Fuel Pump / Sender Unit Replacement ???

89 XJ 4.0 I6 Fuel Pump / Sender Unit Replacement

I had it replaced because of low fuel pressure and long start time. Know my question is the gauge seemed to work fine until after the replacement. It was stuck but after some fuel and slouhing around a bit it started working. Now it won't go down completely. Stays at about the start of the red low fuel indicator. Before the swap it used to go all the way down even the idiot light used to come on, but no more. what could the problem be? Maybe a stuck float? Is it worth taking it back apart?

I think its up to you to decide if its work taking apart again to fine tune it.

If you do though, notice there is 2 small tabs on the sender that stop the float at the top and bottom of its swing, and the swing arm itself can be bent a bit to adjust it.

I'm guessing that if your gauge isn't showing all the way down until the warning light comes on then the bottom out tab isn't bent back enough so it never shows as much resistance (or lack of, I can't remember) as the gauge needs to show it that low.

To tune it just take your sender out and disconnect the fuel pump power and move the swing arm up and down and watch the gauge, then bend the lower tab until it shows lower in to the red and the light comes on.

After that though your swing arm itself might not be horizontal with the bottom of the tank and let it go too low fooling you into beliving you have more fuel left in the tank then you do. I think (since this is how both my sender units were stock) the arm at bottom rest should be level with the bottom of the tank. Just to be safe after fooling with mine a bit I tweaked it up so even when the light comes on I know it still has a decent reserve.

I guess if you really wanted to tune it you would need to add and remove fuel to the tank in measured amounts tuning till it was saying empty when it still had the reserve amount you wanted.

Spanky414 said:

I think its up to you to decide if its work taking apart again to fine tune it.

If you do though, notice there is 2 small tabs on the sender that stop the float at the top and bottom of its swing, and the swing arm itself can be bent a bit to adjust it.

I'm guessing that if your gauge isn't showing all the way down until the warning light comes on then the bottom out tab isn't bent back enough so it never shows as much resistance (or lack of, I can't remember) as the gauge needs to show it that low.

After that though your swing arm itself might not be horizontal with the bottom of the tank and let it go too low fooling you into beliving you have more fuel left in the tank then you do. I think (since this is how both my sender units were stock) the arm at bottom rest should be level with the bottom of the tank. Just to be safe after fooling with mine a bit I tweaked it up so even when the light comes on I know it still has a decent reserve.

I guess if you really wanted to tune it you would need to add and remove fuel to the tank in measured amounts tuning till it was saying empty when it still had the reserve amount you wanted.

Click to expand...

what he said. just be careful if you gonna play with it. I have seen the pickup screen pushed to the side causing the float to not bottom out.