Ford Powerstroke Diesel Forum - Reply to Topic
7.3L IDI (Non-Powerstroke) Diesels Technical discussion of topics related to vehicles powered by the 7.3 Liter In-Direct Injection Navistar engines.

Thread: WD-40, Starting? Reply to Thread
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  Topic Review (Newest First)
11-06-2007 10:20 PM
vitalidle Sure there is a lots of things that can cause fualty gp's. They usually burn out over time from excessive heat. Check the relay first its the easiest test and if its bad replace if its good then you can move to the next proboble cause for your starting problems.
11-06-2007 10:14 PM
84fordforme What about something casuing good gp's to go bad? I rember stumbling across a problem like this, but i can't rember what caused it, or if it even happens in the idi's. Thanks for all the help guys!
11-06-2007 10:12 PM
vitalidle Okay the reason I asked is that all has to factor into your starting. The older and more tired you engine is the harder it will start as it loses compression, but you should be good with only 100 k on the engine. If you replaced the gp's its more then likely the relay is bad.
11-06-2007 10:10 PM
84fordforme its is an 84 ford, the story is that it has a 7.3 idi swapped into it, but honesty i am not sure, everything on it is 6.9 idi, i have not cared enough to find out forsure, i might take the time on day, i had a good diesel mechanic look at it, and told him about the swap and he said it was a clean swap, so i have been trusting that is it indeed a 7.3, with 6.9 parts, such as glow plugs. The milage reads 124,000, so i bielve it has 324,000 with less than 100,000 on the new engine
11-06-2007 10:05 PM
mrnecsteve more use for that miracle liquid WD40...
think i'll start a new thread.
11-06-2007 10:03 PM
84fordforme hahaha, sorry to keep adding, but another question i have is, when i replaced some of my glow plugs, the back 2, or 7,8 cylinder plugs had a gray covering on the tip, sort of like they were dipped in ash, but it was burnt on? what does this tell you more knowledgable guys? thanks!
11-06-2007 10:02 PM
vitalidle What year is your truck and how many miles?
11-06-2007 10:01 PM
2005F250 WD-40 ing is for trucks that run out of fuel not really for cold starts.
11-06-2007 10:00 PM
84fordforme thanks for all the advise guys, i have a new weekend project, dig into the glowplugs. Thanks Now just for my peace of mind, lets say my glow plugs arent cycling fully, and thats causing the starts, theroeticly (sp) it should start after cranking for a couple seconds, and this time will get longer and longer the colder it is? Making a big assumtion that the glow plugs are the issue, what point will it not start?
11-06-2007 09:54 PM
Cj Ford glow plugs bad or the relay for them is bad likely heres the way to check them...

Check each of the glow plug resistance from its terminal to ground with an ohmmeter--the glow plugs should be less than 2 ohms when cold. Another way to test the glow plugs is with a test light (not a LED/circuit tester). Connect the alligator clip to the positive battery terminal and touch the probe to each (unplugged) glow plug terminal. The test lamp will light brightly if the glow plug is good.
Even one open glow plug can shorten the controller on time sufficiently to affect starting.
Next connect the glow plug harness and check for voltage at the relay "hot" terminal with the key off, then check for a voltage drop at the glow plug terminals (86 and earlier) or at the controller/relay "hot" terminal (87 and up) with the relay energized.
If the voltage is low or drops below 10 volts with the relay energized, check for loose connections at the glow plug relay, starter relay or engine harness connector, or bad fuse link(s). Also check for voltage at each glow plug terminal with the relay energized
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