I Need Help Troubleshooting the classic Air Intrusion Problem

[jim x 3]

I Need Help Troubleshooting the classic Air Intrusion Problem

I have been fighting this issue on/off since Oct '13. After sitting 24 hours, truck starts immediately, runs for 1 second, then dies. Considerable cranking is required for restart. After this, truck starts immediately and runs without trouble all day long. Since I'm an electrician and not a plumber, maybe some of you guys who have suffered can give me some advice. To the best of my knowledge, the fuel system components are all stock - as when the truck was new.

I have:

1. Replaced all return banjos, O-rings, and return hose (Typ4) No visible fuel leaks
2. Replaced 5/16" Olives in filter head-IP steel line, both ends (Typ4) No visible fuel leaks
3. Checked Shrader valve for tightness, replaced cap
4. Replaced O-ring @ top of IP (@ check valve fitting)
5. Replaced hose @ top of IP (EL fitting to return steel line that runs back to "T" near cyl 8
6. Added a clear hose section to rubber line from #1 return banjo to filter head - overnight, air bubbles will cluster in the top portion of this hose until hose is completely empty of fuel. Very small bubbles are coming out of the filter head barbed fitting between vacuum switch and Shrader fitting.
7. Replaced the 3/8" olive in the lift pump-filter head steel line (Typ4) No visible fuel leaks
8. Removed and replaced fuel filter and rubber washer in water drain at bottom of filter. Filter was full of fuel when removed, but no fuel spilled down the filter element as I spun it off.
9. Removed and replaced the Shrader fitting and barbed fitting in the filter head, used Rectorseal on threads when replacing. Replaced the Shrader valve core and cap. (If the core is depressed with engine off, bubbles appear in the clear line rapidly and the line empties of fuel - 10 seconds to mimic the 24 hour problem). I thought there was supposed to be a check valve in the barbed fitting, but there was none. ID of that fiting is very small.

Since the problem appears to be localized to the filter head (am I wrong here?) I have not changed anything at the return line "T" fitting(s) near cyl #8 or any fuel lines, FSV, or tank connections. But there are no visible fuel leaks anywhere in those components.

I have not yet messed with the lift pump, filter head fuel heater (power wire has been disconnected since I've owned the truck), the filter head vacuum switch (which is working), or the Shrader valve for air entry at water drain at the bottom of the filter (this is not a standard Shrader core). No visible fuel leaks

My GPs, GPC, batteries, starter, and other electrics are all good, so the problem has been just a daily annoyance (and occasional embarrassment), but it sure is getting old. I know I can mask the issue by replacing the lift pump with an electric that will re-prime my fuel lines prior to start, but I'd like to find the leak.

Any suggestions for me?

Thanks guys,

 

[icanfixall]

Really sounds to me like the lift pump check valves are shot. I did not read anything bout the lift pump being replaced. Also is the valley pan wet under the injection pump. If it is you need to find the fuel leak. It mostly will be the advance plunger on the drivers side of the pump or a gasket on the rear end of the pump. Can't think of any other leak areas. If the pump advance plunger seal leaks the fuel drains out and its going to fire up and die right away like what you describe. Also that leak at the filter head needs to be fixed. That allows the line to the injection pump and the pump to drain dry or nearly dry causing the start and die syndrome...

 

[Wyreth]

I Need Help Troubleshooting the classic Air Intrusion Problem

6. Added a clear hose section to rubber line from #1 return banjo to filter head - overnight, air bubbles will cluster in the top portion of this hose until hose is completely empty of fuel. Very small bubbles are coming out of the filter head barbed fitting between vacuum switch and Shrader fitting.
7. Replaced the 3/8" olive in the lift pump-filter head steel line (Typ4) No visible fuel leaks
I thought there was supposed to be a check valve in the barbed fitting, but there was none. ID of that fiting is very small.

Since the problem appears to be localized to the filter head (am I wrong here?) I have not changed anything at the return line "T" fitting(s) near cyl #8 or any fuel lines, FSV, or tank connections. But there are no visible fuel leaks anywhere in those components.

Well first, the bubbles say the problem is coming from your filter head, or before. Also yes, the barbed fitting is supposed to be a check valve. (little looking in the parts bin and it is P/N: E8TZ-9K061-A ) So that should be replaced with the correct part. Another thing, while the clear line test is showing that the 4th Olive at the back return T is holding air. Now would still be a good time to replace it. I mean you're in there anyway, and you've replaced everything else. Don't let it come back to haunt you in a few months.

Next things I would do are: firstly I would replace the little rubber fuel line that goes between the tank supply hardline and your fuel pump. That is a sneaky place air likes to get in. Then I would replace the fuel heater o-rings. There are several really really good videos on how to do this on Youtube. It is dead simple, and the videos are very clear on how/what needs to be done. After that, if you're still getting air bubbles on your clear line, again replace the little fuel line by the lift pump, but this time with a clear line. Then see if you're getting air from the tank, or from the lift pump side. That will tell you where to go looking next. However, I'd bet it's one of the two things I suggested.

 

[woody5484]

I am having the same problem but am just starting the hunt. Never heard of a 5/16 olive.

(Replaced 5/16" Olives in filter head-IP steel line, both ends (Typ4) No visible fuel leaks)

What is that and what does it look like, just an o-ring?

 

[Zaggnutt]

I have been struggling with air intrusion for a couple months. I am currently switching to manual tank selector valves after isolating the FSV as a major player in the conspiracy... I wanted to add to what Wyreth mentioned regarding the short length of rubber hose that connects the lift pump to the metal fuel line coming from the tank...

On my truck that piece of hose was okay BUT about 4" back along the steel line was a hole at least 1/16" in diameter caused by the steel line rubbing against the fender well. The giveaway was the steel line was wet, but the areas around it were dry. It was very difficult to find for several reasons I won't detail here.

I didn't have any issues with starting or running the truck until the FSV tag teamed the fuel system.

 

[Zaggnutt]

6. Added a clear hose section to rubber line from #1 return banjo to filter head - overnight, air bubbles will cluster in the top portion of this hose until hose is completely empty of fuel. Very small bubbles are coming out of the filter head barbed fitting between vacuum switch and Shrader fitting.

(If the core is depressed with engine off, bubbles appear in the clear line rapidly and the line empties of fuel - 10 seconds to mimic the 24 hour problem).I thought there was supposed to be a check valve in the barbed fitting, but there was none. ID of that fiting is very small.

Should be some sort of check component... Mine is a long thin spring and a plastic ball. Maybe a good place to start.

 

[jim x 3]

Additional Info/Questions based upon your replies

Additional Info/Questions based upon your replies:

The lift pump and its short rubber input hose and hose clamps were all replaced in 12/2012. I believe these components are OK - I did check them for tightness and leaks.

There is no fuel leaking anywhere - I previously checked the surfaces of the IP and the valley pan in particular - all OK.

My return line barbed fitting at the filter head definitely has no check function - I could blow thru it both ways when it was removed. The orifice in this fitting is less than 1/16". In which direction is it supposed to check the flow? - I'm figuring it should only allow flow from return lines into the filter head.

Wy: Fuel heater O-rings could definitely be the trouble even though no fuel is leaking out. Thanks for the part # reference for the correct barbed fitting at the filter head.

*****: An "Olive" is a cylindrical rubber seal found in the fittings at both ends of the 5/16" steel line from filter head to Injection Pump (in my Model Year 1988 configuration, at any rate). The fittings at each end of the line look a little like compression fittings but they actually contain rubber seals - olives. There are 3/8" olives on the 3/8" steel line from lift pump to filter head (at the fitting at input to the filter head) and also in the return line system back near cyl#8. Member Typ4 is a good source for replacement olives.

Good suggestions all - Thanks for the help.

 

[icanfixall]

That return line check valve from the filter to the return line system flows OUTWARDS from the filter. It will check flow trying to enter the filter from the return line system. Caution purchasing a new one. There are 2 sizes. A 3/16 and a 1/4 inch size for the particular return line size you have. Oregon fuel Injection has both sizes. Many members do not know how this check valve works. Its design is to all air and some fuel to flow out of the filter head. Never is to allow fuel to flow back into the filter head. I have not taken one apart but I know it has a spring in it and feel it has a ball checking the flow. I also believe it will allow air out but when the fuel reaches the ball it pushes it closed checking the flow.

 

[Zaggnutt]

That return line check valve from the filter to the return line system flows OUTWARDS from the filter. It will check flow trying to enter the filter from the return line system. Caution purchasing a new one. There are 2 sizes. A 3/16 and a 1/4 inch size for the particular return line size you have. Oregon fuel Injection has both sizes. Many members do not know how this check valve works. Its design is to all air and some fuel to flow out of the filter head. Never is to allow fuel to flow back into the filter head. I have not taken one apart but I know it has a spring in it and feel it has a ball checking the flow. I also believe it will allow air out but when the fuel reaches the ball it pushes it closed checking the flow.

Yep. The ball is on the inside and the spring is on the outer (driver side) of the ball which would check back flow but allow fuel out from the filter head as mentioned.

 

[testlight]

Drain fuel lines, connect to shop air use a regulator turned down to 5 or ten psi spray it all down with soapy water, just like a propane leak test .

Just don't use too much air pressure.

 

[quickster]

I would bet on the fuel heater o rings. I had the same problem last year. No fuel leaks - just air intrusion.

 

[hotshotidi]

get a facet duralift and air brake line for fuel lines it solved all my problems

 

[jim x 3]

To all:

In addition to all I did previously (see original post), I replaced the return line check valve from the filter to the return line system - this did not fix the problem.

But now I think I've finally got it fixed. I waited until dirt/grime affixed itself to the return line caps. #1 was a minor mess, and #8 had a very little grime. All of the others were completely clean. So I (again) replaced the O-rings in #1 and #8 return caps, while re-using the caps themselves, and the transparent portion of the return line now stays full of fuel. The truck starts and runs smoothly no matter how long between starts. Whew.

Regards,

 

[hotshotidi]

Congratulations I'm glad to see u got it all fixed

 

[drinkypoo]

I know this is already solved, but I had a similar problem, had to replace O-Rings on one cap. Those threads are wicked sharp.

I also had drainback until I replaced my filter head check valve spring with a heavier one... because I lost the original