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Erratic gas gauge??


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#1 mtbz71

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Posted 29 April 2005 - 10:16 PM

My 2001 z71's gas gauge works great when you are driving. But if you stop for a minute it goes to empty, As soon as you pull away from the intersection it registers correctly again. If you leave it idling for a long while (3 or 4 minutes) it takes a long time to register correctly again? Is it the sending unit?? Iím not looking forward to changing that. Any other ideas?

Thanks Mark

#2 GM-Tech

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Posted 30 April 2005 - 05:06 AM

Yes, unfortunately, it is the fuel level sensor in the tank. Very common and I can't say I've ever seen any other cause for the condition you describe. Oh, it's possible there's a wire intermittently grounded, etc., but highly unlikely.

Lots of issues with sulfur in the fuel contaminating the contact surface of the fuel level sender card. You can get the level sensor separately, you do not have to buy the entire $400+ fuel pump module.

#3 Trouttrooper

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Posted 30 April 2005 - 09:23 AM

Yes, unfortunately, it is the fuel level sensor in the tank.  Very common and I can't say I've ever seen any other cause for the condition you describe.  Oh, it's possible there's a wire intermittently grounded, etc., but highly unlikely.

Lots of issues with sulfur in the fuel contaminating the contact surface of the fuel level sender card.  You can get the level sensor separately, you do not have to buy the entire $400+ fuel pump module.

<{POST_SNAPBACK}>



Hey GM-Tech, have they modified the sensor at all to correct for the problem? My '99 started doing that before I upgraded to my current beast :jester: . Will I eventually see the same thing pop up on my 05? Is there any preventetive maintenance a guy could do? I know most fuel additives are just a waste of money.
2005 3500 SRW LS Crew Cab Long Bed
8.1/Allison/4:10/locking rear axle

#4 GM-Tech

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Posted 30 April 2005 - 09:40 AM

Hey GM-Tech, have they modified the sensor at all to correct for the problem? 


Yes, they have improved the sender card and this should alleviate the problems we've seen. Your '05 should have it already.

I'm told that GM's fuel injector cleaner added to the tank can help to prevent this problem and in some cases, even correct problems that have already occured as a result of sulfur contamination. I cannot verify that through anything I've seen.

#5 Trouttrooper

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Posted 30 April 2005 - 10:47 AM

Hey GM-Tech, have they modified the sensor at all to correct for the problem?†


Yes, they have improved the sender card and this should alleviate the problems we've seen. Your '05 should have it already.

I'm told that GM's fuel injector cleaner added to the tank can help to prevent this problem and in some cases, even correct problems that have already occured as a result of sulfur contamination. I cannot verify that through anything I've seen.

<{POST_SNAPBACK}>



Thanks!
2005 3500 SRW LS Crew Cab Long Bed
8.1/Allison/4:10/locking rear axle

#6 snoman

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Posted 30 April 2005 - 05:25 PM

Yes, unfortunately, it is the fuel level sensor in the tank.  Very common and I can't say I've ever seen any other cause for the condition you describe.  Oh, it's possible there's a wire intermittently grounded, etc., but highly unlikely.

Lots of issues with sulfur in the fuel contaminating the contact surface of the fuel level sender card.  You can get the level sensor separately, you do not have to buy the entire $400+ fuel pump module.

<{POST_SNAPBACK}>


THis is true and it can also be caused by moisture in wiper strip damaging the surface and cause a dead spot at times. Like said above R & R sending unit is the cure here and keeping tank full seem to help to if vehical sits a lot.
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#7 GM-Tech

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Posted 30 April 2005 - 05:52 PM

I am not aware of any indication that moisture is a problem. The noble metals that are used in the contact surfaces are highly resistant to oxidation or corrosion and are not really affected by water.

#8 snoman

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Posted 01 May 2005 - 07:19 AM

I am not aware of any indication that moisture is a problem.  The noble metals that are used in the contact surfaces are highly resistant to oxidation or corrosion and are not really affected by water.

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In theory, water is one of the most power solvents there is in that given time is will dissovle about anything (though in may take a very long time) plus water also conducts current and it the last thing you want on the senors strip. I have seen more than one sensor knocked out over the years by high fuel water content. Also unless it is gold plated if it conducts electricity it will react with water sooner or later and this is why the military ans NASA has long used gold plated contacts and contacts in critcal connections and areas.
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#9 GM-Tech

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Posted 01 May 2005 - 08:15 AM

I'm sure you are correct, however, in this particular instance, water simply has not been an issue that I've ever heard of. High sulfur contents has been a major pain in the neck.

You may have heard of the incident in May of last year. A refinery that supplied fuel to shell and to a smaller degree, texaco, allowed a fuel to slip out with an extremely high sulfur content. Within a one week period, we had ~20 vehicles come in with totally failed fuel level sensors. Over the course of several weeks, we did well over a hundred of these repairs. This was duplicated in several areas of the Southeast and I think Kentucky. They even closed down all the Shell stations in Miami while they cleaned out the bad fuel.

Water and gas don't readily mix, so I don't know how much moisture content gas could even have unless it was an oxygenated gas, in which case the ethanol could absorb more water than pure gasoline would. If there was enough free water in the tank, a fuel level sensor wouldn't be the first concern because the truck wouldn't even run. As I'm sure you know, they don't run very well on water. Too bad because with today's gas prices, it'd be nice if they did.

#10 Indy

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Posted 01 May 2005 - 08:47 AM

We had a similar problem a couple of years ago here in Canada where we have consistenly higher sulphur content in our gas. Shell had a particularly bad shipment of fuel which not only damaged the senders but also clogged fuel pumps. The problem was sulphur and an additive which caused a sticky brown residue to be deposited. Shell lost a class action court case and was ordered to compensate owners of vehicles that were affected. There were various levels of compensation given to owners of different vehicles which had different symptoms. I received $500.00 Can. plus $50.00 in coupons for Shell gas. I found out about the compensation package the day before it expired and was able to submit my claim just under the wire.
The sender switches had nickel contacts and all newer models now have gold contacts which are not affected by sulphur.

#11 snoman

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Posted 01 May 2005 - 08:53 AM

I'm sure you are correct, however, in this particular instance, water simply has not been an issue that I've ever heard of.  High sulfur contents has been a major pain in the neck.

You may have heard of the incident in May of last year.  A refinery that supplied fuel to shell and to a smaller degree, texaco, allowed a fuel to slip out with an extremely high sulfur content.  Within a one week period, we had ~20 vehicles come in with totally failed fuel level sensors.  Over the course of several weeks, we did well over a hundred of these repairs.  This was duplicated in several areas of the Southeast and I think Kentucky.  They even closed down all the Shell stations in Miami while they cleaned out the bad fuel.

Water and gas don't readily mix, so I don't know how much moisture content gas could even have unless it was an oxygenated gas, in which case the ethanol could absorb more water than pure gasoline would.  If there was enough free water in the tank, a fuel level sensor wouldn't be the first concern because the truck wouldn't even run.  As I'm sure you know, they don't run very well on water.  Too bad because with today's gas prices, it'd be nice if they did.

<{POST_SNAPBACK}>


Yes I heard all about the sulpher problem. I understand that is took out quite a few sending units that no one wanted to accept responsiblity for by default though I did here of the oil compsny picking up the bill on a few on them that complained loud enough.
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#12 GM-Tech

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Posted 01 May 2005 - 02:12 PM

Yes I heard all about the sulpher problem. I understand that is took out quite a few sending units that no one wanted to accept responsiblity for by default though I did here of the oil compsny picking up the bill on a few on them that complained loud enough.


Shell actually paid for all without question. They even provided rental vehicles while the customer's car/truck was being repaired. We did plenty that Shell paid for. When the repair was completed, they sent a guy over with a check for the full amount, no questions asked.

They make enough billions, they can afford to step up to the one or two screws up they make.

#13 snoman

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Posted 01 May 2005 - 05:07 PM

Yes I heard all about the sulpher problem. I understand that is took out quite a few sending units that no one wanted to accept responsiblity for by default though I did here of the oil compsny picking up the bill on a few on them that complained loud enough.


Shell actually paid for all without question. They even provided rental vehicles while the customer's car/truck was being repaired. We did plenty that Shell paid for. When the repair was completed, they sent a guy over with a check for the full amount, no questions asked.

They make enough billions, they can afford to step up to the one or two screws up they make.

<{POST_SNAPBACK}>



That was great PR for them then. Did they advertise that they would fix it or were they quiet about it?
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#14 GM-Tech

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Posted 01 May 2005 - 06:19 PM

That was great PR for them then. Did they advertise that they would fix it or were they quiet about it?


I wouldn't say that advertised the fact, but it was pretty common knowledge. I think there might have been mention of it in various newspaper articles.

#15 mtbz71

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Posted 01 May 2005 - 06:32 PM

Is there any way not to have to pay for this problem? Through gm or a gas company it has been doing this for about a year the truck has 62,000 kilometres on it but no more warranty.
Mark




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