1986 2.8L TBI Fuel Pressure? - S-10 Forum
 
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post #1 of 11 Old 01-05-2009, 11:54 AM Thread Starter
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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?

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post #2 of 11 Old 01-05-2009, 12:40 PM
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Re: 1986 2.8L TBI Fuel Pressure?

11-15 psi, id say you have a bad pump or regulator

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post #3 of 11 Old 01-05-2009, 01:41 PM Thread Starter
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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?
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post #4 of 11 Old 01-05-2009, 02:45 PM
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Re: 1986 2.8L TBI Fuel Pressure?

check to see if one(or both) of the injectors are leaking.

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post #5 of 11 Old 01-05-2009, 04:51 PM
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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.
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post #6 of 11 Old 01-05-2009, 04:56 PM
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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.
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post #7 of 11 Old 01-06-2009, 10:11 AM Thread Starter
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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.
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post #8 of 11 Old 01-06-2009, 11:13 AM
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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.

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post #9 of 11 Old 01-06-2009, 03:40 PM Thread Starter
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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?
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post #10 of 11 Old 01-06-2009, 04:21 PM Thread Starter
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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?
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post #11 of 11 Old 01-06-2009, 04:36 PM
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Re: 1986 2.8L TBI Fuel Pressure?

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Originally Posted by jregezeino View Post
....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.

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