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Discussion Starter #1
As it gets colder, my truck starts slower and slower, sometimes, it will crank slowly and fire up after a few seconds once it gets going, even if its 30 degrees, but some days it will crank for 5-7ish second once it gets going, and fire much later than i expect it to. Does anyone have any ideas why the engine will take longer to fire up sometimes? The colder it is, the slower my old diesel will start, but the random "harder" starts can happen when its like 45 degrees? Anways, my real question is, how do you use WD-40 to start an engine that won't start? I know one of these days its going to be to much for it, and it wont fire up. Do you spray some into the intake tube after you take off the filter cover? Do you crank it while spraying? Sorry if this is a dumb question, but i am not sure. Thanks guys.


If it helps to diagnose the starting issues, i have recently changed the fuel filter, ran injector cleaner, and have new oil in it (15w-40 and i am considering putting 10w-30 in for the winter).

Thanks again!
 

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Sounds like it could be a glow plug relay or glow plug problem.
 

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u definately have a glow plug/relay problem.....get that fixed and it should fire right up for you after the wait to start light goes out..
 

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pull the lid off the air cleaner spray away then crank her up... if you have 2 people spray while cranking that works the best.. we do this for when people run out of diesel in the older trucks to help get them running
 

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Discussion Starter #5
I thought that at first, and since when i bought the truck i had no idea when the last time the glow plugs were changed, i replaced 6 our of 8 (they all tested fine, and the other two were impossible to get to becasue of the fuel line). They cycle for, say 10 seconds, more when its colder, what are signs that my relay is the culprit?
 

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Discussion Starter #6
What is the best way to test the glowplugs? I have heard that something can go wrong with something and fry new glowplugs. Is this possible?
 

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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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Discussion Starter #8
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?
 

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What year is your truck and how many miles?
 

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Discussion Starter #11
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!
 

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Discussion Starter #13
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
 

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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.
 

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Discussion Starter #15
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!
 

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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.
 
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