superbeetle73
Registered User
Just wondering if the returns get kinked or clogged does that put more strain on the ip? Maybe causing no fuel to cool the ip and messing up timing plus smoking like crazy.
what happens if your return line is plugged up or clogged??
- Thread starter superbeetle73
- Start date
all that plus leaking out of the return caps too. they aren't really designed to hold pressure at all.
icanfixall
Official GMM hand model
If the fuel stops from returning out the top of the injection pump the engine will stop running. That "click" we hear and feel is the fuel shutoff solenoid opening allowing fuel to flow thru the pump to cool it and return to the tanks.
junk
Full Access Member
I know I had the smaller tubed 6.9 return kit on my 7.3 that should of had the larger kit and it wouldnt run long at all. Evidently the pumps can be fussy about getting the extra fuel out of them.
So yes I would say that would cause troubles.
So yes I would say that would cause troubles.
Here's the reverse to the smaller diameter hose, too big a hose and there's not enough back pressure to keep fuel in the lines, can cause air intrusion like symptoms. Detroits have an actual fuel restrictor to keep fuel in em.... basically a washer type thingy like you might put in a shower head, reduces flow, but still enough to make it wet! 
Many times a restriction in a return line will cause your IP to inject a higher volume of fuel and overrun the governner. It's a common trick for company truck drivers to carry a pair of vice grips to put on a fuel return line to get more power and speed out of a diesel. Big drawbacks are too much restriction and they wont return to idle very well and very poor engine braking and can blow out seals ( i.e. not reccomended )
Black dawg
Registered User
A completely plugged return wont let the motor run. Any restriction of the return line raises housing pressure in the pump, retarding timing. And yes, if less fuel is going out the return, the pump will in theory run hotter.
the difference in the return lines has nothing to do with the way it runs unless you have a problem elsewhere, gm uses a tiny line and they dont have problems, but a restriction anywhere in the system from the pump outlet will cause it to shut down. I have troubleshooted many of these. lots of plastic lines get pinched when engine swaps are done and can cause problems, my truck was doing it cause the switch valve was messed up on the return side.
about the only problem I haven't had with my return fuel system is a clog, but I've been fighting leaks for over a year and I've made about a dozen attempts to replace/repair they system, al failed.
I'm thinking of machining some metal caps and welding them on, they'd look similar to the existing plastic ones, but no o rings. Not sure if it will work, but they damn straight won't be leaking any more.
I'm thinking of machining some metal caps and welding them on, they'd look similar to the existing plastic ones, but no o rings. Not sure if it will work, but they damn straight won't be leaking any more.
rodroyle2131
Registered User
Ok I have a 1995 Mercedes e300 diesel. My return keeps popping off and spraying fuel everywhere. Because the fuel is coming out of the merge to the return like to the tank is where the pressure is coming from I suspect a blockage somewhere down stream. Side note...I replaced the fuel tank a year ago and noticed that the return line going into the fuel tank looked dry like it hasn't seen any fuel in quite some time. But I wasn't experiencing any return lines popping off so I didn't give it much thought.
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rodroyle2131
Registered User
Additional: So I know it's
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rodroyle2131
Registered User
Going to be hard to believe.
My return lines coming from the injectors is connected to a tee that comes out of the main fuel filter. That tee is connected to a 90° bend fuel line that is connected to a 1 way valve. The one way valve is then connected to the hose that goes to the hard line to the tank.
Like I said, this is going to be hard to believe but the 1 way valve was installed backwards.
I've been driving the car for years and until I started popping the return line I didn't know I had a problem.
I want to thank others here that pointed me in the right direction. I had thought it might have been a blockage but how in the hell does someone install a 1 way valve backwards. Just goes to show you can't take anything for granted.
Roddy
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My return lines coming from the injectors is connected to a tee that comes out of the main fuel filter. That tee is connected to a 90° bend fuel line that is connected to a 1 way valve. The one way valve is then connected to the hose that goes to the hard line to the tank.
Like I said, this is going to be hard to believe but the 1 way valve was installed backwards.
I've been driving the car for years and until I started popping the return line I didn't know I had a problem.
I want to thank others here that pointed me in the right direction. I had thought it might have been a blockage but how in the hell does someone install a 1 way valve backwards. Just goes to show you can't take anything for granted.
Roddy
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rodroyle2131
Registered User
The purpose of the return line is to cool the injection pump and injectors. Trying to defeat the return system will make your injection pump and injectors work harder and fail quicker.
When the blockage is discovered and remedied there shouldn't be any restrictions and the return lines should be free flowing and there shouldn't be any back pressure to pop the return lines. My initial thought was to install some type of clamp to prevent the return line from popping off but that wouldn't resolve the problem. Just hide it.
Case in point: My father was having these bad headaches and the doctors gave him drugs to mask the symptoms. He went on like this for years.
Turns out he had brain cancer.
My point is if something isn't right don't mask the problem. Find out what is causing the problem and fix it.
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When the blockage is discovered and remedied there shouldn't be any restrictions and the return lines should be free flowing and there shouldn't be any back pressure to pop the return lines. My initial thought was to install some type of clamp to prevent the return line from popping off but that wouldn't resolve the problem. Just hide it.
Case in point: My father was having these bad headaches and the doctors gave him drugs to mask the symptoms. He went on like this for years.
Turns out he had brain cancer.
My point is if something isn't right don't mask the problem. Find out what is causing the problem and fix it.
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