Please help with Fuel Pump Power question

[ForcedTorque]

First let me admit I did the Walbro install with 12 volt mod article. I basically followed the earlier posts from Shaeff, and took pictures along the way. Anything technical on it was followed, or verified with Shaeff before I proceeded.


The problem I am having now is that I am not getting power to my relay at times. If I just FP and +b in the diagnostic block, it fires the pump right up, and the car will start up. After that, I can get the car to start a couple of more times (without the jumper), before it goes back to not getting power. I repeat the process to make it start powering again.

Where should I start looking for the problem. Should I assume it is in the engine wiring harness? And if so, How do I go about fixing the problem?

 

[89supracrazy]

I just looked at the wiring print and it is either your circuit opening relay or your fuel pump relay. I would start by jumpering the fuel pump relay over and try that. If it still does that then more than likely it is your circuit opening relay. Ha. I was looking threw the tech section and their you are. So you added you a relay and jumpered the fuel pump relay. So it has to be your circuit opening relay. The circuit opening relay is located in the passenger side kick panel.


Also check where you jumpered the fuel pump relay because the plug is now exposed to weather. Maybe bad connection.

 

[ForcedTorque]

OK, so I'm fooling around with the car again. I have the COR pulled and brought into the house with the multimeter. i did a search on how to test it, and only found this link

http://www.cygnusx1.net/Supra/Librar...px?S=Main&P=22

telling me where to find it (too late). I have also hunted through the cygnus site, but can't seem to find much more info there either. I'd like to just test it. In the thread that I found that link, Jetjock was talking about jumpering posts 1 and 2, but I can't even figure out which post is which. I think I have a spare in my shed, but I'd rather find a part as being bad before I just throw parts at the car.

 

[89supracrazy]

If you have a 12 volt power supply, hook positive to terminal 2 and hook negative to terminal 4. Next read voltage from terminal 1 which is positive and terminal 4 which is negative. If you are getting the 12 volts every time you make and break the negative you should be fine. If sometimes you are getting less than 12 volts your tips are probably burnt. Terminals 3 and 6 are know concern to you because that is only during cranking. Make sure you read voltage not continuity.

 

[ForcedTorque]

Thanks for the help crazy! BUT.......

but I can't even figure out which post is which.

However, I did find this:

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=FI&P=110



Now, while testing continuity between STA and E1, I get a constant continuity. But while looking for it between B and FC, I only get a very faint, and quick litle blip, and not a constant beep. I got my spare out of my shed, and it was just the same. Is that normal, or are both of these bad? I can apply 12 volts to it, but that will have to wait til I get some daylight tomorrow.

 

[jetjock]

Seriously doubt it's the COR but:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=22

 

[89supracrazy]

Here is the link I am going by. If you go by jetjock's link and what I wrote in the previous thread you should be in there. Also don't forget about what I said in the previous thread about the fuel pump relay plug that you have jumpered. Weather takes it's toll on plugs that are exposed. Make sure it is not corroded inside the terminals.


http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=46

 

[ForcedTorque]

Seriously doubt it's the COR but:

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=22

Why would you doubt it was the COR? Did you read what I wrote about testing it last night? The light blip I get when checking for continuity between B and FC just doesn't seem good to me. I am borrowing one for testing tomorrow from a local down car.

BTW...I see no difference in the link you posted, and the one that I posted that now gets an error message.

Here is the link I am going by. If you go by jetjock's link and what I wrote in the previous thread you should be in there. Also don't forget about what I said in the previous thread about the fuel pump relay plug that you have jumpered. Weather takes it's toll on plugs that are exposed. Make sure it is not corroded inside the terminals.

I have checked the jumpered plug, and it looks brand new in there so far. Is there a good way to protect it from corrosion in the future?

http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=46

I do not know how to read an electrical diagram like that. To me, I only see current coming out of the COR in the direction of those arrows (all out). Hopefully the borrowed COR will work tomorrow.

 

[89supracrazy]

I have checked the jumpered plug, and it looks brand new in there so far. Is there a good way to protect it from corrosion in the future?

If it was me I would plug up the fuel pump relay and find the two wires on the relay side and cut them and butt splice them together. That way you have your plug sealed. I would never put a jumper in a plug for permanent use, for testing only. Let us know if the other relay fixed your problem.

 

[Nick M]

Does it stay running? Or does it stall out? If it stays running, it can't be the circuit opening relay for obvious reasons. Can you block of the regulator return and see if it starts easier after shutting down?

 

[jetjock]

Why would you doubt it was the COR?

I do not know how to read an electrical diagram like that. To me, I only see current coming out of the COR in the direction of those arrows (all out)....

That's why...

 

[ForcedTorque]

Problem figured out. Either my Walbro is dead, or a wiring connection has come apart. I'm getting 12-Volts out of the relay, and towards the pump at least as far a the connection at the stock wiring above the access panel. I can only get to one side of the butt connector without dropping the tank, or pulling too hard. Either it is broken loose on the other side of that, or one of my connectors inside the tank has come apart. Otherwise the pump is dead.

 

[Nick M]

There is another relay after the COR. The fuel pump specific relay.

 

[89supracrazy]

There is another relay after the COR. The fuel pump specific relay.

He has that one bridged out. He did the relay mod where you add one in the trunk.

 

[Nick M]

And I didn't read all of his OP. He is describing bad/loose connections. I skimmed then went into replies.