External AFPR added to TBI (pics)

[speedwrench]

I added an adjustable fuel pressure regulator to my 93 350 TBI engine. The stock regulator was holding 11psig. I left the stock regulator in place and installed the external regulator down stream in the return line. I have the pressure now set at 13.5psig and I have noticed an improvement in the engines performance. I haven't had a chance to check the fuel/air ratio yet, but I plan on doing so later this week so I can tweek the pressure. Here are a few pics showing the installation.

The finished installation: A Aeromotive 13301 bypass regulator with Earl's fittings and hose.



This is the Earl's 14mmx1.5 to -6AN fitting needed to connect to the TBI return fitting (part # 991954).




This is the 120degree -6AN fitting (part# 812006)



This is where I cut the return line to install the Earl's 5/16" tube to -6AN adapter (part# 165056).




All the other fittings are regular -6AN fittings and adapters.

[Steveo_supremo]

Looks good, but i don't understand. If your stock fpr is still in place and only allowing 11 psi, how did you get 13.5 just by putting this one in downstream of the stocker?

[speedwrench]

The TBI regulator is a bypass regulator that is downstream of the injectors (even though it is mounted on the TBI). It holds back pressure on the injectors and allows excess pressure to return to the gas tank. The stock spring on most TBI regulators hold about 9 to 12 psig. By installing a external bypass regulator downstream of the stock TBI and increasing the pressure, the stock regulator stays open all the time and the external regulator holds the back pressure at any pressure above the stock regulators set point. If I adjust the external regulators pressure below 11 psig, the stock TBI regulator will take over and hold the pressure at 11 psig. I hope this helps explain it's operation.

[some1else]

Great install. Looks a lot better than my rubber fi hose and hose clamps!!! (maybe i'll rip off your install once I get some extra cash... Can you take a pic of how you mounted that to the engine...? I have mine on the firewall.... How much did all the hoses and fittings set you back??

Sean

[Don454SS]

Clever idea and some great pics! Thanks for sharing this info.

However, I think that unless you are making constant mods or changes, a simple JET AFPR for the oem is much less expensive and a cleaner install. Even though the JET AFPR is difficult to adjust in the oem location, once I got my combo dialed in, I haven't had the need to fool with adjusting the FP since.

Regardless, you did a nice job on your set-up and I'm sure it works well for you.

[speedwrench]

stuckatcuse,
I used the mounting bracket that came with the regulator and mounted it to the thermostat housings driver side stud. I will take a pic of the mount and post it here tomorrow.

The fittings were less than $60 and the 3ft. of hose was $25.



Don454SS,
I considered installing the JET regulator but I am about to start making changes to my engine (new heads, cam, manifold, headers and chip) and thought this install would make it easier to fine tune the pressure. Your are right though about the JET regulator. If all you need is higher pressure and don't plan on any changes to the engine, it's a lot cheaper and not as involving to install.

[Don454SS]

speedwrench, your nice set-up will make adjusts and monitoring very easy. I did a ghetto job on my FP gauge. I installed a permanent 30lb gauge under the truck and just after the oem fuel filter. I used the same oem lines without any hacking, I just made a slight bend in the oem lines to get the gauge fitting between the lines and the filter. I check my FP by peeking under the chassis. Not a very convenient way to check FP, but definitely inexpensive.

I like yours better.

P.S. I used to live in Lafayette, LA.

[BCossette]

Awesome install!!!! Any Idea what size the TB inlet is? I'm gearing up for a similar setup, but im going to be installing a new tank and sendin unit, and running 100% AN lines and aluminum fittings and such -- just wondered if you knew what size the TB inlet adapter I would need, such as (??? to -6an). Thanks.

Oh BTW: I have the 2" bore holley throttle body, and it comes with an adjustable FPR, so all you gotta do is pop a screwdriver up top and turn the dial and it adjusts it -- all I gotta do is put a gauge through the outlet port.

[speedwrench]

BCossette,

The TBI inlet (supply) GM adapter thread size is 16mmx1.5. The Earl's 16mmx1.5 to -6AN fitting part # is 991955. Just so you know, these are listed as power steering fittings but are the correct fitting (with o-ring) for this installation. You can get them at Summit for $5.95 each.

[BCossette]

Alright man thanks a MILLION. I was going to just get a -6an to 3/8" adapter for both of them and get the adapters from those to whatever they were for the throttle body, but im glad I didn't, now all I have to do is get these and go straight to the line. Thanks a million man.

[va454ss]

I also have an Aeromotive external reg, but a different model.

I mounted mine to the bracket that used to hold the ESC module. I was able to do away with the ESC when I converted to the 7060.

I used a factory braided line from a 88-89 TBI truck and plumbed it straight into the reg with adapters. I only had to fab about a 6" line from the return side of the TB to the reg.

Also, I completely eliminated the factory fpr with an alum block off plate.

Sorry, no pics

[BCossette]

I plan on putting a Fram Fuel filter and the pressure gauge on a panel that will be mounted on the firewall somewhere.

[some1else]

Originally posted by va454ss
I also have an Aeromotive external reg, but a different model.

I mounted mine to the bracket that used to hold the ESC module. I was able to do away with the ESC when I converted to the 7060.

I used a factory braided line from a 88-89 TBI truck and plumbed it straight into the reg with adapters. I only had to fab about a 6" line from the return side of the TB to the reg.

Also, I completely eliminated the factory fpr with an alum block off plate.

Sorry, no pics

What did you used for a gasket for the block-off plate? I tried this with my truck and it leaked all over....

[some1else]

Well I broke down and ordered all the parts today, after I realized that my clamped rubber hose is leaking... I could smell fuel and there's some gelled fuel under my reg. I'll take some pics and post here later on. The last thing I want is gas all over the engine. This week some time I should get my ignition, coil, and FPR set and working the way I want...

[va454ss]

Originally posted by stuckatcuse
What did you used for a gasket for the block-off plate? I tried this with my truck and it leaked all over....

Rubber gasket material.

[some1else]

Originally posted by va454ss
Rubber gasket material.

Do you have a brand name? Supplier? Type of rubber?

[no2guncntrl]

Case anyone is interested in using the
stock reg but with a limited adj as far as
#, here's one from CFM-Tech that may
make getting to the adjuster a lil easier..

[Don454SS]

Originally posted by no2guncntrl
Case anyone is interested in using the
stock reg but with a limited adj as far as
#, here's one from CFM-Tech that may
make getting to the adjuster a lil easier..

That thumb wheel design is a nice feature. I have also heard some have used an old spiral-wired long screw driver type tool for adjusting carb screws. They weld an appropriate sized allen head on the tip to use it on the TBI AFPR. I haven't tryed it but think it would work.

[some1else]

i made my stock one adjustable before I went to the aermotive unit. I just cut an allen key to size and used to j-b weld to hold it in there... Worked great.

[no2guncntrl]

I've got to come up with something. I had
to replace the fuel pump in my ride so I went
with a Walbro 190ltr/hr. Now I have a gage
on the feed line right before the TBI, 0-15#
style, and now when the truck cranks and
runs, the FPG needle is pegged past the 15#
right up against the stop at the beginning
of the # numbers. So the Walbro must be
putting out at least 20#.

Speedwrench, is the reg you're using the
Aeromotive 13301 3-20# adj reg ?

I have to fix the stock TBI reg I had
at one time made it adj. Maybe this
will help get the press down. I can't have
an external reg on as I'm in Cal and the
ride would fail the visual part of Cal's
smog test being the fuel sysytem has
been tampered with. I'm not sure what
route to go with.

Any suggestions, advise or tips ? All
are welcomed. Thanks, bg