1990 460 gas problem
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Senior User
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From: California
1990 460 gas problem
So i drive the same distance to work everyday. 4 miles there and yes, 4 miles back. Lately i've been noticing that shes drinking more gas then usuall and as you all know the 460 has a large appetite as it is. So my question is why the sudden change because it is definetly noticable but she runs great as always. Also im moving at the end of the week so my commute will be 12 miles to work. If i tak ethe frewway its 18 miles. So should i take the sidestreets with a thousand red lights or the freeway that is farther.
This is all random i know but input would be appreciated. Maybe some tips on saving gas. Might just take the bus!!
This is all random i know but input would be appreciated. Maybe some tips on saving gas. Might just take the bus!!
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Senior User
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From: California
Right outside of Los Angeles
Fleet Owner
Joined: Oct 2005
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From: Kentucky
When was the last time you did a tuneup with plugs, wires, cap, rotor and filters?
Do you have dual tanks? If yes have you checked the mileage from both tanks?
Any other service work been done lately?
Do you have dual tanks? If yes have you checked the mileage from both tanks?
Any other service work been done lately?
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From: California
Sense then i immediatly changed the oil and i flushed the radiator.
I do have dual tanks, But i only run one tank because the other one the gas gauge does not work on.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
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From: Kentucky
Still does not answer the tune up question
You did answer the dual tank.....these trucks suffer from cross-flow due to the odd design of the fuel system. You may be experiencing this very phenomena....
You did answer the dual tank.....these trucks suffer from cross-flow due to the odd design of the fuel system. You may be experiencing this very phenomena....
Long story short each tank has a pump and check valve. The powered tank pushes fuel out toward the engine AND the other tank. Since the other pump is not running the pressurized fuel will push shut the check valve of the non-powered tank/pump assembly. That's the theory but in practice that check valve remains open therefore the non-powered tank starts to fill with fuel. VERY common issue.
You stated you do not use the other tank, this is a very common mistake and contributes to the problem.
You did answer the dual tank.....these trucks suffer from cross-flow due to the odd design of the fuel system. You may be experiencing this very phenomena....
You did answer the dual tank.....these trucks suffer from cross-flow due to the odd design of the fuel system. You may be experiencing this very phenomena....
Long story short each tank has a pump and check valve. The powered tank pushes fuel out toward the engine AND the other tank. Since the other pump is not running the pressurized fuel will push shut the check valve of the non-powered tank/pump assembly. That's the theory but in practice that check valve remains open therefore the non-powered tank starts to fill with fuel. VERY common issue.
You stated you do not use the other tank, this is a very common mistake and contributes to the problem.
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Senior User
Joined: Oct 2014
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From: California
Still does not answer the tune up question
You did answer the dual tank.....these trucks suffer from cross-flow due to the odd design of the fuel system. You may be experiencing this very phenomena....
Long story short each tank has a pump and check valve. The powered tank pushes fuel out toward the engine AND the other tank. Since the other pump is not running the pressurized fuel will push shut the check valve of the non-powered tank/pump assembly. That's the theory but in practice that check valve remains open therefore the non-powered tank starts to fill with fuel. VERY common issue.
You did answer the dual tank.....these trucks suffer from cross-flow due to the odd design of the fuel system. You may be experiencing this very phenomena....
Long story short each tank has a pump and check valve. The powered tank pushes fuel out toward the engine AND the other tank. Since the other pump is not running the pressurized fuel will push shut the check valve of the non-powered tank/pump assembly. That's the theory but in practice that check valve remains open therefore the non-powered tank starts to fill with fuel. VERY common issue.
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Fleet Owner
Joined: Oct 2005
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From: Kentucky
No, you do not need a new distributor....cap and rotor are HIGHLY suggested.
Replacing the Fuel Delivery Module in the front tank is the best solution for the possible fuel transfer issue, aka crossflow.
For reference from subford:
Replacing the Fuel Delivery Module in the front tank is the best solution for the possible fuel transfer issue, aka crossflow.
For reference from subford:
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Thread Starter
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Senior User
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From: California
Okay ill do it this weekend. Will Fuel Delivery Module make the gauge work as well or is that something else? any other things i should replace why tho hoods open besides, plugs, wires, cap and rotor?
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well that doesnt sound right.. you oughtta be getting atleast 20mpg on the highway with the 460 engine. try checking your blinker fluid reservoir. from factory the 460 engine has a restricted and undersized blinker fluid reservoir that needs to be constantly filled up to function properly unless you get it bored out for high volume. could also be an exhaust bearing. i performed a full camshaft delete on my 460 and saw 30+ mpg.
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Senior User
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From: California
well that doesnt sound right.. you oughtta be getting atleast 20mpg on the highway with the 460 engine. try checking your blinker fluid reservoir. from factory the 460 engine has a restricted and undersized blinker fluid reservoir that needs to be constantly filled up to function properly unless you get it bored out for high volume. could also be an exhaust bearing. i performed a full camshaft delete on my 460 and saw 30+ mpg.
Um? im not sure if that is correct my friend. 30 MPG is impossible for a 460.
I dont even think 20 is within arms reach.
And blinker fluid resevoir? This must be a joke.
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Lol definitely sarcasm mang. lets just say thats my two cents on the gas mileage of a 460! hah but i will throw out there in seroiusness that the 460 trucks like these that i have bought and worked with (which is a good few) have always had their tune ups neglected and specifically the fuel filter neglected. i dropped a tank to do a fuel pump on a 95 a few months ago and the fuel pump screen was clogged to ****. couldnt believe it was still running. ive seen a pattern of dirty *** fuel with these rigs.
Fleet Owner
Joined: Oct 2005
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From: Kentucky
I suggest to change the air, fuel and PCV filters as well as the PCV.
This diagram should work for your truck (it's for a 1991):
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