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post #1 of (permalink) Old 12-23-2000, 12:49 PM
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\'85 Still getting horrible gas milage

As most know already about the trouble I am having with my Bronco. I have rebuilt the carb and am still haveing trouble. It is difficult to start in the morning, wont idle at all, and get bad milage (2-5 mpg), and lacks power horribly. I also replaced the electric choke thermostat and it seems to run better, but still pretty poor. The Fuel bowls are adjusted, choke is properly adjusted, and there is no sign of fuel leaking anywhere. I have an electrical problem some where, but that wouldnt cause a problem like this would it? Could it be the ign. Coil? Timing problem? Also, I removed the smog devices from my truck, what can I use to close off the pipe going to the exhaust from the bottem of the Air Control Valve? And one other thing, I broke the hose that goes from the breather/oil cap to the filter in the air cleaner houseing. And now I notice my truck shoots oil out of the breather hole. Whats going on here, plugged return holes? If so, is there any way to clean them out without remove the valve covers? Maybe "Engine Flush" or some ATF in with the oil? Thanks

Sean Heberly
'85 Bronco 5.8L 4-V XLT: 266K still strong. Winter Truck now.
'86 Pontiac Fiero GT: 4.9L Caddy NorthStar Engine, 11.6 QM @ 107.1 MPH, Poly Susp, KONI's all around, 2 1/2" drop.
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post #2 of (permalink) Old 12-23-2000, 05:50 PM
 
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Re: \'85 Still getting horrible gas milage

Couldn't tell you what the problem is about the carb, but the oil coming out of the breather is blow-by and it sounds like you need a ring job. My 90 bronco has the same problem with blow-by and I found out that i needed new rings when i looked inside i found that it needed more than that so i'm taking out that 5.0L and putting in a rebuilt 5.8L this spring!

90 Bronco w/302 auto. soon to be 351W with a little goodies 31-10.5-15 , 3.55 gears looking for mud!
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post #3 of (permalink) Old 12-23-2000, 08:14 PM
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Re: \'85 Still getting horrible gas milage

Damn, small army tanks get better gas mileage than that. I think I might be inclined just to go buy a new/rebuilt carb, but I've never messed with carbs much so that advice means little. Changing your PCV valve might help the oil think but that does sound like it's pretty bad. Something major must be wrong with that sucker to get that kind of mileage. There are so many factors that it's hard to say just what it could be. Checking the timing wouldn't hurt...checking the wire at the plug to make sure it's getting spark wouldn't hurt either. Make sure plugs aren't fouled, which they probably are considering how much oil is shooting out that vent hole. Good luck, youza gonna need it.

It's a Jeep thing? My Bronco thing will run over your little Jeep thing.

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post #4 of (permalink) Old 12-23-2000, 10:25 PM
 
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Re: \'85 Still getting horrible gas milage

Sean

Before you spend any more money on that motor, think about a compression test and cylinder leak down test. At 266K maybe it's not still going as strong as you think. Someone mentioned rings, could be. Could also be burnt or worn valves.

If you're that worried take it to a mechanic you trust and spend the hour's labour charge to have him diagnose your troubles. Sure sounds like your engine is getting pretty tired.

Best of luck

Malcolm

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post #5 of (permalink) Old 12-23-2000, 11:40 PM
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Re: \'85 Still getting horrible gas milage

Yeah Sean, Malcolm is right. A new carb wont do any good if the engine is shot. A good reman 351W might run ya 1300 bucks but its better that f***in around with a tired machine.

Good luck man.

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post #6 of (permalink) Old 12-25-2000, 03:07 PM
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Re: \'85 Still getting horrible gas milage

I will do a compression test as soon as I can. I am sure the engine is pretty shot, but I still think it should at least idle and run okay, even if getting horrible milage. I think the problem is something else. If I do get a new engine, I want it to be Fuel Injected. How difficult would it be to get a FI engine in there? Also, what will that cost me as opposed to the reman carbed engine? I might just ditch this one and buy a newer one. What year did they start putting FI in the 351 Broncos?

Sean Heberly
'85 Bronco 5.8L 4-V XLT: 266K still strong. Winter Truck now.
'86 Pontiac Fiero GT: 4.9L Caddy NorthStar Engine, 11.6 QM @ 107.1 MPH, Poly Susp, KONI's all around, 2 1/2" drop.
post #7 of (permalink) Old 12-27-2000, 01:59 AM
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Re: \'85 Still getting horrible gas milage

FI on a 351W was standard from 88 and up. It may have been an option on 87's with 351, but I know they definatly came carbed in 87 also.
Good luck.
Tom

post #8 of (permalink) Old 12-27-2000, 01:55 PM
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Re: \'85 Still getting horrible gas milage

If your 85 has the stock Holley 4v, it should be as easy to rebuild as any other Holley, with good results. Sounds like you may have the power valve stuck open or leaking, or some other little internal leak. Should be fairly easy to fix. My 82 with a total aftermarket Holley does this every now and again. It turns out that the gasket between the rear jet plate and the rear of the carb body gets saturated and leaks, dripping fuel into the secondary idle passages all the time. If left long enough, it will slow the idle down and pour black smoke at idle. A new gasket fixes it. Holley says the parts warp over time and will do this. I just fix it every year or so. \

At 266k miles, I would also be looking at things like the timing chain being stretched, and perhaps having jumped a tooth or so. Or the valves getting worn and not sealing real well. Check the cam timing and ignition timing to make sure they are ok.

You really do need to do a compression test. Hard starting is also a sign of tired compression.

You could also be having an ignition problem. If that is suspected, just change it all, it's inexpensive stuff. Start with the coil, the plug wires, the module, and then the dist pickup coil. If the coil or dist pick up get tired or fail in cold or hot modes, they will cause intermittant poor running, and usually, sometime, a not running situation.

post #9 of (permalink) Old 01-04-2001, 07:19 PM
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Re: 5.8L EFI

V-8's were optionally EFI as early as 1983, but it became standard in 88 when ALL domestic vehicles had to be. (4.9L EFI wasn't available until 87.)

I've done the carb-to-EFI conversion, and it's intricate, but not as hard as I thought (or was told) it would be. Doing it factory like I did requires a fuel tank (because of the in-tank pump) and lines, all the engine accessories (because of the serpentine belt), the Y-pipe, the complete engine and engine compartment wiring harnesses, the fuel and volt gauges, some creative wiring, and about $1300. But it is without a doubt the best thing I ever did to my truck.

Buying an EFI truck is easier, but I didn't want to lose all the other mods I had done.

Steve
83 Custom w/95 4.9L EFI, 78 NP435, 83 NP208, 83 D44IFS 3.07, 87 Ford 8.8ABS 3.08, Michelin LTX AT 31x10.50R15
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post #10 of (permalink) Old 01-04-2001, 07:56 PM
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Re: 5.8L EFI

Well, I got a cool X-Mas Present. 2 new Broncos! I got a 95 w/EFI 351 with 60K miles on it, only downside is... It has been rolled and is titled as totaled. The passenger side is all crushed in, but can be fixed for under $2K. The other has yet to be purchased, but I am looking at one in OK. I have to sell my current truck before I purchase the new one. As for my current truck, I took it to a local shop and had them work on it. They said it was running way to rich. They adjusted it and also told me it was being choked...to death, they also adjusted it and it is running good now. I still want a new one for the gas milage purposes. Thanks though. If I do keep mine and not get a new one, I will drop the engine from my wrecked 95 and put it in my 85. Shouldnt be to hard for me, hey, I cramed a 4.6L Caddy NorthStar engine into my '86 Fiero GT. This one should be a walk in the park. Anyone ever put a NorthStar in a Ford Bronco? Just an idea. Someone did put a 351 Ford into a Fiero.

Sean Heberly
'85 Bronco 5.8L 4-V XLT: 266K still strong. Winter Truck now.
'86 Pontiac Fiero GT: 4.9L Caddy NorthStar Engine, 11.6 QM @ 107.1 MPH, Poly Susp, KONI's all around, 2 1/2" drop.
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