Tbi fuel pressure gauge adapter

dave s said:

Did adjusting your fuel pressure help with anything? I bought the same kit, drilled the hole but didn't install the adjuster. I can't for the life of me remember why I didn't install it after having it all ready and on hand when I did the rebuild.

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yes, so I could get my VE tables adjusted to run up to 85% DC at WOT with higher pressure. Without it I was running ~106% which meant the injectors were open all the time!

GrimsterGMC said:

I found this site last year and thought it was Xmas. I put everything I wanted into the cart and went to checkout only to find they don't ship outside of USA/Canada, talk about being gutted, you guys don't realise how lucky you all are having everything at your finger tips. Anyway, I found another way around it using 4 different adapters and fittings so all good after all.

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If you ever run into that issue again send me a message I can likely ship you stuff.

Took these pics today. Looks like it runs around 11 psi at idle. I may have to take the tbi unit back off sometime and install the adj regulator.

Completely forgot my TBI test fittings came in from Jeg's a few days ago. Just opened the package to get some pics and compare them to the Actron setup.

Jeg's had them listed under the brand OEMTOOLS but the bags they came packed in are labeled Great Neck Saw Mfg with the same part #. One thing I noticed right away is they have a snap ring retainer at the swivel portion, instead of just a simple lock ring you would have to pick at on the Actron part.

Next difference I noticed is the ID of the outlet is slightly smaller, and there are a few other minor differences in appearance. They're intended to be the same part but they are definitely not made exactly the same. I suspect the OEMTOOLS one might be easier to disassemble in the event you need to service it; I'd bet there's probably an O-ring or two inside the swivel portion.



OEMTOOLS/Great Neck on the left, Actron on the right.


Either way I don't think you can go wrong. I've used the Actron fitting in the past and the OEMTOOLS looks functionally the same.

Richard

someotherguy said:

Completely forgot my TBI test fittings came in from Jeg's a few days ago. Just opened the package to get some pics and compare them to the Actron setup.

Jeg's had them listed under the brand OEMTOOLS but the bags they came packed in are labeled Great Neck Saw Mfg with the same part #. One thing I noticed right away is they have a snap ring retainer at the swivel portion, instead of just a simple lock ring you would have to pick at on the Actron part.

Next difference I noticed is the ID of the outlet is slightly smaller, and there are a few other minor differences in appearance. They're intended to be the same part but they are definitely not made exactly the same. I suspect the OEMTOOLS one might be easier to disassemble in the event you need to service it; I'd bet there's probably an O-ring or two inside the swivel portion.

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OEMTOOLS/Great Neck on the left, Actron on the right.

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Either way I don't think you can go wrong. I've used the Actron fitting in the past and the OEMTOOLS looks functionally the same.

Richard

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I received mine the other day as well and haven't had a chance to look them over closely yet. Hopefully will get one put in the suburban this weekend and see what kind of fuel pressure I've got.

Thanks again for finding them and sharing the link.

I'm confused. I thought one way to test fp was in line with the fuel filter? After the fuel filter? And could just leave fitting on? I did that for a few years but removed it . Can't remember why. I think gauge got janky. It was the exact kit above someotherguy posted with the 60psi gauge. Still have the gauge...Just looked for fitting but can't find it....
This guy on yt has it before filter...Mentioned he worked for GM dealership....

You "can" test fuel pressure anywhere between the pump and the throttle body, as long as your adapter fits the system.

It's crazy to test pressure BEFORE the fuel filter, because you'd get a false, high reading if the filter plugs.

No, I would not leave the test fitting in place after the test is complete.

Schurkey said:

You "can" test fuel pressure anywhere between the pump and the throttle body, as long as your adapter fits the system.

It's crazy to test pressure BEFORE the fuel filter, because you'd get a false, high reading if the filter plugs.

No, I would not leave the test fitting in place after the test is complete.

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Agreed, either after the filter, or behind the TBI. Whichever works best for your access.

I've seen a few minor variations in manufacture on these fittings - see post #44 just above in this thread ^^^ - they all look very similar with slight differences, which leads me to believe some may be knock-offs of another brand's product. The first ones I got came with the Actron gauge kits. The Actron fitting was left on my '94 C2500LD behind the TBI for several years with no leaks. Installed in 2010, was still on the truck when I sold it in 2015. At that time I hadn't seen any mentions in forums about these having leak issues. It may also be that I installed it in that spot when it was relatively new and wasn't swiveled or moved at all from that point on.

Still, since some HAVE reported leaks, I would absolutely say better safe than sorry. Not all these fitting / gauge / kit makers use seals that are fuel resistant. The very first pressure gauge kit I bought (that didn't come with the TBI fitting) was from ATD and after a few uses, the seal at the hose end hardened up and started leaking.

Richard

Found my old fitting for my actron setup like someotherguy's..60psi gauge.....

Had a spare viton o-ring for throttle body fuel line fitting from my intake gasket replacement/s to use where the one goes in pic...
Valve seems to go up and down on the tbi fitting ok...gets a bit cockeyed..
Hose fitting a bit questionable...
Hmmm. these can be rejuvenated with new seals and stems like other shrader valves...like on ac gauges?
$20 for a new set without tbi gauge is pretty good though.......

Still not convinced the gauge itself isn't sticky but I was able to make the needle move by blowing hard into the fitting while plugging it...

Surely these gauges get questionable after some time? Not like they're liquid filled....
I'll probably try it out as is tomorrow anyway...

If the gauge is old or has been dropped, it's reasonable to question its accuracy. These certainly aren't megabuck top-quality instruments. I've got a little bit of an embarrassment of riches in terms of test gauges (probably 4? maybe 5?) so if one isn't delivering a reading that seems expected based on engine behavior, it's easy enough for me to throw another one on there and see if the results are repeatable.

Richard