Burnt relay board grounds

[japeus]

I am fairly new to this, but. .

I've built two MS units with two relay boards. Everything checked
out o.k. during the build with the stiumulator, checks during
construction, etc.

I've had success starting a GM 350 TBI with the units just to test
them out.

Here's the strange part. I was doing all this to ad MS to a 1978
Ford Bronco with a 302. I hooked everyghing up less the tps,
injectors, and fuel pump to drive around and make sure everything
was talking to the MS o.k. All went great and with the engnine off,
I used the Megaview to see that all information was being read.

Went to start the car. Cranked longer than usual (usually starts
right up, maybe took 4 seconds)but finally started and Megaview
picked up the running engine. I mention the 4 seconds because what
got burnt next seems to be tied to the tach signal and might have
grounded it out until it burnt through.

Here's where trouble began. Somehow the smoke got "let out" from the
Relay board. Specifically, it is the common ground track printed on
the underside of the board for the returns of the CLT, IAT, and
TPS. Since the TPS isn't hooked up, that's out. The CLT and IAT
were reading correctly before starting the car. The only thing I
can think of might be the tach signal, but it's not even tied in
with the ground, correct? All CTS and IAT are GM as recommended.

Any ideas? I didn't think the ground for these sensors carried much
(if any) amperage at all. Has anyone else had this happen? As I
mentioned, I've done two units, but am hesitant to take the other
relay board and start plugging it in as I think it might do it to.
I've read others who ground these items separately (like to the
block), would this be something to try?

thanks for any help,

john, phoenix



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[crayd]

John it sounds to me like you have a bad negative battery cable. If the
negative battery terminal has a smaller wire going to the body, it could
be carrying lots of current while cranking, if the main negative battery
cable is bad. That current would then go thru your Squirt back to the
engine via your sensor grounds, and fry your relay board.

Chuck

1979 F-150 Megasquirted

[mytruckownsit]

Good call that's what I was thinking...

Ross
Dual TBI Vortec 383 Chevy
----- Original Message -----
From: Chuck
To: megasquirt@yahoogroups.com
Sent: Saturday, September 25, 2004 11:42 AM
Subject: RE: [megasquirt] Burnt relay board grounds


John it sounds to me like you have a bad negative battery cable. If the
negative battery terminal has a smaller wire going to the body, it could
be carrying lots of current while cranking, if the main negative battery
cable is bad. That current would then go thru your Squirt back to the
engine via your sensor grounds, and fry your relay board.

Chuck

1979 F-150 Megasquirted


-----Original Message-----
From: japeus [mailto:japeus@yahoo.com]
Sent: Saturday, September 25, 2004 9:19 AM
To: megasquirt@yahoogroups.com
Subject: [megasquirt] Burnt relay board grounds


I am fairly new to this, but. .

I've built two MS units with two relay boards. Everything checked
out o.k. during the build with the stiumulator, checks during
construction, etc.

I've had success starting a GM 350 TBI with the units just to test
them out.

Here's the strange part. I was doing all this to ad MS to a 1978
Ford Bronco with a 302. I hooked everyghing up less the tps,
injectors, and fuel pump to drive around and make sure everything
was talking to the MS o.k. All went great and with the engnine off,
I used the Megaview to see that all information was being read.

Went to start the car. Cranked longer than usual (usually starts
right up, maybe took 4 seconds)but finally started and Megaview
picked up the running engine. I mention the 4 seconds because what
got burnt next seems to be tied to the tach signal and might have
grounded it out until it burnt through.

Here's where trouble began. Somehow the smoke got "let out" from the
Relay board. Specifically, it is the common ground track printed on
the underside of the board for the returns of the CLT, IAT, and
TPS. Since the TPS isn't hooked up, that's out. The CLT and IAT
were reading correctly before starting the car. The only thing I
can think of might be the tach signal, but it's not even tied in
with the ground, correct? All CTS and IAT are GM as recommended.

Any ideas? I didn't think the ground for these sensors carried much
(if any) amperage at all. Has anyone else had this happen? As I
mentioned, I've done two units, but am hesitant to take the other
relay board and start plugging it in as I think it might do it to.
I've read others who ground these items separately (like to the
block), would this be something to try?

thanks for any help,

john, phoenix




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for more response!








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[japeus]

Thanks, I will check that and get back to this. Unfortunately the
truck isn't in my possesion, so it may take me a little to get
back. I will be able to find out about the cable, but won't have a
chance to hook it up for a couple days.

About the relay board, does anyone have an idea of what gauge wire I
should use to go back in and repair it? I'm thinking 22 gauge
should get me in the ballpark, but I'd had to start making hot
points elsewhere.

thanks for the responses,

john




--- In megasquirt@yahoogroups.com, "Ross" <kc7rjk@c...> wrote:
> Good call that's what I was thinking...
>
> Ross
> Dual TBI Vortec 383 Chevy
> ----- Original Message -----
> From: Chuck
> To: megasquirt@yahoogroups.com
> Sent: Saturday, September 25, 2004 11:42 AM
> Subject: RE: [megasquirt] Burnt relay board grounds
>
>
> John it sounds to me like you have a bad negative battery cable.
If the
> negative battery terminal has a smaller wire going to the body,
it could
> be carrying lots of current while cranking, if the main negative
battery
> cable is bad. That current would then go thru your Squirt back
to the
> engine via your sensor grounds, and fry your relay board.
>
> Chuck
>
> 1979 F-150 Megasquirted
>
>
> -----Original Message-----
> From: japeus [mailto:japeus@y...]
> Sent: Saturday, September 25, 2004 9:19 AM
> To: megasquirt@yahoogroups.com
> Subject: [megasquirt] Burnt relay board grounds
>
>
> I am fairly new to this, but. .
>
> I've built two MS units with two relay boards. Everything
checked
> out o.k. during the build with the stiumulator, checks during
> construction, etc.
>
> I've had success starting a GM 350 TBI with the units just to
test
> them out.
>
> Here's the strange part. I was doing all this to ad MS to a 1978
> Ford Bronco with a 302. I hooked everyghing up less the tps,
> injectors, and fuel pump to drive around and make sure
everything
> was talking to the MS o.k. All went great and with the engnine
off,
> I used the Megaview to see that all information was being read.
>
> Went to start the car. Cranked longer than usual (usually
starts
> right up, maybe took 4 seconds)but finally started and Megaview
> picked up the running engine. I mention the 4 seconds because
what
> got burnt next seems to be tied to the tach signal and might
have
> grounded it out until it burnt through.
>
> Here's where trouble began. Somehow the smoke got "let out" from
the
> Relay board. Specifically, it is the common ground track
printed on
> the underside of the board for the returns of the CLT, IAT, and
> TPS. Since the TPS isn't hooked up, that's out. The CLT and
IAT
> were reading correctly before starting the car. The only thing
I
> can think of might be the tach signal, but it's not even tied in
> with the ground, correct? All CTS and IAT are GM as recommended.
>
> Any ideas? I didn't think the ground for these sensors carried
much
> (if any) amperage at all. Has anyone else had this happen? As
I
> mentioned, I've done two units, but am hesitant to take the
other
> relay board and start plugging it in as I think it might do it
to.
> I've read others who ground these items separately (like to the
> block), would this be something to try?
>
> thanks for any help,
>
> john, phoenix
>
>
>
>
> MegaSquirt support is now at www.msefi.com - post your questions
there
> for more response!
>
>
>
>
>
>
>
>
> MegaSquirt support is now at www.msefi.com - post your questions
there for more response!
>
>
> Yahoo! Groups Sponsor
> ADVERTISEMENT
>
>
>
>
>
> -
-----------
>
>
> a..
>
>
> b..
>
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
of Service.
>
>
>
>



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[mytruckownsit]

22 should be fine. Be sure to use stranded wire.
Ross
Dual TBI Vortec 383 Chevy
----- Original Message -----
From: japeus
To: megasquirt@yahoogroups.com
Sent: Saturday, September 25, 2004 2:53 PM
Subject: [megasquirt] Re: Burnt relay board grounds


Thanks, I will check that and get back to this. Unfortunately the
truck isn't in my possesion, so it may take me a little to get
back. I will be able to find out about the cable, but won't have a
chance to hook it up for a couple days.

About the relay board, does anyone have an idea of what gauge wire I
should use to go back in and repair it? I'm thinking 22 gauge
should get me in the ballpark, but I'd had to start making hot
points elsewhere.

thanks for the responses,

john




--- In megasquirt@yahoogroups.com, "Ross" <kc7rjk@c...> wrote:
> Good call that's what I was thinking...
>
> Ross
> Dual TBI Vortec 383 Chevy
> ----- Original Message -----
> From: Chuck
> To: megasquirt@yahoogroups.com
> Sent: Saturday, September 25, 2004 11:42 AM
> Subject: RE: [megasquirt] Burnt relay board grounds
>
>
> John it sounds to me like you have a bad negative battery cable.
If the
> negative battery terminal has a smaller wire going to the body,
it could
> be carrying lots of current while cranking, if the main negative
battery
> cable is bad. That current would then go thru your Squirt back
to the
> engine via your sensor grounds, and fry your relay board.
>
> Chuck
>
> 1979 F-150 Megasquirted
>
>
> -----Original Message-----
> From: japeus [mailto:japeus@y...]
> Sent: Saturday, September 25, 2004 9:19 AM
> To: megasquirt@yahoogroups.com
> Subject: [megasquirt] Burnt relay board grounds
>
>
> I am fairly new to this, but. .
>
> I've built two MS units with two relay boards. Everything
checked
> out o.k. during the build with the stiumulator, checks during
> construction, etc.
>
> I've had success starting a GM 350 TBI with the units just to
test
> them out.
>
> Here's the strange part. I was doing all this to ad MS to a 1978
> Ford Bronco with a 302. I hooked everyghing up less the tps,
> injectors, and fuel pump to drive around and make sure
everything
> was talking to the MS o.k. All went great and with the engnine
off,
> I used the Megaview to see that all information was being read.
>
> Went to start the car. Cranked longer than usual (usually
starts
> right up, maybe took 4 seconds)but finally started and Megaview
> picked up the running engine. I mention the 4 seconds because
what
> got burnt next seems to be tied to the tach signal and might
have
> grounded it out until it burnt through.
>
> Here's where trouble began. Somehow the smoke got "let out" from
the
> Relay board. Specifically, it is the common ground track
printed on
> the underside of the board for the returns of the CLT, IAT, and
> TPS. Since the TPS isn't hooked up, that's out. The CLT and
IAT
> were reading correctly before starting the car. The only thing
I
> can think of might be the tach signal, but it's not even tied in
> with the ground, correct? All CTS and IAT are GM as recommended.
>
> Any ideas? I didn't think the ground for these sensors carried
much
> (if any) amperage at all. Has anyone else had this happen? As
I
> mentioned, I've done two units, but am hesitant to take the
other
> relay board and start plugging it in as I think it might do it
to.
> I've read others who ground these items separately (like to the
> block), would this be something to try?
>
> thanks for any help,
>
> john, phoenix
>
>
>
>
> MegaSquirt support is now at www.msefi.com - post your questions
there
> for more response!
>
>
>
>
>
>
>
>
> MegaSquirt support is now at www.msefi.com - post your questions
there for more response!
>
>
> Yahoo! Groups Sponsor
> ADVERTISEMENT
>
>
>
>
>
> -
-----------
>
>
> a..
>
>
> b..
>
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
of Service.
>
>
>
>



MegaSquirt support is now at www.msefi.com - post your questions there for more response!


Yahoo! Groups Sponsor
ADVERTISEMENT





------------


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b..


c.. .







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or selling a car. FREE Quotes, 360° Tours, Research,
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[japeus]

Thanks you guys,

Turns out the ground cable didn't look so hot, so it was cleaned.
Also, ran two separate grounds from the battery to the body and
engine. Then repaired the board with 30 gauge wire (tiny!)
Couldn't find stranded that small, but seems to work fine.

The coil wire wasn't reading a correct signal on the tach, fixed
that and now it's reading everything like it should.

Still have to install the throttle body and fuel supply, return,
pump, etc., but thought we'd drive it around for awhile to make sure
there are no problems. Hopefully my next post will be a running
vehicle.

thanks again for the help. It was quick, accurate, and got me to
the next step,

john
78 Bronco

--- In megasquirt@yahoogroups.com, "Ross" <kc7rjk@c...> wrote:
> Good call that's what I was thinking...
>
> Ross
> Dual TBI Vortec 383 Chevy
> ----- Original Message -----
> From: Chuck
> To: megasquirt@yahoogroups.com
> Sent: Saturday, September 25, 2004 11:42 AM
> Subject: RE: [megasquirt] Burnt relay board grounds
>
>
> John it sounds to me like you have a bad negative battery cable.
If the
> negative battery terminal has a smaller wire going to the body,
it could
> be carrying lots of current while cranking, if the main negative
battery
> cable is bad. That current would then go thru your Squirt back
to the
> engine via your sensor grounds, and fry your relay board.
>
> Chuck
>
> 1979 F-150 Megasquirted
>
>
> -----Original Message-----
> From: japeus [mailto:japeus@y...]
> Sent: Saturday, September 25, 2004 9:19 AM
> To: megasquirt@yahoogroups.com
> Subject: [megasquirt] Burnt relay board grounds
>
>
> I am fairly new to this, but. .
>
> I've built two MS units with two relay boards. Everything
checked
> out o.k. during the build with the stiumulator, checks during
> construction, etc.
>
> I've had success starting a GM 350 TBI with the units just to
test
> them out.
>
> Here's the strange part. I was doing all this to ad MS to a 1978
> Ford Bronco with a 302. I hooked everyghing up less the tps,
> injectors, and fuel pump to drive around and make sure
everything
> was talking to the MS o.k. All went great and with the engnine
off,
> I used the Megaview to see that all information was being read.
>
> Went to start the car. Cranked longer than usual (usually
starts
> right up, maybe took 4 seconds)but finally started and Megaview
> picked up the running engine. I mention the 4 seconds because
what
> got burnt next seems to be tied to the tach signal and might
have
> grounded it out until it burnt through.
>
> Here's where trouble began. Somehow the smoke got "let out" from
the
> Relay board. Specifically, it is the common ground track
printed on
> the underside of the board for the returns of the CLT, IAT, and
> TPS. Since the TPS isn't hooked up, that's out. The CLT and
IAT
> were reading correctly before starting the car. The only thing
I
> can think of might be the tach signal, but it's not even tied in
> with the ground, correct? All CTS and IAT are GM as recommended.
>
> Any ideas? I didn't think the ground for these sensors carried
much
> (if any) amperage at all. Has anyone else had this happen? As
I
> mentioned, I've done two units, but am hesitant to take the
other
> relay board and start plugging it in as I think it might do it
to.
> I've read others who ground these items separately (like to the
> block), would this be something to try?
>
> thanks for any help,
>
> john, phoenix
>
>
>
>
> MegaSquirt support is now at www.msefi.com - post your questions
there
> for more response!
>
>
>
>
>
>
>
>
> MegaSquirt support is now at www.msefi.com - post your questions
there for more response!
>
>
> Yahoo! Groups Sponsor
> ADVERTISEMENT
>
>
>
>
>
> -
-----------
>
>
> a..
>
>
> b..
>
>
> c.. Your use of Yahoo! Groups is subject to the Yahoo! Terms
of Service.
>
>
>
>



------------------------ Yahoo! Groups Sponsor --------------------~-->
Yahoo! Autos. Everything you need to know about buying
or selling a car. FREE Quotes, 360° Tours, Research,
Blue Book, Compare Vehicles, Buy Used
http://us.click.yahoo.com/kEZsdA/bwnGAA ... /0UzulB/TM
--~->

MegaSquirt support is now at www.msefi.com - post your questions there for more response!