S10 Fuel Guage Prob

[rocky7]

I have a question about the fuel guage, first off I replaced the fuel pump module. Fuel guage got to where it would not read properly is the basic reason for changing the fuel pump + it has 170,000 miles on the OE pump. Now my fuel guage works kinda, when it is full it reads full, but it goes down fairly rapid, now it shows almost empty with only 10 gallons gone. I have done a ohms test on the new pump verses the old, both units read 42 ohms empty ( I know the book states 0 ohms with float on empty, but I checked 9 new ones at the auto store and they all have readings when empty) and 92 ohms with float on full. It is not the 4 pin connector as I have tested that and I have replaced and soldered a new pigtail connector. There has to be some other problem with the fuel gauge, as I stated I was having this problem with the fuel guage before I changed the fuel pump assembly, but I thought that a new module would fix the sending unit part of the fuel guage. If anyone has any further advice on what I might check please let me know. Or if I figure it out I will post and let everybody know what I found out. Thanks

[ctesla]

two items quickly come to mind:
(both unfortunately involve dropping the tank again)
1. ground strap on top of tank-intermittent/loose contact
2. not sure on other tanks, but the more common 16gallon steel saddle tank had plastic type baffles within the tank; and the electric fuel pump/float assembly, if "jostled" upon install can sometimes allow the float to rest on these baffles, causing sporadic and inaccurate gauge readings...

have no idea if either of these cases relates to yours, but hope it helps as a start point;
ctesla

[ctesla]

Originally Posted by rocky7

I have a question about the fuel guage, first off I replaced the fuel pump module. Fuel guage got to where it would not read properly is the basic reason for changing the fuel pump + it has 170,000 miles on the OE pump. Now my fuel guage works kinda, when it is full it reads full, but it goes down fairly rapid, now it shows almost empty with only 10 gallons gone. I have done a ohms test on the new pump verses the old, both units read 42 ohms empty ( I know the book states 0 ohms with float on empty, but I checked 9 new ones at the auto store and they all have readings when empty) and 92 ohms with float on full. It is not the 4 pin connector as I have tested that and I have replaced and soldered a new pigtail connector. There has to be some other problem with the fuel gauge, as I stated I was having this problem with the fuel guage before I changed the fuel pump assembly, but I thought that a new module would fix the sending unit part of the fuel guage. If anyone has any further advice on what I might check please let me know. Or if I figure it out I will post and let everybody know what I found out. Thanks

the other item that came to mind, as soon as I hit the "submit reply" to your post is;
check the Silverado posts, they show that GM had elec contacts on the pump/float unit that were being corroded and/or affected by being submerged in the fuel... maybe a good fuel cleaner additive/cleaner or some acetone in your fuel may clean these contacts (if same) and give back true reading on dash gauge...
also, if it isn't in the tank, the problem maybe a loose ground in the dash; you might try adding your own ground to the unit in the dash, to see.

hope this helps,
ctesla

[OverBoardProject]

Just an idea adding to ctesla's first coment.
If it's the ground, and a steel tank you can just add a ground to the tank. As long as everything is reletivly clean where the sending unit joins the tank it should work.

That will tell you for sure if it's the ground, and it's a good temp fix