Three questions 87 TBI ....

[LT7A]

Originally Posted by 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.

I'm glad to hear that you had a good experience with Brian and that it worked out well. Would be interested to hear about the process of getting your chip dialed in. I have had a different experience with him, as have others. I don't know if you looked at the link, but it details the difference in the construction of the two pumps and that is the greater concern, but the lesser pump sells for roughly 38% less. I'm only commenting on the one he currently sells, no way for me to know which one you have, and you can do the math on all that however you see fit. I have no interest in taking anything away from your experience. But it is information I was glad that I found as I was making my own decision so I am passing it along.

[44th Miss Inf]

Originally Posted by LT7A

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?

The volume isn’t that much of a change, but is enough to make the engine run better. I think the ep386 (tbi pump) is 23gph where the ep381 is around 32gph (I’m at work so don’t have my notes in front of me)
If I remember right, there are only 3 tbi springs, gold 12-15psi, brown 17-18psi, and the 94-95 454 spring (silver? Maybe) again going off the top of my head here.

The 94-95 454 injectors also changed to a smaller size, and higher pressure for better fuel atomization, if I remember right.


And the ep381 CAN provide up to 60 psi of working pressure (they deadhead at around 100psi) but again pressure is set by the regulator, not volume

Edit: also, something I think that may be helping using the “higher pressure” pump is that if the ep386 produces 15 psi, that’s 15 psi with 12 volts. Over the years, corrosion etc, your pump may only be getting say 10 volts, which would only put enough volume out to produce say 11-12psi (just throwing numbers out) where the ep381 will still provide enough volume to produce 15 psi with reduced voltage.

Hopefully this doesn’t complicate the thread

[Greenlee]

Originally Posted by LT7A

I'm glad to hear that you had a good experience with Brian and that it worked out well. Would be interested to hear about the process of getting your chip dialed in. I have had a different experience with him, as have others. I don't know if you looked at the link, but it details the difference in the construction of the two pumps and that is the greater concern, but the lesser pump sells for roughly 38% less. I'm only commenting on the one he currently sells, no way for me to know which one you have, and you can do the math on all that however you see fit. I have no interest in taking anything away from your experience. But it is information I was glad that I found as I was making my own decision so I am passing it along.

Not sure what you are asking. I bought a chip from him about 10 years ago and never had any problems with it. Bought another one from him when I changed the transmission from 700r4 to TH400 and swapped the computer to one from a TH400 truck. He reprogrammed it once for free when my headers were causing the check engine light to come on. When I’ve had other issues that I was stumped on, he helped me out even though it had nothing to do with the chip he sold me. About 3 months ago the truck started dying at stoplights after changing the distributor. Changed the distributor 2 more times thinking the parts store gave me a bad one, and it had the same problem of dying occasionally. He told me how to turn up the idle, and it hasn’t died since. I didn’t even realize you could turn up the idle on TBI until he told me. So I bought 2 chips and a fuel pump from him and it came with 10 years of free trouble shooting advice. Seems like a stand up guy to me.

[Hart_Rod]

Originally Posted by 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!

No problem at all! We're all here to learn and share our experiences in hopes of helping our truck community out. "CIVIL" conversation never hurt anyone, Keep it coming!

OBTW, I ordered the EP377. I figured it is better than stock, and hopefully all my little 305 needs .