Q: Rebuild/Replace TBI Fuel Pressure Regulator

[badco]

I always drill a few holes in the bottom of regulator so it will adjust. Even a new kit with spring usually has to low of fuel psi. Most are lucky if they make 8psi. Gm calls for 14psi but 14 will not run properly(floods) but so far magic number for all i have done has been 12psi and i have had 10x life using a pump for a 96 vortec over tbi pump.

 

[badco]

Unless that "solid nipple" is restricted inside, it's a REALLY BAD IDEA to use them.

The OEM quick-connect has a coolant passage smaller than a quarter-inch diameter. Using a non-restricted nipple can pop the heater core at higher RPM when water-pump pressure adds to radiator cap pressure.

The restriction for the heater is made into the rear water ports on intake gaskets for tbi engine so fittings dont really matter in size

 

[Schurkey]

The restriction for the heater is made into the rear water ports on intake gaskets for tbi engine so fittings dont really matter in size

No.

There IS a restriction in the gasket, but it's not to protect the heater core, it's to re-route engine coolant from the thermostat area of the manifold BACK to the heater outlet connection--warming / stabilizing the underside of the manifold plenum.

That's why there's that big coolant passage on the underside of the TBI intake manifold.

The gasket has a lil' tiny "steam hole" but otherwise blocks coolant flow from the head into the heater outlet fitting.

Photo 1. http://hbassociates.us/K1500_ZZ4_Intake_016.jpg


Note severely-restricted "quick coupler" style heater outlet. This one is a Dorman, but the GM unit is similar.


Photo 2. http://hbassociates.us/K1500_ZZ4_Intake_004.jpg
[Later Edit] Damn, I can't make the photos line up with the text properly. [/Later Edit]

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[LA2SD]

It seems the debate between whether to use a nipple or quick disconnect is a hot button topic around these parts.

I found another thread where this stuff was discussed at length

https://www.gmt400.com/threads/replaced-quick-connect.48367/

I've been running a nipple for the past 85,000 miles, and haven't had any issues with the heater core.

Plus, as far as I know, the male heater hose fitting for the quick disconnect isn't available anymore.

 

[LA2SD]

I think the manuals call for a little light motor oil on the injector o-rings but don't quote me on that. Also been seeing some ads for an orange color threadlocker, can't remember if it's Loctite or Permatex brand but supposedly it holds like red but lets you remove the fastener like blue. Don't know if a throttle body would be the best place to try it out but it would be a neat trick if it really works.

You're right. The shop manual calls for engine oil on the o-rings. I don't think a silicone lube or vaseline would hurt though.

That orange stuff is probably similar to the thread locker that comes "pre installed" on some fasteners and fittings.

I always drill a few holes in the bottom of regulator so it will adjust. Even a new kit with spring usually has to low of fuel psi. Most are lucky if they make 8psi. Gm calls for 14psi but 14 will not run properly(floods) but so far magic number for all i have done has been 12psi and i have had 10x life using a pump for a 96 vortec over tbi pump.

Have any pics?

 

[PlayingWithTBI]

If you want to be able to adjust your fuel pressure, you can get this set up - Adapter, AFPR, and gauge for about $116 (scroll down a little).
http://www.rvmorsemachine.com/product.htm

Looks like this, you just have to bend the MAP vacuum tube a little and drill a hole for the adjusting screw.

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Here's what it looks like installed on my 88 5.7L with a 28LB spring set to 28LBS, LOL.

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[LA2SD]

If you want to be able to adjust your fuel pressure, you can get this set up - Adapter, AFPR, and gauge for about $116 (scroll down a little).
http://www.rvmorsemachine.com/product.htm

Looks like this, you just have to bend the MAP vacuum tube a little and drill a hole for the adjusting screw.

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Here's what it looks like installed on my 88 5.7L with a 28LB spring set to 28LBS, LOL.

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Nice setup, man. I might look into that when I replace the intake manifold. Seems like everything kind of snowballs when I start doing maintenance on the OBS, so I gotta spend on the stuff that needs it most.

After this TBI rebuild, I'm doing the entire front suspension.

 

[LA2SD]

Update:

So, it turns out the threads for the heater hose connector were just fine. It had been about a year since I replaced the connector, and I guess my memory was fuzzy. That, plus the thread sealant I used got blown out the threads. I don't remember what I used the first time, but this time, I used Permatex high temp thread sealant (# 59214), and it did the trick.

Also, the rebuild kit I purchased for the TBI unit didn't come with a spring, so I purchased a "mini" kit that included the spring. The problem is that it was about 27/32" too short. There was nothing wrong with the original spring, and it still provided plenty of tension. So I just cleaned it up, and used it again.

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[LA2SD]

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[LA2SD]

And I picked up one of these to assemble the TBI unit. I've always wanted one. Worked great. No leaks.

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