1986 2.8L TBI Fuel Pressure? - S-10 Forum
S-10 Forum is the resource on GM S-series trucks, Suspension, engine information, Body Modifications, painting tutorials.  Modifications to suit every need, budget and whim

1986 2.8L TBI Fuel Pressure?

Go Back   S-10 Forum > Engine and Drivetrain Tech > 60v6 Forum (2.8/3.4)
New User? Register Forgot Password


 
LinkBack Thread Tools
Old 01-05-2009, 11:54 AM   #1
Registered User
 
Age: 26
Join Date: Nov 2008
Posts: 12
Location:
User is: OffLine
1986 2.8L TBI Fuel Pressure?

What should my fuel pressure be with the TBI on the 2.8? My pump is only putting out about 5 psi and then quickly drops back to zero when the key is 'on' and the pump is priming. Does this indicate a bad pump?
Old 01-05-2009, 12:40 PM   #2
Registered User
 
34blazer's Avatar
 
Age: 31
Join Date: Aug 2007
Posts: 1,053
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

11-15 psi, id say you have a bad pump or regulator
Old 01-05-2009, 01:41 PM   #3
Registered User
 
Age: 26
Join Date: Nov 2008
Posts: 12
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

ok. although, it does seem to be running rich...would that be the TB trying to compensate for the low pressure?
Old 01-05-2009, 02:45 PM   #4
Registered User
 
34blazer's Avatar
 
Age: 31
Join Date: Aug 2007
Posts: 1,053
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

check to see if one(or both) of the injectors are leaking.
Old 01-05-2009, 04:51 PM   #5
Registered User
 
taylordoege's Avatar
 
Join Date: Dec 2008
Posts: 67
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

more info. if you can what kind of tbi, year of your truck.
cuz i have a 93 s10 with a 220 tbi and it has no fuel pressure till you turn the key to start it. it should run from 9-14 psi. the 220 model tbi is different than all of the others because of this. if you have it you can see two lines for fuel one is bigger than the other, 3/8, and the other is 5/16, the big is the main and the 5/16 is the return line.
Old 01-05-2009, 04:56 PM   #6
Registered User
 
taylordoege's Avatar
 
Join Date: Dec 2008
Posts: 67
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

and yea if you get 5 when it runs( if it does) then what 34blazer said, fuel pump and regulator. and i know that it sounds funny but have you checked your fuel filter, it can get cloged if you get gunk in your tank and you run it on E. that gunk can get in your lines and clog it.
Old 01-06-2009, 10:11 AM   #7
Registered User
 
Age: 26
Join Date: Nov 2008
Posts: 12
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

Yeah, i have replaced the fuel filter, and both of my injectors have been swapped out with a combination of four other used ones, all ending up with the same result. It seems as though they are spitting way to much fuel when running (as if they were leaking), but i wouldnt think that out of 6 injectors they would all be bad. I will try the regulator first then pump and let know. Im not sure of the TB model # but it is on an '86 S10 2wd 2.8 litre.
Old 01-06-2009, 11:13 AM   #8
4x4 v6 blazer
 
neo71665's Avatar
 
Age: 34
Join Date: Oct 2004
Posts: 7,507
Location: rison arkansas
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

Sounds like a bad reg. Its allowing the fuel pump to push too much past and flooding the engine.
Old 01-06-2009, 03:40 PM   #9
Registered User
 
Age: 26
Join Date: Nov 2008
Posts: 12
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

Thats what i was thinking too. I had a spare regulator and slapped it on last week, it immediately fired up and ran great. After I ran it for awhile and fired it back up though it was stumbling again.. I have one more that im gonna try in there to see what happens. The only regulator is the one on top of the TB right?
Old 01-06-2009, 04:21 PM   #10
Registered User
 
Age: 26
Join Date: Nov 2008
Posts: 12
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

....Although i have tried pinching off the return line to see how it runs. Doesnt this act as eliminating the regulator?
Old 01-06-2009, 04:36 PM   #11
Registered User
 
34blazer's Avatar
 
Age: 31
Join Date: Aug 2007
Posts: 1,053
Location:
User is: OffLine
Re: 1986 2.8L TBI Fuel Pressure?

Quote: Originally Posted by jregezeino
....Although i have tried pinching off the return line to see how it runs. Doesnt this act as eliminating the regulator?
if you pinch the line you are restricting the flow of fuel, the pressure will spike. also called dead heading the fuel pump.
Sponsored Links
Advertisement
 

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the S-10 Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may 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 On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 06:08 PM.

Powered by vBulletin® Copyright ©2000 - 2011, Jelsoft Enterprises Ltd. SEO by vBSEO 3.2.0
SEO by vBSEO
vBulletin Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.