Poor gas mileage despite rebuild and no engine codes
Thread Starter
Joined: Jun 2007
Posts: 4
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Poor gas mileage despite rebuild and no engine codes
Hello. I recently had my engine bored .030 and I rebuilt it and put it back in my truck. Ever since, then my gas mileage keeps getting worse. I have checked many things and it doesn't help. Any ideas?
Record Breaker
Joined: Oct 2004
Posts: 2,456
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From: Gaylord, MI
RE: Poor gas mileage despite rebuild and no engine codes
Could be things not related to the rebuild. Bad O2 sensors, clogged cat, dirty injectors/fuel system.
Run some high concentration of injector cleaner through the tank. Not to high though, don;t go overboard. Also run some Marvel Mystery Oil in the gas tank, not at the same time as injetor cleaner, and some MMO in the crank case.
Run some high concentration of injector cleaner through the tank. Not to high though, don;t go overboard. Also run some Marvel Mystery Oil in the gas tank, not at the same time as injetor cleaner, and some MMO in the crank case.
Thread Starter
Joined: Jun 2007
Posts: 4
Likes: 0
RE: Poor gas mileage despite rebuild and no engine codes
The injectors are clean, they have been tested and all work 100%. The catalytic converter is not clogged. We replaced one oxygen sensor last night, after testing them. Parts store scan said it was bad. I guess we'll see after we hit the gas station a couple more times!
Thanks for your input! It's greatly appreciated!
Thanks for your input! It's greatly appreciated!
Hall Of Fame
Joined: Jan 2004
Posts: 12,946
Likes: 309
RE: Poor gas mileage despite rebuild and no engine codes
one thing comes to mind... is the tailpipe blacker than normal? it is a possiblity that your fuel pressure regulator has gone bad or is not working right. If the FP is high then it would explain why your mileage took a dump. it would seem pretty coinsidental that it happend during the rebuild. was the truck down long?
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Captain
Joined: May 2007
Posts: 601
Likes: 3
From: Clearwater, FL
RE: Poor gas mileage despite rebuild and no engine codes
Wait a minute.
Before the rebuild you would get 280 / tank and now you get 250 / tank?
Assuming a 20-25 gal fill up; you're only talking about a 1-2 MPG difference. And thats after being bored? Did you expect it to go up?
Before the rebuild you would get 280 / tank and now you get 250 / tank?
Assuming a 20-25 gal fill up; you're only talking about a 1-2 MPG difference. And thats after being bored? Did you expect it to go up?
Thread Starter
Joined: Jun 2007
Posts: 4
Likes: 0
RE: Poor gas mileage despite rebuild and no engine codes
Well, of course we expected to get better mileage!!! We have gotten 420 miles to the tank on an out-of-state trip before!!! In fact, we only got 238 miles out of the last tank! The 318 (bored .030) in our other vehicle gets almost 11 miles to the gallon and it's got a carburetor! See why it doesn't make sense?
Since we had to replace the fuel pump last summer, I know the FPR is new. It took 6 weeks to actually complete the whole rebuild project (4-5 of those were spent waiting on the machine shop).
Since we had to replace the fuel pump last summer, I know the FPR is new. It took 6 weeks to actually complete the whole rebuild project (4-5 of those were spent waiting on the machine shop).
Legend
Joined: May 2005
Posts: 8,663
Likes: 8
From: Central Oklahoma
RE: Poor gas mileage despite rebuild and no engine codes
ORIGINAL: colorado ram
Well, of course we expected to get better mileage!!! We have gotten 420 miles to the tank on an out-of-state trip before!!! In fact, we only got 238 miles out of the last tank! The 318 (bored .030) in our other vehicle gets almost 11 miles to the gallon and it's got a carburetor! See why it doesn't make sense?
Since we had to replace the fuel pump last summer, I know the FPR is new. It took 6 weeks to actually complete the whole rebuild project (4-5 of those were spent waiting on the machine shop).
Well, of course we expected to get better mileage!!! We have gotten 420 miles to the tank on an out-of-state trip before!!! In fact, we only got 238 miles out of the last tank! The 318 (bored .030) in our other vehicle gets almost 11 miles to the gallon and it's got a carburetor! See why it doesn't make sense?
Since we had to replace the fuel pump last summer, I know the FPR is new. It took 6 weeks to actually complete the whole rebuild project (4-5 of those were spent waiting on the machine shop).