Fuel System question

[scoutcamper]

Hey All,

Ive been doing some reading, but i dont see an answer to this specific question anywhere.

My sending unit is going out on my 1990 Jimmy, I am planning to replace it this week with this sender(should be drop in relacement): https://www.amazon.com/Spectra-Premium-SP12L1H-Assembly-Sending/dp/B000VB0ZQ2

I also want to upgrade my fuel pump while i am in there, i plan within the next few months to do heads, cam, exhaust, etc. and I know fuel is a huge part of that. I plan to go with this fuel pump based on everyone saying it will bolt in: https://www.amazon.com/ACDelco-EP38...04119028&sr=8-1-fkmr0&keywords=c+delco+ep+381

My primary question is this: Do I need to replace my fuel pressure regulator when I go to the new upgraded fuel pump?? I see most people go to an adjustable, which I plan to do when i do my heads, but for now do I need to do anything?

Thanks in advance!

 

[dyeager535]

Pump and sending unit look correct, but appears you are buying a sending unit combo with the TBI pump as well, which does you no good. FG12L might be the number for one without the pump. Autozone lists it for a 1987 V10 Blazer. Make sure you don't select the 25 gallon one.

You don't need to mess with the pressure regulator for the pump. In fact, unless you are doing something weird like running the fairly rare high pressure TBI setup, I'd shy away from an adjustable fuel pressure regulator (AFPR) UNLESS you've installed the EP381 and checked pressure, and found that it's under 12PSI or so.

AFPR's are often a bandaid that doesn't stick. If the engine needs more fuel, it generally needs to be done through the PROM. If you are doing heads, cam and exhaust you may or may not need to crutch the tune with an AFPR (bumping pressure up to decrease injector dwell time and provide enough fuel), but that should be done AFTER you install all the components, and see if you can tune it as-is.

Don't know where you are on the tuning aspect of TBI, but it's not a particularly easy road to go down, but going to be absolutely necessary with the mods you are talking about. I mean, if you consider running even halfway correct necessary.

I hate to say it, but heading down the road of serious TBI mods should make you question the engine you are running, and whether you should consider something else entirely.

 

[Kain]

that pump puts out 60 psi, just fyi

 

[scoutcamper]

Pump and sending unit look correct, but appears you are buying a sending unit combo with the TBI pump as well, which does you no good. FG12L might be the number for one without the pump. Autozone lists it for a 1987 V10 Blazer. Make sure you don't select the 25 gallon one.

You don't need to mess with the pressure regulator for the pump. In fact, unless you are doing something weird like running the fairly rare high pressure TBI setup, I'd shy away from an adjustable fuel pressure regulator (AFPR) UNLESS you've installed the EP381 and checked pressure, and found that it's under 12PSI or so.

AFPR's are often a bandaid that doesn't stick. If the engine needs more fuel, it generally needs to be done through the PROM. If you are doing heads, cam and exhaust you may or may not need to crutch the tune with an AFPR (bumping pressure up to decrease injector dwell time and provide enough fuel), but that should be done AFTER you install all the components, and see if you can tune it as-is.

Don't know where you are on the tuning aspect of TBI, but it's not a particularly easy road to go down, but going to be absolutely necessary with the mods you are talking about. I mean, if you consider running even halfway correct necessary.

I hate to say it, but heading down the road of serious TBI mods should make you question the engine you are running, and whether you should consider something else entirely.

I priced FG12L and it appears to be a few dollars more expensive, which makes absolutely no sense to me.

I will stay away from an AFPR, thats good to know.

I have done a lot of tuning on a TPI, never with a TBI, for the first round when I do my upgrades I will probably pay to have one done as a baseline.

Trust me, I would love to swap in a LS1 or LT1, or even a TPI intake(I have one sitting in a tub in the garage), but in California that is nearly impossible with smog rules, so its much easier to make big power if you disguise it within the factory motor.

Thank you for the info!

 

[dyeager535]

I see that now too...ridiculous the sender with pump is cheaper than just the sender. Their loss I suppose. Or cleverness "all I need is the sender", assuming it's cheaper.

You use Tunerpro and moates hardware or similar to do the tuning? if you can find someone that will do a decent job burning chips not a bad way to go, unfortunately those folks seem to be getting fewer and fewer.

If you have all the burning equipment, and knowledge, probably going to be better to do it yourself. I know TBI is a bit different with the PROM socket than the TPI, but IIRC it's not THAT tough to work through.

I tune for my TPI, but that's it. I did a bit for my Dads TBi truck, but then he got rid of it.

 

[scoutcamper]

To update this: did the fuel system upgrades this weekend. First and most importantly: My fuel gauge works now! Also, based on data logging the truck is way happier(BLM's staying within range now, not maxing out...). No real seat of the pants difference other than it starting much easier now.

You use Tunerpro and moates hardware or similar to do the tuning? if you can find someone that will do a decent job burning chips not a bad way to go, unfortunately those folks seem to be getting fewer and fewer.

If you have all the burning equipment, and knowledge, probably going to be better to do it yourself. I know TBI is a bit different with the PROM socket than the TPI, but IIRC it's not THAT tough to work through.

I tune for my TPI, but that's it. I did a bit for my Dads TBi truck, but then he got rid of it.

I use Tunerpro and a EEPROM burner for the TPI(1965 C10 pickup, its a hot rod, not tuning it weekly) but for this truck since its my daily driver im going to go Moates for ease of tuning without downtime.