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Finally left me stranded

No, The Walbro has a built in 'prefilter' screen. Remove the bottom inlet bowl, 1 bolt, to access it. You can order a special course screen for the pump if you have trouble plugging it - I am likely the only one who needed it.
 
Been driving my truck most of the week and I went to leave work again today and it stalled shortly after I hit the accelerator pedal after leaving the parking lot. I was able to run the pump to bleed the air off the filter and after a couple tries, it fired up. I drove home, let it sit a few hours and then took it into town to get some building materials. No issues.

No kinks in any lines that I can see, no wet lines from a pin hole, as far as I can tell. I guess the next step is to drop the tank and remove the sock/check the tank?
 
Before dropping the tank I would make sure you have the proper parts.

Most of all drop a siphon hose in the tank and suck all the fuel out as you can't trust the gauge or any ability to suck fuel through a plugged sock. Careful your siphon doesn't plug up too. Diesel baths from full tank being dropped is not fun.

Does the main fuel filter have silver ribbons in it? This would be from the tank lining meaning you need a new fuel tank.
I can't recommend Lerory's fuel level sender enough.
You should have a new fuel pickup assembly on hand or in stock somewhere. Recall to toss the tank screen. Make sure the vent tube length on the inside of the tank is the same length as the OEM as aftermarket FUBAR's that too giving you the 24 gal length on a 35 gal tank.

Double check you don't have bugs (or cold fuel gelling). http://www.thetruckstop.us/forum/th...ulsd-and-biodiesel-this-can-affect-you.35096/

To see where the air is coming from put a clear line before and after the lift pump. Disconnect the lift pump with the engine running and see if air starts to show up.

And remember any fuel system restriction can vaporize diesel fuel that looks like air. Plugged filters, kinked or internally collapsed hoses, plugged tank sock, or real McCoy air leaks.
 
Thank you for the details, WW. Last fuel filter I pulled out a couple weeks ago looked like the day I put it in about 2-3 years ago.

One thing I have noticed the last few times I've shut the engine off, cold (just start up to move out of the barn or something short), the lift pump doesn't run after shutdown like it did when I first put it on. I know it's warm out, but it should still run a few seconds after I shut it off, due to remaining oil pressure.
 
I had issues with a 95 c1500 6.5 TD- not hearing the LP after the engine was shut off, some stalling, "mystery" air in the lines, etc. I wired my lift pump direct to a manual toggle switch and the problems went away. On T I had some surge, bucking, and stalling along with some air bubbles in the return line occasionally. Ran Leroys 6.5 lift pump harness- world of difference. If it is not running after shutoff then something is off with the LP wiring or the pump.
 
Similar to Chevypoor, I ran a switch & relay as a secondary or backup power supply to the lift pump. If/when the oil pressure switch fails, it's an easy way to get going again. Also, for troubleshooting, you have a way to confidently know the lift pump should be running.

If you just let the oil pressure switch control the relay, and the relay control power to the pump - just run a second switched +12V wire to the same relay, so you could provide the power to control the relay if the oil pressure switch fails & can't.
 
found some tygon clear hose. Am I looking for air in the lines after shutdown, or while running, or both?

I understand the switch idea, but it seems to me that it's a bandage for a looming issue that I'd rather solve if possible.
 
Air: both.
Engine running with a flashlight looks for bubbles.
Engine off looks for bigger stationary bubbles.
Just after stalling look for lines full of air.

You are looking for the source of bubbles. This can be a leaking pickup assembly in the tank, lift pump, and system restriction. For example air free lines at the lift pump mean everything is ok with the lift pump and before it. And with a air free lift pump observation getting air out of the IP can be a restriction elsewhere like a hose or fuel filter/screen.

Note: Aftermarket rotary vane lift pumps just appear to normally have a steady stream of small bubbles coming out of them.

Engine off sitting overnight and you get air on startup is an air leak anywhere letting fuel drain out of the system. This includes injector return lines and injectors sticking open. Recall the fuel return to the tank is submerged in fuel to prevent fuel drain-back and air entering the system.

No joke, I have had lift pumps and fuel heaters leak fuel out of the wire connectors! Yes, fuel pushed down the wires! Pinhole in fuel heater and I don't know how the LP was leaking like that.
 
Pump doesn't run with the engine on. I can remove the fuel pump relay on the fuse block and get power down at the pump by jumping the terminals, similar to priming the filter after a change. Where do I go from here? Is there a chance the relay is bad? Just seems strange that the old LP didn't work, then I put Leroy's new pump on and it worked for a few days, and now does not, except during the glow cycle because I have made an OPS harness with relays.
 
Dang. New OPS, too. Well, two years ago, that is. It probably doesn't have 2000 miles on it. What kills these things? This is the whole reason I did the relay upgrade, in hopes to get more life out of the switch. On edit, would the other lift pump being bad have caused a premature failure on the switch, even with the OPS relay upgrade I did?

What is the proper part number. I went through this in May 2013 and ordered 1924-4500 per the dealer looking up my VIN, but Bill Heath told me that the proper number is 1924-4501. The one in my truck right now is the ..4501.

Has anyone tried Heath's switch? I hear it's a step above the ACDelco part and is also made in the USA. My ...4501 is made in Mexico.
 
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Check to see if you have voltage coming from the OPS. If you have any voltage at all, it should be enough to trigger a relay, Do the dual lift pump relay upgrade. The pump may not be getting enough juice to run. But it will run off a relay.

Do not splice wires as shown. Do it right - like Leroy does it. Source your trigger juice for the relay from the OEM plug that goes to the lift pump, That makes it a plug and play option.

As far as I'm concerned this is a must do on 1995 and older 6.5's

If you do not make your own, buy from Leroydiesel.com You may have to ask for the prime feature.

Can somebody set me straight on whether he makes them all the same or is the prime feature an option?

I prefer a mountable relay socket to a mountable relay. I do not like a relay with wires plugged directly into it with no socket. Makes changing the relay a good chance to mess up.

His is done right. I was just under the hood of the 94 and 95 looking at the splicing I did and wanting to kick myself.

Did you use an AC Delco OPS? You should stick with GM or AC Delco parts for most electrical stuff like that and thermostats. The aftermarket parts just do not have a good track record of performance or longevity.

I believe a bad pump could definitely take out an OPS
 
Do you have a test light to check the OPS? How exactly did you wire in your relay for the OPS to fuel pump. It may be a problem with the relay. The OPS provides power to the fuel pump, so it should be powering the relay to turn on if wired correctly.
 
It is good to use both a test light and a multi meter. Often times the OPS will not put out enough juice to light a test light - depends a lot on the bulb type. - or run the lift pump, but will still put out enough juice to trigger a relay.

I've read 12 volts at the pump before, but it would not run without being jumpered. It had plenty of volts but the OPS would not pass the amps to run it.

Installed the lift pump relay upgrade and it's worked fine ever since. 3 vehicles and never changed the bad OPS's
 
Ferm, you were right. OPS did the trick. Back to the clackity, clack, clack, clunk, clack, clackity... after shutdown, again.

Do you agree with the way I made up my relay harness being proper? I was pretty careful to follow the schematic that can no longer be found in the post I mention, above. For some reason I was thinking it was from Buddy, but I won't swear to it.

Now that I've got a new OPS, I can check amperage at the LP. What sort of amp reading should I be looking for?
 
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