very intermittent no starts

Reply

  #1  
Old 09-11-07, 09:55 AM
S
Member
Thread Starter
Join Date: Sep 2002
Location: illinois
Posts: 67
Received 0 Votes on 0 Posts
very intermittent no starts

only during hot weather above85 degrees,after longer drives(15mi.or more) or numerous short re-starts,car cranks but won't turn over or start but as soon as in gear will stumble and die.After 15-20 minutes starts and runs fine.It's only happened 8or9 times over the past three summers,over about 30,000miles.Fuel pump pressure is ok. getting spark,so i replaced pcm and fuel pump relays didn't that didn't fix the problem.Car is 99taurus 3.0L 97,000miles.
 
Sponsored Links
  #2  
Old 09-11-07, 10:27 AM
F
Member
Join Date: Jan 2007
Location: Central Indiana
Posts: 389
Received 0 Votes on 0 Posts
Cranking but not starting when hot can be a sign of vapor lock - fuel essentially boiling (or turning from liquid to a vapor) in the fuel lines. When things cool down and the vapor condenses the car will then crank and start.

Some things that promote vapor lock: low fuel pump pressure, leaky injector(s), low vapor pressure fuel, excessive engine compartment temps.
 
  #3  
Old 09-11-07, 10:57 AM
S
Member
Thread Starter
Join Date: Sep 2002
Location: illinois
Posts: 67
Received 0 Votes on 0 Posts
thanks

thanks for your reply Formula,one more question,what do you mean by" low vapor pressure fuel".
 
  #4  
Old 09-11-07, 12:15 PM
the_tow_guy's Avatar
Group Moderator
Join Date: Feb 2001
Location: SW Fla USA
Posts: 11,969
Received 52 Votes on 42 Posts
I would look more towards electronics that are being overly heat-sensitive, items like ignition modules, etc often start to fail in this manner.

Vapor lock is almost unheard of in modern fuel-injected systems with in-tank fuel pumps.
 
  #5  
Old 09-11-07, 01:01 PM
S
Member
Join Date: Aug 2003
Location: Cape Cod
Posts: 4,320
Received 0 Votes on 0 Posts
Ditto Mr. Tow Guy
These engines are more prone to ignition type heat related problems

But we need to confirm that the pressure is "OK"
You checked the fuel pressure during the no-start and it was up to specs?
What was it?

Same with spark
Getting spark at the plugs during no-start?

You should have some codes waiting in the computer for you
Can you get those read?
(even an all-clear tells us something)
 
  #6  
Old 09-11-07, 03:19 PM
G
Member
Join Date: Jun 2006
Location: United States
Posts: 2,456
Received 11 Votes on 11 Posts
My $.02 I just had a similar starting problem with a Tercel the Coolant Temperature Sensor, commonly confused with the sending unit for the gauge. The CTS sends signals to the computer to tell it when and how to fire the fuel injectors. After checking fuel pressure and spark(I installed inline spark testers on all 4 cylinders and installed a pressure guage to the fuel line so I could check pressure and spark at the time of failure. To verify the CTS I drilled 3 holes in a thin strip of molding, installed the old CTS, a thermometer and a new CTS and set the molding over a pan of water on the stove and heated the water to simulate the engine warming to operating temp, as the temperature increased I measured the resistance with an ohm meter comparing the old with the new, they were consistent most of the way up to boiling, however the old one went crazy once on the way up and several times while it was cooling back down. I replaced it an no longer have a problem. Sorry for being so long winded that was more than $.02. Have a good one. Geo
 
  #7  
Old 09-11-07, 09:24 PM
P
Member
Join Date: Sep 2004
Posts: 238
Received 0 Votes on 0 Posts
Relay?

had same symptoms on '94 taurus

it was multifunction relay

make sure you know what the fuel pump sounds like w/
key on engine off. you get about a 2 second burst. listen for that next time.

find service port on fuel rail. With car running fine, shut off car and press on valve stem. Remember spray intensity.

next time you have no start, listen for the pump and try to spray gas as before. If you hear the pump and get the same spray pattern, gas is not your problem.

If gas is your problem, beat on the relay. On '94 it is under emissions labels above radiator.
 
Reply
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


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description: