7.3 idi fuel filter light but worse

cragenj3

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Not sure air intrusion is the cause of the engine dieing going down the road though...

Btw
White teflon is not fuel rated.
Also; probably died cuz front tank ran out and the gauge was wonky from selecting tanks recently. I bet that's all it is.

Thanks for everyone's help; I'll be back ******** tomorrow when everything else breaks.
 

cragenj3

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yeah so it didn't lose prime over night; clear hose between IP and driver's front injector still has no air.

I put 5gal in the front tank and switched back to it; symptoms persist.

Must be the TSV or the IP I guess... A stuck injector would show in the clear return lines, ey? And the TSV would show air in my clear line between epump and filter..
 

rdezs

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Can't remember what it's called, but on the driver side of your fuel filter housing there's a brass One Way check valve. Has a bit of fuel line going down toward your injectors. It's a known trouble issue. I believe there is a TSB about that years ago and the fix was to Simply plug it off, not really necessary. If you want to keep it original the replacement is fairly cheap. If the little check ball inside gets stuck it bleeds air into the filter and you lose your prime
 

gandalf

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Okay, lets head back to basics and review everything. The symptoms you've described clearly indicate an air intrusion. Air can enter the system without allowing fuel to leak. You've got to start at the beginning of the fuel system and examine everything, all fuel lines for cracks, all connections, everything. You're sucking air somewhere. Consider replacing all screw type hose clamps if you have any. They sometimes allow air to enter. The high pressure fuel injections clamps are superior.

You stated several times that you've used fuel rated teflon. If a connection has an "o" ring or an olive, then that "o" ring or olive is the seal, and there is no need for teflon tape. If a piece of the teflon break loose and gets to the IP you may have a significant problem.

I think you said that you replaced the injectors, all 8 of them I hope. Did you remove and replace the copper washer in each injector bore? A copper washer must be present and properly seated. Two copper washers, failure to dig out an old washer, will cause problems. An injector without a copper washer, or an injector with 2 washers, may cause an air leak directly into the cylinder. I don't believe that would show as bubbles in the clear lines you've installed.

Lets review also what you have installed, either new or not. List everything you've replaced, including name brand and purchase location. There are a very limited number of parts dealers who have earned our trust. It's way too easy to walk into a parts store and buy a POS part, thinking you've gotten a good deal.
 

Booyah45828

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Filter light comes on due to vacuum at the fuel filter. I think you have a restriction somewhere which causes fuel starvation, starvation leads to vacuum at the filter, which leads to the rough running until it inevitably shuts off.

With an e-pump, run the outlet into a bucket and see how long it takes to pump 5 or so gallons. Restriction can come from hoses collapsing internally, failed fsv valve, foreign objects caught in the hose, or a shower head/pick up plugged solid. Running the tank dry can cause all sorts of crap in the tank to get sucked up and stuck somewhere. You can use shop air to blow backwards into a bucket and see what you catch.
 

chickenpot

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consider that the fuel filter light is a vacuum activated switch. it turns on when your IP's internal transfer pump is pulling a negative space on the clean side of your fuel filter. in most cases indicating a clogged filter. but any other blockage or lift pump failure will cause it to light up.

What is the status of your mechanical lift pump? if i were as frustrated as you i would have hosed a jerry can straight to the inlet of the mechanical pump to rule out anything on the top side/fuel delivery system. if it runs off a jerry can, your fuel issue is gonna be somewhere behind the engine. surely you will have an aha moment, sometimes these trucks require a time/frustration sacrifice in order to reveal a problem
 

cragenj3

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Fuel filter light came on; a mile later I died driving on front tank; probably out of fuel...switched to rear; used schrader to purge air; no start...must've got air into the IP and hardlines. Turn on the epump, crack lines, got it bled plenty...got back in to crank but batteries to dead to spin fast.

Got 20 minute jumper cable charge, span fast few a few seconds, no start. Got a pull start; started 2nd pull... Popped injectors, ran fine for 30 seconds, fuel filter light, died. Won't bump again.

Got home, charged. Starts right up every time but fuel filter light and dies in under 15 seconds.

New fuel filter; wix 3347.
Same symptoms.

No visible leaks but as easy as it is and having a 50 pack of vitol 111s I did new orings. Same symptoms.

So I did new hose but broke the nipple off a few OEM caps; so did Delphi 3/16 return kit. Same symptoms.

New same model epump that lasted 6 months in engine bay. Same symtpoms. New stronger epump. Same symptoms. In series epump (1 a foot after TSV 1 in engine bay) same symptoms.

TSV is new, 6 months old at most.

2ft of clear between epump and filter, 1ft clear between IP and driver's front return cap...no bubbles.................
Hardlines didn't have Teflon, shouldn't need it with their double flares, but what's it hurt to try, so did that.


All filter housing units have Teflon or new seals/olives.
At the schrader, at turn on I'll initially have low fuel pressure and no air...but the time WTS goes off I can shoot fuel and air across the entire engine bay. Couple seconds of air and fuel combo before lower pressure and no air.

Up here in the city; rattle-y old truck; maybe potholes and train tracks broke my in-tank pick ups or maybe my offbrand $50 TSV is junk already.
 

cragenj3

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For some reason I haven't been smart enough to just hook a fuel can up as a diagnostic tool.

I'll do that today, haha.
 

cragenj3

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Alright; well a fuel can a foot before the epump a foot before the filter...same symptoms.
 

cragenj3

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How does the fuel shut off solenoid work? Hot is fuel on or hot is fuel off? I took it out a minute and hotwired it 20 or 30 clicks, a couple of the first hotwires only partially retracted the piston/hook... I'm suspecting that the piston seal in the shut off is bad; so when my IP gets 3psi of fuel it fills my shut off piston and can't always retract easily.

Also; how to adjust the fuel shut off levers in there; mine moves freely but it's resting position is all the way vehicle-forward which ends up being about a half inch away from the throttle spring?
 

Rdnck84_03

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On the FSS hot is fuel on. As soon as it loses battery power it shuts the fuel off. When you have the top cover off the valve is open, when you put the top back on start with it about 1/2"- 3/4" forward of where it should be. Set it down and slide it towards the rear of the truck until the screw holes line up. If you just set it straight down the FSS will miss the tab on the FSV lever and lock the fuel on (I have heard it said it causes a runaway situation. Not sure if that means wide open throttle, or just that you have to remove fuel line and wait for it to run out of fuel to shut it off.)

James
 

Jesus Freak

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On the FSS hot is fuel on. As soon as it loses battery power it shuts the fuel off. When you have the top cover off the valve is open, when you put the top back on start with it about 1/2"- 3/4" forward of where it should be. Set it down and slide it towards the rear of the truck until the screw holes line up. If you just set it straight down the FSS will miss the tab on the FSV lever and lock the fuel on (I have heard it said it causes a runaway situation. Not sure if that means wide open throttle, or just that you have to remove fuel line and wait for it to run out of fuel to shut it off.)

James
It means wide open throttle craziness!
 

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