fuel ecu problem, I think

The 1UZFE EGR Delete Kit is available for sale here.
Michael, I here what everyone is talking about and they may be right but have you checked all the tiny vacume hoses on the top passenger side of the engine for cracking or disconnection (vacume leaks)? Did you clean out your throttle body with carb cleaner? Did you check the TPS sensor? This problem may not be a fuel related problem. You may even want to check for a clogged cat converter... Those are all symptoms of a choking or stalling engine. I experienced similur problems and corrected them with these above suggestions on a few of the 50 or more sc400's I have owned bought and sold in the past. I have never had one fuel related problem, just the others. Good luck...
 
thanks everyone for your input. The vacuum hoses seem to be ok. Is there a definitive test or should i change them anyway. I cleaned the throttle body. I need to understand how to adjust the TPS. I had the engine running with the Fp +B bridge and rotated the TPS till the revs increased. But how do i know when it has switched to IDL a mm as talked about by Pee Wee in a previous response? What does the TPS do? It seems from a cursory examination that it increases engine revs at idle, and why is it a critical factor here. Also how does one check for a clogged CAT converter. also could it be possible that my fuel ecu was not crook in the fisrt place and if not then why did the diagnostics read that it was N/G and give me the code 78. Is it possible that one problem has led to a whole lot more. And lastly why does the engine run when the Fp and +B terminals are bridged does this do more than bypass the fuel ecu. I appreciate the experience out there and want to understandand why things are as they are.
Roger
 
Bridging Fp and +B just purely bypass's the fuel pump ecu, and makes the pump run when ever the key is ON.

The TPS is the throttle position sensor. Basically tells the ecu how far your foot is pushed to the floor.

With your foot off the pedal, and the throttle butterfly completely closed, the TPS tells the ecu that it should go to the idle fuel/timing map, and operate the ISCV.
This happens with the IDL position on the TPS.
With the throttle closed, there should be continuity (electrical) between the IDL pin the TPS, and the E2 pin on the TPS. Its basically a switch to ground telling the ecu that the throttle is closed.

Now, to stop the IDL contact from happening while you are cruising at low speeds (when the throttle is only open a teeny amount) you have to make sure that the TPS switches IDL from continuous to ground, to open circuit.

Do this by putting a multimeter between the IDL pin and the E2 pin (bottom 2 pins If I remember correctly).
It should read <2000ohms with the throttle plate closed.
Now open the throttle a teeny amount (this is where the 1mm came in).
Now rotate the TPS so that the continuity between IDL and E2 goes from <2000ohm, to open circuit (infinite).
Let go of the throttle (or remove the washer/spacer you put in to keep it open that fraction), and it should go back to <2000ohm.
Test it a couple of times.

Easiest way to keep it open 1mm or so is to locate the stop point, and put a thin spacer in there.


I hope that helps you to understand.
 
Where is the main engine management ECU. It seems that there is no power coming from it to the fuel pump ecu. Does it send a signal to the fuel pump ecu? What does no signal or power from the main ecu indicate? There is a red and green wire to pin 22 and the pink wire to pin 21 on the FP ecu has anyone got any idea here. Is there a diagnostics test for the main ecu. These things are out of my depth, I have the car at mechanic who I am told is the sharpest character around town. The questions he has have to do with D1 pink wire and Fpc 22 He seems to think that no signal out of the main ecu may be the critical factor. I have given him a copy of the wiring schematics. I appreciate that my questions have not been very clear here its only because i am trying to interpret his questions. This is getting bigger than Ben Hur!!!!
 
Pink wire goes from Engine ECU to Fuel Pump ECU - that is DI (diagnostics link for the fuel pump ecu, basically a return from the Fuel Pump ECU to the Engine ECU saying that its working).

Red-Blue is the FPC output, or Fuel Pump Controller, its the PWM signal out of the Engine ECU that tells the Fuel Pump ECU what voltage to give to the Fuel pump.

The other 3 wires on the Fuel Pump ECU are Power, Earth, and Output.


The diagnostics for the Engine ECU are the ones you have done already.
There are no diagnostics for the Fuel Pump ECU, they are incorperated into the Engine ECU (Code 78.)

If you have tried another NEW Fuel Pump ECU, then its possible there is a breakdown in communication between the Engine ECU and the Fuel Pump ECU.


All the above is taken from my investigations and searches. Nothing is guaranteed to be 100% correct, but it all makes sense to me.
 
The Main ECU is under a plastic cover at the firewall under the passenger's feet. It helps if you remove the cover under the glovebox where the air-con filter is so you can pull the carpet back to see the black plastic ECU cover which goes the width of the footwell. There are 2 x 10mm nuts securing it at the bottom so you have to pull the carpet back a fair way.
 
Thanks for that info re the main ecu location. Now that I have the wiring diagrams and have talked to the mechanic I can be a bit more specific than my last post which was I admit fairly fuzzy. On the wiring diagram it shows that the fuel pump ecu has 5 pins coming out of it. E, DI, FPC, +B, FP They all give some electrical response at the fuel pump ecu end, except for D1 which is pin 2 and connects with a pink wire to pin 21 on the main ecu. DI at the fuel pump end is dead as a door nail. There is no power or pulse or signal or anything. Can anyone tell me what kind of signal it is supposed to send to, from or between the fuel pump ecu and the main ecu. I hope that it is simply a broken wire rather than dramas in the main ecu. It would make it a lot easier to workout what was happening if I knew the function of DI. Has anyone encountered this before??? Any help out there????

Yours desperately Roger
 
I'm not sure hey Roger.

And I don't have a CRO to measure the output of it.

All I can suggest is finding someone near you with a working car, and measure what his does.
 
Leaking fluid on to the alternator will eventually kill the alternator, but I can't see it causing the problems you have.
 

Attachments

  • rear end.jpg
    rear end.jpg
    165.3 KB · Views: 13
  • supra box.jpg
    supra box.jpg
    207.9 KB · Views: 10
Thanks Peewee
I didn't think that it would but there is so much electronic stuff on this car. Still working at isolating the problem, appreciate your input. Seeing that i cant get a reading of any kind from DI I am going to connect the fuel pump ecu by short wires to its plug so that I can isolate and disconnect DI to see if it makes a difference to the diagnostics. I figure that if disconnecting DI doesn't make a difference and I don't get the error 78 reading then that will have to indicate whether DI is doing its job getting a message from the FP ecu to the main ecu or not. What do you think???
 
You must log in or register to reply here.

Similar threads

88sogreatv8
New Used ECU issues! I think i hydrolocked my engine with fuel
Replies
17
Views
2K
88sogreatv8
88sogreatv8
A
fuel pump ecu
Replies
0
Views
897
alunwill
A
A
fuel pump ECU
Replies
4
Views
2K
gloverman
G
P
Parts sc400 ecu and fuel ecu
Replies
0
Views
2K
pm0xqu13
P
Z
No spark or fuel = bad ecu?
Replies
4
Views
1K
Zukijames
Z
Z
what controls the fuel pump speed command from ecu?
Replies
10
Views
2K
zen
Z
C
Anyone with a service manual: Is there a bench test for a fuel pump ECU?
Replies
6
Views
2K
Zuffen
Zuffen
L
95 Era SC400 - Fuel Pump ECU Ground Question
Replies
0
Views
2K
LT_Chambers
L


Top