bluecadillac Posted August 2, 2008 Report Share Posted August 2, 2008 hi i have a beautiful metallic blue 1990 sedan deville. now for her age she is in great shape i wash and wax it regualry "by hand". she only has 130230 on her strong 4.5 liter v8. now the reason im posting this here is i have a few questions. first someone vandelized my car last night. the keyed her bad it runs from the front turn signal to the back wheel well. i want to know if there is any thing i can do for it now. i plan to get it repainted in the future but is there some kinda miricle cream i can get to rub on there and at least dull this huge blemish. my final question and i dont really know how to explain this so i will do the best i can. i seem to have gas demons that steal my gas from me now my car gets 15-17 city & 22-25 hwy. but when i go off exit ramps turn corners park with the front end on a slant even a slight slant. i lose gas and i dont get it back for a full tank of gas 18 gallons i will lose 5 it runs great not too rich or lean. there are no leaks holes or anything and i have ran it down to e just to see if gauge was wrong and no i was out of gas. thx for your help i really appreciate it Link to comment Share on other sites More sharing options...
Ranger Posted August 2, 2008 Report Share Posted August 2, 2008 Regarding the gas, I would guess that the float is sticking in the tank. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 2, 2008 Report Share Posted August 2, 2008 See if your fuel system holds pressure. A day or so after a fill-up, listen carefully as you remove the filler cap. If there is no pressure differential at all, you might be losing fuel to evaporation. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
bluecadillac Posted August 3, 2008 Author Report Share Posted August 3, 2008 no there is pressure i hear it release everytime i put gas in. its a mystery to me Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 3, 2008 Report Share Posted August 3, 2008 There are only three ways for gas to get out of the car: leaks in the filler cap or tube (which you don't have), the EVAP system (you don't have codes), or the engine. There are five ways to get bad gas mileage out of a Northstar that I know of: Drive in San Francisco or other vertical urban environment. Drive mostly with the engine cold. Use a relentless lead foot. Run the system open loop or with a bad oxygen sensor. Run 15% alcohol fuel in urban driving. If you don't have codes, you don't live in downtown San Francisco or Seattle, and your gas mileage was good until recently and changed without a change in driving habits (or start letting your 16-year-old-son drive it), then your filling station probably switched to 15% alcohol. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
bluecadillac Posted August 3, 2008 Author Report Share Posted August 3, 2008 i dont have a north star i wish i did. i have a 4.5 OHV engine. Link to comment Share on other sites More sharing options...
Texas Jim Posted August 3, 2008 Report Share Posted August 3, 2008 Blue Cadillac, From what I read into your first post... You are getting... 15-17 city & 22-25 hwy. That is not bad at all. There is a problem with a some of the gauges not READING the actual amount of fuel that is REALLY in the tank correctly. The best way to check if you are REALLY losing gas.... Fill it up. Write down your odometer mileage. Do "WHATEVER IT IS" that makes it indicate that you have lost five gallons.. as you state in your post. Immediately fill up again. Write down the mileage. Figure the MPG with a HAND CALCULATOR not by using te DIC. The DIC can only use the info sent to it by the sending unit in the tank. Don't trust it till you have verified your ACTUAL MPG by using the hand calculator method. If the MPG is close to what you normally get... it is just the gauge and you are not really LOSING GAS. It is probably just a sticking float or a bad circuit board on the sending unit sending bad info to the DIC. Remember... the DIC can only display whatever info it is getting from various sensors. If a sensor is bad... your displayed info is bad. Link to comment Share on other sites More sharing options...
Texas Jim Posted August 3, 2008 Report Share Posted August 3, 2008 When did they start putting 15% alcohol in gas? Where are they doing this at? My car runs bad on 10% vs gas without ANY alcohol. I FOR SURE don't want to put any 15% in it. Link to comment Share on other sites More sharing options...
Cadillac Jim Posted August 3, 2008 Report Share Posted August 3, 2008 The maximum alcohol allowable by law is 15% and some suppliers have been using 10% for some time now in the summertime. Our engines are designed to work well with up to 15%. The problem with alcohol and fuel economy is that alcohol doesn't have the combustion energy of gasoline -- in fact nothing else does and is still ignitable with spark, that's why gasoline was selected as the fuel of choice for the Otto cycle engines in the 1890's. In city driving, much of the fuel is used to accelerate the car, and alcohol is really poor at that as compared to cruising at high vacuum. I find a straight 10% reduction in city fuel economy and 5% reduction in highway mileage with 10% gasoline. They make up for it by raising the price of gasoline. -- Click Here for CaddyInfo page on "How To" Read Your OBD Codes-- Click Here for my personal page to download my OBD code list as an Excel file, plus other Cadillac data -- See my CaddyInfo car blogs: 2011 CTS-V, 1997 ETC Yes, I was Jims_97_ETC before I changed cars. Link to comment Share on other sites More sharing options...
Texas Jim Posted August 3, 2008 Report Share Posted August 3, 2008 Here in the Dallas/Ft. Worth area... ALL gas has 10% ethanol added. YEAR ROUND. Fifty miles to the southwest... you can get fuel WITHOUT ethanol. I ALWAYS fill up if I am in that area. Using 10% ethanol hits me with close to a 10% penalty on mileage vs gas that DON'T have ethanol. My car also runs better on gas without ethanol. I would hate to see how it runs on 15%. I remember back in the '70s... when unleaded gas first came out. All new cars could ONLY USE unleaded. (unless you modified the fuel filler tube or bought a little 99 cent adapter that fit on the end of the leaded nozzle and into your tank.) Unleaded was (at first) more expensive than gas with lead in it. The story from BIG OIL was... it was more expensive to make because it had to be refined more because it didn't have the lead to boost octane. A few years later... LEADED fuel was getting more expensive than UNLEADED. The NEW STORY was ... it was more expensive to PUT LEAD into the gas. Most people had forgotton the first story by that time. It seems to me that I am missing SOMETHING about the ADVANTAGES of using ethanol in my car. If you (or anyone else) can explain it to me, I would appreciate it... If I am seeing a 10% penalty in mileage... then I am buying 10% MORE fuel. So... I am using the SAME AMOUNT of REAL GAS plus I am using the dad-blamed ethanol ALSO.. and by using the ethanol.. I am driving up the price of corn and all corn related products. Including the good steaks that I like so well. Thanks for the heads up about the 15% ethanol possibility. Link to comment Share on other sites More sharing options...
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