Compression loss, fuel filter replacement?
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From: Wilmington DE
Compression loss, fuel filter replacement?
I have a 1993 f250 7.3l idi with 280,000 miles. Recently it has lost compression. When I put eether it will fire up and when it starts it runs fine. It's just getting it started is the hard part. I had a friend tell me it may be the fuel filter because it runs perfectly fine once I get it started. The problem is getting it started
Logistics Pro
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From: Western Mass
May also have a return line air leak. What condition are the plastic caps on the injectors and the rubber fuel lines running between them?
There are a couple places air intrusion can happen and that can lead to hard starts as well as glow plug issues.
There are a couple places air intrusion can happen and that can lead to hard starts as well as glow plug issues.
Logistics Pro
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From: Western Mass
Also, be VERY careful using ether on these engines (and any diesel with glow plugs or other preheat systems). You can very easily cause a great deal of damage if the ether hits hot glow plugs and fires off before the fuel is injected.
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From: Muskegon, MI (home)
I hope you don't have to go through what I did on my 84 6.9L. I went through the entire fuel system. All new lines from the tank forward, e-pump conversion, return lines, caps, o-rings, the whole hum dinger. After all that, still had a hard starting issue. To make a long story short after pulling the engine and completely tearing it down, I had valves and seats that were completely shot and broken piston rings. The compression test actually checked out okay, however a leak down test told me the real story about the health of the engine. Now I am doing a full rebuild.
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I guess I really don't specifically know if it is 100% compression loss. I kinda just figured it would be that because once it finally does get running it runs like a dream, no sputtering, nothing. It runs perfect for a truck that old.
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I know that the fuel lines are all good cause that is the first thing that I checked. However I have not checked the caps on the injectors themselves, I've just made sure that the injectors are pressed in.
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Logistics Pro
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From: Western Mass
The caps are plastic and have o-rings under them to seal them. While they may look ok, and not show any fuel leaks, air may be leaking in and causing the fuel to drain out of the fuel filter and back to the tank. Its been found that if they caps/fuel return lines are disturbed, they'll start leaking. Especially if its been a few years since they were done. There is a LOT of info about this on here. The o-rings that generally come with the kits are sub-par. Viton o-rings are better, and need to be lubed up well for the install.
First of all though, do you have any clue if your glow plug system is functioning? Does the 'wait to start' light come on? And if it does, for how long?
There are two very good stickies at the top of the forum, one for the old system, and one for the new glow plug system. You should have the new system in your 1993. Read through that thread.
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probably the glow plug system ..
these fail often and make for very hard starting ..
even on a perfect motor ..
actually especially on a healthy motor ..
this is because it's a big V8 pushing 21:1 compression so it's a bear to turn over
you can not safely use ether with the glow plugs working it will pop out the pre cups and blow your motor ..
you can diagnose and fix the glow plugs - relay - or controler ..
or unhook the small wire towards the driver side on the glo plug relay .. then double check no clicking / no volts at the plugs with a meter .. then you can safely use ether to start
these fail often and make for very hard starting ..
even on a perfect motor ..
actually especially on a healthy motor ..
this is because it's a big V8 pushing 21:1 compression so it's a bear to turn over
you can not safely use ether with the glow plugs working it will pop out the pre cups and blow your motor ..
you can diagnose and fix the glow plugs - relay - or controler ..
or unhook the small wire towards the driver side on the glo plug relay .. then double check no clicking / no volts at the plugs with a meter .. then you can safely use ether to start
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From: Wilmington DE
First of all, the injectors are screwed in to the heads.
The caps are plastic and have o-rings under them to seal them. While they may look ok, and not show any fuel leaks, air may be leaking in and causing the fuel to drain out of the fuel filter and back to the tank. Its been found that if they caps/fuel return lines are disturbed, they'll start leaking. Especially if its been a few years since they were done. There is a LOT of info about this on here. The o-rings that generally come with the kits are sub-par. Viton o-rings are better, and need to be lubed up well for the install.
First of all though, do you have any clue if your glow plug system is functioning? Does the 'wait to start' light come on? And if it does, for how long?
There are two very good stickies at the top of the forum, one for the old system, and one for the new glow plug system. You should have the new system in your 1993. Read through that thread.
The caps are plastic and have o-rings under them to seal them. While they may look ok, and not show any fuel leaks, air may be leaking in and causing the fuel to drain out of the fuel filter and back to the tank. Its been found that if they caps/fuel return lines are disturbed, they'll start leaking. Especially if its been a few years since they were done. There is a LOT of info about this on here. The o-rings that generally come with the kits are sub-par. Viton o-rings are better, and need to be lubed up well for the install.
First of all though, do you have any clue if your glow plug system is functioning? Does the 'wait to start' light come on? And if it does, for how long?
There are two very good stickies at the top of the forum, one for the old system, and one for the new glow plug system. You should have the new system in your 1993. Read through that thread.
Logistics Pro
Joined: Sep 2007
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From: Western Mass
That sounds like the glow plugs are working... Generally if they are burnt out the light will be on for much less time, or not at all. There is more troubleshooting in the glow plug stickies.
What do the fuel returns look like?
Also one thing to try and pull off the fuel filter before trying to start (on a cold start, like after sitting overnight). If its only half full you have an air intrusion issue.
What do the fuel returns look like?
Also one thing to try and pull off the fuel filter before trying to start (on a cold start, like after sitting overnight). If its only half full you have an air intrusion issue.
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