94 Accord - fuel level sending unit

It appears I have a dead spot at about 1/8 full. When it gets to
that level, the gauge suddenly goes to well below empty. But a
while later it comes back up to the right reading. Always happens
at the same spot, so I would assume there's a bad spot in the
sending unit. By the way, when the gauge goes to zero, the fuel
warning light does not come on, so it appears that's a separate
sending unit and circuit, which is a bit surprising.

Anyway, I wonder if I can remove the sending unit from the tank,
inspect it, and possibly scrape the crud off and fix it. That would
require being able to re-use whatever gaskets or seals are involved.
Can anyone with experience in this area tell me if I can do this
without having to use a new gasket?

 

Inspect the gasket and go from there. It is possible you can
re-use it for at least a short period of time. New at your
dealer the gasket should not cost more than around $20.
Online OEM sites list it for around $13 not counting
shipping/handling.

Tests for the fuel sending unit should be in the manual
linked at http://ww1.honda.co.uk/car/owner/workshop.html

 

Sure can. There's an inspection cover, either in the trunk floor or under
the back seat, I can't remember.

The gasket is about five dollars at the dealer. Why is it so important you
re-use the old gasket?

 

Elle says...

Thanks very much.

Can you suggest an OEM site I could buy the replacement
sending unit from, assuming I end up needing that?

 

Tegger says...

Yes, I found it. Just behind the back seat, under the
rear edge of the trunk carpet.

If I can get a new one separately from the dealer at a
reasonable price, it isn't important to re-use the old one.
I just didn't know they would let me off that easy.

Thanks for the reply.

 

Elle says...

Thanks for that link. The manual shows that a "fuel sender
wrench" is needed to remove and reinstall the sending unit.
Do you suppose something else would work? I don't have a
lot of tools.

 

Officially that's what they say, yes.

But you can just use a dull chisel and a small hammer to tap the sender cap
around until it comes loose.

 

Before you buy a new one, one more question: Is it when you
do a certain turn that the fuel gage drops? Because this is
pretty common on old Hondas. Lots of complaints about it
come up at the great site www.honda-tech.com .

To buy the part new, consider the following:
www.slhondaparts.com , California
www.bkhondaparts.com , Illinois
www.hondaautomotiveparts.com , Rhode Island

Note differences in shipping/handling charges. Before adding
s/h, the part will run you around $95 at these sites.
Remember also that increasingly local Honda dealers sell at
internet prices. I learned my local Honda dealer had an
online parts site and now regularly go in with a printout
from its site for a part. They happily honor the internet
price as long as I have the printout. I save on s/h, but I
pay local sales tax and the time it takes to have the part
in hand.

Other options are ebay.com (buy only OEM), where it looks
like wrecking yard fuel sending units are available for
under $100. E.g. for $38 total consider
http://cgi.ebay.com/ebaymotors/1994-1995-1996-1997-HONDA-ACCORD-FUEL-SENDING-UNIT_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQitemZ300269749461QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

From bkhondaparts.com, typing in the part number shows the
same FSU is used on the 94 and 95 Accord.

FSUs are pretty tough. I would consider a wrecking yard one,
especially at yards that have a return policy for 30 days.
So if you do not like the one you get, you can trade it for
another.

I pulled the FSU on my 93 Civic DX without too much
difficulty a few months ago. My 93 Civic tends to read empty
with about 3 gallons of gas in it, so I was thinking of
replacing it. I do have one from a wrecking yard but after
doing resistance tests (per the manul) on both, I am not
sure that the new used one will make all that much a
difference.

 

Ditto. I used a beat-up old screwdriver and a tiny hammer
and freed it pretty easily. Righty-tighty lefty loosy.

There was a paper like dust cover affixed to the top of the
FSU cap on my 93 Civic DX. I do not know its exact purpose,
nor how essential its replacement is.

 

Elle says...

No, I haven't noticed any correlation with turns. It
appears to be related to a specific fuel level - when the
tank is about 1/8 full. When it gets down to that level, it
suddenly goes all the way to the bottom. But then after
driving a while longer - maybe a couple gallons - it's
suddenly back to the right place.

That makes me think it's not the gauge, or a bad connection
or ground, but rather an open spot, or perhaps a grounded
spot, in the sending unit. I've never seen one, but I think
of it as a coil-type potentiomemter, with the contact
attached to the float.

In any case, if I can get it out in one piece, I can put the
ohm meter on it and find out what's going on. And maybe
even fix it if it's possible to get to the innards.

Thanks very much for the links to the parts sites. And I'll
check with my dealer too, just in case.

 

Tegger says...

Thanks. Dull chisels I have several of.

 

Maybe you noticed this already, but I know for my 91 and 93
Civics, it is a certain resistance check of the FSU that is
done to test the FSU. For your Accord, the FSU has a voltage
check done on it. Also, your Accord's FSU is much more
expensive than my Civics'. I have not had a chance to see
what the difference in design is.

You're welcome. Do not hesitate to ask questions at
honda-tech.com, too. Search it using yahoo's search engine,
restricting searches to site:honda-tech.com . Honda-tech.com
is free and for many Honda subjects is even better than this
Usenet forum.

 

I have been watching "movies" at www.auto-repair-help.com and they
recommend using copper or brass to prevent sparks.

Just my 2 cents.

Sam

 

Instead of going through all that trouble for an old car, why not simply
"top off" every EVEN 100 miles? I do that with all my old cars.

JT

 

Elle says...

Well, the sending unit test is just a resistance test -
resistance should change smoothly as you exercise the float.
The gauge test involves voltage, which I can also do.

By the way, the manual says resistance is highest when the
tank is empty, so this tends to confirm my diagnostic theory
that there is something preventing the wiper from contacting
the coil at the 1/8 full position - maybe some kind of
corrosion or crud. That would produce an open circuit, or
infinite resistance, which would make the gauge show below
empty, which is exactly what it does.

 

You are right; the FSU test is a resistance test for your
Accord, my Civic, probably many or all other cars. The ohm
specs for your Accord's FSU are the same (or nearly so) as
my Civics'.

I was reading quickly and was looking at the test for the
fuel gage, not its sending unit, hence the messup.

I googled on the subject a few weeks ago and there was some
chatter about using fuel system cleaners like Chevron
Techron regularly (or right away) to help solve or help
prevent FSU problems. So I agree with your hypothesis above.
Could be crud. The windings on the resistor are mighty fine,
and the instrument itself kind of sensitve overall. ISTM it
would not take much fouling of the windings to cause
malfunction or less than perfect operation.

 

Honda fuel gauges are designed to be pessimistic in the lower range.
Back in the early 1970's when Honda was starting to sell into the USA,
they made careful note of Americans reactions to cars apparently
stranded at the side of the road. They noted that hundreds of people
would drive by a car, and make a mental note of that brand as being
a piece of crap, because it was abandoned at the side of the road. This
would create a negative impression when it came time for the people to
buy a new car. Honda looked at the real reason for the cars being
stranded, and found out most of the stranding was caused by lack
of fuel. The fix was simple... make a pessimistic fuel gauge to make
sure that 99% of Hondas, get fuel put in them by the owner, so there
would be no abandoned Hondas at the side of the road (due to lack of fuel) to
give a false negative reliability impression to hundreds of passing motorists.

For British cars stranded at the side of the road 40 years ago in the
USA... well shit... if they were outta of gas, it was because of the wonky
Lucas Electrics fuel gauge system... the gauge could read ANYTHING...
mostly what was not in the tank!

 

My 93 Civic EX fuel gauge reads full all the time. The FSU ohm tested
out within specs.

What's the fast-track to diagnosing the source of the problem?

Thanks in advance.

 

I would look next at the fuel gage itself, using
http://ww1.honda.co.uk/car/owner/workshop.html. Click on the
link to the 95-97 manual, then click on "Electrical
(including SRS), then select "Fuel Gage." Do the tests.

Your 93 Civic is in the 92-95 generation of Civics, hence
the 95 manual should work.

It seems fairly common for either the FSU or the gage to
fail after a decade or so.

Using yahoo's search engine to search www.honda-tech.com
will turn up many hits on this subject.

My 93 Civic EX fuel gauge reads full all the time. The FSU
ohm tested
out within specs. What's the fast-track to diagnosing the
source of the problem?