Another FSV Question ... I know. I feel stupid for asking

[Kizer]

The '93 IDIT, that I scored a couple of weeks ago, started "surging" at 1/8" tank yesterday (no big surprise). I switched to the front tank ... drove about 20 miles with no issue.

3hrs later, started the truck and drove about 7 miles before surging began again. The truck died and I couldn't get it started.

I got it to the shop, replaced lift pump with new one (mechanical), bled the system at injectors and schrader valve ... now truck will run for (up to) 3 minutes before sucking enough air to kill it.

Bleed the system, starts (and runs smooth) for up to 5 minutes then sucks air and dies.
I went through this process ALL DAMNED DAY (15 - 20 times).

I only kept trying because the truck is parked "nose down" about 2* (no way around it),so I thought I just had a huge air bubble.

The question: Does it sound like FSV to y'all?
I'll have a Jerry Can with me tomorrow ... just thought I'd ask so I could try to order the FSV tonight if necessary.

Thank you in advance,
Kizer

 

[Bio-Bradley]

When you switch tanks, do you hear the FSV click? Try this with the key in the ignition and the ignition in accessory mode. Turn off your radio, blower fan and other things that might make noise so you can listen for the click. BTW, you won't hear the click with the engine running. If you hear it click as you switch tanks, it's likely not the FSV. A common culprit with air intrusion is the fuel injector return lines and rubber seals/plastic caps on each injector. Obviously, there are several places where air can leak in, anywhere in the fuel lines, fuel injector pump, leaky schrader valve, fuel injector caps and fuel injector lines. You also might not be getting enough fuel with a faulty or weak fuel pump, but it sounds like you looked into that already. Are you getting good amounts of fuel to the fuel filter and IP? If you are cracking your injector heads, cranking over the engine and fuel is seeping out the fuel injector heads, you are probably getting enough fuel to each injector. You say it's running smooth for a few minutes. That can tell you a lot. A fuel injector line replacement kit is pretty cheap and an easy fix. Anyone else have any other thoughts?

 

[Kizer]

I Appreciate You Bio-Bradley,

I don't hear the valve operate from the cab ... it's a CC + I shoot left handed = don't hear so well out of my left ear. However, when I manipulate the FSV switch, the sender for each tank reads.

The truck is new to me with about 85,000 on the clock. The return lines and supply line look good / almost new / been replaced and caps don't show signs of leaking. I do get fuel at the injectors for a few minutes then I get air.

I'll try to run it off of the Jerry Can in the morning ... at least I'll know if the air is getting in pre or post pump.

Thanks again for your input,
Kizer

 

[Oledirtypearl86]

How much fuel is in the other tank if lower than 1/4 the shower head might be broken off causing your issue I'd take a couple can of diesel and pour In the tank make sure that it's not out of fuel iv got several Ford's and the fuel gauge is a rough guess at best on all but 1

 

[Kizer]

How much fuel is in the other tank if lower than 1/4 the shower head might be broken off causing your issue I'd take a couple can of diesel and pour In the tank make sure that it's not out of fuel iv got several Ford's and the fuel gauge is a rough guess at best on all but 1

Thank you for your input too.

The front tank reads full.

iv got several Ford's and the fuel gauge is a rough guess at best

I Agree! I have 0 Ford senders that tell the truth!

 

[ifrythings]

How is the fuel line from the frame to lift pump? That line is common to break down and either leak, collapse or suck in air. I would change it just to be safe.

 

[Kizer]

How is the fuel line from the frame to lift pump? That line is common to break down and either leak, collapse or suck in air. I would change it just to be safe.

Thank you, I replaced it when I put the new pump in ... it was in bad shape. I hate that corkscrew / hog tail hose!

 

[Kizer]

Closing comments:

The truck ran great out of the Jerry Can.

I let some fuel run out of the supply line before I reconnected the pump.
Gave the FSV a "love tap" or two.
Started the truck ... been running right since.??

Learned this:

The caps, that come on reman / rebuilt injectors, work great for mitigating your inevitable diesel bath while screwing with the pump. Pic below.

Also: When you run off of a Jerry Can, always select the least full tank ... think "Valdez" ... Jeez, I'll bet that I dumped $5 worth of fuel on the drive before I saw the tank overflowing.

Thanks again for your help.

You must be registered for see images attach

 

[Kizer]

Update: Just got stuck again ... same symptoms.

I let it sit for about 1.5 hrs ... started and got me home.

Heat soak?
Any input is greatly appreciated.

 

[Thewespaul]

When it shut off, what does it do? Does it act like it’s running out of diesel and surge or does it slowly loose power? How old is the fuel filter?

 

[Kizer]

When it shut off, what does it do? Does it act like it’s running out of diesel and surge or does it slowly loose power? How old is the fuel filter?

It acts like it's out of fuel.

The PO had the filter replaced (Motorcraft) about 6k miles ago

Maybe just go ahead and change it? I didn't want to introduce another variable to the problem ... If you think it could be the filter I'll change it now.

Thank you for your help.

 

[Thewespaul]

I would replace the filter just for good measure. Get the one piece filter that doesn’t have the screw on lower half.

If you had to thump the fsv and it worked for a bit I’d wager you have some crap in there clogging the selector valve portion, pull the lines off and blow air through each hose and select both tank and feel the air coming out to confirm that the valve is functioning right. I would put rubber hose on the inlet side of the valve and put two clear filters so you can check for any crud that’s getting picked up in the tank, and you can look for air there if you get it to run out again, you can look underneath and see which tank ran out or if it’s a supply issue upstream the valve.

You must be registered for see images attach

 

[Kizer]

I like the filters at FSV. Thank you for the pic.
Filter replacement to be done shortly ... will post back with results.

 

[Kizer]

I would replace the filter just for good measure

It seems to have liked the filter. 36 mile test drive + over 30 idle and no issues.

I should have just changed it in the first place ... I've never had a plugged filter treat me like that; in the past it's been die and no go... Not this crazy "set for a while then act normal" BS.

 

[Thewespaul]

My wager, is the lift pump was having a hard time pushing through the clogged filter, and you were getting some occasional clogging in the fsv that made enough restriction not to allow fuel pressure. You wait some time or thump the valve and the blockage passes then it’s fine for awhile. Glad it was a simple fix