Hard starting 7.3
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Senior User
Joined: Jul 2004
Posts: 180
Likes: 1
From: st.petersburg, fl
Hard starting 7.3
If anyone can help me I would appreciate it. I have a 2000 f350 7.3. When I first start it it seems to have a fuel problem. It really runs rough like it is running on 4 cylinders. This last for about 20 seconds then it will run ok. Anybody have this problem before. Thanks for any input . Ron
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Let's start with the simple stuff. What oil are you using? How many miles on it? Is it full? How long since the last fuel filter change? Air filter? CEL come on when it's starts up on 4? Codes? Smoke out the tailpipe? If so, what color? Low on power? Using oil? Any signs of oil in the fuel filter bowl?
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
Very low fuel level could mean you're sucking air in with the fuel. Fill the tank up and see if the issue shows up again.
FYI, running the tank very low means you tend to suck up any debris in the tank into the screens in the mixing chamber. If you start to experience issues under heavy load, the first thing to check would be a fuel restriction caused by plugged screens in the mixing chamber.
FYI, running the tank very low means you tend to suck up any debris in the tank into the screens in the mixing chamber. If you start to experience issues under heavy load, the first thing to check would be a fuel restriction caused by plugged screens in the mixing chamber.
Elder User
Joined: Oct 2007
Posts: 672
Likes: 0
From: NJ
Hey Chris. I realize that it is bad to run these trucks out of fuel, witht he priming issues and all, but I always thought the debris-suckup was a wives' tale. I'm not knocking your knowledge at all, you definitely have more experience than I do, it just seems that with the fuel intake on the bottom of the tank, it would always draw fuel from the bottom. Sorry for the hijack.
Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
You're right in a sense Jack, but there are 2 things to keep in mind. 1) when you run the tank very low, whatever debris is in the tank winds up in the bottom of the tank where the fuel pick up is. 2) If you watch when you pump fuel in the tank, you'll notice that diesel tends to foam up when being pumped in the tank. Our electric fuel pump is an on/off type pump, so it pumps the same volume of fuel regardless of the RPM's of the motor. Any fuel not needed by the engine is returned to the fuel tank through the FPR. This excess fuel, when pumped back into a close to empty tank will also foam. If you suck foam up into the fuel pick up, then you end up with a fuel/air mixture. Since the injectors don't react too kindly to air, it can cause a rough running issue.
As for the mixing chamber screens, here are some pics from other threads.
Clean mixing chamber screens
Dirty screens that cause issues
As for the mixing chamber screens, here are some pics from other threads.
Clean mixing chamber screens
Dirty screens that cause issues
Elder User
Joined: Oct 2007
Posts: 672
Likes: 0
From: NJ
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Lead Driver
Joined: Jan 2007
Posts: 6,708
Likes: 5
From: Kiowa CO
To Chris' point, it also depends on where you fill up with diesel on how much garbage can be pumped into your tank without your knowledge. Even fine dirt and dust can make a little sandbar in the tank and it can get stirred up and make its way into your mixing chamber screens.
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Post Fiend
Joined: Mar 2007
Posts: 26,966
Likes: 50
From: Texas
How many miles on the filter? You might check it visually, but running the tank low shouldn't mean you have to replace it. It won't hurt if you do. I'm a fan of fuel additives. Putting some in to lube up the injectors if they got some air in there won't hurt anything.
