Investigating "the why's" of diagnosed problems

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Investigating "the why's" of diagnosed problems

Postby Ken » Tue Oct 30, 2018 10:28 pm

Generally when I find and fix problems, I'll often still waste time continuing to explore why the part failed when it did.
Over the weekend I found the sons VS V6 was hitting a brick wall at around 2800 rpm, got to wondering if the fuel system was keeping up, did a few tests and determined it wasn't.
Threw a pump and filter at it tonight, a lot of black crap fell out of the filter when blowing in the opposite direction, though it still flowed OK, changed it anyway, though now the new pump is in it, it's back to pulling to decent rpm again, though it's now actually too rich, and has to be re tuned.
I noticed the end of the pump where the lead plugs in looked as though it may actually pry off, thinking it's probably where the motor brushes are I attempted to do so, and sure enough it did.
And what do I find, one of the brush leads was not only broken, looks as though it had been for a length of time, it was black and nearly completely arc'd away as though it was making and breaking contact for some time, odd considering the car never cut out, guess the spring was probably taking the brunt of the current too.

VSV6_Pump.jpg
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Last edited by Ken on Wed Oct 31, 2018 1:22 am, edited 1 time in total.

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Re: Investigating "the why's" of diagnosed problems

Postby vlad01 » Tue Oct 30, 2018 11:18 pm

I have found a few times fuel filters containing brush material and copper fragments from the pump.

In fact my brother's 5L vr ute was hitting a wall at 80ks and not wanting to go any faster, just lacked all power but did not miss or sputter and still drive smooth with just no power.

Found the filter was completely blocked with carbon dust as it looked to be 10-15 years old and never changed, he bought it only 2-3 years ago and just never thought to change it yet. What a difference that made lol

On my nephews car, the pump just stopped dead one day and it was the pump, measured the current draw and it was only a few 100mA and not turning at all. Since it was a fair way from home the racv changed the pump at their depot so I never got to look at why it died so abruptly, they normally die a slow death.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Investigating "the why's" of diagnosed problems

Postby Charlescrown » Thu Nov 01, 2018 12:17 pm

I find it interesting how DC motors wear 1 brush away and not the other. I put it down to the direction of current flow.

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Re: Investigating "the why's" of diagnosed problems

Postby vlad01 » Thu Nov 01, 2018 12:27 pm

yes it's normally the negative that wears down on stuff as the elections are emitted from the negative and tend to take atoms with them.

In a tig welder the negative set electrode will erode but remain cooler, switch it to positive and it doesn't erode much but gets much hotter by being subject to being blasted by electrons and negative ions.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.

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Re: Investigating "the why's" of diagnosed problems

Postby j_ds_au » Thu Nov 01, 2018 5:54 pm

Ken wrote:Threw a pump and filter at it tonight, a lot of black crap fell out of the filter when blowing in the opposite direction, though it still flowed OK, changed it anyway, though now the new pump is in it, it's back to pulling to decent rpm again, though it's now actually too rich, and has to be re tuned.

Well, that shouldn't have caused any such side-effect, so something else is wrong. The pump is supposed to deliver in excess of the maximum fuel that may be required, and a pressure valve returns the excess back to the fuel tank, mantaining a fixed pressure at the fuel rail.

Joe.

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Re: Investigating "the why's" of diagnosed problems

Postby pman92 » Thu Nov 01, 2018 6:03 pm

Unless it was tuned with the bad pump or blocked filter, or fuel trims haven't relearnt themselves
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Re: Investigating "the why's" of diagnosed problems

Postby Ken » Thu Nov 01, 2018 9:02 pm

I forgot to mention in the first post, the injectors were changed earlier in the week as it seemed to have a leaky one, and was starting as though it was partially flooded when left overnight, though after changing them, the starting problem was fixed, and nothing else seemed to have changed regarding the way it ran, probably because of the dying pump it would seem.

j_ds_au wrote:
Ken wrote:Threw a pump and filter at it tonight, a lot of black crap fell out of the filter when blowing in the opposite direction, though it still flowed OK, changed it anyway, though now the new pump is in it, it's back to pulling to decent rpm again, though it's now actually too rich, and has to be re tuned.

Well, that shouldn't have caused any such side-effect, so something else is wrong. The pump is supposed to deliver in excess of the maximum fuel that may be required, and a pressure valve returns the excess back to the fuel tank, mantaining a fixed pressure at the fuel rail.

Joe.

You're dead right, I was thinking the same myself last night, though also figured by the amount of black arc'ing on where the brush lead was broken, that maybe I tuned it when the pump was on it's way out, then I got to thinking, hang on dumb-ass, did I even bother to check the part number of the injectors my son bought for the car before he put them in, all I did was over see he was cleaning things good enough and not doing things the hard way.
After checking the number this morning, gave myself a bitch-slap, and set the injector flow rate to what I thought was pretty close based mostly on the flow calc downloaded from here, it now go's way harder than I'd have believed one would, they're actually new VT injectors, yeah I know - kick me.
It now hits the fuel cut-off that hard when he's flat into it, I thought he'd stepped on the brakes..
It now also has a faint whistle sound out the tailpipe from half way through the rev range, and revs so much smoother, feels like the bottom end got a balance job.
The exhaust system had a new "exhaust burning smell' to it when we returned from the first test run after putting the tune back close to where I'd originally had it with the inj flow settings now changed, though we've probably done a few thousand k's since putting the exhaust in it.
339.990 mS/Gram was what I set the Inj flow rate at using the 0280155777 injectors, was originally 361.328
According to the LM1 wideband, it's a good enough tune to use till I throw it on the rollers when I find the time.

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I also opened up an oil pressure switch he had to change on the LS VY a while back, was making the gauge go haywire.
Turns out that whenever it got a wash, the water and whatever else ended up inside the switch, sealed the new one with silastic around where the edge was rolled over to hold it together, in hope of keeping it dry when washed.

Pics a bit out of focus.
VY_Oil_Sw.jpg
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Re: Investigating "the why's" of diagnosed problems

Postby Jayme » Sun Nov 04, 2018 9:45 am

Yeah ls1 + water pain in the ass..... owned it for years finally washed the engine for the first time, dead oil switch dead knock sensors. replace oil switch, disable knock sensors (yes im lazy and they are under the intake manifold in the valley) never washed it again lol it can stay bloody dirty.

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Re: Investigating "the why's" of diagnosed problems

Postby immortality » Sun Nov 04, 2018 10:22 am

I don't think it's just an LS problem but more a GM problem....

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