prodracing.com

Unofficial SCCA Production Racing Forum
It is currently Mon Sep 21, 2020 2:34 am

All times are UTC - 8 hours




Post new topic Reply to topic  [ 28 posts ]  Go to page Previous  1, 2, 3  Next
Author Message
 Post subject: Re: Wiring Help
PostPosted: Wed May 30, 2018 5:06 am 
Offline
User avatar

Joined: Fri Oct 01, 2010 9:21 am
Posts: 1322
Just a short reminder: Fuses and Circuit Breakers are not there to protect the expensive thing. They're there to keep the wires from getting hot and the car burning down.

That's why they are all near the battery on passenger cars; not near the expensive electronics.

Plan accordingly; it'll save you a lot of headaches.

And yes I do have circuit breakers instead of fuses.

No relay tho; I can see why you would need one if you allow the ECU to power the fuel pump. I prefer to control the pump myself with a switch in case I want (or don't want) pressure while the car isn't running, etc.


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Wed May 30, 2018 8:35 am 
Offline
User avatar

Joined: Fri Aug 12, 2011 4:03 pm
Posts: 235
Location: Northeast PA
blamkin86 wrote:
No relay tho; I can see why you would need one if you allow the ECU to power the fuel pump. I prefer to control the pump myself with a switch in case I want (or don't want) pressure while the car isn't running, etc.


The thinking (or directive I got) for using an ECU triggered relay on the fuel pump was that if the engine dies the fuel pump will shut off thus not continue pumping fuel.

The method I used was I have the fuel pump power supply on its own switchable breaker so if I want the ECU "on" without fuel I can kill the fuel pump breaker.
The way I saw it was the fuel pump power supply is now protected by circuit protection, "and" the operation of the fuel pump is still controlled by the ECU so if the engine shuts off so does the fuel pump.

Cheers
jimmy

_________________
Jimmy Pettinato
88 BMW M3 - SPU #98


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Fri Jun 01, 2018 3:21 pm 
Offline
User avatar

Joined: Mon Oct 26, 2009 1:45 pm
Posts: 234
you can still install a switch to interrupt the pump even with a relay.

_________________
Dick Gagliardi
Chicago region
H Production VW Scirocco


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Sat Jun 02, 2018 10:38 am 
Offline

Joined: Tue Oct 27, 2009 9:57 am
Posts: 63
jimmypet wrote:
I like Tefzel wire, but some people dont, it only comes in white so you have to be good with labels.
Stein-Air is the best source for Tefzel.


I wanted to pass on another source for Tefzel mil-spec wire -- Pro Wire. Has all the colors, gauges, circuit breakers you might need. They have less expensive "automotive" grade wire that is good for brake lights, or accessory wiring, if you need to save a few $$.

http://www.prowireusa.com/


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Sun Jun 03, 2018 4:48 am 
Offline

Joined: Tue Dec 31, 2013 10:40 am
Posts: 467
Location: Huntsville, AL
Agreed, Love the guys over at Pro-Wire. If you want to do wiring correctly, they supply top notch components.

Another source for supplies is https://racespeconline.com/

They have very nice components as well.

_________________
Brett W
Huntsville, AL


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue Jun 05, 2018 5:57 am 
Offline

Joined: Sat Apr 08, 2017 6:18 am
Posts: 41
If you have a business account then give SEA-Wire a shot.

We used them alot when I was buying milspec wire for helicopters.


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue Jun 05, 2018 11:05 am 
Offline

Joined: Fri Nov 06, 2009 5:08 am
Posts: 1194
Location: Philly
jimmypet wrote:
blamkin86 wrote:
No relay tho; I can see why you would need one if you allow the ECU to power the fuel pump. I prefer to control the pump myself with a switch in case I want (or don't want) pressure while the car isn't running, etc.


The thinking (or directive I got) for using an ECU triggered relay on the fuel pump was that if the engine dies the fuel pump will shut off thus not continue pumping fuel.

The method I used was I have the fuel pump power supply on its own switchable breaker so if I want the ECU "on" without fuel I can kill the fuel pump breaker.
The way I saw it was the fuel pump power supply is now protected by circuit protection, "and" the operation of the fuel pump is still controlled by the ECU so if the engine shuts off so does the fuel pump.

Cheers
jimmy


The ECU will likely only trigger the fuel pump for a few seconds when the ignition switch is activated and then when the car starts. So having a way to switch the fuel pump off when the ignition is on isn't needed.

It's worth mentioning that you will need a way to run the fuel pump to give a fuel sample. You can just repeatedly cycle the ignition switch and to get multiple occurrences of the couple of seconds the ECU activates the pump. There are other ways to accomplish this. Make sure to consider the safety of your choice. I would not put a manually operated switch allowing you to activate the fuel pump. It could result in the pump being on when it shouldn't be.

-Kyle


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue Jun 05, 2018 12:28 pm 
Offline
User avatar

Joined: Fri Oct 01, 2010 9:21 am
Posts: 1322
disquek wrote:
Make sure to consider the safety of your choice. I would not put a manually operated switch allowing you to activate the fuel pump. It could result in the pump being on when it shouldn't be.


Kinda hard not to if you don't have an ECU?

Don't want to get into a pissing match over a switch - do whatever you think is best - Kyle et al have good advice.

For me, I have THREE fuel pumps (stock tank + surge tank) and I (generally) make more informed decisions about when I want fuel pressure than just, after the ECU turns on.

Seriously, do whatever you feel is best. I like the control of a separate switch. That's just me.


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Tue Jun 05, 2018 2:04 pm 
Offline
User avatar

Joined: Fri Aug 12, 2011 4:03 pm
Posts: 235
Location: Northeast PA
disquek wrote:

The ECU will likely only trigger the fuel pump for a few seconds when the ignition switch is activated and then when the car starts. So having a way to switch the fuel pump off when the ignition is on isn't needed.

Thats how mine functions. If the fuel pump breaker is ON, when I turn on power to the ECU it gives a few second burst to the pump to pressurize the lines then it waits to see rotation.


disquek wrote:
It's worth mentioning that you will need a way to run the fuel pump to give a fuel sample. You can just repeatedly cycle the ignition switch and to get multiple occurrences of the couple of seconds the ECU activates the pump. There are other ways to accomplish this. Make sure to consider the safety of your choice. I would not put a manually operated switch allowing you to activate the fuel pump. It could result in the pump being on when it shouldn't be.
-Kyle


On mine (I can only speak to my setup), If I turn on the MAIN switch and engage the fuel pump breaker with the ECU OFF the pump will run so I can either pressurize the lines, or if I wanted to pump out the cell. I do have to very consciously make those moves with the breakers however.
In that mode because the ECU is OFF its not getting the engine OFF signal from the ECU to open the relay.
I can also use this mode for fuel sample, but I think the last time someone wanted a fuel sample from a regional SPU car was never LOL.

Conversely, if I want to sit in the car, diddle with the ECU with laptop, I can open the the fuel pump breaker and no fuel will ever pump.

Its definitely worth thinking long hard about though.
Going through as many possibilities as one can think of so that you cannot burn your car, house, garage or yourself down.
I thought about mine quite a bit. I tried to make it as hard to screw myself as possible.

The one contingency mine is NOT prepared for is if in a crash the ECU breaker fails or gets knocked OFF, but the fuel pump breaker remains ON and If I were unconscious and not able to kill the main and there was a fuel leak the pump would still run.
I have not figured out a way around that yet.

_________________
Jimmy Pettinato
88 BMW M3 - SPU #98


Top
 Profile  
 
 Post subject: Re: Wiring Help
PostPosted: Wed Jun 06, 2018 9:38 pm 
Offline

Joined: Thu Dec 10, 2015 12:55 am
Posts: 163
I just put this in one of my cars. I have almost the same thing in another. https://www.summitracing.com/parts/qcr-50-864/overview/

It comes assembled and has the main wires to the power source also. Its great because there are fuses you could change during a race if needed and they light up when the switch is on. Which is great for the engine fan or the cool suit etc.


I have literally sold over 1000 MG switches. And they do not use relays except for the starter and a couple of things on the 1977-1980. And what I know for sure is either use really good switches or a relay. The stock switches on the old metal dash MG's last for ages with no problems and the later cheap ones go bad super fast without a relay but do OK with one.

Have Fun :D

_________________
Rob Garrison

FP Mazda Miata
EP 1989 RX7
IT7 RX7
2nd Gen STL RX7


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 28 posts ]  Go to page Previous  1, 2, 3  Next

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 6 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group