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Discussion Starter #1
My 6.2 has been starting hard after sitting a few hours lately, requiring full throttle etc classic air in the fuel symptoms. The throttle shaft is slightly damp, but it always has been since I bought the truck so I never worried about it, and it hasn't gotten any worse. The rubber line from the FFM to the IP is leaking pretty bad though from what little I can see with the intake on, does anyone know what size it is? I have seen either 3/8, 5/16, and 1/4 from my searching. Also, what size is the hose to the brass "T" valve? I put a hole in that from merely moving it when I first bought the truck so I know its time to replace whatever rubber lines I can.
 

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1/4" filter to drain, filter to IP. 3/8" supply from lift pump/fuel tank.

5/16" fuel tank return

Sent from my SM-S920L using Tapatalk
 
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Discussion Starter #3
Thanks for the quick reply! Is there anywhere other common places I should check for leaks? I've read that throttle shaft leaks don't commonly cause hard starting, is there any truth to that? it isn't bad enough that I want to replace the IP if it isn't gonna cause any issues.
 

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My opinion, any fuel leak out is air in .... fix it.

Got a model 80 filter head? Another good leak spot.

I use a mod'd fuel cap and a regulator and set it to 5ish psi and go over the whole fuel system for leaks, any wet spot = fixy time.

:coffee:
 

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Need to repair all places fuel leaks out, or air can infiltrate into the system, including the injection pump. If you do not have a clear line off the IP to the return, do so. Now check the throttle by snapping it a few times (both sides of shaft have seals), any air is too much. Another problem with older IP's, is the advance piston plunger. Try rocking the advance lever a few times, they have a tendency to become pitted over time and tear the plunger seal.

The air pressurizing the fuel tank is a good method, that we do not utilize often enough. We are more prone to just tear it all out and replace......LOL....J&J.
 

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Discussion Starter #6
Look like I'll be replacing the IP when funds allow, until then I'll fix the rubber lines and hope that at least helps the hard starting. It's only really noticeable if its sits more than 1 day. Is the model 80 filter the square one? not familiar with the terminology. It has a big square filter under the air filter bolted to the back of the intake manifold. I haven't changed it yet, but I'm not sure if I want to swap to anything else. I need the fuel heater in the winter, Today is the first time in weeks its been above 0.
 

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94 has a FFM. May want to visit the 6.5 section. The entire system is prone to leaks when the lines and hoses are well aged. I can tell you what i believe but you are best off evaluating the entire system. I ran rubber lines for my 94 covered with 2 different colored wire loom for protection and identification of return and feed lines. Holding up well.
 

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Discussion Starter #8
My 6.2 does not have the same FFM my 6.5 did. The 6.5 was round, the 6.2 is square
 
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You can probably get the IP repaired for just shaft seals.

Yes, the model 80 is the square filter version wither it's fire wall or intake mounted.

The shaft seal leaks could be the only problem you have or 1 of a few. I would go over the whole fuel system and make sure you have no other leaks.

:coffee:
 

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Discussion Starter #10
I sprayed the throttle shaft with carb cleaner on tuesday, they haven't gotten wet since. I think my only major leak that will require immediate attention is the inlet housing hose. I will be updating this thread after I pull the intake manifold off and replace the hoses and get a better look at everything. Thanks everyone for the advise so far!
 

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You can have air leaks INTO the fuel for years, and even more than a decade before it gets bad enough for fuel to leak out. And it can be really bad. Speaking from personal experience. Every and I do mean EVERY rubber hose on the fuel system all the way to the tank is suspect if its more than a few years old. PARTICULARLY if its original.
 

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And some guys only had problems when turning right, for some reason that was the only time it would such air .... and chased it and chased it and chased it ....


:coffee:
 

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When you do the inlet hose, be sure to install a clear line from the injection pump to the return circuit(if you have not already done so). This is the very best way (and simplest) to troubleshoot air in the system. With a clear line, it takes only another minute, and the injection pump seals can be confirmed as good/bad......J&J.
 

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Discussion Starter #14
I pulled the intake manifold today and replaced the rubber lines, totally spaced putting a clear line on. But, the line from the FFM to the IP inlet was shot. it was soaked in fuel, and as soon as I touched the hose clamp it started squirting, the hose clamp had put holes in the line after 25 years of heat cycles. The line to the T valve was hard as rock, and there was a big mouse nest in the valley. The lift pump works flawlessly, it sprays a ton out of the t valve and the motor runs fine with the t valve open. Tomorrow I'll know for sure if my hard starting issue is fixed.
 
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Yup, mice love that lil spot to make a mousy hotel.

Yup, typical, old fuel lines, gata love em.... I got a 6.x like yours with the water drain T up by the water cross over, cheap cause the line was old and cracked, causing a brutal cold start. Owner figured the engine was hooped, I pulled the intake, found the line and replaced it, GTG.

:coffee:
 

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Discussion Starter #16
The verdict is in..... after sitting 17 hours under 10 degrees fahrenheit, it fired right up with no throttle input, other than setting the high idle. Good enough for me!
 

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Awesome to hear!!

Go forth and diesel on ....

:coffee:
 

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Discussion Starter #18
Little update, truck just sat for 2+ weeks, it was 20 Degrees Fahrenheit today, it started right up with no throttle input. If your truck has done ANY prolonged sitting, just replace fuel lines, why mess around with an annoying issue if the fix is so cheap and easy?
 
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