undiagnosed engine problem
Thread Starter
|
New User
Joined: Sep 2012
Posts: 10
Likes: 0
undiagnosed engine problem
I have a 91 F-250, auto, 2 tanks, 150,000 miles. This is a cherry I bought from the original owner in 98. I use it to pull a RV and for recreation not in daily use. The engine has lost power, high pitched backfires in the eng. compartment and the trans. isn't shifting. My tranny man says there is nothing wrong with the trans (new in 99). One morning it wouldn't start and the fuel pumps ran continuously as if no pressure. My mechanic has replaced the fuel pressure regulator, the distributor cap. the coil and checked all pressures (all good). The check eng light is on and indicates a problem with the air pump (new 1 year ago). I don't see that as the problem. When running the engine is smooth at idle. Problem seems intermittant as it runs OK for short periods of time and then suddenly loses power again.
I have a suggestion that the timing belt has slipped or broken and will check that out. Any other suggestions?
I have a suggestion that the timing belt has slipped or broken and will check that out. Any other suggestions?
Lead Driver
Joined: Jul 2007
Posts: 7,868
Likes: 9
From: Rhode Island
Yup, the fuel pumps continuously running indicates the processor inside the ECU is not initializing.
The most probable cause is bad capacitors, which if you're handy with a soldering iron you can fix yourself. If you're not, you can pick up a re-manufactured computer for $100-140.
Also you don't have a timing belt.
The most probable cause is bad capacitors, which if you're handy with a soldering iron you can fix yourself. If you're not, you can pick up a re-manufactured computer for $100-140.
Also you don't have a timing belt.
Thread Starter
|
New User
Joined: Sep 2012
Posts: 10
Likes: 0
Thanks for your reply. I changed belt to chain. Can this be intermittant? Sometimes the truck runs OK but mostly it doesn't. Sometimes it will start, sometimes not. sometimes the fuel pumps act normally and sometimes not. This has confused my mechanic.
Fleet Owner
Joined: Oct 2005
Posts: 20,789
Likes: 1,753
From: Kentucky
Your computer has classic symptoms of internal failure, as noted by several folks already.
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The crystal oscillator (clock) is not always starting in the computer. This could be from high ripple in the circuits caused by bad electrolytic capacitors as noted above or a broken crystal lead or bad crystal.
The bottom line is that you need a new computer and a new mechanic!
The mechanic dose not understand your fuel system and your computer and is costing you extra money.
The bottom line is that you need a new computer and a new mechanic!
The mechanic dose not understand your fuel system and your computer and is costing you extra money.
Trending Topics
Posting Guru
Joined: Oct 2011
Posts: 1,179
Likes: 1
From: Pueblo, CO
This. Any mechanic worth his rates should be able to diagnose without throwing parts at it like some amateur shadetree DIY'er. If the timing chain had broken the truck wouldn't run, if it had jumped a tooth then it would be out of time and run poorly if at all. Your "mechanic" should know this.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
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
Top 10 Ford Truck Tragedies
Joe Kucinski
Thread Starter
|
New User
Joined: Sep 2012
Posts: 10
Likes: 0
Thanks to all. It was the ECU. My mechanic says he checked it early on but got no readings that indicated a problem. Around here (Tallahassee) there are few mechanics who work on older trucks or have even owned one.
Elder User
Joined: Mar 2011
Posts: 923
Likes: 1
From: North Central MA
Hope he did that for free after costing you for all the other work and gave back the labor costs on the rest ... I see not reimbursing you for the new parts you still have but even thats not good ....
Thread
Thread Starter
Forum
Replies
Last Post
escudo
1987 - 1996 F150 & Larger F-Series Trucks
4
Nov 2, 2004 08:06 PM
1trent
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
9
Nov 11, 2002 11:49 AM