TBI Fuel pressure testing and installing gauge

I live in area that I would need to order the exact parts needed to check the fuel pressure. I understand you adjust the pressure at the TBI itself. but do you cut the fuel line and install a gauge and at the same time install a secondary fuel filter.

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TBI Fuel pressure testing and installing gauge

Group: alt.autos.4x4.chevy-trucks Date: Mon, May 30, 2005, 5:57pm (CDT-2) From: snipped-for-privacy@yahoo.ca I live in area that I would need to order the exact parts needed to check the fuel pressure. I understand you adjust the pressure at the TBI itself. but do you cut the fuel line and install a gauge and at the same time install a secondary fuel filter.

ok well what year make and model is you car/truck? And for a TBI the fuel pressure is regulated by the fuel pressure regulater.Not the throttle body itself..And by NO means cut any lines....Why would you need a secondary fuel filter? What exactly are you trying to do? S Cook

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Steve Cook wrote:

Sorry 1990 chevy PU 5.7, so where is the fuel pressure regulator located, my goal is to test the fuel pressure, from my understanding it should be between 9 to 13 PSI, I think the ideal pressure is 10.5 PSI. lower pressure gives lean mixture and to high pressure will give you a rich mixute. So does it make sense to check this pressure and how do you adjust it. As far as a secondary filter, with my marine experience I have always run a secondary see though filter.

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Re: TBI Fuel pressure testing and installing gauge

Group: alt.autos.4x4.chevy-trucks Date: Mon, May 30, 2005, 7:13pm (CDT-2) From: snipped-for-privacy@yahoo.ca Steve Cook wrote: TBI Fuel pressure testing and installing gauge Group: alt.autos.4x4.chevy-trucks Date: Mon, May 30, 2005, 5:57pm (CDT-2) From: snipped-for-privacy@yahoo.ca I live in area that I would need to order the exact parts needed to check the fuel pressure. I understand you adjust the pressure at the TBI itself. but do you cut the fuel line and install a gauge and at the same time install a secondary fuel filter. ok well what year make and model is you car/truck? And for a TBI the fuel pressure is regulated by the fuel pressure regulater.Not the throttle body itself..And by NO means cut any lines....Why would you need a secondary fuel filter? What exactly are you trying to do? S Cook Sorry 1990 chevy PU 5.7, so where is the fuel pressure regulator located, my goal is to test the fuel pressure, from my understanding it should be between 9 to 13 PSI, I think the ideal pressure is 10.5 PSI. lower pressure gives lean mixture and to high pressure will give you a rich mixute. So does it make sense to check this pressure and how do you adjust it. As far as a secondary filter, with my marine experience I have always run a secondary see though filter

Ok the fuel pressure regulator is more than likely under your upper intake. The fuel pressure should be between for this engine 42-55 PSI Your right about the lower and raising of the pressure but you cannot adjust if but you can advance and retard the timing...You will eighter Have a service port or you will need to disconnect your fuel filter and use a adaptor which you can connect a pressure gauge too...A Second filter wont help you much if your trying to keep out water...But there is really no need for a second filter...Why is it your worried about your fuel pressure? S Cook

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Steve, I believe the TBI on this truck is 10-15 psi and the regulator is in the TB itself. If I remember correctly it is under a small cover plate, it is the spring loaded diaphragm type.

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bingo. Finally the RIGHT info.

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wrote:

that right. The regulator is part of the TBI "unit", and as you say the pressure should be around 13lbs. I just went through the fuel pump swap and the mechanic tested the fuel pressure.

They have an adapater that allows a manual fuel pressure guage to be connected to the fuel line that feeds the rear of the injector. I think you connect this near the fuel filter?

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Elbert wrote:

Thanks I think I am getting closer to answer,but where i am starting to loose it,the fuel pump pressure seems easy to read, just but a pressure gauge near the fuel filter. That way you don't have to break the fuel line. Now that is going to show you fuel pump pressure. So the next thing is to take the cover off at the far end of the TBI and adjust the pressure into the TBI to 13 to 15 PSI. So my next question is where do you get that reading from. I some how don't think it would be the gauge that you install at the fuel filter or am I missing something. Where I live you can not just drop into your local chevy dealership and ask them to check TBI presure.

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Re: TBI Fuel pressure testing and installing gauge

Group: alt.autos.4x4.chevy-trucks Date: Tue, May 31, 2005, 6:16pm (CDT-2) From: snipped-for-privacy@yahoo.ca Elbert wrote:

Steve, I believe the TBI on this truck is 10-15 psi and the regulator is in the TB itself. If I remember correctly it is under a small cover plate, it is the spring loaded diaphragm type.

remove ** to email Thanks I think I am getting closer to answer,but where i am starting to loose it,the fuel pump pressure seems easy to read, just but a pressure gauge near the fuel filter. That way you don't have to break the fuel line. Now that is going to show you fuel pump pressure. So the next thing is to take the cover off at the far end of the TBI and adjust the pressure into the TBI to 13 to 15 PSI. So my next question is where do you get that reading from. I some how don't think it would be the gauge that you install at the fuel filter or am I missing something. Where I live you can not just drop into your local chevy dealership and ask them to check TBI presure.

Sorry for the wrong info....Guess its before my time...But Even I learned something today... Thanks for the correction.. S Cook.

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Steve Cook wrote:

I live in Cabo san Lucas MX and the dealer is confused with changing a tire, so I think I have a lot better idea on where to go with. I am running the complete edelbrock Power package. I still think there is some more HP with combination. I am hearing everthing from 10.5 PSI to 13PSI. My understanding is that the higher the PSI with-in reason, the richer the mixture.

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On 31 May 2005 18:16:09 -0700, snipped-for-privacy@yahoo.ca wrote:

As far as I know there is only one pressure to check and thats the "fuel" line pressure, which is generated by the fuel pump and controlled by the regulator. If you are talking about this on a 5.7 TBI 1990 pickup then thats what we are talking about.

Any GM dealer should have the appropriate fuel guage and adapter to check this. I don't know if you live in the US or in another country.

I'm not aware of any other way to check the fuel pressure on a 5.7 TBI truck in this year model range. These engines don't have a port like some of the tuned port engines, that makes it really easy to do. If you want to check the fuel pressure you are going to have to get in-line with the fuel system.

I'm not aware of any way to check the fuel pressure behind the regulator as I think you are saying above. I don't know if the regulators are even adjustable?

Elbert

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Regulators are not adjustable, unless they have a stronger spring available to increase the pressure. If it is computer controlled the richer mixture would be corrected to some extent by the o2 sensor, so that may not in itself make a difference, a performance chip may be the only way to accomplish this.

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Shep wrote:

Yes and no, the regulators don't come from the factor adjustable. There are a few ways around this, remove the FPR assembly and you will notice the adjusting screw on the bottom has a restrictor that can be removed to give you access to the screw. Or you can waste $50 and buy an adjustable billet aluminum assembly. The easiest way around this problem is to drop in a 1/8" thick lug nut spacer washer between the spring and body. The washer will boost the pressure up 1.5 PSI.

This is a much needed mod if you use a performance chip and a 165* thermostat. The extra pressure isn't a problem and the TBI will be fed what is needed under normal "closed loop" conditions. It's when you hit WOT and you are in "open loop" is where you see and feel the benefits of the extra pressure, just get more air in and you'll be fine.

Rita

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Rita Berkowitz wrote:

Thanks for all your input, has anyone had any hands on experience with this companys products. http://www.cfm-tech.com/TBI_Performance.htm

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Rita Berkowitz wrote:

Thanks for all your input, has anyone had any hands on experience with this companys products. http://www.cfm-tech.com/TBI_Performance.htm

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"Shep2" wrote: > Steve, I believe the TBI on this truck is 10-15 psi and the > regulator is in > the TB itself. If I remember correctly it is under a small > cover plate, it > is the spring loaded diaphragm type.

> > > I live in area that I would need to order the exact parts > needed to > > check the fuel pressure. I understand you adjust the > pressure at the TBI > > itself. but do you cut the fuel line and install a gauge and > at the same > > time install a secondary fuel filter. > > ok well what year make and model is you car/truck? And for a > TBI the > > fuel pressure is regulated by the fuel pressure > regulater.Not the > > throttle body itself..And by NO means cut any lines....Why > would you > > need a secondary fuel filter? What exactly are you trying to > do? > > S Cook > > Sorry 1990 chevy PU 5.7, so where is the fuel pressure > regulator > > located, my goal is to test the fuel pressure, from my > understanding it > > should be between 9 to 13 PSI, I think the ideal pressure is > 10.5 PSI. > > lower pressure gives lean mixture and to high pressure will > give you a > > rich mixute. So does it make sense to check this pressure > and how do you > > adjust it. As far as a secondary filter, with my marine > experience I > > have always run a secondary see though filter > > > > Ok the fuel pressure regulator is more than likely under > your upper > > intake. > > The fuel pressure should be between for this engine 42-55 > PSI > > Your right about the lower and raising of the pressure but > you cannot > > adjust if but you can advance and retard the timing...You > will eighter > > Have a service port or you will need to disconnect your > fuel filter and > > use a adaptor which you can connect a pressure gauge too...A > Second > > filter wont help you much if your trying to keep out > water...But there > > is really no need for a second filter...Why is it your > worried about > > your fuel pressure? > > S Cook > > > > > > -

TBI trucks run at much lower pressure. It should be about 11 to 15 PSI from tank and around 9 to 10 PSI on injectors after regulator.

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