Been chasing other issues, now is my injection pump dead?

[The_Josh_Bear]

Ok now we are getting somewhere! Having zero flow out of the IP(while running) means for certain you have zero flow INTO the IP, or its junk.
These IP's are a flow-through design, the extra fuel cools them down and the housing pressure differential is used to control the timing. No fuel coming out screws up the pressure differential, if nothing else. There is a minimum spec for idle flow rate but I can't find it in all my Googling... psi is different than flow.
Does anyone know the idle flow rate Ford/International calls for on the IDI? I know the max rate at 0psi is about 32gph. (I feel like it's 1 liter in 30 seconds but I can't confirm.)

Also what I can't remember is if the schrader valve is pre filter or post filter...I feel like it was pre filter which doesn't tell you how much flow is getting to the IP.
At this point I'd be removing the line to the IP and checking flow rate through that with the e-pump. See how much is making it through the filter. Also there's an inlet screen on the IP inlet, get a mirror and check that out for debris while you're at it.

@IDIBRONCO has you covered on the fuel drain back issue in post #12. The best way to confirm it's happening is to just pull the filter in the morning. If it's half full you've got fuel drain back. If it's all the way full, you don't.

 

[Cant Write]

Unfortunately my gauge is a standard gasoline type with a higher range than the couple psi this system runs, but the needle still comes up a tic.

I bought this a few years back, I find it quite handy on old rigs....

Vacuum/Pressure Gauge Kit | OTC Tools

otctools.com

Harbor freight has one for $20 I saw. Otherwise you are in better hands than me, stick with it and these awesome folks will get you over this hurdle!

 

[vagabond0351]

It can. It can make it so the engine starts up normally and then dies when the air gets into the injector pump. Air will replace the fuel as it drains back to the tank. Then it's a major B-word to get the air bled back out so that the engine has fuel again. This only happens on start up.

ok. that is how I thought that worked, but I dont -think- its whats happening with me because I had been driving it down the highway for 10-15 minutes before the brief fuel stop where it progressively ran worse then stalled then wouldnt restart.
none the less I will inspect all my lines and filters and such again and make sure air is bled and not intruding. I need to go get another strap wrench. was even at harbor freight today but forgot. problems always come up when theres lots else going on eh

It is possible that they are related. On my first 1985 F250, I had a universal inline filter before my cheap electric pump. The truck would have air in the fuel system. Once it got started, then it would run fine. It finally got to the point where the engine would starve of fuel at higher RPM. I finally had a light bulb click on and checked that inline fuel filter. It was pretty clogged. Once I replace it, I no longer had the problems. The only thing that I can think of is that the restricted filter held a little bit of a vacuum on the fuel after it went through the filter. That would be enough to make the fuel start draining back to the tank.
I'm not saying that this is your problem, just that it's a possibility.

Ok, that is how I thought it worked, and I'm inclined to think thats -not- what I'm experiencing because I was idling for a few minutes in the driveway then 10+ minutes driving down the highway before stopping at the fuel station. If I had drainback enough to cause this problem, I -assume- it would have stopped me much earlier on the trip? Then probably wouldnt have been able to keep driving at diminishing stints after that?

Ok now we are getting somewhere! Having zero flow out of the IP(while running) means for certain you have zero flow INTO the IP, or its junk.
These IP's are a flow-through design, the extra fuel cools them down and the housing pressure differential is used to control the timing. No fuel coming out screws up the pressure differential, if nothing else. There is a minimum spec for idle flow rate but I can't find it in all my Googling... psi is different than flow.
Does anyone know the idle flow rate Ford/International calls for on the IDI? I know the max rate at 0psi is about 32gph. (I feel like it's 1 liter in 30 seconds but I can't confirm.)

Also what I can't remember is if the schrader valve is pre filter or post filter...I feel like it was pre filter which doesn't tell you how much flow is getting to the IP.
At this point I'd be removing the line to the IP and checking flow rate through that with the e-pump. See how much is making it through the filter. Also there's an inlet screen on the IP inlet, get a mirror and check that out for debris while you're at it.

@IDIBRONCO has you covered on the fuel drain back issue in post #12. The best way to confirm it's happening is to just pull the filter in the morning. If it's half full you've got fuel drain back. If it's all the way full, you don't.

If the Schrader is pre filter, that would make the blockage suggestion make a lot more sense.
To confirm, the line from IP to the return rail should be 'one way' out of the IP and -while running- should always see flow, correct?(again I've got the original filter-to-return deleted) Is that what youre saying above?

Unfortunately I still havent gotten to this, and now probably cant for a few days. Also with the new filter-to-IP fittings and hose, I basically cant pull the line without destroying the ends it bites so tight. Small frustration with further troubleshooting. But as soon as possible I will address the suggestions and report back. I'd love to solve this for less money than a new IP, but I'm also convincing myself it may run a lot better with a new IP anyway...

 

[The_Josh_Bear]

Ok, that is how I thought it worked, and I'm inclined to think thats -not- what I'm experiencing because I was idling for a few minutes in the driveway then 10+ minutes driving down the highway before stopping at the fuel station. If I had drainback enough to cause this problem, I -assume- it would have stopped me much earlier on the trip? Then probably wouldnt have been able to keep driving at diminishing stints after that?

Fuel drainback happens slowly and overnight. After first start, die, crank crank crank, run-- it doesn't come back until you park again overnight. Does not affect running or parking for minutes or even hours.

If the Schrader is pre filter, that would make the blockage suggestion make a lot more sense.
To confirm, the line from IP to the return rail should be 'one way' out of the IP and -while running- should always see flow, correct?(again I've got the original filter-to-return deleted) Is that what youre saying above?

Yep, that's what I'm saying. I found some pictures online and the schrader and return check valve fitting are both before the filter, the vacuum switch is the one after the filter. You can always pull the vac switch and replace with some kind of barb or whatever you can slip a hose over and check flow that way. I think you can even swap the scrader and vac switch and just remove the schrader core to slip hose over that.

Unfortunately I still havent gotten to this, and now probably cant for a few days. Also with the new filter-to-IP fittings and hose, I basically cant pull the line without destroying the ends it bites so tight. Small frustration with further troubleshooting. But as soon as possible I will address the suggestions and report back. I'd love to solve this for less money than a new IP, but I'm also convincing myself it may run a lot better with a new IP anyway...

Given the age of that factory IP, it's a good idea to start saving. But hey, it could be something else and you'll get some more life out of her!