Oh, OK, thanks for the results !!

 

Ask Mr Black he just went thru this
https://www.corvetteforum.com/forums...-pressure.html

 

Yep. Sorry about that. I should have mentioned that I was finally able to properly diagnose the problem earlier this morning.

Interesting. His situation is a bit different because it sounds like he has a fairly modified fuel system.... even though it is still relying on the stock check valve. Apparently he added a check valve up near the feed line to the fuel rail under the hood. If you look back at post #5 of this thread you'll see where I mentioned doing the exact same thing. However, now that I have those parts (shown above) on order, I'm going to give this a try first. Thanks for the link.

 

I have actually come up with a 3rd option (plan C?) that will allow me to add a check valve AT the fuel filter location without modifying anything on the vehicle. I will simply disconnect the supply line "quick disconnect" fitting at the factory fuel filter and connect that line onto my check valve, then plug the other end of the check valve back onto the fuel filter. Essentially I am just adding a check valve in-line right before the fuel filter. And this should be perfect because according to the line drawing I have of the fuel system on a 97-98 Corvette, my check valve will be roughly 10-12 inches further down line from the factory check valve. (if you could straighten out he fuel line and measure it) All my parts should be here today and I will create a post with pictures later this evening to show what I am talking about.

My favorite part is the fact I do not have to cut or modify ANYTHING from the factory. My car is original with zero aftermarket mods, except mag ride delete with standard shocks installed. In fact, if I wanted to remove my check valve I could easily do that and return the car back to 100% factory in about 5 minutes.

Stay tuned.

 

There has been a delay in parts delivery, of course. (what else is new. lol) I said I would reply last night with pictures but that didn't happen because of the delay. The parts may be here today or possibly Monday. I will post my reply with pictures and a description as soon as I can.

 

All the parts finally arrived Sunday night.... well, not really. Part of the original order still hasn't even been shipped yet but I placed a duplicate order last night just in case..... and I'm glad I did. Anyway...

First, I must say this project got completely out of hand. Every time I would run it through my mind it got more complicated than it needs to be. (and more expensive)

Based on this diagram below that I found on this site, the factory check valve appears to be in the fuel line (which they no longer sell) right before the fuel filter. I decided a great place to install a new check valve would be at the fuel filter and use the quick connect fittings on the filter to make this happen.






I had several different ideas about how to make this work but after thinking them through for a while I could always come up with reasons why they were bad ideas. Eventually I landed on this idea pictured below and now I'm committed to make it work.... even if it did get a little bulky. lol.

I watched a video on YouTube from "My Corvette Life" to get an idea of how much room I had to work with and how the factory fuel lines are actually laid out. Screenshot/photo credits to "My Corvette Life". These are the pictures that I used below to help me visualize what I was physically working with.... along with buying an actual Corvette fuel filter to use for mock up. (and eventually install into the car with the new check valve)










You can see the amount of room I have to work with and how the factory fuel line comes from over the top of the frame rail.... well, it looks like a frame rail....either way, the supply fuel line come from the top, down.

A few disclaimers before we get to my finished project.... Yes, I have mixed a few aluminum fittings with brass fittings..... and yes there could possible be a galvanic reaction with the dissimilar metals... however, I can think of many examples where vehicle manufacturers and automotive parts manufacturers use brass fittings in aluminum parts so if they can do it, so can I. lol. Another disclaimer, the Corvette fuel supply line is 3/8 inch.... I am using 1/4" pipe fittings for this project which actually has a LARGER inside diameter than the factory 3/8 fuel line. So, no restriction from using too small of fittings. How can this be? Well, they're pipe fittings..... nothing about a 1/4" pipe fitting actually measures 1/4 inch. Same with any other size of pipe and fittings. And lastly, the sharp 90 degree turns in my setup COULD possibly cause a restriction but it's a pressurized system and I don't think the flow rate is fast enough to for it to make a difference. Not to mention, the ID of my setup is LARGER than the rest of the fuel line on the vehicle so that should help, too. It appears that GM wasn't worried about sharp 90 degree turns either.... notice the 90 degree fitting on the factory fuel line going to the filter in the picture above? Apparently smooth laminar flow isn't a requirement on a 345 horsepower fuel system with 3/8" lines. lolol.

This is my finished idea below. I can simply unplug the factory fuel supply line from the fuel filter, then snap my check valve attachment onto the fuel filter.... it uses the same style of quick connect as the factory fuel line, and then reconnect the factory supply line onto my check valve setup. It just makes one big loop around, through the check valve, and then back to the filter. This series of pictures below shows step by step. I had an extra fuel line here that I used to imitate the factory supply line to add to the visual effect.


This is what I came up with and what it looks like before install.



This is what the stock filter setup looks like (below)




This is what the filter looks like with my check valve attachment snapped onto the filter. (below)





And this is what it looks like with the factory fuel line snapped back onto the check vale attachment. (below)







I plan to install this tomorrow at some point. Not shown in the pictures are two cushion clamps that I plan to use to help mount the check valve attachment so the weight of all those brass fittings are not hanging on the filter alone. I will probably just use a few self tapper screws to mount the cushion clamps..... or if I get fancy, maybe I will use a few riv-nuts.

Lastly.... Like I said, there are MANY different ways to make something work in this application. I probably could have gotten away with the check valve itself and two long nylon fuel lines to loop around in big sweeping turns (so it doesn't kink) to make the connections but this is what I ended up with. I wll try to get a picture or two when I install it tomorrow.

If you made it this far.... thanks for wasting your time on my thread. lolol.

 

I was thinking of making a new flex line from the fire wall to the engine with a check valve but so far I haven't found anyone who makes a female GM fuel line connector. Only male GM connectors are sold and the OTC 7629 sets are out of stock everywhere.

 

If you buy these two fittings linked below and then make a steel braided -6 fuel line made with a check valve somewhere in the middle you would basically have what you're talking about, I think..... I was thinking about doing that same same thing but I decided to put the check valve near the rear of the car like GM designed it. Does it make a difference? Probably not..... But I only wanted to do it once.


These are similar to the black fittings I used on my project pictured above. (but I also had to buy an adapter to go from -6 to 1/4" pipe tread) The female fitting linked below will snap right onto your fuel rail.

 

Well, it's installed. The car is fixed. It holds 55 psi when I turn the key off. It would go to zero PSI in about 2 seconds before the repair.

I will say that I didn't think it was going to work at first. I built the attachment based on the screenshots from a you tube video. Well, that car in the video must have aftermarket exhaust because there appears to be A LOT MORE room on that car, compared to my car with factory exhaust. It's almost impossible to get a hand up onto the fuel filter let alone work on it. The hardest part was getting the factory fuel line off the fuel filter to begin with. The two tabs that you squeeze to unlock the connector were turned 90 degrees from how my thumb and finger could squeeze them. I eventually got it. Then installing my attachment only took a minute. it snapped right into place. I still want to get a cushion clamp installed to help hold the weight.

Does anyone know what that surface is behind the fuel filter and check valve attachment? Is that a frame rail? Is there anything directly behind that surface? I'd like to run a screw into that surface but I don't want to damage anything that may be behind it. It seems like it might be plastic???

Anyway... A few pictures:

 

Is this hard to replace? I just purchased one?

 

@ brian 1 Ingenuity at it's best...someone needs to make these or something similar for the community. I would buy a couple just to have.

 

I have no idea how hard it is to replace.... but it's probably a good afternoon's worth of work. A hoist would make it much easier.

You just purchased one? Recently? Where?

I have searched everywhere over the last few weeks and I couldn't find one anywhere. GM stopped making them. That's what i was told anyway.

 

Thanks!

I could certainly give you a parts list of the items I used to make the check valve attachment..... But I won't make them for sale to the public. I do not want the liability.

 

Finally received the check valve and installed it. It helped some but the injectors might be leaking into the cylinders when the engine is hot, more troubleshooting is needed.
Here's the installed black AN6 Fuelab check valve and hose with GM connectors at both ends:

 

Sorry for the late reply....

That is a very nice and clean install. Good job, Sir!

One of the things I tested while doing my own diagnosis was to verify if the fuel rail (which includes injectors) would hold pressure.

I pulled both fuel lines from the fuel rail and replaced them with a section of rubber test hose. (my fuel test kit had enough fittings to make this work) Then I used two pairs of pinch-off pliers to conduct my test.....

Step 1. Punch off the rubber fuel return line right near the fuel rail.
Step 2. Turn the key on and dead-head the fuel pump to maximize fuel pressure on the supply side of the system.
Step 3. As soon as the system reaches full pressure (within a few seconds) quickly pinch off the rubber fuel supply line right near the fuel rail. This needs to be done before the pump turns back off. Or, use a scan tool to bidirectionally keep the pump running long enough to complete this step.
Step 4. At this point the fuel rail and injectors are under full system fuel pressure. Both fuel lines are pinched off and holding pressure from escaping. Keep an eye on your pressure gauge. If your fuel pressure gauge holds pressure steady, then the injectors are not leaking. If the gauge does NOT hold steady and you're losing pressure, then you may need to lift the fuel rail up to physically see which injector is leaking/dripping.

This is how I diagnosed my problem and to make sure my injectors were not leaking..... I'm sure there are many other ways.

Again sorry for the VERY late reply.

 

My car has problems with the crankshaft position sensor which was replaced recently, this winter the wires will be checked. The fuel system is fine. Brian1, what did you determine was your problem or haven't you found it yet?

 

You HAVE to replace your CKP sensor with OEM !!…you should have checked the wiring before replacing the sensor.

 

Any chance you could list the items that were used? Interested in doing this same setup!

 

From the engine fuel rail: Earl's OE Fuel Line EFI Quick Connect fitting 3/8" to 6AN #361-AT991966, Podavelle 6AN female to 6AN female straight (Amazon), Fuel Lab check valve (Summit # 71702), Evil Energy 6AN hose end fitting 90 degree swivel for CPE braided hose (amazon), Kraken Automotive 6AN nylon braided hose (about 1/2 foot long Amazon), Evil Energy 6AN hose fitting staight swivel for CPE braided hose black (Amazon), another Earl's 6AN to 3/8" OEM #361-AT991966 to connect to the firewall supply line. These parts are as close as I could find from last years orders so it should be accurate but might not be. As seen in the above original photo, two padded supports were made to lessen the load on the plastic firewall lines but this was optional.
Here's a top view photo:


A closeup of the firewall side fittings:

 

You are awesome! Thanks!