Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

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digge
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Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

Post by digge » Fri Jun 23, 2017 2:38 pm

Hi

Im helping a friend of mine who is using a V6 Alfa 164 3.0 24V -94 engine to build a trackcar.
He was almost finished but had some trouble with the electrics so he asked me to help him diagnose and fix the issue.

The problem is the fuelpump doesnt want to start and the reason for it is that the ECU never give ground on pin 1 (ECU side) to the fuelpump relay s12a (pin 85). What could be the problem causing this issue, is the ECU shot or is can there be some kind of wiring or other fault that prohibits this?

I tried hardwiring a ground to the relay and then i can fire up the engine and everything works but would much rather have it done right. Any ideas would be appreciated.

Have started looking into using my OBD2 cable and from what i can gather it should just be a few pins to break out and hook up the right way and the right software to be able to read out any error codes?

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Tamariini
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Post by Tamariini » Thu Jun 29, 2017 5:50 am

Is the fuel supply inertia switch connected or bypassed/disabled completely? maybe some problem there i might guess?
--Alfa Romeo Giulia 2.0T 2017--
--Fiat 500 2016--
--Alfa Romeo 75 3.0 V6 Turbo 1988--
--Alfa Romeo 75 3.0 V6 1987--
--Alfa Romeo 75 2.5 V6 24v 1986--
--Alfa Romeo Spider 2.0 TS 1972--
--Alfa Romeo Spider 3.0 12v 1999--
--Maserati 3200 GT 2001--

digge
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Post by digge » Thu Jun 29, 2017 9:40 am

Where would such a switch/sensor be located? I will admit that my skills are more in the electronics realm and not so much the engines and stuff.
From what i understood about the fuelsystem, there is only a pressure regulator connected to the air inlet with a hose (non electric), is there some other switch/sensor that youre talking about?

Either way what you say sounds plausible.

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Tamariini
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Post by Tamariini » Thu Jun 29, 2017 1:03 pm

Inertiaswitch (crash switch) cuts the fuel supply/power from the fuel pump on an accident. I am not 100% sure if 164 had one but GTV and 155 from the same era definitely had those switches and i have a feeling my 164 Q4 had one also but hard to remember for sure...

If someone has wiring diagram for that car it would be easy to find the switch (if any) and with jump wire start the car.
--Alfa Romeo Giulia 2.0T 2017--
--Fiat 500 2016--
--Alfa Romeo 75 3.0 V6 Turbo 1988--
--Alfa Romeo 75 3.0 V6 1987--
--Alfa Romeo 75 2.5 V6 24v 1986--
--Alfa Romeo Spider 2.0 TS 1972--
--Alfa Romeo Spider 3.0 12v 1999--
--Maserati 3200 GT 2001--

digge
Posts: 6
Joined: Sun Jun 11, 2017 3:03 pm

Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Post by digge » Thu Jun 29, 2017 4:56 pm

Ahh

Now im with you, and nope that is not the case here (i think). The ECU is supposed to make one pin ground to the relay to actuate it. That does not happen though so both pins to relay is 12V. So unless there is an inertia switch hooked up to the ECU as an input there isnt one in this case. There is nothing inline between relay and ECU and the cable itself measures good.

Might just investigate if there have ever been something like that though, cause if its hooked up as an input that could well be the problem.

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Alfan
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Post by Alfan » Sat Jul 01, 2017 8:52 am

The inertia switch was introduced in 1995, since this is 1994, it should not be the case.

Which realy are you using for this, one with a red stripe like this?

viewtopic.php?f=2&t=1388" onclick="window.open(this.href);return false;
1994 Alfa Romeo 164 Q4 Proteo Rosso 550.000km
1989 Lancia Thema 8.32 Verde Indy 270kkm
2001 Alfa Romeo Spider 3.0 24V Blue Lightning 65kkm
2011 Alfa Romeo Giulietta Multiair TCT Bianco Pastello 195kkm
2015 Alfa Romeo 4C Rosso Competizione 100kkm

digge
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Post by digge » Sat Jul 01, 2017 9:58 am

The owner have replaced the relays with new bosch ones. I belive both of them is with diode if thats what youre asking.

HaydnW92
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

Post by HaydnW92 » Thu Apr 30, 2020 11:32 am

I realise this thread is a few years old but did you ever find a solution to this issue? I'm having the exact same problem at the moment.
1999 Alfa GTV 3.0 V6 24V
1992 Maserati 222 4V (project)

(Ex)1994 Alfa 164 Q4 3.5 Savali Cosworth
(Ex) 1991 Alfa 164 3.0 Cloverleaf
(Ex) 1995 Alfa 145 1.6 8V

digge
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

Post by digge » Thu Apr 30, 2020 2:23 pm

I grounded one of the pins on the relay to bypass the issue if i recall correctly. If it was an ecu fault or something else i dont know, never investigated further. If you measure on the coil pins on relay i think there was 12v on both if i recall. Just disconnect the one that needs to be ground and ground it.

HaydnW92
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Location: United Kingdom

Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

Post by HaydnW92 » Thu Apr 30, 2020 2:28 pm

Thanks for your response. Yes, that's the exact same problem I'm having! It should be 0v on pin 85 but it gets 12v instead.

So you installed a permanent ground on pin 85 of the relay? I thought about doing that but I wondered if it would cause any problems?
1999 Alfa GTV 3.0 V6 24V
1992 Maserati 222 4V (project)

(Ex)1994 Alfa 164 Q4 3.5 Savali Cosworth
(Ex) 1991 Alfa 164 3.0 Cloverleaf
(Ex) 1995 Alfa 145 1.6 8V

digge
Posts: 6
Joined: Sun Jun 11, 2017 3:03 pm

Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

Post by digge » Thu Apr 30, 2020 3:14 pm

In my case it was a car meant for track use, so bare minimum is ok, and there is extra main power switches and stuff due to racing regulations so the owner wasbt that bothered, and if i recall correct, as long as ignition is in of position, there is no 12 on either side of relay.

HaydnW92
Posts: 246
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Location: United Kingdom

Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump problem

Post by HaydnW92 » Thu Apr 30, 2020 3:36 pm

Yeah that makes sense. I think you're right about the relay not receiving voltage with the ignition off but I will check this. Hopefully this will fix my problem.

Thanks for your responses.
1999 Alfa GTV 3.0 V6 24V
1992 Maserati 222 4V (project)

(Ex)1994 Alfa 164 Q4 3.5 Savali Cosworth
(Ex) 1991 Alfa 164 3.0 Cloverleaf
(Ex) 1995 Alfa 145 1.6 8V

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