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11-14-2019, 12:36 AM | #1 |
Junior Member
Join Date: Jan 2016
Posts: 26
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Extremely Frustrating Change in Fuel Consumption
Suddenly after getting 14 to 15 MPG with my 39 Ford Fordor Sedan Deluxe my mileage suddenly dropped to 7. Initially thought it might be the carburetor that gave me good service (one rebuild) for 20 years. Found out it was cobbled together from 3 carbs. Anyway, I replaced it in the event it was causing the problem with a 91-99 rebuild. Same issue with no improvement. Burning extremely rich with black soot out of the tailpipe (no smoke) and new spark plugs being black with soot after 40 miles.
Any ideas out there? Appreciate any help, Dave |
11-14-2019, 01:25 AM | #2 |
Senior Member
Join Date: May 2010
Location: MN
Posts: 7,053
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Re: Extremely Frustrating Change in Fuel Consumption
Low compression will effect efficiency. I'd look at the fuel jets also and the 94 power valve.
If you feel confident on the parts and ability rebuild it yourself. Think charlieny is the goto for 94s Last edited by Tinker; 11-14-2019 at 01:33 AM. |
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11-14-2019, 02:00 AM | #3 |
Junior Member
Join Date: Jan 2016
Posts: 26
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Re: Extremely Frustrating Change in Fuel Consumption
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11-14-2019, 02:04 AM | #4 |
Senior Member
Join Date: May 2010
Location: MN
Posts: 7,053
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Re: Extremely Frustrating Change in Fuel Consumption
Going on vague info. Rebuilt does not rebuilt right. Best of luck!
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11-14-2019, 02:18 AM | #5 |
Senior Member
Join Date: May 2010
Location: Qld, Australia
Posts: 4,221
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Re: Extremely Frustrating Change in Fuel Consumption
Read my post on increase in fuel use from a while back on our 33,
Lawrie |
11-14-2019, 06:22 AM | #6 |
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Join Date: May 2010
Location: Melbourne Australia.
Posts: 2,079
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Re: Extremely Frustrating Change in Fuel Consumption
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11-14-2019, 07:15 AM | #7 |
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Join Date: Jun 2013
Location: Marana Arizona
Posts: 1,776
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Re: Extremely Frustrating Change in Fuel Consumption
Don't know where you are located? If you are in the "frozen North" it is a good time to send the carb off to CharlieNY for a rebuild. Charlie Schwednler (716) 662-9159.
Great fair and honest guy that knows those 94's... Chap |
11-14-2019, 09:55 AM | #8 |
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Join Date: Nov 2012
Location: Wichita KS
Posts: 16,132
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Re: Extremely Frustrating Change in Fuel Consumption
If it is burning rich then there is too much fuel vs air. That just about means that the carburetor is suppling too much gas or the air flow is being blocked. Might be too much fuel pressure into the carb, but odd that would occur after working ok in the past. So try it with the air cleaner removed and eliminate that possibility. If that is not it, then most likely it is a carb issue. New/rebuilt does not equate with correct.
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11-14-2019, 03:34 PM | #9 |
Senior Member
Join Date: May 2010
Location: NJ
Posts: 6,182
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Re: Extremely Frustrating Change in Fuel Consumption
If this is new problem, have you checked the ignition system? Possibly a bad condenser?
Have you also checked that the air cleaner isn't clogged up? |
11-14-2019, 04:51 PM | #10 |
Senior Member
Join Date: Jul 2016
Location: Lake worth Florida
Posts: 1,104
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Re: Extremely Frustrating Change in Fuel Consumption
All above plus possible running too cold , winter fuel blend ?
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11-14-2019, 08:23 PM | #11 |
Senior Member
Join Date: Oct 2015
Location: Bonita, CA
Posts: 1,374
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Re: Extremely Frustrating Change in Fuel Consumption
Tires inflated properly? Muffler collapsed inside? Fuel leak(s)? Dragging brakes? Dwell and timing correct? Proper heat range on plugs?
Phil Swanson |
11-16-2019, 12:58 AM | #12 |
Junior Member
Join Date: Jan 2016
Posts: 26
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Re: Extremely Frustrating Change in Fuel Consumption
Been off line for a while. Thank you all for your suggestions and I will read through them now.
Dave |
11-16-2019, 04:46 AM | #13 |
Senior Member
Join Date: May 2010
Location: Solihull, England.
Posts: 8,756
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Re: Extremely Frustrating Change in Fuel Consumption
Ruptured power valve.
Wrong power valve. Incorrect power valve gasket. Warped housings allowing vac leak affecting power valve. Just some of the many things that could cause an over rich condition. |
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