Low Fuel Lamp: How many gallons left when light goes on?

Does anyone have any idea as to how much fuel is left when the low fuel light comes on?
Len
HAPPY NEW YEAR ALL

IIRC about two gallons.

HOWEVER don't do that unless you absolutely have to because the fuel pump depends on the fuel for cooling (it's a little metal can in a plastic cup and it gets real hot) so if you do this too many times you **will** be soon replacing the fuel pump. I think in practice it's a great idea to keep more than 1/4 tank "inventory" in (again it's for the cooling).

One thing to think about also is the recently-discussed (on this forum) difference between winter and summer gas. If you are storing the car with winter gas in the tank you *really should* use a fuel stabilizer like Sta-Bil.

Albertj

Albert is right, but I've made it 50 miles after that stupid light has come on lol.

Without a signature, I don't know exactly what model you're driving Len, but don't let Albert make you too paranoid...

The "cooling fuel" in the buckets of non-supercharged cars is replenished by the fuel return line from the engine, so in most conditions the cup will remain full even while you coast into the gas station.

Personally, I think the SC cars are probably impervious to low-fuel conditions, because they not only have the return fuel dropping into the cup, they also have some fuel split off from the pump output itself - which in turn pulls even more fuel into the cup by running through a venturi nozzle on the bottom... Plus, in supercharged cars, the pump is often running at only half-power in the first place because of the pump-speed-control module. I run down to the light on almost every tank, and as far as I know I'm still on the original pump.

^^^ good info, Mark. I didn't know that stuff. (+)

Thank you, Aaron.

I also should've added my 2 cents about the main question: With variances in sending units, "your mileage will vary"...

My original sender left me about 2.5 gallons when the light came on, but my replacement seems to only leave me 1.5. So figure conservatively unless you're as anal as I am, and bring a can of gas along to run the tank dry to find the usable capacity, then refill it as soon as the light comes on to find the difference...

Was the replacement sender the exact same OEM part?

AA wrote:

Was the replacement sender the exact same OEM part?

For the life of me I can't find my post from when I replaced it, but I did find the related photo in my Flikr account.
As far as I remember, the sender and the spare pump I bought at the same time were Delco/Delphi.
I remember being impressed that the sender came with the whole wiring harness/connectors/ballast resistors...



EDIT: I also found the eBay confirmation in my "Car" email folder - good thing I don't clean things out!
They are Delco, and he even added '97 Riviera to his listing title after our transaction. (The SC MU35 fuel
module using the same sender as the NA MU-33 - along with untold others, like S-10 pickups....) LINK

Thank you all for your input. When my light came on yesterday I filled up and the tank took 15 gallons, since the tank capacity is 19.5 gallons am I to assume that I had 4.5 gallons left? if the answer to this is yes then obviously they all vary and this does not make sense to me. I was just curious in case of emergencies but I will err on the side of caution and fill up when the light comes on.
As a PS. I Seafoamed my engine over the week end along with the oil. I will be changeing the oil in approx 150 miles with Lucas 20/50 plus a stabiliser. With the mod to the supercharger and the clean engine I can feel a marked difference in performance. I have also located transmission mounts for under 50 bucks each. The l/h rear rubber insert from Anchor and the front from Rockauto. If anyone would like more info please e mail me.
Len

Thank you all for your input. When my light came on yesterday I filled up and the tank took 15 gallons, since the tank capacity is 19.5 gallons am I to assume that I had 4.5 gallons left? if the answer to this is yes then obviously they all vary and this does not make sense to me. I was just curious in case of emergencies but I will err on the side of caution and fill up when the light comes on.
As a PS. I Seafoamed my engine over the week end along with the oil. I will be changeing the oil in approx 150 miles with Lucas 20/50 plus a stabiliser. With the mod to the supercharger and the clean engine I can feel a marked difference in performance. I have also located transmission mounts for under 50 bucks each. The l/h rear rubber insert from Anchor and the front from Rockauto. If anyone would like more info please e mail me.
Len

Lenrapkins wrote:

Thank you all for your input. When my light came on yesterday I filled up and the tank took 15 gallons, since the tank capacity is 19.5 gallons am I to assume that I had 4.5 gallons left? if the answer to this is yes then obviously they all vary and this does not make sense to me. I was just curious in case of emergencies but I will err on the side of caution and fill up when the light comes on.
As a PS. I Seafoamed my engine over the week end along with the oil. I will be changeing the oil in approx 150 miles with Lucas 20/50 plus a stabiliser. With the mod to the supercharger and the clean engine I can feel a marked difference in performance. I have also located transmission mounts for under 50 bucks each. The l/h rear rubber insert from Anchor and the front from Rockauto. If anyone would like more info please e mail me.
Len

You say the tank took 15 gallons... that's within the variables, which include:

- some gas pumps (by law) are temperature-compensated and register more or less fuel than they deliver, by volume, depending on fuel temperature.

- your fuel tank will 'click' different pumps off at different fullness (varies a little not so much but still measurable) depending on conditions - weather, the condition of the fuel delivery nozzle, and other factors

- you did not say if you topped the tank off. Topping off is a bad idea because it can mess up the vapor recovery system, but the point is you did not say. Depending on conditions you could have added a gallon or 2.

Any more observations?

Albertj

Thanks Albertj. No I definately did not top off. Could you tell me what one poster means when he says "gutted air box lid" and what is the purpose/benefits?
Len

20w50 is awful heavy for these low revving, tight tolerance engines. If I had your engine and the engine was not a burner or a blower I would stick with the 10w30, but maybe switch to the Lucas synth or Mobil 1 or some such. I don't know if Lucas is really a PAG synthetic (mobil 1 is) but IIRC the Lucas additive pack is similar for the 10w30 as the 20w50, just the base oil is heavier.

I switched to Mobil1 before 50K miles on my car (now am at 230K+), use 10w30 except the dead of winter (jan - march) then 5w30.

20w50 is great for high revving aircooled engines. The SC3800 does not even crack 2000 RPM until well above legal highway speed....

So I'm not saying Oh You Shouldnt Use 20w50. I'm just saying I've run 10w30 in one SC 3800 series II engine for almost 200,000 miles and the engine is not making 'overhaul me' indications of any sort (does not even drip on the garage floor) and since you posted the PS I thought you might find this comment helpful.

Your further thoughts?

Albertj

Lenrapkins wrote:

Thanks Albertj. No I definately did not top off. Could you tell me what one poster means when he says "gutted air box lid" and what is the purpose/benefits?
Len

"gutted air box lid" just means to remove the resonator/muffler from the airbox. It is obvious when you open the box and IIRC it's actually on the case side not the lid side...

My personal opinion: I dont' want the noise and I don't have a heavily modified engine that needs the smidge of extra airflow so I did not & don't plan to do it.

If I remember your mods right, if you do this mod to it will add noise but if you actually put the car on a dyno probably no significant benefit. If you search this site you'll find much discussion about the airbox lid thing. I am sure others will chime in, hopefully someone who's actually measured the results with something objective - other than their subjective butt dyno.

Albertj

As stated in another thread, I just got my factory service manuals last evening. I was reading the sections on preventative maintenance and specifically on engine oil. The manually specifically calls for 10W30 and stresses not to use anything else. You can use thicker weight oil as a band aid for a "loose" or warn out engine if you are experiencing low oil pressure, but you're putting off the inevitable engine rebuild.

I'm a mobile 1 guy myself. But I also use shell rotella in my aircooled vw engines for the added zinc content which is needed in flat tappet engines. I've also used castrol syntec in one of my prior astro vans, and I also like the synthetic shell diesel products for my dodge cummins engine.

If you ever get the opportunity to open an engine up that has been run its entire life on a traditional dyno oil, and the same with a synthetic oil, the differences are amazing! It obviously costs a little more per oil change, but i'd rather spend a little more now, to prevent the huge expense of a new car or engine replacement down the road. Back when I started college, many moons ago, I bought a used 86 pontiac pariseane w the 305ci V8 in it. The car had 63,000 miles on it when I got it. I immediately switched it over to Mobile 1 10w30 and never looked back. I sold the car for $500 less than what I paid with 240,000+ miles on it. The engine was still going strong, but I sold it because I was living in the NE at the time and winters had taken their toll on the poor girl. The rust was starting to "bloom" all over. Sucked!

Bottomline go mobile 1 10w30 and never look back!

VegasScott

Lenrapkins wrote:

Thank you all for your input. When my light came on yesterday I filled up and the tank took 15 gallons, since the tank capacity is 19.5 gallons am I to assume that I had 4.5 gallons left? if the answer to this is yes then obviously they all vary and this does not make sense to me.
Len

This is another of those cases where you really should put your car's information in the Signature file in your Profile... The '95's had about 19.5 usable gallons, but for some reason the rest of the cars had only 17.5 to 18.

albertj wrote:

Lenrapkins wrote:

Could you tell me what one poster means when he says "gutted air box lid" and what is the purpose/benefits?
Len

"gutted air box lid" just means to remove the resonator/muffler from the airbox. It is obvious when you open the box and IIRC it's actually on the case side not the lid side...

My personal opinion: I dont' want the noise and I don't have a heavily modified engine that needs the smidge of extra airflow so I did not & don't plan to do it.

Albertj

I assume he is speaking about me, Albert, and I agree with you about not removing the resonating chambers at the bottom of the airbox. However, the lid does have that big, red restrictor attached to 2 hollow posts, which restricts the size of the outlet, the primary area of the filter being used, and isolates the IAT sensor from the airflow... That is what I removed with a little Dremel work.

Eldo wrote:

albertj wrote:

Lenrapkins wrote:

Could you tell me what one poster means when he says "gutted air box lid" and what is the purpose/benefits?
Len

"gutted air box lid" just means to remove the resonator/muffler from the airbox. It is obvious when you open the box and IIRC it's actually on the case side not the lid side...

My personal opinion: I dont' want the noise and I don't have a heavily modified engine that needs the smidge of extra airflow so I did not & don't plan to do it.

Albertj

I assume he is speaking about me, Albert, and I agree with you about not removing the resonating chambers at the bottom of the airbox. However, the lid does have that big, red restrictor attached to 2 hollow posts, which restricts the size of the outlet, the primary area of the filter being used, and isolates the IAT sensor from the airflow... That is what I removed with a little Dremel work.

Thank you for correcting me.

I would remove neither the resonator nor the restrictor. BUT it's not like it's gonna kill his car either. Would you mind recapping what you did & why or putting a link back to your earlier explanation.

My take on the airbox work: Just sayin' I would not do it. NOT saying don't do it.

Albertj

VegasScott wrote:

As stated in another thread, I just got my factory service manuals last evening. I was reading the sections on preventative maintenance and specifically on engine oil. The manually specifically calls for 10W30 and stresses not to use anything else. You can use thicker weight oil as a band aid for a "loose" or warn out engine if you are experiencing low oil pressure, but you're putting off the inevitable engine rebuild.

I'm a mobile 1 guy myself. But I also use shell rotella in my aircooled vw engines for the added zinc content which is needed in flat tappet engines. I've also used castrol syntec in one of my prior astro vans, and I also like the synthetic shell diesel products for my dodge cummins engine.


Bottomline go mobile 1 10w30 and never look back!

VegasScott

Scott,
I agree, synthetic oil does everything better. I am familiar with the Zinc issue in modern day oils. Most engine have roller cams, so they have reduced Zinc in motor oil also due to emissions issues. Early on, guys were using diesel oil, but that had it's draw backs as diesel oil is formulated for low revving diesel engines, and the anti foam additive package is not suitable if you want to turn some RPM. Most guys I know are now using the oil on the market that has the extra Zinc in it like Joe Gibbs, or Brad Penn oil. You can also just add ZDDPlus to any oil you care to use including synthetic. I myself use 5W/30 Amsoil in my Riviera, and change it twice a year. In my GS, I have been using Red Line 10W/40 with a bottle of ZDDPlus.

LARRY70GS wrote:

VegasScott wrote:

As stated in another thread, I just got my factory service manuals last evening. I was reading the sections on preventative maintenance and specifically on engine oil. The manually specifically calls for 10W30 and stresses not to use anything else. You can use thicker weight oil as a band aid for a "loose" or warn out engine if you are experiencing low oil pressure, but you're putting off the inevitable engine rebuild.

I'm a mobile 1 guy myself. But I also use shell rotella in my aircooled vw engines for the added zinc content which is needed in flat tappet engines. I've also used castrol syntec in one of my prior astro vans, and I also like the synthetic shell diesel products for my dodge cummins engine.


Bottomline go mobile 1 10w30 and never look back!

VegasScott

Scott,
I agree, synthetic oil does everything better. I am familiar with the Zinc issue in modern day oils. Most engine have roller cams, so they have reduced Zinc in motor oil also due to emissions issues. Early on, guys were using diesel oil, but that had it's draw backs as diesel oil is formulated for low revving diesel engines, and the anti foam additive package is not suitable if you want to turn some RPM. Most guys I know are now using the oil on the market that has the extra Zinc in it like Joe Gibbs, or Brad Penn oil. You can also just add ZDDPlus to any oil you care to use including synthetic. I myself use 5W/30 Amsoil in my Riviera, and change it twice a year. In my GS, I have been using Red Line 10W/40 with a bottle of ZDDPlus.

I admit that my Mobil1 oil changes are 4 qts M1 plus 1/2 qt Rotella Blue Synth for diesels...

Well, well well I live and learn, I always ran 20/50 in my Jags because of high revs and I thought the same for my Riv but now that you mention it I have rerely seen the tacho over 2000 when cruising at 70-80 mph. I am goin to take the 20/50 back to the store in the morning and get 10/30 mobil one as my preferred next choice. Thanks Albertj and Scott for your input.
Happy motoring.
Len

Lenrapkins wrote:

Well, well well I live and learn, I always ran 20/50 in my Jags because of high revs and I thought the same for my Riv but now that you mention it I have rerely seen the tacho over 2000 when cruising at 70-80 mph. I am goin to take the 20/50 back to the store in the morning and get 10/30 mobil one as my preferred next choice. Thanks Albertj and Scott for your input.
Happy motoring.
Len

Rule of thumb is you run the thinnest oil that gives you sufficient oil pressure for the RPM. For the 3800, that is 10 psi for every 1000 RPM, so at 6000 RPM, you need 60 psi of oil pressure. I have a good mechanical oil pressure gauge in my Riviera. I run 5W/30 Amsoil synthetic, and oil pressure is excellent. It never drops below 35 psi at in gear idle, and if you breathe on the gas, it shoots up to about 63 psi. That is outstanding, I wish my 455 did that. The 3800 oil pump is vastly superior to the earlier 3.8 V-6 designs. Newer cars run even thinner oil because of tighter control on clearances. 0W/20 is common. Thicker oil can be a band aid for a worn engine, but when it is not needed, it does two things, wastes HP, and further heats the oil.

I just want to point out that I agree about thicker oil for worn engines, but I can't see the theory of thicker oil (20W-50) being for higher revving engines... It's 20 weight when cold, and 50 weight when hot - not exactly something you want to have if you're gonna' zing high revs.
I ran 20/50 in my 400 inch Grand Am, but it was of course a torque monster, and also had 270,000 miles on it when I sold it.

albertj wrote:

Eldo wrote:

albertj wrote:

Lenrapkins wrote:

Could you tell me what one poster means when he says "gutted air box lid" and what is the purpose/benefits?
Len

"gutted air box lid" just means to remove the resonator/muffler from the airbox. It is obvious when you open the box and IIRC it's actually on the case side not the lid side...

My personal opinion: I dont' want the noise and I don't have a heavily modified engine that needs the smidge of extra airflow so I did not & don't plan to do it.

Albertj

I assume he is speaking about me, Albert, and I agree with you about not removing the resonating chambers at the bottom of the airbox. However, the lid does have that big, red restrictor attached to 2 hollow posts, which restricts the size of the outlet, the primary area of the filter being used, and isolates the IAT sensor from the airflow... That is what I removed with a little Dremel work.

Thank you for correcting me.

I would remove neither the resonator nor the restrictor. BUT it's not like it's gonna kill his car either. Would you mind recapping what you did & why or putting a link back to your earlier explanation.

My take on the airbox work: Just sayin' I would not do it. NOT saying don't do it.

Albertj

Well, there seems to be a flaw in the Editboard programming... or in my understanding. Just like yesterday when I couldn't find my post about replacing the fuel sending unit, I just poked around my Profile and the system says I have 366 threads that I've posted in, but it won't take me back more than 8 pages - to May 1, 2010.

However, my reasons were basically what I posted above - all 3 factors were significantly affected by the red restrictor, and it only made one change in the sound: the cold-start 'growling' of the supercharger. It only lasts for a few minutes, and after that the removal barely increases the 'desirable' whine and nothing else. From reading other posts, removing the airbox or intake-pipe resonators makes a much bigger difference in noise...
That is why I specifically put "gutted airbox lid" in my Signature.

Quote :

Well, there seems to be a flaw in the Editboard programming... or in my understanding. wink Just like yesterday when I couldn't find my post about replacing the fuel sending unit, I just poked around my Profile and the system says I have 366 threads that I've posted in, but it won't take me back more than 8 pages - to May 1, 2010.

You are seeing all 366 topics (7 pages x 50 topics/page + the remainder on page 8). However, these are not all the topics you've ever posted here - the system only tracks your last ~365 topics. It may be a flaw, but it has always been this way, and it applies to all members, even me. I'll check on this to see if there are any answers to be found.