Go Back   VetteMOD.com > VetteMOD Technical Discussion > EFI

Reply
 
Thread Tools
  #1  
Old 08-23-2017, 08:55 AM
BangkokDean's Avatar
BangkokDean BangkokDean is offline
Thailand | Addict
 
Join Date: Mar 2008
Location: Bangkok
Posts: 3,348
My Photos: (14)
Default Bucking when driving

Hi, My L98 motor all of a sudden has started bucking or pausing when driving. It idles OK cold or hot 183*. I set the TPS to .54 volts using two paper clips + to the center wire and the to the top wire.

The fuel pressure with key on is 30lbs and after 30 minutes key off it drops to 16lbs.

When running the fuel gauge bounces all over the place 10 to 50 very fast.

The Trans is a 700R4 I drive in drive and overdrive with the same surging.

Please let me know what you all think the problem is, thanks
Attached Images
File Type: jpg fuel gauge.jpg (233.1 KB, 4 views)
__________________
[Only registered and activated users can see links. Click Here To Register...]
From the land of smiles
Bangkok Dean
Reply With Quote
  #2  
Old 08-23-2017, 10:15 AM
BBShark's Avatar
BBShark BBShark is offline
United States | All About VetteMOD
 
Join Date: Mar 2008
Location: Ohio
Posts: 4,194
My Photos: (238)
Default

Isn't the pressure supposed to be 43psi?
__________________
Reply With Quote
  #3  
Old 08-23-2017, 12:48 PM
BangkokDean's Avatar
BangkokDean BangkokDean is offline
Thailand | Addict
 
Join Date: Mar 2008
Location: Bangkok
Posts: 3,348
My Photos: (14)
Default

The fuel gauge is all over the place when running. is the natural?


[Only registered and activated users can see links. Click Here To Register...]
Reply With Quote
  #4  
Old 08-23-2017, 09:20 PM
BBShark's Avatar
BBShark BBShark is offline
United States | All About VetteMOD
 
Join Date: Mar 2008
Location: Ohio
Posts: 4,194
My Photos: (238)
Default

It should be steady. Are you measuring it on the fuel rail?
Reply With Quote
  #5  
Old 08-23-2017, 09:38 PM
mrvette's Avatar
mrvette mrvette is offline
United States | Phantom of the Opera
 
Join Date: Mar 2008
Location: NE Florida
Posts: 15,301
My Photos: (3)
Default

Quote:
Originally Posted by BangkokDean View Post
The fuel gauge is all over the place when running. is the natural?


[Only registered and activated users can see links. Click Here To Register...]
FB comes up with N/A on your link.....

yup 42 something is fine at idle, anything lower is suspect, pull the vac line to the regulator and look for gas....much lower pressure and you in trouble....check that the pump is getting a full voltage basically same as alt is putting out....if it does and you ain't got pressure, I have to say either bad fuel filter or pump....
__________________
"Hell, there are no rules here ... we're trying to accomplish something." Thomas Edison
I have a little list, let ALL of them be MIST......
I love how Progressives want to have Darwinism taught in schools but denied as a reality in life.
All products should say "Do not use if your stupid."


[Only registered and activated users can see links. Click Here To Register...]
Reply With Quote
  #6  
Old 08-24-2017, 04:12 AM
BangkokDean's Avatar
BangkokDean BangkokDean is offline
Thailand | Addict
 
Join Date: Mar 2008
Location: Bangkok
Posts: 3,348
My Photos: (14)
Default

Quote:
Originally Posted by BBShark View Post
It should be steady. Are you measuring it on the fuel rail?
Yes directly on the rails.
Reply With Quote
  #7  
Old 08-31-2017, 10:47 AM
BangkokDean's Avatar
BangkokDean BangkokDean is offline
Thailand | Addict
 
Join Date: Mar 2008
Location: Bangkok
Posts: 3,348
My Photos: (14)
Default

Fixed, changes the in tank fuel pump and the fuel filter, now 43 lbs fuel pressure. runs like it should.

The only new problem is when at running temps it is difficult to start. Takes several tries to start?

Last edited by BangkokDean : 09-01-2017 at 06:08 AM.
Reply With Quote
  #8  
Old 09-11-2017, 07:28 PM
Belgian1979vette's Avatar
Belgian1979vette Belgian1979vette is offline
Belgium | Addict
 
Join Date: Apr 2008
Location: Koersel/Belgium
Posts: 1,678
My Photos: (104)
Default

Quote:
Originally Posted by BangkokDean View Post
Fixed, changes the in tank fuel pump and the fuel filter, now 43 lbs fuel pressure. runs like it should.

The only new problem is when at running temps it is difficult to start. Takes several tries to start?
vacuum leak
__________________
Opinions are like assholes, everyone has got one, but everyone thinks everyone else's stinks.
Reply With Quote
  #9  
Old 09-13-2017, 07:54 AM
BangkokDean's Avatar
BangkokDean BangkokDean is offline
Thailand | Addict
 
Join Date: Mar 2008
Location: Bangkok
Posts: 3,348
My Photos: (14)
Default

Quote:
Originally Posted by Belgian1979vette View Post
Quote:
Originally Posted by BangkokDean View Post
Fixed, changes the in tank fuel pump and the fuel filter, now 43 lbs fuel pressure. runs like it should.

The only new problem is when at running temps it is difficult to start. Takes several tries to start?
vacuum leak
Finally fixed the problem. The in tank fuel pump had a leak in the fuel line in the tank itself. Now it holds 45 lbs pressure and actually starts right away and runs better than it had in the past.

Finally...
Reply With Quote
Reply


Thread Tools

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT. The time now is 01:32 PM.
 


Design by: vBulletin Skins Zone
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.