Air in the system...

[16Vjohn]

Hey guys. I'm having trouble with my 86 6.9. After leaving the truck to sit for about a month, I am now having start up issues. I will start it up, the engine fires for about 3-5 seconds, it sputters and dies just as if it were running out of fuel. I then have to crank for 30+ seconds to get it to fire, after that, runs great. Logic would dictate that having sat for over a month that a fuel line must have dried out or something. I inspected the injector pump and cant find any signs of leaking. The little lines inbetween the injectors. None are wet and all appear to be in good condition. The connections to the fuel filter look tight. I tried looking at the tank selector valve but it was just a huge ball of grease under there and couldnt really see anything. Are there any common areas of failure for this on these trucks? I would appreciate some advice instead of going through the whole system and replacing everything. Thanks!

[PLC7.3]

Do you still have the OEM fuel water separator........ have you drained it lately if so then it may be stuck open. If it is then air will enter the fuel system, so put a 3/8 bolt up the drain hose and see if that helps.

[16Vjohn]

Where is the water separator located? I'm guessing this is part of the fuel filter flange... Thanks.

[joe f350]

in on the fire wall driver side

[16Vjohn]

wow... I never noticed that device before. I use it to hold my spare quart of oil!! It looks like one of the previous owners deleted it. There are no lines running to it. Any other ideas?


Edit:

Another question then... Could the injector pump be the cause of this? Is there anywhere the pump could be leaking that may cause this specific issue? It sounds like I am going to have to chase gremlins this weekend and check everything.

[tjc transport]

the fuel return line cap o-rings are probably leaking. air is smaller than fuel, so you can get an air intrusion condition and not have a fuel leak.

[16Vjohn]

Ok, so today I am going to go back and double check all the return lines. Can you elaborate on teh location of the return cap o rings? Thanks for the replies.

[tjc transport]

on top of each injector there is a cap with the return lines attached.
under each cap is o-rings.
they will let air in, but not let fuel out, so most people do not realize they are leaking.

the best way to tell for sure if it is the return lines, is to check to see if the fuel filter is full after sitting overnight.

[Marianna2003]

Hey guys! Why don't you install an electric fuel pump on your vehicles? An investment of about $48.00 +shipping on Ebay will eliminate the need to spin the motor over to prime the injection pump. All you have to do is buy an EP 80-16. It puts out between 6-9 PSI. You can cut a 5-6" section out of the steel line between the mechanical pump and the filter, use the enclosed rubber hoses and clamps and run some wires to switch in the cab and you're ready to prime your system. If you don't want to spend the time to run the wire into the drivers compartment, you can use alligator clips to power up the pump when it is needed. The beauty of these pumps is they are flow through, meaning you can still use the mechanical pump to run down the road. The electric can be used only as necessary without any inconvenience. You could run on just the electric pump if you wanted to. AC had one of these running for about 10,000 hours. It never did fail, itb was shut down to inspect it for wear. It is the same pump that was used on the Imitation diesels that GM fousted off on us in the 80's. I would also suggest replacing the GPs with AC 12Gs or Autolite 1109s. Before you install any glow plug, you should ALWAYS power it up with a battery charger of at least 10 amp capacity. You can use your battery as long as it is in good shape. These GPs are temperature controlled internally and if you leave them powered up for too long, the only thing thatwill happen is, they will stabilize around 700 deg F. THEY WILL NOT BURN UP! BERU ZD9 GPs will melt down if left on too long. They do not have any temperature control. They will heat until the inconel sheath melts (somewhere around 2000deg F).

[tjc transport]

Originally Posted by Marianna2003

Hey guys! Why don't you install an electric fuel pump on your vehicles? An investment of about $48.00 +shipping on Ebay will eliminate the need to spin the motor over to prime the injection pump. All you have to do is buy an EP 80-16. It puts out between 6-9 PSI. You can cut a 5-6" section out of the steel line between the mechanical pump and the filter, use the enclosed rubber hoses and clamps and run some wires to switch in the cab and you're ready to prime your system. If you don't want to spend the time to run the wire into the drivers compartment, you can use alligator clips to power up the pump when it is needed. The beauty of these pumps is they are flow through, meaning you can still use the mechanical pump to run down the road. The electric can be used only as necessary without any inconvenience. You could run on just the electric pump if you wanted to. AC had one of these running for about 10,000 hours. It never did fail, itb was shut down to inspect it for wear. It is the same pump that was used on the Imitation diesels that GM fousted off on us in the 80's. I would also suggest replacing the GPs with AC 12Gs or Autolite 1109s. Before you install any glow plug, you should ALWAYS power it up with a battery charger of at least 10 amp capacity. You can use your battery as long as it is in good shape. These GPs are temperature controlled internally and if you leave them powered up for too long, the only thing thatwill happen is, they will stabilize around 700 deg F. THEY WILL NOT BURN UP! BERU ZD9 GPs will melt down if left on too long. They do not have any temperature control. They will heat until the inconel sheath melts (somewhere around 2000deg F).

very very very bad advice.
the autolite and ac glow plugs are absolute crap that will burn out within 1 week of instalation, and then the tips will swell and force you to pull the heads to replace them. the ONLY glow plugs to use in a ford or international are the MOTOCRAFT/BERU plugs.

and an electric fuel pump will do you no good if you have bad return line o-rings, because once the fuel drains back to the fuel tank, you are still going to have to bleed the air out of the system before it will start.

[Marianna2003]

You are not reading the entire post if you think that I gave you bad advice. The Autolite 1109 & AC 12G GPs are dual coil plugs. They have two coils in series inside of the sheath. As the heater coil heats up, the 2nd coil's resistance increases limiting the current through the plug. This will prevent the system from overheating and melting the sheath. If you don't believe me buy one and try it. If you have one of the BERU plugs, try it. Just hook it up to a 10 amp battery charger and see how hot your BERU gets. I'll bet you remove the power because you don't want to destroy the plug. The AC & Autolite plugs will get red hot and stay that way. You are thinking of the old AC 8Gs and Autolite 1108 GPs which as you stated are CRAP. As for the electric fuel pump, you may have to be patience, but you can leave it on for a half hour or so and it will push fuel through the entire system. Not only that, if you run out of fuel, you won't have endanger your starter to get started, just turn on your electric fuel pump and bleed the air out of your filter and you should be ready to go. $50.00 dollars of prevention is worth more that $100.00 worth of cure. I guess if you like the aggravation of fighting with your engine to purge the air out, have at it.

[tjc transport]

sorry. you could tell me those glow plugs were gold plated, and you were also going to give me $50 for each one i put in.
you know what??
it will still be a cold day in hell before i ever put anything but a MOTORCRAFT/ BERU glow plug in any of my trucks. the first set lasted 16 years.
that and the fact that ford and international ONLY use the beru, i think i will stick with them

[Marianna2003]

More power to you. Have a nice day.

[16Vjohn]

I'll check out the o rings and report back. Thanks guys.

[rupejosh]

do not run an electric and mechanical pump together!!!! it could blow the diaphram in the mechanical and fill your motor with fuel.if you want to use an electrical delete the mechanical pump.