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Return line check valve?

47K views 12 replies 8 participants last post by  chuckster57 
#1 ·
ok so ive got a 7.3 idi in a 73 f250 :thumbsup: and upon first start up it runs sort of rough (like air in the system) but if you shut it off and start it right back up in runs smooth ( like its primed back up). i can hear fuel running back in the tank when i shut it off so do i need a check valve to keep the return side primed? if so should i put it close to the tank or the engine?

thanks
Ben
 
#2 ·
You do not need to add a check valve to the return lines. It is normal for excess fuel used to cool the IP, etc to run back into the tank and drain from the return lines.

As you said, it sounds like you have air intrusion. A hard start/rough idle when started is typical of air intrusion. Hard start can also be caused by bad glow plug(s), starter, batteries, etc. You might want to see if you can purge some air from the schrader valve. Add a clear line at the hose indicated in the picture:

to see if you get air bubbles. Check for leaks around your lift pump, fuel filter housing and injectors.
 
#3 · (Edited)
IIRC the line that comes from the top of the IP has a check valve in it. Could be stuck, allowing fuel drain back.

PETE: help me out here. Or is the check valve in the brass fitting in the filter header, where the return line attaches.
 
#4 ·
The check valve is in the line from the filter header to #1 injector return line.... that is to allow any air in the filter to be vented to the return line instead of the IP.

Read up on air intrusion....... Ford diesel 6.9 7.3 IDI

Also see the filter leak points....same page. The filter heater "black connector on the top" if wet could mean a leak. Orings can be replaced in it.
 
#7 ·
Maybe the seals on the ends of the supply line from the filter header to the back of the IP. Should be snug enough to hold a seal. Mine leaked out when the truck sat for a while. Replaced and good to go!!
 
#9 ·
Welcome to the Diesel Stop.

That part is called an injector return cap. Excess fuel not injected into the cylinder, is routed back into the fuel supply. There is 2 O rings on each injector and that cap is pushed on over them. Leaks occur when either the O rings fail or the cap fails.

You could buy just the one cap from your local dealer, but odds are the rest of them are going to follow suit. Better to replace the whole thing.

What you need is called an injector installation kit. It will have all new caps O rings line and clamps. Different price and quality depending on where you purchase.


Sent from AutoGuide.com App
 
#10 ·
You could buy just the one cap from your local dealer, but odds are the rest of them are going to follow suit. Better to replace the whole thing.
Yep, especially since removing the hoses from the #1 cap will cause the #3 to wiggle and probably break its seal. I avoid touching any part of the fuel return system whenever possible, it's the weakest point in the design of this engine. An all-metal rail using copper washers to seal and being held on with nuts, like on Cummins & Perkins engines, would have been a better idea IMO.
 
#11 ·
Even just metal rails using the same O-Rings to seal would be a major improvement. I have every intention of building one soonish. I think I will tackle the rebuilding the truck camper project first, though. That should be fun compared to the travel trailer project :p
 
#12 ·
My 2004 F-250 is very hard to start after sitting for over 24 hours. I have to crank continually for about 60 secs 2 or 3 times until the oil pressure is up. it feels as if the fuel pressure is way down or fuel drained back. is there a check valve in the system to prevent back flow?
please help
Ralph
 
#13 ·
return line check valve?

Your truck has a completely different engine and fuel delivery system. I would post your question in the 6.0 forum, but it sounds like HPOP issue.
 
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