6.9 what the heck is going on!

chillman88 · Oct 12, 2019

Is there a tank switching valve on your truck? When mine failed it acted similar.

Have you tried gently blowing air backwards from the soft line feeding the lift pump to the tank? I've had debris from a failed showerhead partially plug the lines and cause a starvation issue. I see you flushed the lines but I don't know what your method was.

Have you tried running from a Jerry can hooked up directly to the lift pump? That would bypass all the lines and the pickups just to be SURE. It's a free test which is the best kind.

dgr · Oct 14, 2019

And run the return line off the back of the engine to the Jerry can.

Grange Bond · Oct 15, 2019

Check fitting at return on pump it has a small glass bead in it blow it out with compressed air . I had clear little pieces blocking it. It causes all sorts of problems if stuck open it doesn't have enough pressure in the pump if stuck shut it over fuels lots of smoke

Thewespaul · Oct 15, 2019

Grange Bond said:
Check fitting at return on pump it has a small glass bead in it blow it out with compressed air . I had clear little pieces blocking it. It causes all sorts of problems if stuck open it doesn't have enough pressure in the pump if stuck shut it over fuels lots of smoke

If that’s the case with your pump then you have other issues, likely with your advance piston. The glass ball gets pushed out of the way of that fitting when the cold advance is on, and the pump should operate like normal with zero housing pressure. It just advances the timing and increases cranking fuel slightly.

Dodonne2 · Oct 16, 2019

Update..

I ran compression tests today and everything checked out rsnging from 280-300 psi using a crappy $50 tester from Amazon.

I cleaned every fuel line and every single fuel line running from engine to the tank selector valve under the chassis. The ssme problem exists.

It will chug twice on start up then die. Holding throttle wide open it will run for 3 seconds then die spitting lots of white smoke.

I have pressure at the fuel filter at the shrader valve.

I ran a Jerry can today but didnt have the return line off the back of the engine heading into the Jerry can. I will retest in a few hours and update.

This is starting to sound like a bad IP to me. Could the timing have slipped? Could I try adjusting the static IP timing a few degrees cover to compensate for internal slippage wearable?

Dodonne2 · Oct 16, 2019

I retested with proper Jerry can set up and the same problem persists. Wont run unless I hold throttle open and it will fire up and rev up to 2000ish rpm before it dies. If I dont give it theottle it will chug once maybe twice, Though now it sometimes turns over another extra time before dieing with the Jerry can attached.

Thewespaul · Oct 16, 2019

Those comp numbers are pretty low. With it starting and dying imediatly like that I would say either a metering valve issue or fuel supply issue, like air intrusion or no fuel pressure.

Dodonne2 · Oct 16, 2019

What metering valve issue could there be? Im not familiar with the metering valve at all

Yeah they are low but I had the same numbers on my other 6.9 truck years ago when I tested it. I wonder if it isn't crappy testers on the market. I got it on Amazon

Thewespaul · Oct 16, 2019

Metering valve is inside the injection pump, its controlled by the governor and fuel shut off valve, it could be possible that is stuck shut and it needs loosening up by hand. You just remove the top hat, take note how you remove it, it only comes off one way and needs to be slid back on the same way. In the back of the pump at the bottom is the metering valve controlled by a black L shape rod that is attached to the throttle shaft, you can see where there is a ramp which the fuel shutoff valve actuates on, you need to rotate that back and forth until the valve moves freely and takes no effort to move.

Dodonne2 · Oct 17, 2019

UPDATE:
The truck ran for about 10 seconds today and then died. Ran again for a 7 seconds or so then died. It sounds great when its running then shuts off and back to same old symptoms. Now wont start at all.
I dropped the exhaust at the muffler and was stoked thinking I found the problem for the first 10 seconds it ran. Its not the muffler. I'm thinking its the metering valve in the injection pump. Any other thoughts before I pull the pump cover?

Selahdoor · Oct 17, 2019

Dodonne2 said:
UPDATE:
The truck ran for about 10 seconds today and then died. Ran again for a 7 seconds or so then died. It sounds great when its running then shuts off and back to same old symptoms. Now wont start at all.
I dropped the exhaust at the muffler and was stoked thinking I found the problem for the first 10 seconds it ran. Its not the muffler. I'm thinking its the metering valve in the injection pump. Any other thoughts before I pull the pump cover?

My only thought is that it is intimidating to mess with the IP like that, for the first time. So I can understand why you did the muffler before trying it.

But once you take that cover off and ****** with that valve, you are going to discover just how easy it is, and will wish you'd done it before anything else. LOL

Just make sure you get the cover back on, correctly.

Philip1 · Oct 17, 2019

Its possible the wire going to the fuel shutoff solenoid is damaged and is losing connection when it fires up and the engine moves. I would connect a jumper wire from the battery to the solenoid to bypass the whole electrical system just in case that's the issue.

dgr · Oct 18, 2019

Keep something like a phone book handy and remove the air cleaner and stud when you first start it after putting the cover back on the IP. If it runs away, cover the intake manifold with the phone book.

Dodonne2 · Oct 18, 2019

Thanks for the run away advice.

I ran a wire from the battery directly to the IP seliniod and it didnt make a difference. Same symptoms

I'll pull the IP cover today.

Selahdoor · Oct 18, 2019

dgr said:
Keep something like a phone book handy and remove the air cleaner and stud when you first start it after putting the cover back on the IP. If it runs away, cover the intake manifold with the phone book.

If you haven't trashed, or removed the screen that covers the intake, then a simple plastic bag will do the trick. Or a rag.

Just have to cover the entire thing and do so as quickly as possible.

I have sometimes wondered if that is why that screen is there. It certainly doesn't keep dirt out. It would keep rodents out, of course. But I don't think Ford was thinking about mice when they put that there.

6.9 what the heck is going on!

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