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1989 Silverado getting bad mileage
I have a 1989 Silverado 1500 4X4 with 350cid and automatic transmission. I used to get 17-19mpg, now I'm lucky to get 10mpg. I used to be able to drive about 190 miles on a 1/4 tank of fuel, now it takes me 3/4 of a tank to go the same distance!! I've done all the basic things: tune-up, changed all the filters, and oil, checked for brakes dragging, checked exhaust system, checked intake system, checked the fuel system for leaks, tire psi, and there is no "check engine light" or codes. The exhaust(when at operating temp) still smells rich. The engine runs smooth with no missing in any rpm range. I've ran out of ideas, can someone please help?? Thank you in advance. [&o]
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RE: 1989 Silverado getting bad mileage
maybe cat is clogged and blocking exhaust. should not make smell rich, but could reduce milage. Also if running rich, could be throttle position sensor staying open or some other throttle body part. Also check if thermostat is stuck. If truck cannot warm up properly may run rich to try to warm up. My old jeep use to do the latter.
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RE: 1989 Silverado getting bad mileage
The cat was removed and a test pipe installed. The thermostat was replaced, as was the temp sensor.
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RE: 1989 Silverado getting bad mileage
mines a '88 2wd and im having the same problem...
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RE: 1989 Silverado getting bad mileage
hey, check your oxygen sensor if its bad that will really drag gas mileage down. i have a 90 chevy silverado and the engine light came on checked with key and told me it was bad, but now i dont know because my damn odometer and mileage doesnt work, the dealerships charge somuch for so little. i had to make aluminum door panels, and cast new door handles out of bronze because of the cheap pot metal kept breaking even casted the 2500 emblems in bronze look awsom when mounted on my 70 firebird scoops. put a 99 yukon gmc grill on it with a early 60s chevy emblem on it
guess quite bragging lol try some fuel additives, or you can do like i did and make your truck as light as possable, still working on that but for a three quarter ton with less weight that succas gone. check underneith your truck as welll because between the cab and the fuel line. cab rubbed hole in it fricken genuises at the plant didnt see that one comming lol hope this helps |
RE: 1989 Silverado getting bad mileage
ORIGINAL: goldfever hey, check your oxygen sensor if its bad that will really drag gas mileage down. i have a 90 chevy silverado and the engine light came on checked with key and told me it was bad, but now i dont know because my damn odometer and mileage doesnt work, the dealerships charge somuch for so little. i had to make aluminum door panels, and cast new door handles out of bronze because of the cheap pot metal kept breaking even casted the 2500 emblems in bronze look awsom when mounted on my 70 firebird scoops. put a 99 yukon gmc grill on it with a early 60s chevy emblem on it guess quite bragging lol try some fuel additives, or you can do like i did and make your truck as light as possable, still working on that but for a three quarter ton with less weight that succas gone. check underneith your truck as welll because between the cab and the fuel line. cab rubbed hole in it fricken genuises at the plant didnt see that one comming lol hope this helps |
RE: 1989 Silverado getting bad mileage
how many mi. do you have on the truck?
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RE: 1989 Silverado getting bad mileage
ORIGINAL: GEARHEADRT how many mi. do you have on the truck? |
RE: 1989 Silverado getting bad mileage
Replace the Coolant Temperature Sensor. If it's sending the wrong temp to the computer, it will run rich (computer thinks engine is cold).
Oops. Just noticed date. Well, hope it helps. |
RE: 1989 Silverado getting bad mileage
im still on here, imma check that out...it dont hurt to look...
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