Not the normal cross-fueling problem

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Aug 13, 2011 | 11:06 PM

Fordenthusiasts

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Tuned

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From: Kingman, Ks

Not the normal cross-fueling problem

I researched this issue quite a bit and haven't found one like mine. My problem is I can fill both tanks full, then drive on the front tank only, and when I switch to the rear tank (if it matters I switch from front to rear tank when front reaches 1/4 tank left) it shows less than full. Most of the time it shows just to the left of the full mark but not to the 3/4 mark. I have verified that after filling up the rear tank that the level reads a little over full, so its not a bad sending unit. Also I only get about 60-70 miles on the tank before it gets to the halfway mark, whereas my front tank can get 120-130 miles at half. And the rear tank normally gets about 2 mpg worse than the front.

I thought I had the cross-fueling issue but what I've found seems to say that the check valves go bad and fill the other tank, but I never use the rear tank before the front one, so it can't pump fuel into it. Plus a lot of what I have read says that by 1995 (which is the year of my pickup) the problem was fixed.

So do I have gas just disappearing, evaporating, or is it actually the cross flow problem and I just don't understand it?

Aug 14, 2011 | 11:34 AM

subford

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From: Easton,Ks

Sounds like you have a hole in the rear tank and it is leaking fuel as you drive on the front tank.

Aug 14, 2011 | 12:43 PM

Bankrupter

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From: North Central MA

Odd you bring this up. I noticed my rear tanks do the similar thing past few fill ups on my 95 and I drive it the same. front to rear.. My rear tanks also gives me way less range but its smaller then my front. I know my rear has no leaks. Also know my front vent line does. Other then the gauge reading lower, then after fill up, it has no issues. I thought it was just the way it filled being a utility body and having the inherent tube issues. Watching this thread to see what you find.

Aug 14, 2011 | 03:12 PM

Fordenthusiasts

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Tuned

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From: Kingman, Ks

A hole is actually kind of what I wanted to hear, because that means that I'm really not getting as bad of gas mileage I as thought and can be fixed. On the other hand hopefully it is repairable without having to buy a new tank.

Another thing I forgot to mention. Lately I have been smelling a strong gas odor coming from under the hood and it seems to be coming from the evaportive (charcoal?) canister. It is strong enough that you can smell it walking around the vehicle and also in the cab. It has been really hot here lately, highs 110-115 degrees, so is it possible that somehow the gas is being evaporated out through a vent line or something. I've never really looked at how the fuel system is plumbed and whether or not it could even evaporate through a vent line.

I guess in the mean time I'll burn up the gas in the rear tank and take it down to inspect it.

So it is probably not the crossfueling problem? Any more ideas?

Aug 15, 2011 | 08:18 AM

Fordenthusiasts

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Tuned

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From: Kingman, Ks

Morning bump to see if anybody else has had this issue.

Aug 15, 2011 | 08:28 AM

Conanski

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From: Ottawa, Ontario

Quote:

Originally Posted by Fordenthusiasts

Another thing I forgot to mention. Lately I have been smelling a strong gas odor coming from under the hood and it seems to be coming from the evaportive (charcoal?) canister. It is strong enough that you can smell it walking around the vehicle and also in the cab. It has been really hot here lately, highs 110-115 degrees, so is it possible that somehow the gas is being evaporated out through a vent line or something.

That's a key piece of info that could explain your problem. Gas is stored in underground tanks where the temperature is very low compared to what it is above ground, and gas like any fluid expands with temperature. So if you completely top up your tanks there is no room left for expansion when the fuel volume heats up and it will be forced into the evaporative system. In general you should never add fuel to a tank after the automatic shutoff cuts off the pump, but especially when it's stinkin hot outside.

As for the gauges reading different... that's common and there isn't much you can do about it.. maybe change the float(level sender) inside the tank but there's no guarantee a new one will be more "accurate" in terms of tank proportions.

Aug 15, 2011 | 08:46 AM

Bankrupter

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From: North Central MA

Quote:

Originally Posted by Conanski

As for the gauges reading different... that's common and there isn't much you can do about it.. maybe change the float(level sender) inside the tank but there's no guarantee a new one will be more "accurate" in terms of tank proportions.

Even if they read past full after fill up ? I can handle this explanation... Means I have no further work to add to the ever growing list