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[ 17 posts ] |
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Backfiring and fuel smell
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Eck
Official CCB Member
Joined: Thu Oct 25, 2012 9:33 pm Posts: 2460
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Backfiring and fuel smell
So after driving about 50 miles today, I was getting close to home and started to hear some backfiring and specifically if I really tried to get on it. It also seemed sluggish. Pulled it into the garage and could smell gas. I checked for leaks at the fuel rail but couldn't see any. When the vehicle is running, I'm getting at least 30-40 psi but as soon as I shut it off, the pressure drops to 0 immediately. It used to hold pressure and slowly drop.
Any ideas what to check for? Obviously I'm running EFI- and no codes or check engine issues.
_________________ 69 Wagon, 351W, Explorer EFI & Serpentine, ZF5, 35" tires, 3.5 SL, 2 BL, WARN 8274
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Sun Apr 12, 2015 5:34 pm |
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Rox Crusher
Official CCB Member
Joined: Sun Oct 10, 2010 5:36 pm Posts: 3980 Location: Roxborough Park, Colorado
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Re: Backfiring and fuel smell
I would check the fuel pressure regulator which is mounted on the fuel rail.
See if the vacuum line to it is still connected and in tact.
_________________ 1977 Sport, 351w OBDII EFI motor, 4R70W auto, 4:88 gears, ARB lockers, 3.5" suspension, 33" tires.
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Sun Apr 12, 2015 6:29 pm |
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Eck
Official CCB Member
Joined: Thu Oct 25, 2012 9:33 pm Posts: 2460
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Re: Backfiring and fuel smell
_________________ 69 Wagon, 351W, Explorer EFI & Serpentine, ZF5, 35" tires, 3.5 SL, 2 BL, WARN 8274
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Sun Apr 12, 2015 7:02 pm |
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landshark
Official CCB Member
Joined: Fri Oct 14, 2011 12:16 am Posts: 3942 Location: Denver, Wash Park Area
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Re: Backfiring and fuel smell
Maybe tap on the fpr and see if your pressure changes After shut off. Is the fpr new or from the jy?
_________________ 1976 Bronco "Green, Yellow, whatever", 1969 Bronco "Red", 1972 Bronco Stocker "Kind of Blue/Grayish"
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Sun Apr 12, 2015 7:21 pm |
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Rox Crusher
Official CCB Member
Joined: Sun Oct 10, 2010 5:36 pm Posts: 3980 Location: Roxborough Park, Colorado
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Re: Backfiring and fuel smell
It sounds like the fpr is bypassing too early.
You've got enough fuel pressure to idle, but not enough to feed it under load.
They are cheap to replace.
_________________ 1977 Sport, 351w OBDII EFI motor, 4R70W auto, 4:88 gears, ARB lockers, 3.5" suspension, 33" tires.
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Sun Apr 12, 2015 7:38 pm |
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Moab Mike
Official CCB Member
Joined: Mon Jan 03, 2011 2:59 pm Posts: 1940 Location: Witness Protection Program
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Re: Backfiring and fuel smell
I would check your dizzy again.
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Sun Apr 12, 2015 7:58 pm |
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Eck
Official CCB Member
Joined: Thu Oct 25, 2012 9:33 pm Posts: 2460
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Re: Backfiring and fuel smell
_________________ 69 Wagon, 351W, Explorer EFI & Serpentine, ZF5, 35" tires, 3.5 SL, 2 BL, WARN 8274
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Sun Apr 12, 2015 8:01 pm |
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landshark
Official CCB Member
Joined: Fri Oct 14, 2011 12:16 am Posts: 3942 Location: Denver, Wash Park Area
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Backfiring and fuel smell
Fpr is cheap. Mine went out on the 76 about a month after I got it running. Jy parts are hit and miss sometimes.
_________________ 1976 Bronco "Green, Yellow, whatever", 1969 Bronco "Red", 1972 Bronco Stocker "Kind of Blue/Grayish"
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Sun Apr 12, 2015 8:09 pm |
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Moab Mike
Official CCB Member
Joined: Mon Jan 03, 2011 2:59 pm Posts: 1940 Location: Witness Protection Program
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Re: Backfiring and fuel smell
I didn't see your second comment. I was thinking if your fuel pressure was at 30-40 PSI your FPR was good.
It makes sense if your backfiring you are running lean but that doesn't explain why your not getting lean codes. It your FPR is bad that would explain 0 fuel pressure.
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Sun Apr 12, 2015 8:14 pm |
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Viperwolf1
Official CCB Member
Joined: Tue May 07, 2013 10:37 pm Posts: 1485
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Re: Backfiring and fuel smell
Look for leaks at every connection of the fuel system. Injectors to rails, regulator, lines to rail, pressure gauge, etc.
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Sun Apr 12, 2015 10:22 pm |
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B.O.B.
Official CCB Member
Joined: Thu Nov 11, 2010 10:31 am Posts: 770
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Re: Backfiring and fuel smell
Mine did the same thing and I had some leaking injectors. My old ranger had a bad fpr and fuel was leaking out the exhaust. Probably one of the two. Since it just started I would get fpr
_________________ 71' bronco, np435 w/trailbanger, 302 efi, 35" KM3 on 17x9 Fuel Anza, warn xd9000i, cage arms, 5" lift
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Mon Apr 13, 2015 6:16 am |
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landshark
Official CCB Member
Joined: Fri Oct 14, 2011 12:16 am Posts: 3942 Location: Denver, Wash Park Area
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Backfiring and fuel smell
Sometimes you can pull the plugs to see if one is running "rich" sometimes an indicator of an injector leaking down.
_________________ 1976 Bronco "Green, Yellow, whatever", 1969 Bronco "Red", 1972 Bronco Stocker "Kind of Blue/Grayish"
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Mon Apr 13, 2015 7:49 am |
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Rox Crusher
Official CCB Member
Joined: Sun Oct 10, 2010 5:36 pm Posts: 3980 Location: Roxborough Park, Colorado
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Re: Backfiring and fuel smell
With the rig cold
Cycle the key off and on a few times, which will trigger the pump to pressurize the system.
Then crawl all around the engine bay and underneath looking for leaks at all the connections.
If you locate it, clean it up or let it evaporate before starting so you don't have a fire in your hands.
I had a small leak at the fitting where the fuel line connects to the fuel rail. It was hard to see / find.
_________________ 1977 Sport, 351w OBDII EFI motor, 4R70W auto, 4:88 gears, ARB lockers, 3.5" suspension, 33" tires.
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Mon Apr 13, 2015 7:58 am |
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Digger
Official CCB Member
Joined: Fri Jun 21, 2013 8:53 pm Posts: 1276
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Re: Backfiring and fuel smell
Check FPR.
I've had two get old, rupture and dump fuel straight into the intake via the vacuum line. They are not bulletproof.
_________________ Cummins R2.8 diesel, ZF5, AtlasII, HP44/BB9, ARBs, coiled / linked suspension, 37" KO2s, full cage, bumpers, etc. Build Thread:
Average 23.5 mpg, Best tank: 25.1 mpg
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Mon Apr 13, 2015 4:06 pm |
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Eck
Official CCB Member
Joined: Thu Oct 25, 2012 9:33 pm Posts: 2460
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Re: Backfiring and fuel smell
New FPR did not cure me. I am fairly sure I sprung a leak somewhere towards the back of the engine. Hoping to remove the upper intake and cycle the fuel pump to see if I can figure this out...
_________________ 69 Wagon, 351W, Explorer EFI & Serpentine, ZF5, 35" tires, 3.5 SL, 2 BL, WARN 8274
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Mon Apr 13, 2015 9:00 pm |
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Eck
Official CCB Member
Joined: Thu Oct 25, 2012 9:33 pm Posts: 2460
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Re: Backfiring and fuel smell
So I had a bad fuel injector in my #2 hole. (Let the jokes commence). Was able to soak up the intake, blow out the spark plug hole, change the oil and fire it up. The engine runs much smoother now than it did before. It seemed like the entire engine vibrated.
The stupid thing is that when I last rebuilt the engine I decided to go with professionally rebuilt injectors instead of JY parts. Now I have a JY injector back in.
Big thanks to Phil for fielding my call and walking me through what to do.
_________________ 69 Wagon, 351W, Explorer EFI & Serpentine, ZF5, 35" tires, 3.5 SL, 2 BL, WARN 8274
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Tue Apr 14, 2015 8:33 pm |
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kbank6
Official CCB Member
Joined: Sun Apr 14, 2013 5:00 pm Posts: 306 Location: Greeley, CO
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Re: Backfiring and fuel smell
Let it go....let it go.......
_________________ 73 Ranger (Holy Crap, replacing the door post is so much fun!)
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Tue Apr 14, 2015 9:24 pm |
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