Fordmods Logo

fuel pressure - should it drop this much? 

 

Page 1 of 1 [ 3 posts ] 

 
 Post subject: fuel pressure - should it drop this much?
Posted: Fri Mar 17, 2006 12:45 am 
Getting Side Ways
Offline
User avatar

Posts: 596

Joined: 6th Nov 2004

Gallery: 11 images

Ride: BA mkII XR8

Location: NEWCASTLE
NSW, Australia

i set up a fuel pressure gauge in the xr8 2 try & find a few problems with the tune, & have found that when set to 43 psi with the vacuum off at idle the pressure styas around 37 - 40 psi whilst cruising at low rpm,but soon as i raise the rpm in a cruise style of driving the fuel pressure actually drops to the low 30 's.
this is where the engine has been pinging lately & also the temp has started to rise considerably aswell.
is it normal for the pressure to drop so much? & if not should i restrict the amount of vacuum to the regulator? any help would would be appreciated

 

_________________

Image
IF YOU HAVE IT UNDER CONTROL
YOU SIMPLY DON'T HAVE ENOUGH POWER!!!
Detroit 8V71 for sale, taking offers

Top
 Profile  
 
 
Posted: Fri Mar 17, 2006 5:41 pm 
Getting Side Ways
Offline
User avatar

Age: 38

Posts: 1440

Joined: 7th Nov 2004

Ride: 320kw BA XR8

Location: Adelaide
SA, Australia

It will be lower during cruising because there is more vacuum there (especially with aftermarket cams), but once you start giving it a bit of throttle you should see it rise pretty quickly (you need load on the engine though, free reving won't tell you much). The main thing to look for is the fuel pressure at WOT under full load, if thats declining below the vac off figure then your fuel pump probably isn't able to keep up.

The pinging on light/medium throttle is probably caused by the fuel saving / emissions measures that ford have programed into the EEC (if you are still running the factory computer), which are normally amplified in modified cars.
Top
 Profile  
 
 
Posted: Fri Mar 17, 2006 8:15 pm 
Getting Side Ways
Offline
User avatar

Posts: 596

Joined: 6th Nov 2004

Gallery: 11 images

Ride: BA mkII XR8

Location: NEWCASTLE
NSW, Australia

I have set up a fuel pressure guage to watch whilst driving it, and there was no drop in pressure at all.
so I looked in a few different ares, first with the cooling system and BINGO! problem #1 the manufactor of the radiator has taken short cuts with it ,where the cores are soldered thru the ends it looks like they have been cut with pliers, leaving the openings crushed almost together, in fact that tight that any build up of rust or whatever acctually blocks them, by the way it's only 3 months old.
Problem #2 was just a gasket between the intake and a 3/8'' spacer, and it was leaking EGR back thru a couple of runners, possibly caused by the heating problem?
thanks for the reply, cheers kenny

 

_________________

Image
IF YOU HAVE IT UNDER CONTROL
YOU SIMPLY DON'T HAVE ENOUGH POWER!!!
Detroit 8V71 for sale, taking offers

Top
 Profile  
 
Display posts from previous:
Sort by  
 Page 1 of 1  [ 3 posts ] 

Who is online

Users browsing this forum: No registered users and 8 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

 

 

It is currently Tue Dec 19, 2017 7:35 am All times are UTC + 11 hours

 

 

(c)2014 Total Web Solutions Australia - Australian Web Hosting and Domain Names