Three questions 87 TBI ....

[Hart_Rod]

#1: I need to replace the fuel pump on my 87 TBI. See several options on Rockauto.com - Delphi and Bosch. Either one better than the other or same same, different name?

https://www.rockauto.com/en/moreinfo...84253&jsn=4132

https://www.rockauto.com/en/moreinfo...84253&jsn=4133

#2: Also replacing EGR valve, I'm assuming one is as good as the other?

#3: The gas pedal spring on the TBI seems waaaaay to stiff. The truck only has 35K miles on it. I've driven other a lot of 86 and older and never had to press as hard as I do on the TBI truck. Does anyone know of a replacement spring that will rectify this issue?

Thanks in advance!

[44th Miss Inf]

I replace the TBI pumps with the later Vortec pumps, as the tbi pumps seem to barely supply enough fuel to a small block, much less a big block. The Vortec pumps supply more fuel. I’ve done this for about 20 years and never had an issue.

[Hart_Rod]

Originally Posted by 44th Miss Inf

I replace the TBI pumps with the later Vortec pumps, as the tbi pumps seem to barely supply enough fuel to a small block, much less a big block. The Vortec pumps supply more fuel. I’ve done this for about 20 years and never had an issue.

Thanks, Do you have a year and part number?

[kwmech]

My wife always complains about the 'stiffness' of the pedal on our 91 Suburban. I think I may pull the TB off the truck and see if I can unwind the coil spring by a turn and see if that makes a difference

[44th Miss Inf]

Originally Posted by Hart_Rod

Thanks, Do you have a year and part number?

Ep381 is the AC Delco number for the Vortec pump (96-97 Chevy).

[LT7A]

I am replacing the fuel pump in a 93 TBI truck. I looked into it carefully for exactly the reasons that 44th Miss Inf mentioned. My concern with the EP381 is that it provides 60 PSI for a system that can only use about 15. That means most of the fuel is going to be returned to the tank. That process can heat it up which is bad for the life of the fuel pump. I also discovered as an aside, that since in-tank fuel pumps are cooled by the fuel, it is better not to get below a quarter of a tank. Back to the business at hand, there is another choice, which is the one I bought - EP377. It is the pump for 94 and 95 big blocks. It is rated at 30 psi. I wish I had it installed and could apprise you of the results. Bottom line, it provides more pressure which all seem to agree is a benefit to the TBI system. Even though the 60 PSI pump will work, I feel better about not quadrupling the pressure on the 28-year-old fuel system in my truck. Electrical current draw seemed worth my consideration as well. That said, I have not heard of problems with the 60 PSI pump being installed. The EP numbers are AC Delco. You would probably be fine with Delphi if that's what you prefer. I don't have the confidence that Bosch designs would work as well as AC Delco or Delphi based on knowledge of another component.

[Hart_Rod]

Originally Posted by kwmech

My wife always complains about the 'stiffness' of the pedal on our 91 Suburban. I think I may pull the TB off the truck and see if I can unwind the coil spring by a turn and see if that makes a difference

Kewl. Let me know what you figure out.

Originally Posted by 44th Miss Inf

Ep381 is the AC Delco number for the Vortec pump (96-97 Chevy).

Thanks for the info.

Originally Posted by LT7A

I am replacing the fuel pump in a 93 TBI truck. I looked into it carefully for exactly the reasons that 44th Miss Inf mentioned. My concern with the EP381 is that it provides 60 PSI for a system that can only use about 15. That means most of the fuel is going to be returned to the tank. That process can heat it up which is bad for the life of the fuel pump. I also discovered as an aside, that since in-tank fuel pumps are cooled by the fuel, it is better not to get below a quarter of a tank. Back to the business at hand, there is another choice, which is the one I bought - EP377. It is the pump for 94 and 95 big blocks. It is rated at 30 psi. I wish I had it installed and could apprise you of the results. Bottom line, it provides more pressure which all seem to agree is a benefit to the TBI system. Even though the 60 PSI pump will work, I feel better about not quadrupling the pressure on the 28-year-old fuel system in my truck. Electrical current draw seemed worth my consideration as well. That said, I have not heard of problems with the 60 PSI pump being installed. The EP numbers are AC Delco. You would probably be fine with Delphi if that's what you prefer. I don't have the confidence that Bosch designs would work as well as AC Delco or Delphi based on knowledge of another component.

Thanks for the info, I agree with your thinking .

[v30crewcab]

when the cable gets bad it gets hard to press. I would try replacing the throttle cable.

[Corts60]

I've seen some TBI units that have a dual throttle spring. Spring inside a spring in other words. Maybe you could check and remove one of those springs and see what you get?

[Hart_Rod]

Originally Posted by v30crewcab

when the cable gets bad it gets hard to press. I would try replacing the throttle cable.

That's a possibility, but this truck only has 35K miles on it and nearly every TBI truck I've driven is the same way.

Originally Posted by Corts60

I've seen some TBI units that have a dual throttle spring. Spring inside a spring in other words. Maybe you could check and remove one of those springs and see what you get?

Good idea!

[1976gmc20]

I never had that problem with our 91 Suburban, but my 89 K1500 has a binary spot and a real lurch at low speeds.

Our VFD used to have a ~94 K3500 with the same problem. I thought it was a problem with the GMT400 and not the squarebody TBIs.

[LT7A]

A little clarification on my input for the fuel pump. I have not actually installed the EP377. I have read input from one person online who has done it and recommends it. I have read multiple places that the EP381 that 44th Miss Inf recommended has been installed without a problem and works well. My concerns and detailed info came from my own research when I talked to a local hot rod mechanic and he mentioned the 60 psi. I ran it by an east coast TBI 'guru' and he was not receptive, but had never tried it. I think it's important that we share our thoughts and ideas but not at the expense of someone else's input. In this case, a proven solution versus a proposed solution (so far). Well reasoned research, but not yet installed, versus numerous notations on the internet that the EP381 works. I had literally done my research a couple of weeks ago and was glad to be able to tell about it.

[v30crewcab]

it won't be 60 psi on that truck. the throttle body has a regulator in it that keeps it at 15 psi. it'll just be a better pump.

[Greenlee]

This guy has a lot of good info on his site. I bought a chip from him and he has helped me several times with trouble shooting when I had TBI questions.

https://harristuning.com/product/ac-...381-fuel-pump/

[THI]

Originally Posted by v30crewcab

it won't be 60 psi on that truck. the throttle body has a regulator in it that keeps it at 15 psi. it'll just be a better pump.

To add to this, the Vortec pump provides more volume which can be an issue with the TBI pump. My brother is running a Vortec pump on his 1993 K1500 Blazer with a Vortec 454 (stock) on TBI. The standard pump could not provide enough fuel, the Vortec pump work perfectly with 15 psi

[LT7A]

Originally Posted by v30crewcab

it won't be 60 psi on that truck. the throttle body has a regulator in it that keeps it at 15 psi. it'll just be a better pump.

Really? This is how I see it. The regulator manages the fuel at the injectors. The fuel pump will pressurize the line from the tank to the regulator to 60 psi. Whatever fuel the regulator does not allow to the injectors goes back to the tank. A 60 PSI pump will return a lot more fuel to the tank than a 30 PSI pump. The regulator is located at the throttle body and is spring actuated so it does not send a signal to modulate the in-tank pump. Unless I've got something wrong in how the system works, the supply side of the fuel system is pressurized at 60 PSI except for what goes to the injectors.

[LT7A]

Originally Posted by THI

To add to this, the Vortec pump provides more volume which can be an issue with the TBI pump. My brother is running a Vortec pump on his 1993 K1500 Blazer with a Vortec 454 (stock) on TBI. The standard pump could not provide enough fuel, the Vortec pump work perfectly with 15 psi

That 454 is not the motor that that came in that Blazer. 94 and beyond big blocks require more fuel pressure. This information doesn't necessarily relate to a truck that retains its stock 350. As stated above, the high pressure pump will work well as far as how the truck runs. It's when it might stop running that concerns me, due to putting four times the design pressure on 25+ year old fuel lines and fittings. I have an active imagination. For instance, a fitting opens up and lets 30 PSI worth of fuel start spraying under the truck or under the hood. The fuel pump has no problem keeping up with that since it is still providing twice the needed fuel pressure despite the 30 PSI leak.

[LT7A]

Originally Posted by Greenlee

This guy has a lot of good info on his site. I bought a chip from him and he has helped me several times with trouble shooting when I had TBI questions.

https://harristuning.com/product/ac-...381-fuel-pump/

Brian has definitely taken the time to post much of what he has learned from working on these trucks. There is some worthwhile information there because it is hands-on. However the pump that he sells is not equivalent to the EP381 you want if you're going to go with the high pressure pump, as detailed in the thread below. If you decide you do want the pump that he offers, it's available for 35 to $40 less elsewhere.

https://www.impalassforum.com/thread...-same.1259497/

[44th Miss Inf]

Originally Posted by LT7A

Really? This is how I see it. The regulator manages the fuel at the injectors. The fuel pump will pressurize the line from the tank to the regulator to 60 psi. Whatever fuel the regulator does not allow to the injectors goes back to the tank. A 60 PSI pump will return a lot more fuel to the tank than a 30 PSI pump. The regulator is located at the throttle body and is spring actuated so it does not send a signal to modulate the in-tank pump. Unless I've got something wrong in how the system works, the supply side of the fuel system is pressurized at 60 PSI except for what goes to the injectors.

The EP381 is CAPABLE of producing 60 psi in the right conditions. I’ll try to explain this a little clearer than mud (my fault, I know what I want to say, but getting it written out understandable is another issue)

Pressure takes a pump capable, and a restriction to happen. (I dealt with hydraulics for 20 plus years in the oilfield) By your thinking, I could put an open ended line on the pump with a gauge and get 60psi. I doubt you would have near about that. Your regulator (restriction) on a tbi doesn’t have a bypass, as it is a flow thru design, and is what sets your pressure. If your regulator is set for 15 psi, and you have more than 15 on the inlet side of the TBI, either your regulator is bad, or your return line is too small, which causes a restriction.

Hopefully that is understandable.

[v30crewcab]

the reason the fuel pump will do 60psi is the regulator its attached to. the regulator controls the pressure in the entire system between the pump and regulator, thats literally its whole job. it won't have 60psi in the line unless the regulator sticks closed. It will flow a little more volume, but the regulator will just bypass it.
I have a civic with a fuel pump in it big enough to run my larger injectors for a turbo setup, but I never got around to finishing the turbo install. been running fine for almost 10 yrs that way, no issue with a larger pump.

[LT7A]

Thanks, I appreciate the effort to explain. Although one would have to be pretty limited in their processing ability to not know that without a restriction, you would not develop pressure. That pump is going to try to make 60 PSI and the regulator regulates the pressure for what's downstream - what gets through to the injectors. So if it bleeds off the excess pressure by flowing that fuel through, then it is sending a bunch of unneeded fuel back to the tank, right? That would alleviate the concern about overpressuring the line, I agree. But doesn't 60 PSI circulate more fuel needlessly?

Also, since you aren't achieving 60 psi, there is less chance of developing a leak due to pressure, I agree. However, if I do get a leak, it couldn't it grow into a much bigger deal, since the pump could keep up with it for a lot longer?

Also, I can't say for sure that the 30 PSI pump draws less current than the 60 psi, but it stands to reason. If so, why have that electrical load?

I think we all agree that these trucks benefit from having more than the 13 PSI that the stock pump puts out. If there was a 20 psi pump, it would provide all that one could ever need short of forced induction, probably. So to me 30 PSI is already overkill. Since both pumps are plug and play, I don't understand the reasoning behind installing something that provides so much more than what is needed. Is it solely based on the information put out there by others? Or the idea that if a little more is good, then a lot more is better?

[Greenlee]

My family had a 1988 GMC that we bought new. It had a stiff accelerator peddle from the day we bought it. I loved the truck. I ended up putting over 300k miles on it, but I always thought accelerator was a little too stiff.

I don’t know all the technical stuff about the fuel pumps, but I know I’ll never by another one from a parts store like O’Reilly’s or Autozone. They are junk. I had 3 pumps that didn’t last more than 2 years. I bought last one from Brian at TBI chips. Don’t care if I paid too much. That dude has given me a bunch of free advice over the years.

[LT7A]

Hart_Rod, I hope you have gotten what you needed from this thread and don't mind if I throw in a tangent. If you do mind, just say so and I will start a new thread. This has already attracted some guys with experience with the TBI motors and so I wanted to ask another question.

Assuming it's okay with HR, I wanted to ask if any of you guys had installed a non-stock fuel pressure regulator spring? It seems simpler than doing the adustable fuel pressure regulator mod. If you did, did you notice a difference? Where did you get the spring? Did you also have a new chip burned? Thanks!

[THI]

Originally Posted by LT7A

That 454 is not the motor that that came in that Blazer. 94 and beyond big blocks require more fuel pressure. This information doesn't necessarily relate to a truck that retains its stock 350. As stated above, the high pressure pump will work well as far as how the truck runs. It's when it might stop running that concerns me, due to putting four times the design pressure on 25+ year old fuel lines and fittings. I have an active imagination. For instance, a fitting opens up and lets 30 PSI worth of fuel start spraying under the truck or under the hood. The fuel pump has no problem keeping up with that since it is still providing twice the needed fuel pressure despite the 30 PSI leak.

The 454 TBI trucks and 350 TBI trucks came with the same fuel pump from the factory, the 1995 Tahoe came from the factory with the Vortec pump even though it was a TBI 350 engine. It has been a common upgrade for at least 20 years to use the Vortec pump as a replacement for the TBI pump, especially if you have done any upgrades like cam and exhaust. The pump pushes volume, it does not control pressure. The regulator controls pressure as long as there is sufficient volume, excess volume is returned to the tank. GM did not think it was an issue for the 1995 Tahoe to use a higher volume pump,

[LT7A]

Originally Posted by THI

The 454 TBI trucks and 350 TBI trucks came with the same fuel pump from the factory, the 1995 Tahoe came from the factory with the Vortec pump even though it was a TBI 350 engine. It has been a common upgrade for at least 20 years to use the Vortec pump as a replacement for the TBI pump, especially if you have done any upgrades like cam and exhaust. The pump pushes volume, it does not control pressure. The regulator controls pressure as long as there is sufficient volume, excess volume is returned to the tank. GM did not think it was an issue for the 1995 Tahoe to use a higher volume pump,

The EP377 is the factory fuel pump for 94 and 95 454s at 30 PSI. The question remains: why provide three to four times the volume the system can use?