Rebuilt 350 - Abysmal Fuel Econ

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Nalanthi

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Makes sense.
I might as well.



Thanks again, gents - I'll keep this thread updated.
 
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I think Irishman is going somewhere with his thoughts on it... as I think (and stated) - why would I have been getting ****** econ on the old inline - and why on two different carbs on a freshly rebuilt engine that isn't giving the vac gauge symptoms of having internal problems? I'm sitting here questioning my build and am starting to think - maybe that's not the case. Maybe my build is fine and my own doubts are keeping me from thinking outside of the proverbial box.
Click to expand...

This is what I was trying to say. Something wasn't adding up with the gasmileage even on the 6, that was why I asked about odometer errors, etc. SOMETHING other than the engine, I think the carb stuff is barking up the wrong tree as well.

Gast tank leaking, etc, to me sounds like stuff to look for. I really think it is something not invilving your engine, or carb.

Gas tank, tranny has no gear lube, rear end has no gear lube, thing is stuck in 4wd, etc. Also, with 31" tires, you should be able to burn the rubber completely off the tires with a stock 350. I was able to do that with stock (and tired) 350, 36" mudders, and 3.73 gears no problem! You sure there's not something hanging up? Ujoint? I am trying to figure out how though, since anyhting I can think of would be causing significant drivability issues! Real mystery here!!!
 
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The only thing that is sorely obvious is the fact that I need to replace my power steering pump. It's a POS that works quite well when moving, but from a near-stop, it's all armstrong steering to get into a parking space.

I just went down the road with a co-worker and it's more the same - starts, runs, idles, and drives. She won't shred (as mentioned), but she'll go as good as an underpowered gen1 does.
 
rich weyand

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Change out the power steering fluid for full synthetic P/S fluid. Big difference.
 
rich weyand

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How old is the gas in the tank? Could that be a problem with the mileage?

What's in common between the six and the 350? Tank(s), the gas in them, the fuel line setup (no return), the clutch/trans/diff, the brakes, wheels and tires, the odometer.

I think you would notice if the speedo read out at 1/2 or 2/3 actual speed. If the brakes were dragging, they should heat up and you would smell them. Same if the clutch was slipping.

Lack of return line still seems most likely culprit. I think. <head scratch>

Any chance of getting an A/FR meter on it?
 
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Gas is new.
The tank isn't leaking, nor are the new hoses.
I smell no brakes and the clutch was installed newly when the engine was built.

I don't have an A/FR gauge at my disposal - probably wouldn't be a half bad idea down the road.

You're absolutely correct on the 'puzzling' department.
 
Skweegle89

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Im no expert on fuel economy, nor geography, but has anybody taken into account that your Albuquerque is a mile above sea level? Don't you have to adjust your carb to compensate for that much elevation?
 
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WEll seeing as we have ruled out everything but shoving a stick of dynamite in the filler tube. Have you tried that ? LOL.

I guess you got a few things to fix:

Heater hoses,

Power steering pump/gear ?

Clean up around headers,

Check floats,

Make sure gas tank is venting properly,

check over driveline for any issues,


If all that fails to turn up something we can go with dynamite or or ? LOL.

Damn I hate getting stumped. One time I was working on an Izuzu or ikea or some damn foreign 4wd compact and I was about to do the dynamite routine when my pops says " just calm down and think foreign" I had a good chuckle and you know what ? the next thing that happened was I got that stupid bolt to go where it was supposed to go. Couldn't believe it after fighting it for about 45 min.
 
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Skweegle, I calibrated this carb for altitude. It was totally sipping fuel on the K5.

Ogre - Stumped on something as easy as mechanical... THAT sucks.

Aside from a successful 700R4 rebuild, the hardest and most confusing job was the "straightforward" swap from a Ford "Cosworth" 2.9l to a 4.0l in my Bronco II that I built as a trail rider. THAT was one thing after another, followed by an extensive comparison of the electrical layouts between 1990 (the BII) and 1994 (the donor Exploder I drove home for $500). She ran for a day, popped a head, so I scrapped the whole top end and went from the ground up, rewired some more, etc.
Hell - I don't even have to Fix Or Repair Daily.
But I digress, I did that build because everyone else I wheel with are XJ fanboys and I wanted to do something different. It goes where they go.

When I get a chance, I'm going to tear the living hell out of everything BUT the engine.
 
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Nalanthi said:
Skweegle, I calibrated this carb for altitude. It was totally sipping fuel on the K5.

Ogre - Stumped on something as easy as mechanical... THAT sucks.

Aside from a successful 700R4 rebuild, the hardest and most confusing job was the "straightforward" swap from a Ford "Cosworth" 2.9l to a 4.0l in my Bronco II that I built as a trail rider. THAT was one thing after another, followed by an extensive comparison of the electrical layouts between 1990 (the BII) and 1994 (the donor Exploder I drove home for $500). She ran for a day, popped a head, so I scrapped the whole top end and went from the ground up, rewired some more, etc.
Hell - I don't even have to Fix Or Repair Daily.
But I digress, I did that build because everyone else I wheel with are XJ fanboys and I wanted to do something different. It goes where they go.

When I get a chance, I'm going to tear the living hell out of everything BUT the engine.
Click to expand...

What if its the engine ? LOL

NO me and pops changed out an engine on this little 4wd thing like you would your chevy, only thing is there isn't room to do it that way, but we did it. Had to get about 5' of extensions to get the bell housing bolts in LOL
 
mtnmankev

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Well gentlemen, I guess the old saying is true:

If it's got **** or wheels, it's going to cause you trouble.

Sorry, I couldn't resist .........
 
Driver4r

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:lol: Ive heard that one a time or two lol
 
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I actually have a lead now.
I didn't notice any rich smell at idle, but as I was pulling into my yard, my neighbor (downwind of me) came to me and said "dude - you're running rich as all hell when you're on your throttle". Today of all days I switched it up by driving home uphill. I NEVER approach home that way. I generally drive uphill, two right turns, and coast downhill to park on the street.
Presumably the fumes are gone by the time I land.

It's not dripping - so it has to be coming from the exhaust.

I think that I'm going to be looking REALLY hard at the fuel pump and floats in the carb.
Odd - that fuel pump was fine on the K5's 350.
 
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rich weyand

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You might have dynamited the fuel pump not having the return line hooked up. Not having the return line was the problem then, dynamited pump is the problem now. Or you might have bent the float/valve assembly in the carb with overpressure due to no return line.
 
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I'm going to pick up a new pump hopefully this weekend if spare change allows.
As much as I've been advised to pick up an electric pump, I still want to stick with the tried and proven mechanical pump.

Wondering if I should go pump and eventual regulator - or pump only.

I must have been completely oblivious - OR, I was idling fine and leaving a trail of fumes in my wake. Of course, the big area of second-guessing and confusion was poor econ on the old 6 and a rebuilt qjet prior to. Maybe that 6 was just tired.

Either way, I'm still going to do some other underhood cleanup/checking other components.


I'll keep results posted.
 
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