TPI for blazer. Which sending unit/fuel pump?

[INSIDIOUS '86]

I'm taking my 84 k5 and going to do a TPI swap in it. Anyone know of a fuel sending unit/fuel pump that will work for the factory 30 gal tank?
Part numbers please and thanks!

[bdiamond]

An 87-91 blazer TBI pickup/sending unit with a 87-89 or so TPI pump on the bottom?

[INSIDIOUS '86]

Originally Posted by bdiamond

An 87-91 blazer TBI pickup/sending unit with a 87-89 or so TPI pump on the bottom?

That's what I was thinking but I'm not sure. I haven't done this before but surely someone had to have

[Rich84]

87 tank with sending unit with TPI pump is the best setup.

I have an inline pump pulling thru the stock sending unit for 3 years and about 12,000 miles with no trouble.

[Jonboy]

If you are using an inline pump, an Airtex E8248 will work well, if you will be going in tank, use a Delco EP381. Both of those are LS applications, but the extra fuel will not be a problem. The regulator will send back what fuel it doesn't want.

[SkinnyG]

I intend to do TBI on my '77.

I plan on using the factory mechanical pump to pull fuel out of the tanks.

The mechanical pump will fill a "surge" tank.

The surge tank will feed an external high pressure pump to the injectors.

The injectors will return to the surge tank.

The surge tank will return to the appropriate fuel tank.

I already have fuel pickups with return lines installed, and a later model tank switch.

I have a similar setup on my Super 7 (two pumps and a surge tank) and you can practically run on fumes, as the injector pump is never starved of fuel. Probably a good way to go for off-roaders, too.

[DirtyLarry]

Here's a good place to compare.... all A/C Delco numbers

EP386 – TBI (12 psi fuel pressure)
EP377 – TBI (24 psi fuel pressure) 1994/1995 7.4L
EP241 – TPI (43 psi fuel pressure)
EP381 – Sequential EFI (62 psi fuel pressure....late model LS Gen III and Vortec Big Blocks L29 7.4L & L18 8.1L)

All of these pumps are dimensionally the same and will fit a TBI fuel sending unit. They are also capable of producing slightly higher fuel pressures above what I posted next to the part numbers. The psi I listed is just the psi rating of the injection systems typically associated with the EFI type.

For a TPI, I would go with the TPI intended fuel pump, which is a EP241 from an F-body TPI equipped car. A EP381 is nice high pressure pump but the TPI fuel pressure regulator may have a harder time holding it back fuel pressure causing the engine to over fuel or excessive pressure to the point where it could lead to the demise of the pump from pushing up against a low psi regulator.

BTW….. This site is your friend and one of the most valuable parts catalogs I use for my engine swapperoo projects. Just look up the fuel pump part number for a vehicle that used the same engine as you are looking to swap in.

I learned all of this fuel pump stuff the hard way as I ran my 8.1L on an EP241 for a while. It ran great but ran out of steam under long hard acceleration. Once I figured out I had the wrong pump in it I installed an EP381. WOW! What a difference! Plus I was able to bump my fuel pressure up a big higher (8.1L’s love higher fuel pressure ~ 68 psi)

[INSIDIOUS '86]

Sweet thanks guys!

Now is a tbi tank baffled or is it the same as prev years?

[Bloodhound]

Baffled.

[Rich84]

The guy at fuel injection connection who makes the wiring harness recommended the airtex E2000 for an inline pump. That's what I have. The only thing I did to the stock sending unit was extend the return line to the bottom of the tank. 84 tank with no baffles and I have not experienced any fuel starvation problems even as low as about 1/8 of a tank.

[Jonboy]

Originally Posted by Rich84

The guy at fuel injection connection who makes the wiring harness recommended the airtex E2000 for an inline pump. That's what I have. The only thing I did to the stock sending unit was extend the return line to the bottom of the tank. 84 tank with no baffles and I have not experienced any fuel starvation problems even as low as about 1/8 of a tank.

From what I have read, the E8428 is the improved version of the E2000. Those had a tendency to overheat in certain situations, from what I read (google search...). Did you keep the 1/4 " return on your sending unit, Rich? How did you extend it?

[Rich84]

Originally Posted by Jonboy

From what I have read, the E8428 is the improved version of the E2000. Those had a tendency to overheat in certain situations, from what I read (google search...). Did you keep the 1/4 " return on your sending unit, Rich? How did you extend it?

Yes I did..If your talking about at the rail..I extended it with a union and steel to the factory TPI fuel lines.

[Jonboy]

I was talking about the sending unit. Just curious how you extended it.

[DirtyLarry]

Originally Posted by INSIDIOUS '86

Sweet thanks guys!

Now is a tbi tank baffled or is it the same as prev years?

As Bloodhound said, you would need a baffled tank. Back to your original question requesting part numbers these are the Napa part numbers for what I would use if I were to do this swap. Napa sells real nice Spectra tanks and sending units that are made in Canada. Not the Taiwanese cat scat found through LMC and most everywhere else. You can probably find these same bits cheaper online but will get nailed on the tank freight where it might still be cheaper to buy through the local Napa store.

31 Gallon Tank: PN GM14C


K5 Blazer TBI Sending unit: FG12L This sending unit includes the lock ring and o-ring.


I don’t believe in aftermarket fuel pumps, especially frame mounted pumps (Airtex, Walbro or whatever) A/C Delco is the only pumps I trust for EFI swaps.
EP241 – Summit Racing $65.97


Fuel lines you will have to figure out. A 88-91 K5 donor at the boneyard might be the best choice for the lines that run from the tank to the union just below the cab doors then figure out the rest on up to the fuel rail. TBI fuels might just work as well. I dunno

[SkinnyG]

My point in using a surge tank filled by the mechanical pump, was that you do not need to purchase a baffled tank, or two baffled tanks and two pumps if you have dual tanks (as I do). Simply purchase one external pump and buy/fabricate a surge tank and plumb it. Easy peasy.

Unless you are after an "OEM look...."

[DirtyLarry]

Originally Posted by SkinnyG

My point in using a surge tank filled by the mechanical pump, was that you do not need to purchase a baffled tank, or two baffled tanks and two pumps if you have dual tanks (as I do). Simply purchase one external pump and buy/fabricate a surge tank and plumb it. Easy peasy.

Unless you are after an "OEM look...."

Yeah, that sounds kind of hokey. OEM look and installation quality is the best way to approach these EFI projects if you want them to look right and be dependable.

Reminds me of something like this creative TPI setup

[SkinnyG]

Originally Posted by DirtyLarry

Reminds me of something like this creative TPI setup

Hey - I LIKE that! I'd put TWO carbs on it, though!