personally opened an ECM up.
measuring 12.5 at the o/w pin 17 on ecu but only 9.5v on the y/bl pin 9. so 9.5 at the y/b at the relay.
i was reading this
Orange/Blue - 12V permanent
Orange/White - 12V switched (via ignition switch)
Yellow/Blue - Control line from ECM
Yellow/Red - 12V power feed to fuel pump and injectors (switched via the relay)
Yellow/Blue wire conditions:
Immediately after KEY ON it goes low (near zero volts) for about 3 seconds. This is the "fuel pump prime" cycle.
When the Kill Switch is cycled, the FP prime cycle is also initiated.
With only KEY ON and engine not cranking and not running, it will be nearly 12V.
With KEY ON and engine cranking, it will go low (zero volts).
With KEY ON and engine running, it will be low.
In a nutshell - Y/B wire low = FP runs; Y/B wire high = FP is off.
If the Yellow/Blue wire stays high all the time, the FP relay will not engage.
Orange/Blue - 12V permanent
Orange/White - 12V switched (via ignition switch)
Yellow/Blue - Control line from ECM
Yellow/Red - 12V power feed to fuel pump and injectors (switched via the relay)
Yellow/Blue wire conditions:
Immediately after KEY ON it goes low (near zero volts) for about 3 seconds. This is the "fuel pump prime" cycle.
When the Kill Switch is cycled, the FP prime cycle is also initiated.
With only KEY ON and engine not cranking and not running, it will be nearly 12V.
With KEY ON and engine cranking, it will go low (zero volts).
With KEY ON and engine running, it will be low.
In a nutshell - Y/B wire low = FP runs; Y/B wire high = FP is off.
If the Yellow/Blue wire stays high all the time, the FP relay will not engage.
That is correct. :yes That is why I noted that the ECM which is driving the Yel/Blu wire down to 1.5V is probably OK. That leaves about 9 to 10 volts dropped across the relay's coil which should be enough to activate it. If it is not activating, there is either resistance in the Org/Wht wire upstream from the relay, or the relay is bad.......
In a nutshell - Y/B wire low = FP runs; Y/B wire high = FP is off.
If the Yellow/Blue wire stays high all the time, the FP relay will not engage.
Also verify that the Org/Blu wire stays near 12 volts when there is a load on it (pump is running). It is not uncommon for corrosion to develop in the terminals upstream on that wire, :banghead which will limit the voltage available to the pump and injectors - making them less effective.
i have gone over most of the connectors on the bike cleaning and applying dielectric grease. but most of them look perfect. i used to have a 99 750 srad so i am familiar with suzuki connector issues lol
With notes from D'Ecosse and previous SRAD experience, you should be good to go. I'm surprised you even posted the question. :laughi have gone over most of the connectors on the bike cleaning and applying dielectric grease. but most of them look perfect. i used to have a 99 750 srad so i am familiar with suzuki connector issues lol
Seriously, let us know what you find. As I mentioned earlier, the ECM's FP output does fail sometimes, but not often.
ya just my luck that the po bought a used ecu that had duff fuel pump circuit. worst case i wire the relay direct to ground for now. I was more curious if there was a actual surface mounted transistor that i could repair inside the ecu. i am in the process of stripping the silicon off one the ecu of the ecu the po bought to look at it, i am curious to see the motherboard anyway.
Then you might be interested in this thread. http://www.tlzone.net/forums/search.php?searchid=1156632 It is huge, but I'm pretty sure there are some photos of the exposed ECM board in there. :devious If not, there is still a bunch of technical info in it...... I was more curious if there was a actual surface mounted transistor that i could repair inside the ecu. i am in the process of stripping the silicon off one the ecu of the ecu the po bought to look at it, i am curious to see the motherboard anyway.
Unfortunately, some ECMs are sold on ebay and elsewhere, even when they are know to be defective. The purchaser usually has no way to verify its condition until it is too late. :banghead
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