New fuel pump, cranks but no still no start - F150online Forums

Go Back  F150online Forums > F-Series Trucks > 1997 - 2003 F-150
New fuel pump, cranks but no still no start > New fuel pump, cranks but no still no start
1997 - 2003 F-150
Sponsored by:
Sponsored by:

New fuel pump, cranks but no still no start

Reply

 
 
  #1  
Old 12-04-2017, 06:21 PM
Junior Member
Thread Starter
Join Date: Dec 2017
Location: Texas
Posts: 3
New fuel pump, cranks but no still no start

AT my wits end here. Sorry for this lame introductory post to this wonderful place. I've been reading here a very long time but now I actually need to ask a question.
So last Sunday, after my truck (2003 f150, 4.6) ran beautifully up until at night when I go to start it to get my food. Just kept cranking. Told my brother immediately it wasn't getting any fuel.
We all deduced that it was fuel related/ fuel pump so we waited till I had time to get to it. Well we messed the relays - nothing. I changed the pump today and managed to get it fired twice but now it still wont start either.
Fuel filter changed as well. No pressure at the fuel rail before either but with the new pump it seems rather low. Plugged in a programmer to get readings from the computer and I found that the RPM doesn't go up at all when cranking leading to a no-start. Before the fuel pressure was also really low and it still is low unless I cycle the ignition.
Well the repeated cranking took its toll on the motorcraft battery, and even after charging it I don't think the voltage is enough. It drops too low, it seemed to want to start fine when it was at 14v but anything 12 or below is a no-go. This could also be either the PCM relay or the crankshaft sensor. Worst case is an electrical short somewhere which is something I can't deal with. Anyone else got themselves out of similar situation?

Also we tested the old fuel pump and it was fine. Truck only has over 128k miles.
 

Last edited by themick; 12-04-2017 at 06:23 PM.
Reply With Quote
  #2  
Old 12-04-2017, 07:34 PM
glc's Avatar
glc
glc is offline
Senior Member
Join Date: Dec 2006
Location: Joplin MO
Posts: 35,622
What is the pressure at the rail after you turn the key on? Use a gauge, needs to be at least 28 psi.
 
Reply With Quote
  #3  
Old 12-04-2017, 09:36 PM
Senior Member
Join Date: Oct 2002
Location: St. Louis (Out in the woods)
Posts: 6,246
1. Fully charge the battery, otherwise you'll probably waste even more time.

2. Shortcut to see if you have a fuel supply problem: Shoot some starting fluid into the MAF sensor then crank and see if it fires. If it does, you have a fuel delivery issue. If not, fuel isn't your problem.
 
Reply With Quote
  #4  
Old 12-05-2017, 04:36 PM
Senior Member
Join Date: Aug 2011
Location: ky.
Posts: 683
I would check the crank position sensor or the wiring and connections to it, since it showed no RPMs on the scan tool when cranking it.
 
Reply With Quote
  #5  
Old 12-05-2017, 08:47 PM
Junior Member
Thread Starter
Join Date: Dec 2017
Location: Texas
Posts: 3
I charged the battery. Changed both the camshaft sensor AND the crankshaft sensor. Still nothing. Not getting much fuel pressure either just like before with the old pump. (which doesn't stay on long enough since it won't start at all)
Still no RPMs on the scan tool either which leads me to believe it is back at the PCM relay or fuse box. I read a similar post to mine and it ended up being the poles/grounds for the relay itself. I think mine did get a little hot. Sorry for being a little vague this has been too tedious.
 
Reply With Quote
  #6  
Old 12-05-2017, 10:19 PM
Senior Member
Join Date: Jan 2002
Location: Wilmington,NC
Posts: 3,762
What is the fuel pressure at the shrader valve with the key on? USE a gauge.
 
Reply With Quote
  #7  
Old 12-05-2017, 11:12 PM
Senior Member
Join Date: Jul 2004
Location: Easton, Pa.
Posts: 5,672
mick, you keep going the way your going about this you will never find the problem unless its luck.
WHAT is the fuel pressure at the fuel rail port after you cycle the ignition on and off 'several' times.
Does the pressure hold?
You have to either eliminate this to prove it is the problem and not jump all over the truck.
What if there is more than one issue at the same time? You would not know unless you test one area at a time.
Good luck.
 
Reply With Quote
  #8  
Old Yesterday, 10:00 PM
Junior Member
Thread Starter
Join Date: Dec 2017
Location: Texas
Posts: 3
It's 40 PSI when I cycle it. When the scanner reads 0 rpm it won't start period. It's been nearly 2 and half weeks of it not running. The only times I had it running were 2 times while it was flat in the garage. It still wouldn't continuously start even after that. I'm trying to go along the wiring and still can't find any faults or fraying either.
I just don't see it being the PCM due to that being too hefty a purchase. If it was that why would everything else still work/read on the computer and scanner? I'm hoping someone else here had the same exact conditions as me because I've tried everything short of blowing the money on a PCM or new junction box - which the connectors for the relays looked fine underneath.
 
Reply With Quote
  #9  
Old Yesterday, 10:27 PM
Senior Member
Join Date: Jul 2004
Location: Easton, Pa.
Posts: 5,672
I don't understand what your talking about for RPM.
40 psi is ok for fuel pressure.
The PCM is powering up or the fuel pump or it would not run.
Check for voltage on the coils and fuel injectors. They are needed just as much as fuel.
Then does the fuel pump run again at cranking. At least test with a voltmeter.
As it is now the RPM thing may be an indication but you have to find out why when its absent.
Ignore it and do the trouble shooting for the basics.
May even be an intermittent fuse in its holder.
Until you get a lead, it will not clear itself.
Good luck.
 
Reply With Quote
  #10  
Old Today, 08:10 AM
Senior Member
Join Date: Oct 2002
Location: St. Louis (Out in the woods)
Posts: 6,246
I just don't see it being the PCM due to that being too hefty a purchase.
That is an illogical reason for you to rule out the PCM. Based on the ambiguous results so far, the PCM cannot definitely be excluded or included in the list of suspects.


Did you try the spray test I recommended over a week ago?

What is the state of the THEFT light during a failed starting attempt?
 
Reply With Quote
 
 
 


Thread Tools
Search this Thread
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 Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Sponsors

All times are GMT -4. The time now is 09:52 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: