ECMB problems Fuel pump? Relay? Gray wire is ground?

ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby 4barrel [OP] » December 19th 2011, 2:16am

Hello I hope you guys can help out. I have searched for this best I could and have some info, but not %100 sure I'm right.
1995 astro AWD.
After dropping 400.00 on some front end parts and a muffler. Took it for test ride and drove great for about 2 hours with some stop and go at stores.
Turned a corner going to buddy's house and it just shut down. Hasn't restarted since. Almost like someone hit a "kill switch" now I can't remember but think the oil gauge or the fuel gauge, was either all over or dead? (sorry had a long few months since, and that day was a write off).
So the "ECM-B fuse blew. Replace and it pops as soon as I turn key "on". This fuse is a 15amp and that is what it is marked on the fuse box under dash.
I have got this far today based on the searching I've done.
The ECMB fuse IS hot at all times. There are 2 relays under hood on Pass. side. The one that has the Org. Gray. grn/white, black/white....
If I remove this relay, fuse won't pop.
The org. wire now has +12v from the fuse. the black/white is a neg. ground. the green/white I am unsure what I should see here? And the gray has continutity to ground. There is a gray wire with a terminal taped next to relay.
If I remove the gray wire from the relay harness the fuse won't pop and the relay will "click". So my guess is the green/white is a power from the VCM and the black/white are doing the job.
So I have removed the oil sender plug and, +12v at orange wire. Checked continutity from gray @ relay to the gray @ sender and good. but still shows a "ground" @ either point.
So is this ground becuase it goes through a "motor/pump", and that is what happens? Or because of a short to ground along the way? Or pump is dead?
Can I use jumper from orange to gray? at the relay harness or the sender plug to energize the pump? Or is the ground at gray wire going to be a place you dont want to put a hot to at the moment? Is that extra wire at the harness the "test wire" others speak off? Should it show ground at rest?
Haven't looked under van yet thats tomorow LOL. Is there a harness to test at under van for the pump? Instead of dropping tank (last thing want, has about 3/4 tank).
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4barrel
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby Lumpy » December 19th 2011, 7:56am

I got a little bit lost in your description.. :poke:

It's likely the relay you're describing, on the firewall, is the fuel pump relay.

I think somewhere in your description you make reference to the fuel pump test lead
that comes out of the harness at the firewall connection.

That test lead shows ground on my 89 when the engine is off.
BUT, if it is connected to ground and you turn the key to ON,
it blows the ECM fuse.

So I'm not exactly sure where to go from here. I'm not sure exactly what you've
discovered and/or tried. But make sure that FPump test wire is NOT grounded. Normal
function for that wire is if you connect +12VDC, it causes the fuel pump to run.
If it's found it's way to touching metal ground, it's blowing your fuse.


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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby 4barrel [OP] » December 19th 2011, 5:29pm

Lumpy wrote:That test lead shows ground on my 89 when the engine is off.
BUT, if it is connected to ground and you turn the key to ON,
it blows the ECM fuse.

So I'm not exactly sure where to go from here. I'm not sure exactly what you've
discovered and/or tried. But make sure that FPump test wire is NOT grounded. Normal
function for that wire is if you connect +12VDC, it causes the fuel pump to run.
If it's found it's way to touching metal ground, it's blowing your fuse.
Lump


Thanks Lumpy,
Yes I am sure that it is the fuel pump relay I am working with.
You say "your" gray wire/test lead, shows ground at rest, nothing on? What about if key is on and pump is working? bet it flips to Hot :think:
But think that this is one of those times that the "relay" causes what looks like a ground!
If the relay is energized (key on) that gray wire will get +12v? I think?? (can someone confirm this.)
Also seen times when a motor with one terminal to ground will show ground on other terminal, BUT if hook a hot lead there. The motor will work.

I do relize that most of time putting + power to a ground makes fuses go pop. ( But that sometimes, could "show" ground and not actualy be "connected" directly to ground)
What I need to know then is.
How do I know if the gray wire is touching ground, or just shows ground because of a relay or because the "pump" is a type of "motor" that is hooked to ground on one side?
If a fuel pump is done/finished/cooked/blown, will it cause a "short condition" and pop the ECMB fuse?
Untill now my Theroy was to find the "OTHER" connections on that gray wire, disconnect harnesses and see if fuse pops. if it does then we know its not that device or the problem is from harness back to relay.
So thats why I disconnected the oil sender, If it was the sender shorting "inside" -- with wires off it still pops so guessing the oil sender isn't to blame.
So also guessing that because the wire is still connected to pump under van, the problem lies from the sender or relay >> to the pump (if it is a short to ground).
Also the diagram I have shows gray wire goes to the VCM as well. So could this be causeing a flip flop ground like a relay does?
If there was a harness to disconnect the pump just before the tank (or under van) then I could disconnect it then try again if fuse blows then problem isn't the pump its from that harness BACK!!!
Also could supply power to the tank side of harness, to see if pump is live or dead. Possibly avoiding the "short to ground" if there is one
My Best guess is the gray wire or what ever is connected to it, IS shorted out, and if it is connected to the relay it pops fuse as soon as the relay is energized though Ign. switch and VCM!
But at same time My mind tell me that the pump could just simply be shot. LOL!!
So basicly today need to crawl under van see if can find a harness for pump? Anyone know if there is one and where it may be?
:confused:
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby Lumpy » December 19th 2011, 7:51pm

I think you previously stated that if you REMOVE the fuel pump relay, the fuse will NOT blow.
I think I'd start my focus there - at the RELAY and it's connection(s).

Sounds like you're comfortable reading schematics and so forth.
Remove the relay, then apply FUSED +12VDC to the relay terminal that supplies the fuel pump.
Looks like that's #120 on my diagrams. That should be essentially the same as that fuel pump
test wire. Apply +voltage to either of those and if the pump runs, doesn't blow the fuse, I think
you've then narrowed it down to the relay or somewhere between the relay and the ECM. That's
a lot more optomistic (and maybe realistic) finding than to wonder if it's a wire buried in the
harness between the firewall and the top of the gas tank.

My fuel pump relay had a badly degenerated plastic socket on the harness side of it's connection.
I did a lot of fabbing and rigging to form a more solid contact housing. None of the connections
were shorting or touching. But it didn't look safe. Looked like they might easily develop into
a problem.

Always suspect the cheapest and closest parts first.. :D



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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby 4barrel [OP] » December 19th 2011, 9:03pm

Ok so as suspected a fused power to the gray wire @ fuel pump relay, or the test lead or even the gray wire at the oil pump sender. pops instantly.
So I found a post about a harness next to the trans on driver side. disconnected this 3 wire plug and boom the ground went away from the gray wire.
So further back about 10" from the top of tank, the wires are in the loom. knowing I can do a proper repair job, (enough slack to work with) I cut the gray wire there & ground is gone. problem lies beond this point to the tank.
YAY!!! I get to drop a tank :banana: I am going to place my bet it is the pump. At least this tank looks easier than most I have dealt with. Those stupid "J" hooks that ALWAYS break!!!! :screaming:

You are right about my "talent" I have done car audio and custom builds (Relays are fun to mess with) for about 12 years now. So I tend to pickup on this stuff quickly when I want to! (I am slightly deslexic as can tell from my posts LOL) But find the schematics of today almost easier than older ones.
***So I need to stress this ***
This is one of those times If I had used the VERY Dangerous way, and just kept trying larger amp fuses. The short MAY lie IN THE TANK!!!! This would "push" all the power to the short and act like a heating element hanging In 3/4 tank of gas!!!!!
Sounds like a simple end to my problem now to think about it :think: LOL!!!
If YOU HAVE A POSSILE SHORT TO GROUND, A lower amp fuse is ok for searching as a ground will pop the fuse no matter the size. UNLESS the wires give first . this usually ends in a melted insulation and only greats a even harder to find problem.
So as I mentioned before the best way I know to hunt possible wiring gremlins is work from suspect device <<<<< back to the feed while checking
@ the source! Just my :2: And It helps to know what the wire is supposed to be or supposed to do!!
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4barrel
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby 4barrel [OP] » December 19th 2011, 11:17pm

Lumpy wrote:My fuel pump relay had a badly degenerated plastic socket on the harness side of it's connection.
I did a lot of fabbing and rigging to form a more solid contact housing. None of the connections
were shorting or touching. But it didn't look safe. Looked like they might easily develop into
a problem.

Always suspect the cheapest and closest parts first.. :D


Here is my idea for the fuel pump relay, socket. and replacement.
As I said before play with 12v relays alot. most common is the SPDT or even the SPST like what you use for fog lights. We mostly use the 30A or 30/40a. ones. Depending on what voltage the green/white wire has. (12V ?) One could use these to replace the original. You can use spade terminals and heat shrink to make decent connections, or get the harness for a proffesional touch.
http://www.the12volt.com/relays/relays.asp
So just like the stock, the orange wire goes to pin 30, geern/white goes to pin 85, black/white goes to pin 86, gray goes to pin 87.
Technicly one could use a SPDT and use the extra pin 87a to go to a blinking LED, So when ever the fuel pump relay isn't energized, a fake security light will be but also acts as tell tale that relay not on or working.
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby 4barrel [OP] » December 20th 2011, 9:56pm

Well I have spent all yesterday aft. and this morn. fighting with 1 stupid &*^% fuel line connection before removing straps and lowering tank. The first one was damn near finger tight. This one will not let go!!!
I use Bolt Blaster and love the stuff. I even went to liquid wrench. NEVER been beat with BB. By now I could yell at it and it would loosen LOL :shrug:
I know get the heat LOL BOOM!!! I think will take father in law up on offer to just get it fixed. I just like to have some satisfaction of fixing my own stuff :doh:
No garage and getting colder, my jack is acting up anyway, just makeing excuses now so I can justify it.
Priced out a delphi pump for $102 can. any idea what the job runs (hours) shop rate varies here for $100-$130.00 I think, haven't paid mechanic in years. :banghead: :banghead: :banghead: :banghead: :banghead:
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby RECox286 » December 21st 2011, 12:01am

If everything goes according to the book and you don't run into problems due to rusty plumbing, nuts and bolts, etc, the job can take as long as

a whole day and a case or two, or as short as a couple of hours and a sixpack or two. (and of course anything inbetween) Depends on the shape of

things, and if you've done the job a half dozen times before, know what tools you need, if you have them on hand, and the like.

Bob

Don''t give up, it is not an impossible job, and it will be easier the next time.
Start a fire for a man and he will be warm for a day.
Set a man on fire and he will be warm the rest of his life.

Sent using two Progresso soup cans and a string
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby Lumpy » December 21st 2011, 4:32am

4barrel wrote:
Priced out a delphi pump for $102...




Delphi pump for your 95 is $69.79 BEFORE the 5% discount at RA.


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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby 4barrel [OP] » December 21st 2011, 7:12am

Never did Rock auto thing. We are in canada EH :doh: I will keep looking for a cheaper one. but I dunno.
I got the wife to talk to her dad and he will help out. But his buddy may not be able to do till next week. So we will see.

Wife says something about I have to accept others trying to help, :blah: :blah: :blah: lol.
At least I figured out the "potential" wiring issue :ty:
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Re: ECMB problems Fuel pump? Relay? Gray wire is ground?

Postby RECox286 » December 21st 2011, 3:40pm

I have noticed that some guys feel that accepting help emasculates them.

I have noticed that some guys have a way of getting others to do any thing.

I have noticed that it is easier for some guys to do "do it themselves".

I have noticed that some guys work harder to get out of a job than it would be to do it.

I have noticed that some gutys work well with other guys, no matter whose job it is.

I have tried to be one of those last guys because it feels pretty good at the end of the day.

Bob
Start a fire for a man and he will be warm for a day.
Set a man on fire and he will be warm the rest of his life.

Sent using two Progresso soup cans and a string
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