Notices
1987 - 1996 F150 & Larger F-Series Trucks 1987 - 1996 Ford F-150, F-250, F-350 and larger pickups - including the 1997 heavy-duty F250/F350+ trucks

7.5 efi idle issue

Thread Tools
 
Search this Thread
 
Old Dec 15, 2016 | 01:44 AM
  #1  
Arcticoffroad's Avatar
Arcticoffroad
Thread Starter
|
New User
Joined: Dec 2016
Posts: 5
Likes: 0
7.5 efi idle issue

Hey guys I have a issue with my truck it's a 97 f250 7.5 with e4od. I just replaced the fuel pumps end of oct. About 2 weeks ago it started acting up on the rear tank idle would surge up to 1000rpm them drop while the computer tried to get to base idle. It will happen when hot or cold. And sometimes it will die and sometimes it won't. Then it started happening on the front tank. I pulled codes and have a 121 for a tps sensor. Before I go and check voltage settings is there anything else I could be missing..
 
Reply
Old Dec 15, 2016 | 10:13 AM
  #2  
Lead Head's Avatar
Lead Head
Lead Driver
15 Year Member
Photogenic
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
If the issue started on only one tank, I'd go get a fuel pressure gauge and check your fuel pressure.
 
Reply
Old Dec 15, 2016 | 12:31 PM
  #3  
Kaleo's Avatar
Kaleo
Senior User
Joined: Oct 2003
Posts: 110
Likes: 0
From: Alaska
I had a similar problem. Idle would surge to 1200 then down to 500. Sometimes it would die. Got the same code for TPS sensor and another for O2 sensor rich. Tested the TPS and it was in range. Replaced the O2 sensor, no change. Fuel pressure tested good. Swapped AIC with a good one, no change. Can't remember what I did to check the MAP sensor, but that ended up being the problem on mine.
 
Reply
Old Dec 17, 2016 | 06:01 PM
  #4  
Arcticoffroad's Avatar
Arcticoffroad
Thread Starter
|
New User
Joined: Dec 2016
Posts: 5
Likes: 0
Ok so I got a chance to test fuel pressure at idle it is 30-32 psi koeo 42psi. Running with reg disconnected 40psi. Tested tps voltage was 4.1v? Not .9 like I was thinking it should be. I think possibly someone had adjusted it incorrectly before. Anythoughts.
 
Reply
Old Dec 17, 2016 | 07:22 PM
  #5  
timbersteel's Avatar
timbersteel
Logistics Pro
Joined: Mar 2005
Posts: 4,698
Likes: 47
From: Mexico, Missouri
Originally Posted by Arcticoffroad
Ok so I got a chance to test fuel pressure at idle it is 30-32 psi koeo 42psi. Running with reg disconnected 40psi. Tested tps voltage was 4.1v? Not .9 like I was thinking it should be. I think possibly someone had adjusted it incorrectly before. Anythoughts.
4.1v suggests that you probed the 5.0v reference voltage from the PCM.
There is a Green wire and Orange wire. The Black wire would be ground. One of the other 2 should be Signal return and VReference.
 
Reply
Old Dec 17, 2016 | 07:36 PM
  #6  
Arcticoffroad's Avatar
Arcticoffroad
Thread Starter
|
New User
Joined: Dec 2016
Posts: 5
Likes: 0
Nope 1 wire was 4.1 one was ground and one have 5v.o v
 
Reply
Old Dec 17, 2016 | 07:41 PM
  #7  
Lead Head's Avatar
Lead Head
Lead Driver
15 Year Member
Photogenic
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
In that case your TPS has shorted internally.
 
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Sk8Crash69
1987 - 1996 F150 & Larger F-Series Trucks
7
Aug 1, 2018 12:26 PM
bc18
1994.5 - 1997 7.3L Power Stroke Diesel
11
Aug 11, 2017 09:28 AM
GCF
1978 - 1996 Big Bronco
6
Aug 27, 2011 02:15 PM
BLUEOVAL1992
1987 - 1996 F150 & Larger F-Series Trucks
5
Feb 25, 2010 03:35 AM
77bigblock
1987 - 1996 F150 & Larger F-Series Trucks
2
Nov 8, 2006 05:30 AM




All times are GMT -5. The time now is 04:36 PM.

story-0
Rezvani's Latest Post-Apocalytic Monster Is a Ford F-150 Raptor Underneath

Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.

By Verdad Gallardo | 2026-05-30 18:33:59


VIEW MORE
story-1
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer

Slideshow: 10 most expensive Ford trucks ever sold on Bring a Trailer.

By Joe Kucinski | 2026-05-27 16:24:34


VIEW MORE
story-2
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)

Here's everything that has changed for the latest model year.

By Brett Foote | 2026-05-27 16:17:28


VIEW MORE
story-3
Top 10 Ford Truck Tragedies

Slideshow: Top 10 Ford truck tragedies.

By Joe Kucinski | 2026-05-18 19:34:33


VIEW MORE
story-4
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make

And it might be even better than that.

By Brett Foote | 2026-05-18 19:26:42


VIEW MORE
story-5
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!

Slideshow: Does lowering an F-150 Lobo RUIN the ride quality?

By Michael S. Palmer | 2026-05-18 19:20:37


VIEW MORE
story-6
Ford's 2001 Explorer Sportsman Concept Looks For a New Home

Slideshow: Ford's bizarre fishing-themed Explorer concept has resurfaced after spending decades largely forgotten.

By Verdad Gallardo | 2026-05-12 18:07:46


VIEW MORE
story-7
10 Best Ford Truck Engines We Miss the Most!

Slideshow: The 10 best Ford truck engines we miss the most.

By Joe Kucinski | 2026-05-12 13:09:47


VIEW MORE
story-8
2026 Shelby F-150 Off-Road: Better Than a Raptor R?

Slideshow: first look at the 810 hp 2026 Shelby F-150 Off-Road!

By Brett Foote | 2026-05-12 12:50:07


VIEW MORE
story-9
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!

Slideshow: Everything You Need to Know about the 2027 Super Duty Carhartt Package!

By Michael S. Palmer | 2026-05-07 17:51:06


VIEW MORE