MORE Fuel System Problems

RBBailey

Well-known member
Callsign: KF7KFZ
So I've been carefully watching my gauge go down and using my 19 mpg average as a way of seeing where the gauge is versus how much fuel I should have in the tank. This is a new tank, new pick up and return, new lines, new sedimenter, new filter, new electric pump. I finally put the pump in when the standard lift pump finally failed, leaving me stranded with about 3 gallons left in the tank. The engine starved when I went up or down steep hills on the way to work or home. I figured this was because of sloshing about, and the pump just not being able to keep up. Well.... it has happened again, with the electric pump.

If I go with the average mpg, I should have at least 2 gallons left in the tank, but I started running out of gas on relatively level driving. I'm not sure if I'll be able to make it to a fuel station after work. As I mentioned in another thread before putting the fuel pump in, my low fuel warning light also seems to have stopped working in the midst of this attempt to figure out all this stuff. The gauge reads just above the 1/8 mark, which should be around 3 gallons left, and is where the light used to start coming on.

In other words, why am I running out of fuel before I actually run out of fuel? Is there something wrong with my pickup? Also, is there any chance of fixing the fuel warning light?
 

Red90

Well-known member
I would check the pickup height. It should be as close to the bottom of the tank as possible. It would not be surprising if a replacement part was not quite right.

As to the low fuel light, what model year is the original truck and wiring? If it is before the 200TDI introduction, it is integral with the level sender. There is a second wire with a separate contact on the float. Normally this is around 1/4 to 1/3 level on the gauge. Check the light wiring.
 

Napalm00

Well-known member
Agree with above. The pickup should be the tube that is connected to the sender on the side of the tank in a 110.

If you're pulling fuel from the top elbow you will definitely run out of fuel before the tank is empty.
 

RBBailey

Well-known member
Callsign: KF7KFZ
So, I could imagine that the tube isn't reaching quite far enough, but how would I go about fixing that?... Bend it? Put an extension on it?

The pickup/return are piped correctly.

It is a 1988 V8 wiring harness, and the light worked when I put the new pick-up/sender in four months ago (along with everything else). I was guessing that it was flickering at about 3 gallons left.
 

Red90

Well-known member
Yes, just bend the pickup. Make sure you have the angle of the sender in the tank correct. The pickup should sit inside the recessed area on the bottom of the tank. If you have it on an angle, everything will be not working correctly.

 

Red90

Well-known member
Test the low fuel contact when you have the sender out. Read the wiring schematic first to understand how it works.
 

RBBailey

Well-known member
Callsign: KF7KFZ
I know that the pick up tube does come down into the center of the tank, into that recessed area. But I can't confirm how far down it goes towards the bottom of the tank. 1/2 inch? I'd probably have to remove the whole tank again to figure it out.
 

Red90

Well-known member
I would have it level with the bottom of the tank. The gap from the inlet to the steel would be the depth of the recess.
 

RBBailey

Well-known member
Callsign: KF7KFZ
Sounds good. I am trying to think if I might have taken a photo of that before closing the tank up. I don't think it was hovering much higher than that, but I can't remember. And I'm wondering if there might be a way for me to get a borescope in there.
 

Napalm00

Well-known member
You could just remove the filler hose and look with a flashlight. Just bend it into position
Or

You can bend it and put it in position and just feel if it touches the bottom of the tank. If it does touch just move it back up slightly

I have mine set so that the tube edge is about three or four millimeters above the bottom of the tank
 

RBBailey

Well-known member
Callsign: KF7KFZ
This is the pic I took when I put the tank in. I can't remember if this was just me looking in to fit it over the baffles, or if this was after it had been slotted and locked. If the latter, then this seem like probably my problem. If it was when I was just experimenting, it really doesn't mean anything.

https://flic.kr/p/2c4hSM3
 
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