Fuel pump rewire
02-01-05, 03:41 PM
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Fuel pump rewire
Simple question. I have an 87 TII in a 89 N/A. I did the fuel pump rewire project today and am having a problem. The relay fires when i turn the key, the car starts, then about 5 seconds later the relay clicks again and the car dies. I noticed that the write up on the rewire said something about N/A's not having the resistor relay. Could this cause a problem, or is the wires still the same in the TII and N/A of this series. Any other suggestions will be appreciated
02-01-05, 03:52 PM
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Series five non-turbo and turbo both should have the Fuel Pump Resistor Relay.
Did you keep the series five wiring? Complete series five wiring? Or half and half so to speak?
Did you keep the series five wiring? Complete series five wiring? Or half and half so to speak?
02-01-05, 03:58 PM
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Well, all the wiring is the same except for the emission harness. You see i was an idiot and wired in the ecu from the 87 TII. But the wiring harness that would hook to the resistor is the same. Im also using the resistor from the S/5. I was thinking maybe my MAF is bad and sending the wrong signal.
02-01-05, 05:45 PM
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I know a s4 NA doesn't have a resistor relay. I had to wire in the resistor relay in my t2 swap when I rewired my fuel pump. Maybe if you let us know how exactly you rewired it we can find a problem. Most likely you have a mismatch from s4 tii harness to s5 na harness. I know just going from s4 na to tii is a mess when it comes to fixing the wiring (even with swapping the harness). I'm still working out all the bugs....
02-01-05, 05:51 PM
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I have heard that the s/4 had no relay, but i pulled out a relay just like the one im using, and from the same place as the in the s/5 from the s/4. Also what was used to controll the resistance in the s/4. I car is wired up like a s/4, it has the s/4 ECU and emmision harness. That could be why im getting no current to the original resistor wires. How would i go about wiring this up as if this car was an s/4 TII to s/4 n/a swap, instead of a s/4 TII to s/5 n/a.
Last edited by RotaryPower27; 02-01-05 at 05:55 PM.
02-01-05, 07:31 PM
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Wanted to post some figuring i did and see if my assumption is correct.....
Going by the resistor plug: (E) is the Resistor in from 12v and (F) is the resisted output. (A) is the Relay in and (B) is the Relay out. (C) is the 12v in which sends a signal through (D) to the ECU.
When the ECU grounds (D) is causes the pump to see the resisted current from (F). When the ECU does not ground (D) it causes the pump to see the full 12v (B).
I may have them backward but it all comes down to the same thing. I think i may have a problem were (C) and (D) connect in the front of the car.
I think i can run a wire from 1K of the ECU and from a switched 12v source to replace (C) and (D) and this should work fine.
Going by the resistor plug: (E) is the Resistor in from 12v and (F) is the resisted output. (A) is the Relay in and (B) is the Relay out. (C) is the 12v in which sends a signal through (D) to the ECU.
When the ECU grounds (D) is causes the pump to see the resisted current from (F). When the ECU does not ground (D) it causes the pump to see the full 12v (B).
I may have them backward but it all comes down to the same thing. I think i may have a problem were (C) and (D) connect in the front of the car.
I think i can run a wire from 1K of the ECU and from a switched 12v source to replace (C) and (D) and this should work fine.
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02-01-05, 10:05 PM
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The series four turboii did have the Fuel Pump Resistor RElay. The 87 non-turbo did not.
Putting a series four emission harness in a series five with a series four ECU. You must have done quite a bit of pin swapping at the ECU plugs. There quite a bit different, aren't they?? Probably I guess.
On a series four turboii, the ECU's pin 3D removes a ground on the Fuel Pump RElay and Resistor when the car is boosting and allows full voltage (BR wire at the ECU and changes to a GR wire at the Relay and Resisto).
On startup, the ECU removes this ground for a moment or two, then reapplies that ground to give you approx 9vdc during normal driving.
So, what I'm implying, is, temporarily remove that wire from the plug at pin 3D of the ECU or remove it temp at the Fuel Pump Resistor Relay. Then give it a try. If it still does the same, then do the opposite. Apply a solid ground on that wire AT the Fuel Pump Resistor Relay and give it a try. Just a trouble shooting deal to see if the car will run in on configuration or the other.
Which AFM are you using???????? The series four or series five??????? If using the series five afm with the series four ECU, I think that MIGHT be the problem.
Sorry, I never compared the series four ECU pinouts with the series five ECU pinouts. I'd expect quite a difference, but that could be overcome using the ECU pinouts from the series four compared to the series five and doing the wire swaps in the ECU plugs. It'd be time consuming, but not that difficult and you'd have to double check what you did.
Putting a series four emission harness in a series five with a series four ECU. You must have done quite a bit of pin swapping at the ECU plugs. There quite a bit different, aren't they?? Probably I guess.
On a series four turboii, the ECU's pin 3D removes a ground on the Fuel Pump RElay and Resistor when the car is boosting and allows full voltage (BR wire at the ECU and changes to a GR wire at the Relay and Resisto).
On startup, the ECU removes this ground for a moment or two, then reapplies that ground to give you approx 9vdc during normal driving.
So, what I'm implying, is, temporarily remove that wire from the plug at pin 3D of the ECU or remove it temp at the Fuel Pump Resistor Relay. Then give it a try. If it still does the same, then do the opposite. Apply a solid ground on that wire AT the Fuel Pump Resistor Relay and give it a try. Just a trouble shooting deal to see if the car will run in on configuration or the other.
Which AFM are you using???????? The series four or series five??????? If using the series five afm with the series four ECU, I think that MIGHT be the problem.
Sorry, I never compared the series four ECU pinouts with the series five ECU pinouts. I'd expect quite a difference, but that could be overcome using the ECU pinouts from the series four compared to the series five and doing the wire swaps in the ECU plugs. It'd be time consuming, but not that difficult and you'd have to double check what you did.
02-01-05, 10:19 PM
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Yea that is eventually what i did. I used the emission harness from my S/4 so that all stayed the same. Then i spent about 6 months tracing diagrams and finally got the S/5 engine and chassis harness attached to the S/4 ECU plugs. It was a joke and i will never do it again but whatever.
Your right about 3D, i was looking at the S/5 wiring diagram. I'll give this a try and see what i get.
Thanks
Your right about 3D, i was looking at the S/5 wiring diagram. I'll give this a try and see what i get.
Thanks
02-01-05, 10:23 PM
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I just looked at the series five ECU pinout.....and your diagram. I don't see how this is going to work if you have a series four ECU. Pin 1K puts the ground on the Fuel Pump
Resistor Relay but the series four ECU uses pin 3D. Or have I misunderstood what your doing/have done????? Always possible.
Personaly, I would have elected to leave the series five ECU and harness in place, used the series five afm. Just have made small changes to to emission harness to complement the series four engine.
This engine has run before you did the fuel pump rewire??
Resistor Relay but the series four ECU uses pin 3D. Or have I misunderstood what your doing/have done????? Always possible.
Personaly, I would have elected to leave the series five ECU and harness in place, used the series five afm. Just have made small changes to to emission harness to complement the series four engine.
This engine has run before you did the fuel pump rewire??
02-01-05, 10:28 PM
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Originally Posted by HAILERS
On a series four turboii, the ECU's pin 3D removes a ground on the Fuel Pump RElay and Resistor when the car is boosting and allows full voltage (BR wire at the ECU and changes to a GR wire at the Relay and Resisto).
On startup, the ECU removes this ground for a moment or two, then reapplies that ground to give you approx 9vdc during normal driving.
.
On startup, the ECU removes this ground for a moment or two, then reapplies that ground to give you approx 9vdc during normal driving.
.
02-01-05, 10:37 PM
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It sounds like the relay is working fine (as the car starts and runs for a couple of seconds), but when the relay opens, current for the pump is supposed to go through the resistor. This doesn't seems like it's happening. Verify that all connections to and from the resistor are is good shape. There are two units to the resistor relay, one is the relay (4 wires to a sqaure box) and the resistor (finned rectangle with two wires). Check for continuity from the 12V lead to resistor and resistor to pump.
02-01-05, 10:52 PM
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No, Hailers is right. The system is fail-safe, so if something goes wrong with it the pump receives full voltage all the time. The relay is a normally-closed one, and the ECU must activate it to lower the fuel pump voltage.
02-01-05, 10:56 PM
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Pin 1K on the series four ECU, which you have, is for the Shift Indicator Light.
Pin 1K on a seies five car is a ground when the engine is not boosting and that ground is removed when your boosting. On a series four, this function is done by pin 3D.
A lot depends on how you wired the series four ECU into the series five car and just swapped the series four and five Emission Harnesses.
Pin 1K on a seies five car is a ground when the engine is not boosting and that ground is removed when your boosting. On a series four, this function is done by pin 3D.
A lot depends on how you wired the series four ECU into the series five car and just swapped the series four and five Emission Harnesses.
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