Chugging 7.3--help!!
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Chugging 7.3--help!!
I Have My 97 7.3 That Idles Rough,and Upon Acceleration Seems To Chug A Little Bit.at Speed Like 70 Mph Its Fine,you Dont Feel Anything,but Press On Acc A Little Bit And She Chugs.no Cel Light Either. I Am Going To Change The Fuel Filter First As It Seems Like It Started Doing This After I Switched Tanks.thanks For Any Help!!
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Well 35 Miles And It Still Chugs.changed Fuel Filter,cleaned Fpr Screen,checked Wiring Harness Connections At Valve Cover.all Is Good,but She Chugs In Overdrive From About 50-65 Mph.kick It In The Booty,keeping Rpms Up,and It Doesnt Seem To Chug.i Kicked Od Off And Keeping The R's Up At 2100 And Up It Seems Ok.from A Dead Dig,it Doesnt Seem To Chug If You Have Yer Foot To The Floor.idles Like Crap,chugging Up And Down From Roughly 400rpm To About 700rpm.could This Be The Harness Under Th Valve Cover?or Would It More Likely Be An Injector? I Have Changed Cam Sensor Before For Other Problems.this Seems Like Fuel To Me,almost Like It Starves Only Under An Overdrive Load.i Do Appreciate Any Extra Help On This!!thanks To All Who Respond!! This Is Frustrating For Me As I Dont Have Much Time To Work On This,and I Live An Hour One Way From Work.
Playing in the Dirt
Joined: Oct 2005
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From: Southwest Georgia
O.K. lets see; did you check your fuel pressure? What was it? Check the Timmerman nut on the back of the FPR. Check the connections on the FPR. Unplug the ICP (ignore the CEL) and check idle, then drive it and check for chugging (if it idles better and runs better, then replace the ICP). Unplug each valve cover connector (one at a time) and see if one of them does not change the way the engine runs (if you unplug one and it does not change the way it runs, then you need to check the UVC wiring and/or injectors for that plug). Let us know. Others will be along to add more input.
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Well,earlier Today I Changed Fuel Filter Drained Bowl And Cleaned Fpr Screen.truck Started Right Up And Idled Smoooth! Thought I Was Done,drove Truck About Two Miles Shut It Off, Restarted To Go Home And It Idled Crappy.i Have Not Checked Fuel Press Yet,but I Did Replace Fuel Pump About 4 Mos Ago Due To Leak.also Tonite When I Was Messing Around With The Truck Running,the Fpr Feels Extremely Hot,and The Fuel Coming Out Of The Schrdervalve Also Is Hot!do Not Know If This Is Normal,but What Is The Fuel Press At The Valve Supposed To Be? And I Do Not Have A Cel Light That Comes On.so ,no Codes Either.oil Was Changed Less Than 1000 Miles Ago,and Still Looks Good.i Use Castrol Hypuron 1540 Synthetic Blend And Have Used For Many Years Now With No Problems.air Filter Is Good As It Was Changed Same Time As Oil.ive Been Checking The Forums And Many Seem To Point To Bad Harness Under Valve Cover.at Idle It Sounds Like Its Missing On Random Cylinders.last Weekend I Had To Change My Starter And Battery Cables As The Cables Were Corroded Causing Starter To Crank Slow Which Also Fried The Starter.i Wonder Could This Excessive Draw Maybe Have Had Some Effect On The Harness Under The Vc?thanks Again Very Much For The Help!!
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Post Fiend
Joined: Apr 2004
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From: Silver Lake Dunes, MI
PlowHand your dpoing a good job on this one. Fuel pressure should be 40-70 psi that spec but it really should be no lower than 50psi. The UVC harness is a very good possibility right now. you can check those injectors with an ohm meter
here is how the plug it setup. 2 plugs per valve cover
1 2 3 4 5 (pins)
- - - - -
1 and 5 are glow plugs 2 and 5 are low side to one injector each, 3 is the high side to both injectors. place the neg. on 2 or 4 and the positive lead on 3 then switch the neg to the second pin either 2 or 4 depending on which you did first.
if you have anythign over 3 ohms you have an issue with that harness and or injector solenoid. this doesn't test the mechanical side of the injector
here is how the plug it setup. 2 plugs per valve cover
1 2 3 4 5 (pins)
- - - - -
1 and 5 are glow plugs 2 and 5 are low side to one injector each, 3 is the high side to both injectors. place the neg. on 2 or 4 and the positive lead on 3 then switch the neg to the second pin either 2 or 4 depending on which you did first.
if you have anythign over 3 ohms you have an issue with that harness and or injector solenoid. this doesn't test the mechanical side of the injector
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Thanks Guys! I Just Went Outside And Started Truck Up And Had The Icp Harness Unplugged.the Truck Loped Until I Stepped On The Acc Pedal.reved Up Ok And Dropped Down To About 400-500rpm When I Let Up.seemed Like It Idled Alittle Better But As It Started To Warm Up It Seems Like The Idle Starts To Get A Little More Erattic.i Plugged The Icp Back In And The Idle Is Till Errattic.also If The Fuel Press Is Supposed To Be That High It Doesnt Seem Like It When I Depress The Schrader.i Do Not Have A Guage Here At Home,so I Hopefully Can Make It To Work Tom. And Check When I Get In. I Thank You Guys Again For All The Help.this Hopefully Gets Me In The Right Direction.i Dont Mind Spending The Money On Parts,my Thing Is Limited Time To Work On It And My Drive Time To And From Work Sucks If I Break Down On The Road! PS. WOULD LOW PRESS AT THE SCHRADER INICATE BAD PUMP OR FAULTY IPR?
Last edited by DAN-D-DIESEL97; Apr 13, 2007 at 09:57 PM. Reason: ADD TO POST
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I Dont Know As I Just Changed Cps About 2 Mos Ago.could Be Bad,but This Morning Truck Fired Up And Ran Perfect All The Way To Work.i Am Going To Do A Fuel Press Test When Im Done Working As Plowhand Said To Doublecheck.also Im Going To Put An Inline Filter On The Frame Hopefully To Help With Any Junk In The Fuel As There Was Some Debris In The Bowl And The Screen.nothing Unusual Though As Ive Had Minor Stuff In There Before.thanks!
Playing in the Dirt
Joined: Oct 2005
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From: Southwest Georgia
Originally Posted by DAN-D-DIESEL97
PS. WOULD LOW PRESS AT THE SCHRADER INICATE BAD PUMP OR FAULTY IPR?
The IPR regulates the high pressure oil system pressure, it has nothing to do with fuel.
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From: Wagontown, PA
Lots o thoughts
I just spent quite a bit of money solving virtually the same problem. These were my symptoms:
1. Maintaining "Steady State" speed was virtualy impossible. Even when at a stop and in park if I bumped the RPM's up to say 1700, it would hold that for about three seconds before dropping significantly down to 1200 RPM. On the highway this translated into a maddening struggle to find the "Sweet spot" in throttle position. The solution was manyfold as what I was experiencing was a result of many little probs (I still haven't fixed them all).
a. Injector control module (replaced) $900.00 + or -
b. Valve cover gaskets (replaced) $250.00 + or -
c. Under valve cover Wire Harnesses (replaced) $250.00 + or -
I recomend that you take some time to fully troubleshoot the system. Problems like these don't usualy have a simple solution, they are usually the result of a "Cascade"; i.e. more than one significant failure. This makes it extremely difficult to locate the one bad apple because there are usually many bad apples.
Keep your stick on the ice
1. Maintaining "Steady State" speed was virtualy impossible. Even when at a stop and in park if I bumped the RPM's up to say 1700, it would hold that for about three seconds before dropping significantly down to 1200 RPM. On the highway this translated into a maddening struggle to find the "Sweet spot" in throttle position. The solution was manyfold as what I was experiencing was a result of many little probs (I still haven't fixed them all).
a. Injector control module (replaced) $900.00 + or -
b. Valve cover gaskets (replaced) $250.00 + or -
c. Under valve cover Wire Harnesses (replaced) $250.00 + or -
I recomend that you take some time to fully troubleshoot the system. Problems like these don't usualy have a simple solution, they are usually the result of a "Cascade"; i.e. more than one significant failure. This makes it extremely difficult to locate the one bad apple because there are usually many bad apples.
Keep your stick on the ice
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Joined: Mar 2006
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From: troy, Mo
Originally Posted by plowhand
O.K. lets see; did you check your fuel pressure? What was it? Check the Timmerman nut on the back of the FPR. Check the connections on the FPR. Unplug the ICP (ignore the CEL) and check idle, then drive it and check for chugging (if it idles better and runs better, then replace the ICP). Unplug each valve cover connector (one at a time) and see if one of them does not change the way the engine runs (if you unplug one and it does not change the way it runs, then you need to check the UVC wiring and/or injectors for that plug). Let us know. Others will be along to add more input.