Go Back   Ford Truck Enthusiasts Forums > Misc. > Fuel Injection, Carburetion & Fuel System
Sign in using an external account
Register Forgot Password?


Reply
 
 
 
 
LinkBack Thread Tools Search this Thread
  #1  
Old 06-17-2013, 11:00 PM
MV7 MV7 is offline
New User
 
Join Date: Sep 2012
Posts: 22
MV7 is starting off with a positive reputation.
Fuel Pump Voltage

First of all, thanks for reading this post and offering any insights you might have.

2001 Excursion 7.3 started missing the other night. Great loss of power, but made it home. Rough idle, "clacky". Next morning, did the following in order: 1) Pulled the fuel filter inspected, 2) removed all fuel from the bowl 3) replaced bowl fuel with Seafoam 4) installed new filter (my typical procedure). Without starting, I then 5) removed HPOP oil from reservoir and 6) filled with fresh oil using exact amount removed as a gauge for what to replace.
Started, idle smooth for a time. Increased rpm by depressing accelerator. Began running rougher and rougher accompanied by white smoke. Finally quit and would not restart. Cranking easily, tachometer showing RPM during crank.
Suspected no fuel getting to fuel bowl. 7) Drained fuel bowl using valve on back of bowl. 8) Turned ignition to "on" to get fuel pump to run 9) removed new filter, no fuel in bowl 10) With fuel filter out of the bowl, removed fuel filter and quickly cycled the ignition to "on" and back off -- no fuel entered the bowl. 11) Removed leads from fuel pump. 12) Checked voltage across leads as ignition cycled to "on": 6.5 volts. 13) Checked fuel pump fuse (20A Maxi fuse in location 112 -- BLOWN!) 14) Replaced fuse, performed voltage test: 11.55 volts 15) Checked battery voltage: 12.44Volts.

So, with all that, how in the world does the fuel pump get 6.5 volts with the fuse blown? I looked closely at the fuse and there was no slag or connection in the element.

Today I have pulled the 9-pin and 42-pin connections on the valve covers as well as the connectors to the glow plug relay module (used on Ex's) to inspect wires and connections. All looked fine. I plan to us some LP5 electro contact cleaner to clean all the connections and put some electrical grease on the connections, but the big question is where did that 6.5V come from with the fuse blown. I plan to pull the fuse and do the same test to see if the 6.5V is still there.

Thanks for any insights you can provide.
Reply With Quote
  #2  
Old 06-18-2013, 07:09 PM
LxMan1's Avatar
LxMan1 LxMan1 is offline
Moderator
 
Join Date: Dec 2001
Location: Louisville,Ky.
Posts: 22,266
LxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant future
Not sure where the stray voltage came from. it should be battery voltage to run. It must have backfed from another circuit. Perhaps an issue with the fuse panel itself.
Reply With Quote
  #3  
Old 06-18-2013, 10:43 PM
MV7 MV7 is offline
New User
 
Join Date: Sep 2012
Posts: 22
MV7 is starting off with a positive reputation.
Quote:
Originally Posted by LxMan1 View Post
Not sure where the stray voltage came from. it should be battery voltage to run. It must have backfed from another circuit. Perhaps an issue with the fuse panel itself.
Thanks, LxMan1. That certainly seems plausible. I did notice a bit of dust (just a bit) on the firewall end of the panel. Related? Maybe. If the stray voltage is coming from the load side of the fuse, I suppose pulling fuses would ID the culprit (probably start with the closest firstest). But it could be touching anything anywhere in a harness so that's just wishful thinking.

Tonight I checked resistance of the glow plugs at the 9-pins... #7 was open. With 160k on her, I'm pulling both valve covers and replacing them all. I suppose a good time to do some under v-cover maintenance, deep cleaning, and some minor mods I've been putting off.

Again, thanks for responding. That got my little pea-brain spinning to figure how to find it. I am documenting what I do and find to share it with everyone.
Reply With Quote
  #4  
Old 06-18-2013, 11:37 PM
fmc400's Avatar
fmc400 fmc400 is offline
MSEE
 
Join Date: Apr 2004
Location: Austin, TX
Posts: 10,386
fmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud offmc400 has much to be proud of
Are you sure the fuse was completely open? Sometimes fuses fail in a "partial" state such that they act like a large resistor; depending on the load downstream you'll see a drop across the fuse. I've run into that a couple times with older glass fuses, but not blade fuses.
Reply With Quote
  #5  
Old 06-19-2013, 12:54 PM
MV7 MV7 is offline
New User
 
Join Date: Sep 2012
Posts: 22
MV7 is starting off with a positive reputation.
Quote:
Originally Posted by fmc400 View Post
Are you sure the fuse was completely open? Sometimes fuses fail in a "partial" state such that they act like a large resistor; depending on the load downstream you'll see a drop across the fuse. I've run into that a couple times with older glass fuses, but not blade fuses.
Thanks fmc400! I took a closer look (a VERY CLOSE LOOK). It appears that the fuse is completely blown, but one side is at about 0.5mm or less. If you can look at my uploaded pictures, there is a shot of the blown element. Thanks for the reply... still snooping for possibilities. Though I wish no ill on anyone, I'd love to hear if someone saw the same thing...
Reply With Quote
  #6  
Old 07-04-2013, 03:46 PM
MV7 MV7 is offline
New User
 
Join Date: Sep 2012
Posts: 22
MV7 is starting off with a positive reputation.
Likely resolved, but still confused...

Quote:
Originally Posted by LxMan1 View Post
Not sure where the stray voltage came from. it should be battery voltage to run. It must have backfed from another circuit. Perhaps an issue with the fuse panel itself.
LxMan1, Another member did a very gracious thing and pulled his fuel pump leads and tested voltage under the same scenario... KOEO (2003 F-250 7.3L). After 20sec at batt volts, voltage dropped to 6.6V... just like mine. I don't know why but I feel A LOT better now.
Reply With Quote
  #7  
Old 07-05-2013, 07:44 PM
LxMan1's Avatar
LxMan1 LxMan1 is offline
Moderator
 
Join Date: Dec 2001
Location: Louisville,Ky.
Posts: 22,266
LxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant future
Strange indeed!!
__________________
Jimmy- FTE Moderator

88 5.0 LX Mustang
63 F100 351W/C6

Reply With Quote
  #8  
Old 07-05-2013, 08:09 PM
MV7 MV7 is offline
New User
 
Join Date: Sep 2012
Posts: 22
MV7 is starting off with a positive reputation.
Quote:
Originally Posted by LxMan1 View Post
Strange indeed!!
Yes, but "Tugly" figured it out... it is a small amount of current sent via the PCM to monitor pump health. It is apparently normal. I realize that I have a lot to learn!
Reply With Quote
  #9  
Old 07-06-2013, 01:54 PM
LxMan1's Avatar
LxMan1 LxMan1 is offline
Moderator
 
Join Date: Dec 2001
Location: Louisville,Ky.
Posts: 22,266
LxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant futureLxMan1 has a brilliant future
Gotcha, good to know.
__________________
Jimmy- FTE Moderator

88 5.0 LX Mustang
63 F100 351W/C6

Reply With Quote
Old 07-06-2013, 01:54 PM
 
 
 
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
Another NO START rplatt7 1999 - 2003 7.3L Power Stroke Diesel 33 03-22-2014 10:44 PM
2000 F350 w 7.3 no fuel in bowl ranger9010 Super Duty & Heavy Duty 27 10-01-2013 04:52 PM
Fuel Pump Voltage Question: 2001 7.3L PSD MV7 1999 - 2003 7.3L Power Stroke Diesel 14 07-05-2013 04:27 PM
Won't start after changing out fuel pump finerant 1994.5 - 1997 7.3L Power Stroke Diesel 6 03-17-2013 11:00 PM
Urgent help needed....fuel pump ?s 1BadHabit 6.0L Power Stroke Diesel 9 01-31-2012 09:28 PM


Go Back   Ford Truck Enthusiasts Forums > Misc. > Fuel Injection, Carburetion & Fuel System

Tags
7.3 no start, fuel pump, voltage

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

Forum Jump


Participate In The Forums

Create new posts and participate in discussions. It's free!

Sign Up





All times are GMT -5. The time now is 02:02 AM.


Powered by vBulletin® Version 3.8.7 AC1
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Advertising - Terms of Use - Privacy Statement - Jobs
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford is a registered trademark of the Ford Motor Company.

vbulletin Admin Backup