My kits include olives. Always have
Leaking return lines
- Thread starter Ddizzy77
- Start date
I bought a set a year ago, didnt work at all. Installation is a pain and the locations of the ports are nearly impossible to get fuel lines on
Macrobb
Full Access Member
Because it doesn't matter at all. The entire return side of the system can be empty of fuel for all that it matters - let it drain to the tank!
The /only thing/ that matters is that the /supply/ side stays full of fuel. That is, from the tank, through the filter, to the IP.
Now, what usually happens is that you get a leak somewhere high in the system - maby at the return caps.
Gravity will pull the fuel downward on the supply side(and back to tank) if there isn't something preventing it - either a check-valve, or a vacuum being drawn from the return side(remember - for fuel to flow back, something has to replace it).
This is why a check valve works wonders - you get a break in the return line somewhere, break the vacuum, fuel tries to flow backwards to the tank... and stops due to the check valve.
The fuel /before/ the check valve does the same thing - to "fall" back to the tank, it would need something to replace it and just won't(unless you had another leak at the check valve inlet).
edit:
To visualize this better, think about a straw and a glass of water. You can dip the straw into the glass of water, put your finger over the top, and pull it out of the glass... the straw stays full of water!
Why? Because your finger is acting like a check-valve, preventing the water in the straw from falling. Pull your finger away from the top, letting air in... and suddenly it all falls down and out of the straw.
SD94
Registered User
My 94 did that it was a loose connection on the supply line to the injector pump
You are correct, the supply side is what you need to keep full. But the supply side is hooked directly to the return to the tank. There are return lines coming off the filter head and I remember one I had to replace somewhere up front of the ip. So where there is a route, it will take it. Of course you know your check valve will only stop backward flow, the return line at the rear is forward so fuel will freely flow through your new check and down the rear return line.
Flow does not go freely to the return if there is pressure on the supply side. I’ve had a check valve on my supply side for years and my fuel system will hold 5 psi for days. This is because there is a small pressure relief valve on the top cover of the ip that is designed to hold some fuel pressure inside the top of the ip. When you add a check valve they work together to hold pressure in the system without drain back.
If all this is true, then why does a small air leak at one of the o-rings at the injectors drain all the fuel down? I don't know where it is, but there is a factory check valve somewhere on the supply side originally if I recall.
Here's a couple that this place sells. Looks like it fits the later trucks and is on the return line only, not the supply. Still trying to find out something.
https://oregonfuelinjection.com/sho...-1994-6-9-7-3-l-idi/filter-check-valve-92-up/
https://oregonfuelinjection.com/sho...-7-3-l-idi/check-valve-late91-early92-14-inc/
https://oregonfuelinjection.com/sho...-1994-6-9-7-3-l-idi/filter-check-valve-92-up/
https://oregonfuelinjection.com/sho...-7-3-l-idi/check-valve-late91-early92-14-inc/
In this thread, he says the check is really a air bleed off. So I may be wrong, there is no check in the supply. If it were that simple, you would think Ford or International would have put a check in the supply line. I am still doubtful that will fix the o-ring leakage problems.
https://www.oilburners.net/threads/7-3-filter-head-checkvalve.56794/
https://www.oilburners.net/threads/7-3-filter-head-checkvalve.56794/
Because if air can replace the fluid in the lines then it will drain back to tank, if it is sealed it won’t. The injectors are past the ip, and there is no factory check valve on the supply side. If there was then you wouldn’t be able to blow through the line back to the tank.
I’m not saying this is a cure all, just a simple tip that helps.
tbirdfiend281
Full Access Member
sorry to thread hijack, but you mean to tell me, they cost 360$ and they do not work? thats insane.
I got the cheapest version and made my own lines but no, did not work at all. Maybe he has found a different machinest since then but the machine work was pretty poor imo.
If anyone wants to buy it from me
tbirdfiend281
Full Access Member
I am still skeptical about the kit though, they do not have any pictures of it installed on a motor. I will have to look and see if the compound turbo motor has them on it.
