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post #1 of 7 (permalink) Old 01-14-2013, 11:56 AM Thread Starter
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Surging and rough idle

The last couple days my truck has been running weird. The engine has been surging randomly while I am driving. Also the engine will start running rough after I start it, especially if it has just been run a few minutes prior. The engine has also started to run rough at a normal idle several times.

Just a little under 2 years ago I bought a return line kit and installed that. I do not see any visible signs of fuel by any of the injector caps. Also, I have a racor fuel/water separator and I do not see any fuel leakage elsewhere in the system. I also replaced the lift pump less than a year ago.

Before I installed the current return line kit, I was having problem with rough idle, but it would clear up after a 30 sec or so of running. This is the first time I have had the engine run like this after driving for a bit. Does this seem like maybe I need a new return line kit again, or could there be something else that I am missing?

1986 F250 w/Banks turbo
C6 auto, 3.55 gears

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post #2 of 7 (permalink) Old 01-16-2013, 07:35 PM Thread Starter
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Just wondering if anyone has any input on my problem? I am thinking that I will just plan on purchasing another return line kit and go from there. My biggest concern has been the engine surging and rough idle after it has been running for a few minutes. I never had that happen before I put in the current return line kit. Before I installed the current kit, I was only having problems with rough idle and stalling right after I started the engine.

1986 F250 w/Banks turbo
C6 auto, 3.55 gears
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post #3 of 7 (permalink) Old 01-16-2013, 08:41 PM
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I wouldn't concentrate on the return lines, but rather check all potential sources of air intrusion. Fuel heater O-rings, WIF sensor, return lines & caps, etc. You might save yourself the hassle of doing return lines. Or you may find that the return lines AND something else are letting air in.


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post #4 of 7 (permalink) Old 01-17-2013, 08:13 AM
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Other than leaking return lines should have no effect on a running engine. I would first check for leaks on suction( supply side) to include the tank pickup.
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post #5 of 7 (permalink) Old 01-17-2013, 10:21 AM
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I had almost the same problem and I found I had #4 cylinder going dead. I found I had a injector stop working on #4 cylinder. So I ordered all new injectors and installed em and it went away.

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post #6 of 7 (permalink) Old 01-17-2013, 10:21 AM
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Surging and rough idle

If you still have the factory water separator on the firewall, the drains are a known issue. Clamp a bolt in the rubber drain line, and see if that helps.

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post #7 of 7 (permalink) Old 01-23-2013, 12:11 AM
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Surging and rough idle

When have fuel filters been changed?

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