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

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

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

Postby 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--
--Alfa Romeo 159 3.2 JTS SW Q4--
--Alfa Romeo 75 3.0 V6 Turbo--
--Alfa Romeo 75 3.0 V6--
--Alfa Romeo 75 2.5 V6 24v--
--Alfa Romeo Spider 2.0 TS 1972--
--Maserati 3200 GT--
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

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

Postby 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--
--Alfa Romeo 159 3.2 JTS SW Q4--
--Alfa Romeo 75 3.0 V6 Turbo--
--Alfa Romeo 75 3.0 V6--
--Alfa Romeo 75 2.5 V6 24v--
--Alfa Romeo Spider 2.0 TS 1972--
--Maserati 3200 GT--
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

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

Postby 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
1994 Alfa Romeo 164 Q4 Proteo Rosso 535.000km
1989 Lancia Thema 8.32 Verde Indy 260.000km
2015 Alfa Romeo 4C Rosso Competizione 75.000km
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Re: Alfa 164 3.0 V6 24V -94 engine transplant, fuelpump prob

Postby 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.
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