Computer issues
Thread Starter
|
Post Fiend
Joined: Mar 2011
Posts: 10,080
Likes: 5
From: Backwoods of Snowflake AZ
Computer issues
OK I am 99% sure my computer on my 88 F150 4x4 302 C6 has gone bad. Fuel pump will keep running, can't pull any codes, and it has died on me twice. I pulled the computer to see if their are any signs but I don't see any. Their is a bunch of green stuff all over the computer that I am not sure what it is but not sure if that means anything? I am thinking of replacing it but I don't see the code on my computer on the computers at oriellys or autozone.
Anybody know what to do in this instance?
Also maybe you guys can verify it is the computer.
My symptoms are constantly running fuel pump, the codes will not pull (I tried two different code readers), it will run alright then a CEL will come on and it will start bucking, sputtering, and backfiring then stall. The CEL will only come on after a few miles of it being in the normal temperature. The idle is between 850 and 950.
Specs on the truck are:
1988 F150 302 4x4 C6 reg cab long bed
engine has been bored to a 308 (.040 over), 31-255-5 comp cam, and HO pistons otherwise stock for now.
Trav
Anybody know what to do in this instance?
Also maybe you guys can verify it is the computer.
My symptoms are constantly running fuel pump, the codes will not pull (I tried two different code readers), it will run alright then a CEL will come on and it will start bucking, sputtering, and backfiring then stall. The CEL will only come on after a few miles of it being in the normal temperature. The idle is between 850 and 950.
Specs on the truck are:
1988 F150 302 4x4 C6 reg cab long bed
engine has been bored to a 308 (.040 over), 31-255-5 comp cam, and HO pistons otherwise stock for now.
Trav
Thread Starter
|
Post Fiend
Joined: Mar 2011
Posts: 10,080
Likes: 5
From: Backwoods of Snowflake AZ
Just put a different computer in and it attempted to pull codes but wouldn't. It tried but it would never give a code so that is a step moved forward. Fuel pumps are still continually running. Thinking maybe a stuck relay or bad FPR.
Trav
Trav
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
The FPR has nothing to do with the fuel pumps running or not running.
If the fuel pumps will stop when you turn off the key then the fuel pump relay is OK.
Unplug the computer and see if the fuel pumps still run. If they stop then the second computer is also bad.
If the fuel pumps will stop when you turn off the key then the fuel pump relay is OK.
Unplug the computer and see if the fuel pumps still run. If they stop then the second computer is also bad.
Thread Starter
|
Post Fiend
Joined: Mar 2011
Posts: 10,080
Likes: 5
From: Backwoods of Snowflake AZ
I thought the fuel pump relay has power from the battery to the ignition switch on the column to the relay to the pump? If it does how would it keep running if the switch is cutting off power?
I will try unplugging the computer to see what it does but the code reader got ready to pull the codes but wouldn't do anything because of the fuel pumps still running.
Dad is telling me that the rear antilock light has something to do with why I can't pull codes I keep telling him this isn't like OBDII where they are fully on the same system am I correct?
Trav
I will try unplugging the computer to see what it does but the code reader got ready to pull the codes but wouldn't do anything because of the fuel pumps still running.
Dad is telling me that the rear antilock light has something to do with why I can't pull codes I keep telling him this isn't like OBDII where they are fully on the same system am I correct?
Trav
Fleet Mechanic
Joined: Mar 2014
Posts: 1,926
Likes: 116
From: Saskatchewan Canada
Geez I hate acronyms!
FPR could mean Fuel Pressure Regulator or Fuel Pump Relay.
If you're going to use them, explain them!
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
So if the contacts stick the pump will run with the key off.
The power for the coil of the fuel pump relay comes from the battery -> Ignition switch -> coil of the power relay -> to ground. The power for the contacts of the power relay come from the battery -> fuse link (1991 and older) -> power relay contacts -> fuel pump relay coil -> EEC Computer for ground.
Turning the key off drops the power relay coil and the contacts open dropping power to the fuel pump relay coil and it will drop out and turn off the fuel pump.
/
Last edited by subford; Jun 27, 2015 at 03:20 PM. Reason: added diagram
Trending Topics
Fleet Owner
Joined: Aug 2005
Posts: 23,667
Likes: 301
From: Easton,Ks
FPR on the under the hood sticker and in all Ford manuals stands for Fuel Pressure Regulator.
Note the OP used it first.
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
|
Post Fiend
Joined: Mar 2011
Posts: 10,080
Likes: 5
From: Backwoods of Snowflake AZ
Unplugged the computer and it wouldn't turn the pumps on at all. Plugged the computer back in and pumps for a couple times wouldn't turn on then after that a couple times they turned on and turned off like it was supposed to then after that it went right back to always running.
I put a new set of relays on and the same thing.
Sometimes they stay on sometimes they won't kick back in at all since unplugging and plugging in the computer.
Dad says it is the ignition switch but I don't believe him.
Trav
I put a new set of relays on and the same thing.
Sometimes they stay on sometimes they won't kick back in at all since unplugging and plugging in the computer.
Dad says it is the ignition switch but I don't believe him.
Trav
Thread Starter
|
Post Fiend
Joined: Mar 2011
Posts: 10,080
Likes: 5
From: Backwoods of Snowflake AZ
Turned out somebody bypassed the fuel pump to run continuasly and put the STI Plug in the wrong spot. Fixed all that and I got the pump to work fine and pulled codes.
Somebody bypassed the fuse link sticking a relay there.
Trav
Somebody bypassed the fuse link sticking a relay there.
Trav
Thread
Thread Starter
Forum
Replies
Last Post
forest337
1987 - 1996 F150 & Larger F-Series Trucks
3
Oct 4, 2009 11:51 AM
corvette99
1987 - 1996 F150 & Larger F-Series Trucks
3
Sep 21, 2008 03:51 PM
Timken
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
16
Jan 14, 2004 05:18 PM