Fule guages not accurate

[CBNASH]

IT gets to the last quarter white mark then its empty. should I just pull the tanks and readjust the floats?

[icanfixall]

Yes, you can do the float adjustment but why? You will have the sender out and they are a known problem part. Just replace them. The rear tank is really the worst tank to work on. Many members remove the bed to access the tank sender. The front tank is easy. All you need to do is remove the lines and electrical from the sender and a hammer and chiesel or screwdriver to knock the retaining ring loose and just pul it out. The tank stays in place and fuel can be any level in it. The better idea is to run the front tank down so you will know what the gage is showing on a dry tank. The last 1/2 to 1 inch is not going to draw out but watch the new gage if you leave any fuel in the tank. When filling the tank just add 5 gallons at a time and watch the gage for level. When the sender is out look at the hole it fits. You will see a locating tab that aligns the sending unit. It wiil only fit one way. Its really an easy job from under the truck. I have done mine twice. The first time I adjusted the float. Didn't change anything. The second time the suction plastic part had broken off and I ran out of fuel with 3/8th tank. Not good on the injection pump. The fuel lubes it and cools it. Running it out of cooling and lube helps it wear out fast. Its only money though. Geez... [img]/ubbthreads/images/graemlins/shrug.gif[/img]

[Mr_Roboto]

If you are saying that the truck runs out of fuel when it reads 1/4 tank, the fuel pickup is probably broken off.

Now if it is truly empty and you can put 19 - 20 gallons in the tank when it reads 1/4 tank then either the sender or gauge is bad.

If you have dual tanks and it runs out at 1/4 tank reading on both tanks, and you can refill with 19 - 20 gallons on both tanks then the gauge itself is bad.

[OkieGringo]

There is a plastic extension on the bottom of the pickup which contains a by-pass valve and the filter/screen. Unfortunately, this plastic part breaks off and/or the by-pass valve rots (rubber). It is there to allow the engine to get fuel if the bottom of the tank has enough water to freeze and plug up the normal pick-up.
If the plastic has broken off at the top where it attaches to the metal tube of the pickup (as both of mine were) you'll run out of fuel at about the 1/4 tank level. The new sending unit/pickup is a "Ford Stealership Only" item. Go here: http://www.parts.com/partlocator/ind...?siteid=213787 after selecting your make and model, you need to look under "Electrical" to find the fuel sending unit. The 'units' are about $20.00 less at this site than at a "Stealership"($100.00+/-), but I don't know if "the shipping charges" will make it less in the long run. The front and rear units are different with different part #s. And even NEW sending units aren't very accurate. When/if you install new SUs fill the dry tank with 5 gallons of fuel and check what the gauge shows, add 5 more, check etc...Have fun. [img]/ubbthreads/images/graemlins/smokin.gif[/img] OkieGringo

[90734x4]

i just did mine 3 weeks ago. it was an easy job. i couldnt find anything wrong with my old sending unit but it would start to run out of fuel right below a half tank. replace all the hardware while you have it out and use plenty of anti sieze. i also put a new brake line in while i was there

i do most of most of my work on a lift so its all easy for me [img]/ubbthreads/images/graemlins/smile.gif[/img]

good luck
matt

[sputterputz]

I have a slightly different problem, my rear tank/gauge reads fine, but when I switch to the front tank, it pegs off the chart (to full) it will come down but I run out of fuel about 1/2 tank. I know that I have replaced the ft tank sending unit, the rear has not been replaced when I have owned the truck, (since 145K) my dad owned it before that since it was new, he cannot remember what we replaced. I have replaced gauge clusters I dont think it has anything to do with the switch unless there is a separate gounding system for each tank through the switch and the ground is loose or gone on the front tank.

this is on a 89 f-250 lariat 225k

side note my cruise control is toast too...

[Nitrochris]

[ QUOTE ]
I have a slightly different problem, my rear tank/gauge reads fine, but when I switch to the front tank, it pegs off the chart (to full) it will come down but I run out of fuel about 1/2 tank. I know that I have replaced the ft tank sending unit, the rear has not been replaced when I have owned the truck, (since 145K) my dad owned it before that since it was new, he cannot remember what we replaced. I have replaced gauge clusters I dont think it has anything to do with the switch unless there is a separate gounding system for each tank through the switch and the ground is loose or gone on the front tank.

this is on a 89 f-250 lariat 225k

side note my cruise control is toast too...

[/ QUOTE ]

Same exact problem on my 89 F-250 too.

[DSBlack]

Well, at least you know the issue is between the switching valve and the tank. If it were in front of that then both tanks would have the issue.

[CBNASH]

Thanks guys that helps alot.

[c2m]

[ QUOTE ]
If you are saying that the truck runs out of fuel when it reads 1/4 tank, the fuel pickup is probably broken off.

Now if it is truly empty and you can put 19 - 20 gallons in the tank when it reads 1/4 tank then either the sender or gauge is bad.

If you have dual tanks and it runs out at 1/4 tank reading on both tanks, and you can refill with 19 - 20 gallons on both tanks then the gauge itself is bad.

[/ QUOTE ]

so... if i can only put about 10 gallons in the front and rear tank what do i need to do to fix this???
please help

[JCDiesel89]

I have a similar problem, only mine stays off the chart full until its coming close to empty then shoots down to empty. The second tank does the same just in a little different order. Sending unit or could it be something in the dash?

[netzgeist]

[ QUOTE ]
I have a similar problem, only mine stays off the chart full until its coming close to empty then shoots down to empty. The second tank does the same just in a little different order. Sending unit or could it be something in the dash?

[/ QUOTE ]

I have this problem too...midship tank reads off the chart full until I'm almost out of fuel, then drops to around 1/8. That's how I know that I'm running low. when I'm on that border line where my guage bounces between off the scale full and 1/8 depending on when I hit a bump or brake to stop, I know I'd best start looking for some fuel. Would love to hear what folks think the cause is... BTW, gauge works on rear tank no problems...

[cdnsarguy]

Depending on the use of the tank over the years one may have been used more than the other...... If so the sender may be worn out in certain areas of travel giving these bad readings.

NASH for the 93 year...... and maybe others not sure.

Here are the fuel guage test #s

22 ohms sent to the guage it reads empty "E"

145 ohm sent to the guage it reads full "F"

Here are the sender test #s

Sender at empty stop 14-18 ohms

Sender at full stop 154-162 ohms

If anyone wants the FSV test PM me your email with Subject: FSV test

[hesutton]

New or old, the stock sending units on these trucks are garbage. Replaced the sending units on my truck. Three months later, pulled the bed off to work on the senders (they were inaccurate from the factory) and to replace the fuel selector valve. On both sending units, the P.O.S. "shower-head" fuel pickups where both floating in the bottom of the tanks!!! [img]/ubbthreads/images/graemlins/eek.gif[/img] [img]/ubbthreads/images/graemlins/vomit.gif[/img] [img]/ubbthreads/images/graemlins/rolleyes.gif[/img] Both of the bypass valves on the pickups were out and also floating in the tanks!!! [img]/ubbthreads/images/graemlins/vomit.gif[/img] These were new and only in the tanks for 3 months! That design is pretty crappy.

I made my own pickup out of good fuel line and I cut an inverted "V" (or fishmouth - or whatever you want to call it) on the bottom to keep the line from sucking on the bottom of the tank. If I ever need a new sender, I will pitch the factory fuel pickup in the crapper and replace it with a piece of fuel line from the get go. They are function poorly and you will have problems, even with new senders. Fix it with the fuel line trick. Otherwise, you will have the same problem sooner than you would think.

Heath

[griffin]

when you replace the lift pump with the red holley what do you put in place of the old lift pump do you have to cover it up with something