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Discussion Starter · #1 ·
I've decided to make a play truck out of a 1998 SWB Chevy silverado. It had a V-6 air suckin' piece of junk engine in it and I decided to take an older 350 carb engine with a 700 R4 trans and put it in this truck. Of course I knew there'd be some "conversions" to overcome and some wires to delete but right now, I'm trying to find a fuel pressure regulator to reduce the pressure for the fuel injection system down to something the carb can handle. I believe I've read that the fuel pressure on this truck is 60 psi. I need to locate a pressure regulator that'll turn that pressure down to 5-6 psi. Anyone know of such a regulator? I may end up taking the tank off of a 1992 wreck that I have and putting it and the fuel lines on this truck. I prefer the simpler way of fuel pressure regulation.
 

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You can pull the fuel pump/sending unit.
Replace the pump with a line deleting the pump.

Then run a mechanical off the block.


I am not 100% if you can just pull through with the old pump still in place. At the very least it is a restriction and you should run new fuel lines anyway.

I imagine your loosing the abs and the dash cluster. You may need to change the radiatior, transmission crossmember, and driveshaft.
 

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Use two regulators inline together.
Use a EFI type regulator to knock the high pressure down to 15 psi or so, then use the regular carb style regulator to knock it down further to 3-5 psi for the carb to deal with.

I'd use a bypass type for the high pressure reg such as Holley #12-882 or #12-886, then a common dead head style for the carb pressure, such as Holley Sniper #80000103.

It'll be a bunch cheaper than the Aeromotive specialty piece and do the same job. Both Holley regs together total about $110

The reason for the EFI reg to be the bypass type is to prevent over choking the EFI pump in the tank and burning it up.
 

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Discussion Starter · #6 ·
Aeromotive sells a regulator for exactly this application. It will likely cost you more than just deleting the factory pump and using a regular mechanical pump for the carb.

Thanks for the response. That little guy is pricey. It made me start thinking of deleting the high pressure pump and putting an inline pump outside the tank. The 350 used to be in the wrecked '92. I started thinking about swapping the tanks or seeing if the fuel pump from the '92 can be slid into the carrier for the sending unit in the '98. I'll have to investigate. I already have a Holley 12-887 regulator that'll reduce the 16 psi from the TBI fuel pump to 6. I've even considered investigating whether or not a pump is available that'll fit in the spot where the high pressure pump is that'll send a steady 6 psi to the carb and eliminate the need for a pressure regulator altogether.

Regards.
 

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Discussion Starter · #7 ·
Use two regulators inline together.
Use a EFI type regulator to knock the high pressure down to 15 psi or so, then use the regular carb style regulator to knock it down further to 3-5 psi for the carb to deal with.

I'd use a bypass type for the high pressure reg such as Holley #12-882 or #12-886, then a common dead head style for the carb pressure, such as Holley Sniper #80000103.

It'll be a bunch cheaper than the Aeromotive specialty piece and do the same job. Both Holley regs together total about $110

The reason for the EFI reg to be the bypass type is to prevent over choking the EFI pump in the tank and burning it up.
Thanks for taking the time to reply. That configuration actually crossed my mind. I wonder if there's a low pressure pump that can be slid into the pump carrier / sending unit of the '98 that will just deliver 6 psi to the carb and eliminate all the hardware.
 

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Discussion Starter · #8 ·
You can pull the fuel pump/sending unit.
Replace the pump with a line deleting the pump.

Then run a mechanical off the block.


I am not 100% if you can just pull through with the old pump still in place. At the very least it is a restriction and you should run new fuel lines anyway.

I imagine your loosing the abs and the dash cluster. You may need to change the radiatior, transmission crossmember, and driveshaft.
Hello, and thanks for the reply. Unfortunately, the 350 block is one of the later models that has a place for a mechanical fuel pump molded into the block but none of the machining necessary for a plunger rod was ever done to it.

How will changing a fuel pump cause the ABS to stop working? I have a larger radiator ready to go in. The tranny of the '98 was a 4L60E which I replaced with a built 700R4. The driveshaft fit with no problem and the crossmember had to be moved to the forward set of holes in the frame to make everything line up properly. I did have to replace the motor mounts for the V6 with the ones for a V8 which mount directly on the crossmember under the engine.
 

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Thanks for taking the time to reply. That configuration actually crossed my mind. I wonder if there's a low pressure pump that can be slid into the pump carrier / sending unit of the '98 that will just deliver 6 psi to the carb and eliminate all the hardware.
Not that I'm aware of, the 15+ psi pump for earlier year TBI engines is all I can think might fit, and still requires the lower pressure regulator.

The two regulator and bypass line back to the tank solution i laid out is about the lowest cost way your going to find of solving this and eliminates the need to even mess with the pump already in the tank along with any wiring changes.

The high pressure regulator gets fuel first, sends 15 psi(it's lowest setting) forward to the low pressure regulator for the carb while at the same time bypassing the rest of the unneeded pressure and fuel volume right back to the tank.
Very nearly the same as the stock EFI system did.
 

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Hello, and thanks for the reply. Unfortunately, the 350 block is one of the later models that has a place for a mechanical fuel pump molded into the block but none of the machining necessary for a plunger rod was ever done to it.

How will changing a fuel pump cause the ABS to stop working? I have a larger radiator ready to go in. The tranny of the '98 was a 4L60E which I replaced with a built 700R4. The driveshaft fit with no problem and the crossmember had to be moved to the forward set of holes in the frame to make everything line up properly. I did have to replace the motor mounts for the V6 with the ones for a V8 which mount directly on the crossmember under the engine.
Is your 350 from 98 also? If so, you have the L31 Vortec.
I am interested to know what cam, and intake setup you will run? Also the plans for the rest of the truck. That is a pretty good little motor to start with.
 

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Your removing alot of electronics and many people delete the ABS module even when the truck still has the fuel injected engine.

A tbi in tank pump can be used with the later sending unit. I know going from TBI to LS the LS pump is smaller and requires a bit of hose. Also a bit of spliceing if you dont by the adapter. But the larger tbi pump should still fit in your sending unit.
Then its up to a regulatior to knock the pressure down and return the fuel to the tank.
My prefrence is Aeromotive as far as regulatiors go.
I would run a vacume based tbi charcoal canister with a carb.
 

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I would have never thought of using two fuel pressure regulators in order to keep your in tank fuel pump from an EFI system. If I were to ever want to setup an electric fuel pump again that would be a good route to go. I luckily can use a mechanical fuel pump but if I could run an in tank fuel pump I sure would on my truck. I have already gotten rid of all the factory stuff as they were so old they cracked at the connectors etc.

I had to remove my pump in the tank and extend the hose further in the tank. If in the future I would want to do this I would most likely just get a fuel cell to put in my bed and get an electric fuel pump that I could install with the said sending unit that is in the cell if such a thing even exists to do that. This is some good info here. Good luck on your truck and sounds like a nice ride once you get it all done.
 

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... then a common dead head style for the carb pressure, such as Holley Sniper #80000103...
Could you please double check that part number? I found the first two numbers but I can't find this one anywhere.

Any thoughts on this regulator? This one is said to drop the pressure all in one unit.

 

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Could you please double check that part number? I found the first two numbers but I can't find this one anywhere.

Any thoughts on this regulator? This one is said to drop the pressure all in one unit.

Sniper regulator is right on Holley's web site, listed as in stock...
Sniper 80000103 4.5-9 PSI Fuel Pressure Regulator - Carbureted (holley.com)

Earl's #12803ERL, Quick Fuel #30-803QFT, and Holley #12-803 are all the same regulator with the exception the Holley is chrome plated and $15 more expensive.

The Mallory regulator you linked will also work, it's just rather expensive......the two regulator deal I outlined was just the most budget way to deal with it.
You can take your pick though, it's all good :cool:

One thing to remember that has to be done....the bypass line needs to be the same size(or bigger) as the feed line. It cannot be a smaller line.
The regulator has to be able to bypass every bit of fuel, such as at idle, or the regulator will become choked and no longer hold the set pressure, it will rise.
 

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You’re into a tough row to hoe. Starting in 96 everything, this includes the panel instruments goes through the computer. simply dropping in an old 350 with a 700R4 is just the beginning of your headaches.

I’m not even getting very deep into the fuel system simply because you are looking into an electrical system abyss. Basically for fairly easy to back date 1995 pickups with a V8’s and some V6’s is the end of fairly easy to swap to pre computer days. Easy in that the integration level of OBD I is pretty simple where things like turn signals, braking, panel instruments vehicle security, etc. are all stand alone. 96 starts OBD II on the V8’s, some V6’s actually started in late 94 as GM beta tested OBD II on some V6 models without their customers knowledge. The easiest solution you can employ is to obtain a 98 model year V8 with a 4L60E trans and have your computer modded to operate the V8’s injection.

Bogie
 

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Is your 350 from 98 also? If so, you have the L31 Vortec.
I am interested to know what cam, and intake setup you will run? Also the plans for the rest of the truck. That is a pretty good little motor to start with.
Good question, but if it had a carb from the factory, it's pre-87, I think. And 84-86 350s (at least the truck versions) had carbs with some type of electronic controls, which is something the OP would definitely not want to use.

Then again maybe the 350 has an aftermarket manifold and a Holley! :unsure:
 

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Not sure about GM, but on a Mustang I found that OBD-II and CAN bus meant that the instrument panel did not actually connect to the engine. The engine sensors “reported” to the computer, and the computer then told the instrument panel what reading to display. You couldn’t just ground or power a sensor, and then see what reading you got. The gauges use stepper motors, not simple resistance or voltage measurement.


.
 

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My '96 S-10 (swapped with a Buick GN drivetrain) had the earliest iteration of OBDII. Nothing important went through the gauge cluster. I used a "tach" cluster from another S-10 as mine didn't have it, and by using the sensors off the original engine, everything communicated just fine. Did have to recalibrate the tach as the Buick GN engine output a different signal. Removed all the ABS stuff, removed the airbag and went with an aftermarket steering wheel and pre-94 adapter.

Russ
 

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