If you have been cranking and cranking and cranking your IDI, and it never seems to catch, then you might have air in your injector lines.\u00a0 The Injector Pump (IP) creates hundreds of PSI of pressure in the injector lines.\u00a0 The injectors “pop” at a high pressure, which sprays diesel fuel into the cylinder head.\u00a0 If there is air in that injector line, the\u00a0IP output pressure\u00a0is padded by the bubbles and the requisite high<\/strong> operating<\/strong> pressure<\/strong> is never achieved.\u00a0 Without high pressure, the injectors do not pop, and those air bubbles never leave the injector line.<\/p>\n The owner must purge that air manually in order to get the injectors popping, and ultimately get the engine running.<\/strong><\/p>\n <\/p>\n Preparation:<\/em><\/p>\n You will need to bleed the air from your injector lines if one or more of the following things occurred:<\/p>\n I personally prefer to use the stumpy Craftsman 5\/8″ wrench<\/a>, because it fits in the van engine bay a lot easier.\u00a0 Also, the quality of the wrench is paramount, because you don’t want\u00a0an inferior-brand wrench\u00a0rounding the hex on the injector lines.<\/p>\n If there is build up or grime on your injectors and lines, clean them off.<\/p>\n <\/p>\n How to Check If there is Air in the Injector Lines<\/em>:<\/p>\n If you have been cranking and nothing seems to start the engine, “crack” a few injector lines.\u00a0 “Cracking” means to unthread the end of the injector line at the top of the injector.\u00a0 You only need to unthread it a few threads.\u00a0 Taking the injector line off the injector is ok, but it is a pain to reinstall quickly, so I recommend just unthreading it a few threads so that the air can find a path out.<\/p>\n With 3 or 4 lines “cracked,” turn over the engine for about five to ten seconds with the accelerator fully depressed.\u00a0 A properly-purged fuel injection system should dribble diesel fuel immediately out of the lines.\u00a0 If nothing comes out, this affirms there is air in the IP and\/or lines.<\/p>\n <\/p>\n Ruling External Problems Out<\/em>:<\/p>\n First, check to make sure you are getting fuel to the Schroeder valve<\/a> on the diesel fuel filter.\u00a0\u00a0Read this article FIRST\u00a0which explains how to check your\u00a0Schroeder Valve<\/a>.<\/p>\n Second, make sure you have proper batteries.\u00a0 They need to be at least 12.3V to make the IDI crank well on a good day.\u00a0 You will need a lot more voltage and amperage for the upcoming injector line purge cranking.\u00a0 Slow rotation will not fire these beasts up.\u00a0 Also, if the batteries are old, don’t crank well, have a bad cell, or don’t take a charge will be a problem.<\/p>\n Third, make sure your starter and cables are in good order.\u00a0 This cranking process might put some strain on them.<\/p>\n <\/p>\n Bleeding Process:<\/em><\/p>\n To reiterate, “cracking” means to unthread the end of the injector line at the top of the injector.\u00a0 You only need to unthread it a few threads.\u00a0 Taking the injector line off the injector is ok, but it is a pain to reinstall quickly, so I recommend just unthreading it a few threads so that the air can find a path out.<\/p>\n With the injector lines cracked and the accelerator completely depressed, crank the engine for no longer than\u00a015 seconds<\/strong>.\u00a0 Cranking the engine for a long duration will burn up the starter.\u00a0 Let the starter rest for 2 minutes before beginning the 20-second cranking process again.\u00a0 Keep repeating this 15-on-2:00-off cranking interval until you start to see diesel creeping out of the top of the injectors. (see image below)<\/p>\n Using the paper towel, wipe the dribbling fuel off.\u00a0 Once the spurting fuel is consistent (not just random bubbles), use the 5\/8″ wrench to tighten the end of the injector line on the injector.\u00a0 The quicker you torque it down, the less likely the fuel is going to work its way out of the crack, and the less likely it will lose its prime.\u00a0 So the moment you see consistent flow out of the injector line, immediately tighten it, and the better off you’ll be.<\/p>\n One-by-one, you will tighten down the lines.\u00a0 By the time four or five lines are tight, the engine will start to sputter.\u00a0 It might even start.\u00a0 Give the engine half throttle to work out any remaining bubbles.\u00a0 As soon as possible, torque down the remaining injectors.\u00a0 Any delay will result in diesel fuel spraying all over the engine bay.\u00a0 There may be a few minutes of a rough idle, because remaining bubbles might need to work their way through the injectors.<\/p>\n At this point, the IDI should be idling.\u00a0 If not, keep on reading.<\/p>\n <\/p>\n Troubleshooting<\/em>:<\/p>\n A while back, I had an IP that wouldn’t provide any fuel to the injectors at all.\u00a0 I had checked everything, and the IP had fuel in its reservoir, but it wouldn’t push a drop to the injectors.\u00a0 Eventually, I learned that my IP Metering Valve was stuck.\u00a0 This is not a basic procedure, so I’m not going to go into detail on how to resolve that in this article, but some explanations are located on FTE<\/a>.\u00a0 Also, here is an article and video I made to explain how to adjust your metering valve, if you feel the need to do it:<\/p>\n How to Manipulate the Metering Valve on 6.9 \/ 7.3 IDI Injector Pump<\/a><\/p><\/blockquote>\n\n
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<\/a>Tools necessary:<\/p>\n\n
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<\/p>\n![\"\"](\"http:\/\/www.nickpisca.com\/diesel\/wp-content\/uploads\/2018\/03\/20180314_bleedsfw.jpg\")
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