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Old 02-12-2010, 09:15 PM
 
Location: Full time RV"er
2,403 posts, read 5,618,432 times
Reputation: 1459

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I have a 1996 Ford 350 , 7.3 diesel , runs great down the road but some times when I come to a stop it sits there stumbling ( idling at about 550 rpm's for a few seconds then straightens out all by its self. anyone out there had a similar experance ? tested injectors , valve cover connections fuel pump switches relay's , all check out ok . Thanks any help will be accepted.
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Old 02-13-2010, 03:05 AM
 
10,868 posts, read 41,128,193 times
Reputation: 14009
Outside of the need for clean good quality fuel, clean filters (air and fuel), and clean motor oil per the owner's manual intervals ....

When was the last time you ran an injector cleaner through this motor?

These old powerstroke's don't like high percentages of bio-diesel fuel or low cetane fuel, if that's what you've had to put in it lately.

I've had pretty good success with Lucas FI cleaner, among several others ... Power Service also seems to work well. At one time, I used a 50/50 blend of these two when I had gotten a really bad load of fuel traveling through Ohio; the combination of Cetane improver and injector cleaner started to clean up the engine performance immediately and it took about 200 miles to clean out the injectors ....

I stumbled upon the Lucas FI cleaner at a fuel stop in Ohio, where we'd pulled in to get better fuel and top up the tanks ... somebody had bought a quart and used enough out of it to treat their tanks, and then left the remaining product sitting by the pump. Having never used it, and needing to fix my truck, I figured "what the heck, I'll give it a try" ... and was very impressed with the results. The knocking sound under load went away and the motor smoothed up over the miles afterwards.

If that doesn't help the situation, then you're looking at starting to check out the connection to the computer, then the mechanical aspects of the oil pump and the injector fuel delivery system.

Also ... you haven't had the truck "jumped" or used it to "jump start" anybody else, have you? The computers in these trucks can be sensitive to voltage surges from these situations and can get flaky, if not outright failed electronically in small areas of the mapping.
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Old 02-13-2010, 08:14 AM
 
Location: Full time RV"er
2,403 posts, read 5,618,432 times
Reputation: 1459
Quote:
Originally Posted by sunsprit View Post
Outside of the need for clean good quality fuel, clean filters (air and fuel), and clean motor oil per the owner's manual intervals ....

When was the last time you ran an injector cleaner through this motor?

These old powerstroke's don't like high percentages of bio-diesel fuel or low cetane fuel, if that's what you've had to put in it lately.

I've had pretty good success with Lucas FI cleaner, among several others ... Power Service also seems to work well. At one time, I used a 50/50 blend of these two when I had gotten a really bad load of fuel traveling through Ohio; the combination of Cetane improver and injector cleaner started to clean up the engine performance immediately and it took about 200 miles to clean out the injectors ....

I stumbled upon the Lucas FI cleaner at a fuel stop in Ohio, where we'd pulled in to get better fuel and top up the tanks ... somebody had bought a quart and used enough out of it to treat their tanks, and then left the remaining product sitting by the pump. Having never used it, and needing to fix my truck, I figured "what the heck, I'll give it a try" ... and was very impressed with the results. The knocking sound under load went away and the motor smoothed up over the miles afterwards.

If that doesn't help the situation, then you're looking at starting to check out the connection to the computer, then the mechanical aspects of the oil pump and the injector fuel delivery system.

Also ... you haven't had the truck "jumped" or used it to "jump start" anybody else, have you? The computers in these trucks can be sensitive to voltage surges from these situations and can get flaky, if not outright failed electronically in small areas of the mapping.
Thanks for your response . Yes every other tank full of fuel , I use LUCAS additive for lube and cleaning injectors. No don't use my truck to jump start other vehicles. this is a strange thing happening , did a test run for trouble shotting injectors check good. oil temp sender showed defaulted , replaced that, thought it might be an air leak in the hoses so i replaced all! fuel lines from pump through to the water trap , still the same , have changed the TPS ( throttle position sensor) no change, only other will be the computer . I am going to swap out mine with a friends truck to see if any change .
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Old 02-14-2010, 12:46 AM
 
Location: mississippi
50 posts, read 118,069 times
Reputation: 65
When you say you changed the TPS You mean the cam position sensor? The old one were black I believe i think the new ones are blue or gray.Do the Rpms jump around alot when it does this?
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Old 02-15-2010, 08:13 PM
 
Location: Full time RV"er
2,403 posts, read 5,618,432 times
Reputation: 1459
Quote:
Originally Posted by hivoltage View Post
When you say you changed the TPS You mean the cam position sensor? The old one were black I believe i think the new ones are blue or gray.Do the Rpms jump around alot when it does this?
No its the Throttle Position Sensor on the side of the gas pedal , Yes the Rpm's drop to about 550 then go back to 750 and the engine runs smooth again , anything over 1,000 rpm's the truck runs fine, lots of smooth power. ????/
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Old 02-15-2010, 08:21 PM
 
Location: Full time RV"er
2,403 posts, read 5,618,432 times
Reputation: 1459
Quote:
Originally Posted by hivoltage View Post
When you say you changed the TPS You mean the cam position sensor? The old one were black I believe i think the new ones are blue or gray.Do the Rpms jump around alot when it does this?
, No what I replaced was the throttle position sensor on the gas pedal . The idle drops to about 550 when the stumble begins ,then goes to normal 750 and runs smooth like there is nothing wrong at all. Any time the rpm''s get to 8-900 rpm's it runs fine lots of power and smooth running . no black smoke either. STRANGE to say the least>??
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Old 02-19-2010, 09:17 PM
 
33 posts, read 226,104 times
Reputation: 22
i was gona tell you to replace your throttle position sensor but its obviously not the problem. check your head temp. sensor.
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Old 02-20-2010, 12:16 AM
 
Location: U.S.A.
3,306 posts, read 9,006,224 times
Reputation: 2919
Quote:
Originally Posted by sunsprit View Post
Outside of the need for clean good quality fuel, clean filters (air and fuel), and clean motor oil per the owner's manual intervals ....

When was the last time you ran an injector cleaner through this motor?

These old powerstroke's don't like high percentages of bio-diesel fuel or low cetane fuel, if that's what you've had to put in it lately.

I've had pretty good success with Lucas FI cleaner, among several others ... Power Service also seems to work well. At one time, I used a 50/50 blend of these two when I had gotten a really bad load of fuel traveling through Ohio; the combination of Cetane improver and injector cleaner started to clean up the engine performance immediately and it took about 200 miles to clean out the injectors ....

I stumbled upon the Lucas FI cleaner at a fuel stop in Ohio, where we'd pulled in to get better fuel and top up the tanks ... somebody had bought a quart and used enough out of it to treat their tanks, and then left the remaining product sitting by the pump. Having never used it, and needing to fix my truck, I figured "what the heck, I'll give it a try" ... and was very impressed with the results. The knocking sound under load went away and the motor smoothed up over the miles afterwards.

If that doesn't help the situation, then you're looking at starting to check out the connection to the computer, then the mechanical aspects of the oil pump and the injector fuel delivery system.

Also ... you haven't had the truck "jumped" or used it to "jump start" anybody else, have you? The computers in these trucks can be sensitive to voltage surges from these situations and can get flaky, if not outright failed electronically in small areas of the mapping.
+1

I started running power service cetane boost (~0.7oz/gal) and noticed improvement immediately, been running it ever since.
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Old 02-20-2010, 02:00 AM
 
Location: Suffolk County, NY
874 posts, read 2,416,568 times
Reputation: 452
I have a 2001 Excursion with the 7.3 Powerstroke diesel and had a similar problem. Mine was doing what you are describing for a little while and then it started to stall on me occasionally. For some reason my problem did not make the "check engine" light come on. At the same time this was happening I received a recall notice for the cam sensor. The dealer told me I would have to wait two weeks for an appointment and I did not feel like waiting so I bought a new one and changed it myself. This solved my problem. I do not know all of the years the cam sensor was recalled for but I do have a neighbor with a 1999 F-350 who also had the recall. It is easy to change yourself since the cam sensor is located on the front of the engine and you can get to it from under the truck. There is one bolt that holds it in. It took me all of five to ten minutes to change.
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Old 02-20-2010, 06:53 PM
 
Location: Full time RV"er
2,403 posts, read 5,618,432 times
Reputation: 1459
Quote:
Originally Posted by Egobop View Post
I have a 2001 Excursion with the 7.3 Powerstroke diesel and had a similar problem. Mine was doing what you are describing for a little while and then it started to stall on me occasionally. For some reason my problem did not make the "check engine" light come on. At the same time this was happening I received a recall notice for the cam sensor. The dealer told me I would have to wait two weeks for an appointment and I did not feel like waiting so I bought a new one and changed it myself. This solved my problem. I do not know all of the years the cam sensor was recalled for but I do have a neighbor with a 1999 F-350 who also had the recall. It is easy to change yourself since the cam sensor is located on the front of the engine and you can get to it from under the truck. There is one bolt that holds it in. It took me all of five to ten minutes to change.
Thanks guy's for all your tips, found the problem today! it was the alternator. Low voltage at times when the truck came to a lower idle. this morning it quit altogether. Got a new replacement ( life time replacement) installed it , works fine and the problem is gone also!
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