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| Bad gas mileage (Page 1/2) |
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M.aaron80
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JUN 03, 09:47 PM
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I have a 86 gt. 2.8 5spd it’s only getting about 100 miles on a tank of gas. What can cause this? I have done a tune up, replaced map, 02,IAC. Timing is good.
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Patrick
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JUN 03, 10:15 PM
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Have you checked for fuel pressure drops (with a fuel pressure tester) when power to the fuel pump is cut? It could indicate a leaking fuel regulator and/or injector(s).
What temperature thermostat do you have installed?
Make sure the CTS and/or MAT aren't reporting a temperature of minus 50° to the ECM.[This message has been edited by Patrick (edited 06-03-2020).]
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M.aaron80
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JUN 03, 10:22 PM
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I forgot to mention I have it straight piped and I did replace coolant temp sensor. What is the MAT again?
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M.aaron80
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JUN 03, 10:26 PM
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0oh k. I found out the Mat is the sensor in the air filter I replaced that also
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Patrick
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JUN 03, 10:28 PM
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Replacing them (especially with the crap that's being sold these days) doesn't guarantee that the new parts are functioning properly.
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M.aaron80
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JUN 03, 10:28 PM
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I have not checked fuel pressure, and how to I check if it’s reporting minus 50°?
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M.aaron80
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JUN 03, 10:29 PM
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Patrick
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JUN 03, 10:33 PM
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| quote | Originally posted by M.aaron80:
...and how to I check if it’s reporting minus 50°?
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That's just a number that I picked out of the air, but it's important that the ECM is being fed the correct information. (Cold temperatures require the engine to run richer.) You need either a scanner or software such as WinALDL which will inform you as to what all the sensors are reporting.
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theogre
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JUN 04, 12:17 AM
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Note:
When trying to calc MPG...
Use same pump at 1 station.
Pump Nozzles at 1 stations, worse across locations, can lie when a car is Full.
If you "Stuff the Tank" after Nozzle shuts off will have more issues calc the MPG. Worse, that can cause EVAP problems when liquid fuel expanse when warm to hot.
Plus...
How many gallon are use to fill your tank? Not a spec in a book. Amount you buy at station pumps.
Book spec is True Empty as in Completely Dry to Full.
Full w/ OE gauge? Not really. Full is mainly when Pump Nozzle first shunt off.
You never see that even for most New cars because of tank and pump design never sucks tank dry even when you run out. For many cars means 0.5 to 2 gallons you can't use.
If anyone replace the pump and did the job wrong can have worse problems and trap more gas you can't use.
And/Or
Many Pump Nozzles have problems of many types...
Nozzle itself is iffy/bad.
1 or more Nozzles in a area doesn't play well w/ some cars.
Example: Many "Coax" pump systems design to recover fumes at filling time causes many problems w/ a lot of vehicles in the 90's to now.
These Nozzles and hose to it pump fuel out and suck fumes in. Many nozzles had plastic bellows over the nozzle part and while no longer used in most markets but still sucks fumes.------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)
The Ogre's Fiero Cave
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Gall757
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JUN 04, 11:34 AM
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Now that you have an SES light that works, check for codes to fix the mileage problem.
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