Opened drain and it stalled out

[LouWon]

I also installed a fuel pressure gauge, maybe next time I will get a warning of some kind

 

[69Roadrunner]

Just removed the line from the fuel pump at the filter - no fuel. Was it a coincidence it stopped running as I cracked open the drain valve? hmmmm

No, you got air in the system. Remove dog house and crack the injector on passenger side of the head have someone crank it while you crack open the injector nut till you see fuel coming out. It should start back up after you do this!

 

[Mogman]

No, you got air in the system. Remove dog house and crack the injector on passenger side of the head have someone crank it while you crack open the injector nut till you see fuel coming out. It should start back up after you do this!

If you open the fuel filter drain valve while running and it sucks in air and dies then ether the lift pump is bad or there is a problem with the suction line to the tank, a stuck check valve or a plugged fuel tank pickup sock, besides this thread is about 8 years old, I hope the OP has figured it out by now

 

[69Roadrunner]

If you open the fuel filter drain valve while running and it sucks in air and dies then ether the lift pump is bad or there is a problem with the suction line to the tank, a stuck check valve or a plugged fuel tank pickup sock, besides this thread is about 8 years old, I hope the OP has figured it out by now

I'm confused here on the bad "Lift Pump", IF the vehicle is running and driving around, but you bleed the fuel filter drain valve and it shuts off, how is the LIFT PUMP bad? It has been running until i hit the drain valve. Hope that makes sense......

 

[69Roadrunner]

I also installed a fuel pressure gauge, maybe next time I will get a warning of some kind
View attachment 672377

That's a nice set up. Where did you tie into the fuel line? before the injector pump? Great idea!!!

 

[69Roadrunner]

I never looked at the date, lol.....besides, no one ever answered the question with a fix, and it just happened to me, so i figured i'd share my fix in case someone else does a search like i did and this same thread pops up, this time it will possibly help someone.

 

[Mogman]

I'm confused here on the bad "Lift Pump", IF the vehicle is running and driving around, but you bleed the fuel filter drain valve and it shuts off, how is the LIFT PUMP bad? It has been running until i hit the drain valve. Hope that makes sense......

The IP has a charge pump built in, if the lift pump is bad the engine can run with only the charge pump pulling fuel from the tank, it usually will have low power but it still can be started and run, but when the flow is stropped by opening the drain valve and allowing air in it is normally very hard to get the flow started again.
This can also be a bad check valve, have you removed the check valves yet?

 

[Mogman]

If the lift pump, pickup sock, check valves and fuel lines are OK there will be a positive pressure at the fuel filter and fuel will rapidly flow out of the drain when running.

 

[69Roadrunner]

The IP has a charge pump built in, if the lift pump is bad the engine can run with only the charge pump pulling fuel from the tank, it usually will have low power but it still can be started and run, but when the flow is stropped by opening the drain valve and allowing air in it is normally very hard to get the flow started again.
This can also be a bad check valve, have you removed the check valves yet?

I have NOT removed any check valves. She starts every time and runs fine. Doesn't seem to be starving from fuel. Sorry, what is the "IP" ?
Thanks for explaining this. I did order a Lift Pump and should be in this week. It seems like a normal Fuel Pump as far as changing it out.....

 

[Mogman]

So to farther elaborate, if the lift pump is bad and the charge pump in the IP (injection pump) is pulling fuel, then all of the fuel "delivery" system has a vacuum on it including the filter, so if you open the drain valve and no fuel comes out you should immediately close the valve because the IP is now pulling in air instead of fuel.

 

[69Roadrunner]

So to farther elaborate, if the lift pump is bad and the charge pump in the IP (injection pump) is pulling fuel, then all of the fuel "delivery" system has a vacuum on it including the filter, so if you open the drain valve and no fuel comes out you should immediately close the valve because the IP is now pulling in air instead of fuel.

oh boy!! I think i'm understanding this now. The IP is supplying the fuel and not the Lift Pump? Gotcha....Thank you so much man!!

 

[Mogman]

When you change the lift pump you MUST insure the push rod is pushed up into the block, there are two common ways to do this.
I remove the two 1/4" screws from the plate behind the pump and remove the plate and rod and coat the rod with grease and push it back into the block, put the plate back on and install the pump.
Others use something to reach in at the same time as installing the pump and push the rod back in the block, I have enough trouble doing one thing at a time let alone two.

 

[Mogman]

There are also two check valves, one each in the suction and return fuel lines just ahead of the fuel tank, these can be troublesome.
Most folks just remove them and replace them with a piece of fuel hose, they are installed with two short pieces of fuel hose each from the factory so removing them is rather easy.
IIRC one hose is 3/8 and one (return) is 5/16

 

[69Roadrunner]

When you change the lift pump you MUST insure the push rod is pushed up into the block, there are two common ways to do this.
I remove the two 1/4" screws from the plate behind the pump and remove the plate and rod and coat the rod with grease and push it back into the block, put the plate back on and install the pump.
Others use something to reach in at the same time as installing the pump and push the rod back in the block, I have enough trouble doing one thing at a time let alone two.

Ok, gotcha!! That helps a lot man!! Thanks again!
My Lift Pump should be here on Thursday. I guess it's still ok to drive if needed as i have been all this time, lol

 

[69Roadrunner]

There are also two check valves, one each in the suction and return fuel lines just ahead of the fuel tank, these can be troublesome.
Most folks just remove them and replace them with a piece of fuel hose, they are installed with two short pieces of fuel hose each from the factory so removing them is rather easy.
IIRC one hose is 3/8 and one (return) is 5/16

Any simple way of checking the check valves?
I'll change out the Lift Pump and try opening the fuel filter drain bleeder and see IF it stalls out, hopefully fuel will bleed out....Thanks again!!!

 

[Mogman]

Ok, gotcha!! That helps a lot man!! Thanks again!
My Lift Pump should be here on Thursday. I guess it's still ok to drive if needed as i have been all this time, lol

You can bolt the pump up with the rod out of place, this almost always breaks the rod and or damages the pump.
If you cannot get fuel out of the drain when running I would not get too far from home until you get it fixed.
You can disassemble the check valves, clean them and re-install them, but they are not needed and like I said most just immediately remove them when they get their trucks, they do put more strain on the lift pump as it has to pull hard enough to unseat the check valve.

 

[69Roadrunner]

You can bolt the pump up with the rod out of place, this almost always breaks the rod and or damages the pump.
If you cannot get fuel out of the drain when running I would not get too far from home until you get it fixed.
You can disassemble the check valves, clean them and re-install them, but they are not needed and like I said most just immediately remove them when they get their trucks, they do put more strain on the lift pump as it has to pull hard enough to unseat the check valve.

Ok, i should be able to see this Lift Pump ROD? and whether or not it's installed correctly, right? Last thing i want to do is break something else, lol....i searched u-tube on humvee Lift Pump installation and nothing coming up. I'd rather be prepared and spare any guessing.

 

[Mogman]

It is easy to see when the pump is removed, it will fall as far as it can out of the block, the small plate behind the fuel pump prevents it from falling out.
It is however fairly difficult to get something under the end of the rod and push it back into place at the same time you are installing the pump basically handing the end of the rod over to the pump arm without dropping it, that is why I just remove the plate and grease up the rod so it stays in place.
The gasket behind that plate is the same used on SBC and BBC (chevy) motors from the 70s so you can go to any parts house and get this gasket, just specify say a 1970 chevy with a 350 gasser engine.
This is what it looks like.

 

[69Roadrunner]

It is easy to see when the pump is removed, it will fall as far as it can out of the block, the small plate behind the fuel pump prevents it from falling out.
It is however fairly difficult to get something under the end of the rod and push it back into place at the same time you are installing the pump basically handing the end of the rod over to the pump arm without dropping it, that is why I just remove the plate and grease up the rod so it stays in place.
The gasket behind that plate is the same used on SBC and BBC (chevy) motors from the 70s so you can go to any parts house and get this gasket, just specify say a 1970 chevy with a 350 gasser engine.
This is what it looks like.
View attachment 938307

Mogman, THANK YOU very MUCH for all this information, man!!!! I owe you a cold beer!!! lol

 

[Mogman]

Ok, i should be able to see this Lift Pump ROD? and whether or not it's installed correctly, right? Last thing i want to do is break something else, lol....i searched u-tube on humvee Lift Pump installation and nothing coming up. I'd rather be prepared and spare any guessing.

It is hard to see the rod when installing the pump, why I do it the way I do, but others have been successful without removing the plate.