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Fuel Sending Unit: Years Compatible w/ 1991?

B

BALTANAKT

NAXJA Forum User
Location
Berthoud, CO
Does anybody know which years the sending units were compatible with the 1991?

I replaced my unit about 6 years ago with something from the parts store (which was supposed to be gtg) and due to different resistance in the design its been reading wrong ever since... Would kinda like to straighten this out at some point.

Also, if anyone has a nice one out of '91 on their shelf...Lemme know!
 
1991-1995.

1986- will not function at all
1987-1990 4.0L will function in a pinch but the fuel gauge will be backward and nonlinear. I am guessing this is what you have... unless your VIN tag was swapped and you actually have an 87-90 and put a 91-95 sending unit in it because the VIN/title said 91*
1987-1990 2.5L will not function at all (wrong fuel pressure)
1991-1995 are functionally identical to what you have
1996 will function if you really have to but you'll be splicing wiring, blocking off a fuel return line, and they're hard to find anyways
1997+ will not fit at all

* to eliminate this as a chance, you can check the following:
90 down, the ECU is under the dash over the gas pedal, there is no PDC under the hood on the right side by the battery, the air intake tube is bolted to the top of the throttle body with 3 screws and a metal clamping plate, and the speedometer is cable driven with a blue plastic rear housing on the instrument cluster.
91-95, the ECU is by the air filter housing in the engine bay, the PDC is just aft of the battery under the hood, the air intake tube is held onto the throttle body with a plastic wraparound clip, and the speedometer is electrically driven from a sensor on the back of the tcase with a white plastic rear housing on the instrument cluster.
 
I don't know the details as to why, but I believe the '94-'95 are different from '91-'93.
 
Have you checked the resistance? It should be 5-105 ohms.
 
kastein said:
1991-1995.

1986- will not function at all
1987-1990 4.0L will function in a pinch but the fuel gauge will be backward and nonlinear. I am guessing this is what you have... unless your VIN tag was swapped and you actually have an 87-90 and put a 91-95 sending unit in it because the VIN/title said 91*
1987-1990 2.5L will not function at all (wrong fuel pressure)
1991-1995 are functionally identical to what you have
1996 will function if you really have to but you'll be splicing wiring, blocking off a fuel return line, and they're hard to find anyways
1997+ will not fit at all

* to eliminate this as a chance, you can check the following:
90 down, the ECU is under the dash over the gas pedal, there is no PDC under the hood on the right side by the battery, the air intake tube is bolted to the top of the throttle body with 3 screws and a metal clamping plate, and the speedometer is cable driven with a blue plastic rear housing on the instrument cluster.
91-95, the ECU is by the air filter housing in the engine bay, the PDC is just aft of the battery under the hood, the air intake tube is held onto the throttle body with a plastic wraparound clip, and the speedometer is electrically driven from a sensor on the back of the tcase with a white plastic rear housing on the instrument cluster.
Click to expand...

Wow thanks for the complete run down...

Since installing the parts store sending unit years ago, my gauge has functioned strange. It moves in the correct direction but it does not accurately represent the amount of gas in the tank.

For instance, I will fill up, gauge reads full. Drive 40 miles, gauge reads 3/4 full. When the light comes on, I have another 100mi+ (5.8gal+) of fuel.

Also curious if there is a unique version from 91-93 as per Anak?
 
Anak is correct. I have compared them side by side and they did in fact change the pump used and as I recall, the shape of the hangar/sending unit bracket and possibly the pickup sock. However as long as you swap the whole unit they are interchangeable as their resistance curve and all other specs and fitment are equivalent.
 
Yes!

Change the filter!!

An old filter full of sediment will lead to an early fuel pump death.

I would recommend also getting new fuel injection rated fuel hose and fuel injection rated hose clamps to go along with it (yes, fuel injection hose clamps are different from the regular worm drive clamps).

If there is a likelihood of dropping the tank this would be the time to replace the grommets for the two rollover vents and the vacuum lines that go to them.

If you are planning to not drop the tank you may want to get the AC Delco large O-ring for the fuel pump module to tank seal. The AC Delco unit has three tabs around the perimter which help to keep it centered while you try to work the lock ring into place. That is AC Delco P/N G10, GM P/N 22515965. Or, if you have to deal with looking it up by vehicle try a 1990 Chevrolet C2500, 5.7L. That is the truck that introduced me to that part, but it probably applies to a wide range of vehicles.
 
No way. Where has this gasket been all my life? I've been using the regular O ring with some vaseline gobbed on it to keep it in place.

Speaking of which, the lock ring for these can be found at AutoZone under part number LO-01. That's two letters, then dash, then two numbers. You WILL have to explain this to the guy at the register looking it up or it won't come up because they'll inevitably type it as L-zero-oh-1 or something. It comes with an O ring but not the fancy one shown above.
 
I'm with Kastein - I had no idea this existed, but now I think I might need to buy one "just in case" (even if I never actually need it).

Don't know how you tumbled into that part, Anak, but that's a heck of a find...
 
I have gotten mine from Napa. I think it is Gates branded.
 
Rob Mayercik said:
I'm with Kastein - I had no idea this existed, but now I think I might need to buy one "just in case" (even if I never actually need it).

Don't know how you tumbled into that part, Anak, but that's a heck of a find...
Click to expand...

FWIW, I found that gasket doing this job: https://www.naxja.org/forum/showthread.php?t=1166956

There is a pic of the O-ring in there, though it doesn't show the tabs particularly well.

By coincidence this job happened to come close on the heels of helping Varmint #1 with his fuel pump. After having recently fought with his O-ring it didn't take much to see the value of those tabs. I have since tried out the GM O-ring on my own XJ and it definitely makes that part of the job go easier.
 
That was an interesting read, thanks for the link.
 
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