Fuel Sender

[Joe_IDI]

Just purchased a new to me 1990 F350 with a 7.3 IDI engine and ZF-5 Transmission.

Having a few issues, but one I would like to address now is the fuel sender / tank.

Rear tank is missing. Front tank is not working correctly. It has a hard time filling up and stops picking up fuel before it is empty. Gauge also does not work.

Dropped tank today to do harpoon mod. It appears to already have been done by previous owner. PVC pipe is cut even with tank.

Why is it almost impossible to fill tank even though harpoon mod is done?

Is this the right sending unit? Does not look like the ones I see online.

I put tank back on truck without fixing anything because it's my daily driver until I fix my Jeep, would like to fix this soon. Any help appreciated.

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[gandalf]

Let's deal with one problem at a time. I'll have a go at "running out of fuel before the tank is empty".

Based on your pictures, the pickup tube and the 'showerhead' strainer have broken off. The metal tube coming out of the sending unit seems to have a piece of hose and a hose clamp. That hose should be long enough to barely reach the bottom of the tank. When it breaks off like your's has, it starts sucking air when the tank is still 1/4 full.

Calculate the proper length of additional tube and clamp it on. Cut a V notch in the bottom of the new tube so it won't have a chance suck tight to the bottom of the tank.

The gauge not working is an altogether different problem. I'll let somebody else answer that one.

 

[IDIoit]

if the gauge is reading full, you have a ground issue.
if the gauge reads empty, most likely your sender is bad..
now this all depends if your FSV is in proper working order.

both senders tie into the fuel switch valve, so a bad switch valve could also be the culprit.
you can get a 38 gallon rear tank for about 100 bucks.
you would then have to use a gasser sending unit with the fuel pump deleted.
and then modified like posted above.

if you cant fill the tank correctly, first thing i would do is pull the vent and make sure its clear of debris, and the check valve works.

 

[gandalf]

if the gauge is reading full, you have a ground issue.
if the gauge reads empty, most likely your sender is bad..
now this all depends if your FSV is in proper working order.

...

Where would the ground be? Is there any spot more likely than others?

 

[IDIoit]

Where would the ground be? Is there any spot more likely than others?

the ground also goes to the FSV.
and then through the dash harness, would need a schematic to tell you where it goes from there.
perhaps to the gauge itself?
that lill ******* creates more problems than its worth
both my 90 and my 87 had gauge problems.
the 90, i replaced the FSV and everything was primo
my 87, i deleted the damn thing and things worked perfect.

on other vehicles, i have literally zip screwed a wire to the frame and wrapped it around the pick up tube externally on the sender.

 

[Joe_IDI]

Thank you Gandalf and IDIot.

Will find time to try your suggestions and come back to let you know how it goes.

 

[Joe_IDI]

Attached 3/8th tube to end of pickup. Cut V in bottom.

Had to crank a lot of air out with shrader valve open. Finally started up.

About 2 miles down road fuel filter light came on and truck cut off.

Had to purge a lot of air. Got it started again. Kept purging air and it would run for 5 min or so and cut off. Repeated for about 5 hours.

This morning dropped tank again cut tube shorter. Only about 1 Inch long now. It started right up. Fuel filter light comes on when going over 30 mph.

I cut it off at Walmart and had to purge a lot of air to get it started again.

Should I just remove that tube to get it running again? Did I cause a new problem somewhere?

Any help appreciated.

 

[OLDBULL8]

You would be better off getting the shower head and install it. there not that expensive.

If you use a hose on the end of the pickup, you have to weight it or it can float up, then the same problem.

The ground (Neg 12V) goes thru the float resistor, the grounding wire from there is tied to the sender, the sender cap is grounded to the tank, the tank is grounded to the straps, the straps are grounded to the frame. The one wire on the connector goes to ground. also.

Below is the typical fuel gauge circuit.

 

[riotwarrior]

Fuel hose mod works pretty good...shower head works better.

As mentioned...the little white ROLL over valve should be checked for free movement of ball and the hose is not plugged.

If it cannot breathe allow air in it can cause a hard time for fuel pump to draw fuel from tank after driving or running for a while.

 

[Joe_IDI]

I took hose off and it runs fine.

Was considering using metal line and joining it together with hose and two clamps.

Will probably replace the whole sender one day soon.


Thanks for help.

 

[riotwarrior]

Sounds like hose was collapsing

Get showerhead....

 

[icanfixall]

My guess is the rubber hose was kinked somehow so suggestion about the black shower head suction is the best bet for no more suction issues. Can't go wrong with a part number and the bag. Check ebay for this part too. As for replacing the complete sender.. Don't. they are expensive when found and not much wrong with what you have now that can't be fixed.

 

[idi_econoline]

Thx, gentlemen.... my head dropped recently -- fortunately, at a good time, in a safe, daylit place. AAA was fairly quick, too.

Ordering a new head from ebay. Good time to drop the tank and replace the probably-original hoses on the outside, and clean any pieces at the bottom.

Probably should have reverse-blown air in to clear any bits in the line, before adding fuel, but will be driving it around the neighborhood tomorrow before going anywhere real. Trusting any such crud will make itself known.

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[ericboutin]

My guess is the rubber hose was kinked somehow so suggestion about the black shower head suction is the best bet for no more suction issues. Can't go wrong with a part number and the bag. Check ebay for this part too. As for replacing the complete sender.. Don't. they are expensive when found and not much wrong with what you have now that can't be fixed.

Don't mean to hijack but I've been following this and now I got a question too......can the sender be repaired? I've got the same issues....1/4 tank issue but also my gauge no worky for the front tank. I'm definitely gonna order that shower head from amazon, but can the sender be repaired because as you say they are expensive!