7.3 idi problem

[JackAsserson]

I replaced the lift pump, still the same issue, air in the system. I ran it off a boat tank, lost the air, but still no start. Battery is brand new and charged. I just plugged it in the block heater. Will try again in the morning. I’m thinking it’s taking air in somewhere, and glow plugs aren’t all working. Hopefully that’s it, and not a compression issue

Assuming that it's original equipment and not added to a different truck.

It's possible. That might be a good place to start.

I can't see how that could possible cause a fuel issue. This sounds like either a tall tale or an astounding coincidence.

This sounds like a bad lift pump to me. There should be a stream coming out of the Schrader valve when the e pump is running. I know for a fact that the fuel can hit the #2 injector (the first one on the driver's side) when I depress the Schrader valve on my truck. I'm running a Holley blue.

 

[JackAsserson]

I replaced the lift pump, still the same issue, air in the system. I ran it off a boat tank, lost the air, but still no start. Battery is brand new and charged. I just plugged it in the block heater. Will try again in the morning. I’m thinking it’s taking air in somewhere, and glow plugs aren’t all working. Hopefully that’s it, and not a compression issue

I will say IM getting fuel to injectors. I think it may start in the morning with the block heater, curious to see if it will idle for more than 30 seconds off the fuel jug

 

[Brian VT]

Temps. here were in the teens all week. I didn't bother plugging in my block heater (I don't know if it even works).
My truck (6.9 N/A) starts just as easily as it does in summer. 7-8 seconds of glow then almost instant vroom. YMMV.
I do want to look into my block heater as I think it may help get the oil up to temp. sooner?

 

[KansasIDI]

Temps. here were in the teens all week. I didn't bother plugging in my block heater (I don't know if it even works).
My truck (6.9 N/A) starts just as easily as it does in summer. 7-8 seconds of glow then almost instant vroom. YMMV.
I do want to look into my block heater as I think it may help get the oil up to temp. sooner?

I don’t plug in unless below zero.

My ‘mileage’ is the same in this instance. 7.3 IDI with Hypermax turbo/intercooler/exhaust system, maxed Moose IP and possibly one of the last sets of Russ injectors, set to 2100 PSI.

RIP Russ, you will be dearly missed. Words can’t quite express how deeply so.

 

[JackAsserson]

It’s 40-50s here but that’s COLD in tx

I don’t plug in unless below zero.

My ‘mileage’ is the same in this instance. 7.3 IDI with Hypermax turbo/intercooler/exhaust system, maxed Moose IP and possibly one of the last sets of Russ injectors, set to 2100 PSI.

RIP Russ, you will be dearly missed. Words can’t quite express how deeply so.

 

[IDIBRONCO]

It’s 40-50s here but that’s COLD in tx

That's true. I've been in San Antonio in January. The temperature was in the mid 60s. Most people were going around in heavy coats while I was driving around with the driver's side window halfway down thinking what nice weather it was!

 

[chickenpot]

I replaced the lift pump, still the same issue, air in the system. I ran it off a boat tank, lost the air, but still no start. Battery is brand new and charged. I just plugged it in the block heater. Will try again in the morning. I’m thinking it’s taking air in somewhere, and glow plugs aren’t all working. Hopefully that’s it, and not a compression issue

It should at least pop on a few if it has low compression but doubt that's it. if it's remotely cold where you're at, it's gonna need the glow plugs working. you can caveman a screwdriver across the posts of the GP solenoid for 8 seconds or so. that will fire any and all of the working plugs.. make sure shut off solenoid is energized as well of course just as a precaution. last resort crank it over for 5 seconds or so, give it a very short sniff of ether, and crank again. should pop off for you

 

[Old Goat]

Temps. here were in the teens all week. I didn't bother plugging in my block heater (I don't know if it even works).
My truck (6.9 N/A) starts just as easily as it does in summer. 7-8 seconds of glow then almost instant vroom. YMMV.
I do want to look into my block heater as I think it may help get the oil up to temp. sooner?

Plug the Block heater in, you should here is sizzle with in 30 seconds. With thee Coolant and Block warm the Oil will warm quicker.

 

[JackAsserson]

It should at least pop on a few if it has low compression but doubt that's it. if it's remotely cold where you're at, it's gonna need the glow plugs working. you can caveman a screwdriver across the posts of the GP solenoid for 8 seconds or so. that will fire any and all of the working plugs.. make sure shut off solenoid is energized as well of course just as a precaution. last resort crank it over for 5 seconds or so, give it a very short sniff of ether, and crank again. should pop off for you

So, I’ve run a hot wire to the shut off solenoid. I’ll test glow plugs today, it’s been on the heater all night so I’m about to give it a shot. The only reason I’m worried about low compression is the amount of blowby coming out of the valve cover hose while cranking. I notice the oil pressure gauge is also reading below normal while cranking

 

[JackAsserson]

Well, it immediately started right up with the boat tank and block heater. For the first time it id also idling. So I’ve got two problems, glow plugs, and a leak using the factory tank. Any pointers on where to check? It’s running ok off this boat tank

 

[JackAsserson]

on the boat tanker the fuel pump seems to stay full, whereas on factory tank it’s jumping from full to empty the whole time

 

[JackAsserson]

Been driving the truck around on the factory tank for about 30 minutes with no problem. Somehow as I was running off the boat tank the fuel line from the factory tank started spitting out fuel, so I guess the mechanical pumped kicked on? Anyways it’s running and shifting flawlessly

 

[Brian VT]

Tank selector valve? These are notorious for failing.
Water separator? Mine is near the brake booster. Not sure if your truck came with one. They are known to fail/leak.
Shower head(s)? These are the fuel pickup ends in the tanks. They can fall apart, or off, and you'll be sucking air if your fuel is starting to get low. Add more fuel and then you'll know.

 

[JackAsserson]

Full tank. Got home , parked, immediately died

 

[JackAsserson]

Looks like fuel return line is leaking. The blowby is pretty substantial , I’m not sure if that’s common with these?