Uncommanded acceleration
Thread Starter
|
Senior User
Joined: Feb 2009
Posts: 372
Likes: 0
From: Westfield, MA
Uncommanded acceleration
I have a new problem, well not really a problem yet, just strange. I have noticed when I am on the highway at a constant speed, sometimes the truck will accelerate enough to pick up 5 or more mph. Any ideas what might cause this to happen? Otherwise the truck is running great.
Senior User
Joined: Oct 2008
Posts: 246
Likes: 0
From: Loganville,GA
I have a new problem, well not really a problem yet, just strange. I have noticed when I am on the highway at a constant speed, sometimes the truck will accelerate enough to pick up 5 or more mph. Any ideas what might cause this to happen? Otherwise the truck is running great.
I have had this problem but at Low Speeds, When my truck gets low on Diesel. On my truck when it gets just below 1/4 of a Tank It starts Accelerating Like I have a Turbo somtimes Without pushing the Pedal Down anymore then it already is.
Postmaster
Joined: Jan 2010
Posts: 4,319
Likes: 4
From: Elk City, OK
Ford 6.0 & 7.3 Diesel tank Fuel Filter Screen 1990-07 - eBay (item 360324906660 end time Jan-01-11 14:49:19 PST)
replace that part if its doing that at 1/4 tank. its sucking air.... the screen gets brittle and breaks.
replace that part if its doing that at 1/4 tank. its sucking air.... the screen gets brittle and breaks.
Senior User
Joined: Oct 2008
Posts: 246
Likes: 0
From: Loganville,GA
Ford 6.0 & 7.3 Diesel tank Fuel Filter Screen 1990-07 - eBay (item 360324906660 end time Jan-01-11 14:49:19 PST)
replace that part if its doing that at 1/4 tank. its sucking air.... the screen gets brittle and breaks.
replace that part if its doing that at 1/4 tank. its sucking air.... the screen gets brittle and breaks.
Lead Driver
Joined: Apr 2008
Posts: 6,945
Likes: 13
Mine does this as well, mostly just when the timing advance is on.... will be goin goin goin and it will just surge foreward to beat hell, im talkin with more power than you get when you mat it, and when you let off it will fall flat on its face for a sec and idle like crud, then good to go again till you hit that one little spot apparently.
Im sure its a problem with the IP internals, more specifically timing, but curious if anyone has had this, heard of it, or knows why.
Hijack over
Im sure its a problem with the IP internals, more specifically timing, but curious if anyone has had this, heard of it, or knows why.
Hijack over
Postmaster
Joined: Jan 2010
Posts: 4,319
Likes: 4
From: Elk City, OK
Mine does this as well, mostly just when the timing advance is on.... will be goin goin goin and it will just surge foreward to beat hell, im talkin with more power than you get when you mat it, and when you let off it will fall flat on its face for a sec and idle like crud, then good to go again till you hit that one little spot apparently.
Im sure its a problem with the IP internals, more specifically timing, but curious if anyone has had this, heard of it, or knows why.
Hijack over
Im sure its a problem with the IP internals, more specifically timing, but curious if anyone has had this, heard of it, or knows why.
Hijack over
Trending Topics
Lead Driver
Joined: Apr 2008
Posts: 6,945
Likes: 13
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Thread Starter
|
Senior User
Joined: Feb 2009
Posts: 372
Likes: 0
From: Westfield, MA
I'll have to pay closer attention to the fuel level when it happens again. I don't think its the CDR. I cleaned it at the last oil change but I guess it wouldn't hurt to do it again. It doesn't do it very often so maybe it is fuel level related.
New User
Joined: Feb 2009
Posts: 12
Likes: 0
A sudden surge of acceleration on a mechanical diesel is virtually always a sign of air intrusion. It doesn't have to be the tank pickup but that's the way to bet. Replacing the OEM foot is a terrible idea because the design is garbage. Replace it with a ~5" piece of 3/8 ID fuel line and a clamp. I've done both my tanks because both feet failed. Both feet were gummy when extracted from the tank, which indicates chemical attack. You can put in another stupidly designed pickup foot or you can fix the problem permanently.
Posting Guru
Joined: Sep 2008
Posts: 1,840
Likes: 1
From: On the prairie
I just addressed this same issue. The truck would idle fine when warm but would start like crap when let sit overnight. It would also surge when accelerating when getting over 2k RPM's before shifting, and with O.D off at 60mph (2600 RPM) it was acting fuel starved. Also when warming up it would surge violently betwee 1000 and 1500 RPM for up to 30 sec before settling down. I pulled my sending unit which showed no signs of cracking and the pickup foot was in great condition. However, the elbows that the fuel lines hooked to were very badly rusted as were the metal lines between the tank selector valve and the lift pump. I was unable to track down a complete sender/pickup tube assembly so I was forced to jury rig the one I have. I broke the elbows off and drilled a hole in the top of the sender big enough for a piece of 3/8" I.D hose to fit through and used a grommet and plenty of RTV sealant to keep it tight. Also, the metal lines were ditched and 3/8" hose was run on both the supply and return side from the tank to the pump and from the return to the tank. I'll have to wait until mornig to see if my starting issue has ceased but during driving the surge seems to have gone away. Hope this helps.
Senior User
Joined: Mar 2007
Posts: 185
Likes: 0
From: San Diego, CA/ Yuma, AZ
I am still having the same issue with mine. here is a post I posted awhile ago, but never figured it out. maybe worth your reading.
Mine does it every morning after about 5 mins of driving and when I am going about 15mph, especial at 1K exactly on the Tach. it surges and feels like i gained 100 hp, the RPMs drop about 200 rpms, then its gone, I can bring it back to 1K rpms and it does it again.
Weird,
https://www.ford-trucks.com/forums/8...pply-pump.html
Mine does it every morning after about 5 mins of driving and when I am going about 15mph, especial at 1K exactly on the Tach. it surges and feels like i gained 100 hp, the RPMs drop about 200 rpms, then its gone, I can bring it back to 1K rpms and it does it again.
Weird,
https://www.ford-trucks.com/forums/8...pply-pump.html
Lead Driver
Joined: Apr 2008
Posts: 6,945
Likes: 13
I am still having the same issue with mine. here is a post I posted awhile ago, but never figured it out. maybe worth your reading.
Mine does it every morning after about 5 mins of driving and when I am going about 15mph, especial at 1K exactly on the Tach. it surges and feels like i gained 100 hp, the RPMs drop about 200 rpms, then its gone, I can bring it back to 1K rpms and it does it again.
Weird,
https://www.ford-trucks.com/forums/8...pply-pump.html
Mine does it every morning after about 5 mins of driving and when I am going about 15mph, especial at 1K exactly on the Tach. it surges and feels like i gained 100 hp, the RPMs drop about 200 rpms, then its gone, I can bring it back to 1K rpms and it does it again.
Weird,
https://www.ford-trucks.com/forums/8...pply-pump.html
Thing i dont get, how does air intrusion = more power... after all this is a diesel. Any extra air coming shouldnt matter, or should LOSE power by displacing fuel.
Thread
Thread Starter
Forum
Replies
Last Post
Kasey
1987 - 1996 F150 & Larger F-Series Trucks
4
Jan 2, 2004 05:00 PM