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Discussion Starter · #1 · (Edited)
Hi,
Got myself a "SUN-CP7817 TESTER GM TBI PRESSURE"
It is basically a gauge that fits on an adapter that one is supposed to connect between the TBI unit (feed inlet) and the feed line end. threads and diameter are just great but ...

Problem is this adapter is 2 inches long (or so) and the pipe is so rigid it would not accept it.
I tried to bend the rigid pipe a bit after removing all the fittings at the engine front and side but I had to stop not to crack the pipe.

User manual says it has to be connected at the fuel filter but mine is quick coupling !

I need the gas pressure to set my ECM EBL flasher correctly.

Anyone did it before ?? Should I modify the fuel pipe with some flexible stuff ??? (if yes what to use ??)

Thanks
 

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Your other option is to take the original connector to a machine shop and have them drill and tap a flat (or more than one flat) for the pipe thread. If you tighten it and pick a specific flat, you can get the port facing the correct direction. It gets a little thin, but it will fit. You are only dealing with less than 15 PSI.
 

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Hi,
Got myself a "SUN-CP7817 TESTER GM TBI PRESSURE"
It is basically a gauge that fits on an adapter that one is supposed to connect between the TBI unit (feed inlet) and the feed line end. threads and diameter are just great but ...

Problem is this adapter is 2 inches long (or so) and the pipe is so rigid it would not accept it.
I tried to bend the rigid pipe a bit after removing all the fittings at the engine front and side but I had to stop not to crack the pipe.

User manual says it has to be connected at the fuel filter but mine is quick coupling !

I need the gas pressure to set my ECM EBL flasher correctly.

Anyone did it before ?? Should I modify the fuel pipe with some flexible stuff ??? (if yes what to use ??).

Thanks

I bought one on ebay from xtremefi (i think) and I just jammed it in there. It was tight but, because I did it when I had the TB off, I then unbolted the lines from the block to give them more play, then connected all the fuel lines to the TB, then bolted the TB down, I had to fight it into position to start the first bolt but it went in OK after that.
I plan to install high pressure soft lines from the passenger side frame rail to the TB soon, that will solve the problem
 

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Discussion Starter · #4 ·
High pressure soft line of what kind ???

Where do you connect them to the original (black plastic) line and how ??

Then do you plan to modify the routing cause I don't understand why it comes from the front of the engine ...

Thanks again !
 

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My car has metal fuel lines to the TB...........
Search Summit racing for hardline to an- adapters from earl's or summit, there are two types, one type requires flaring the hard line and one uses a compression fitting. they sell high pressure fuel line as well as low pressure. if you run the stock fuel pump the low pressure stuff will work fine. I have a TPI pump and plan to go to TPI injection so I will use the high presssure fuel line. I don't know why they brought it around the front of the motor either, for TBI, it would seem easier to attach from the rear!
Here is a thread at a honda (cwm8) site that will give you the basics..........
http://www.honda-tech.com/showthread.php?t=1452210

High pressure soft line of what kind ???

Where do you connect them to the original (black plastic) line and how ??

Then do you plan to modify the routing cause I don't understand why it comes from the front of the engine ...

Thanks again !
 

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I believe they ran the hardlines the way they did to keep the nylon lines away from the exhaust manifold, and allow for some flexability in the plumbing between the engine and frame. It would be good if there were an adapter to take pressure readings at the nylon/steel connection on the passenger side.
 

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I bet you could put one there between the nylon and the steel line, then run a braided line up to the top of the wheel well for a gauge.

I believe they ran the hardlines the way they did to keep the nylon lines away from the exhaust manifold, and allow for some flexability in the plumbing between the engine and frame. It would be good if there were an adapter to take pressure readings at the nylon/steel connection on the passenger side.
 

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Discussion Starter · #10 ·
Funny how they mixed hard line and nylon.

I expect between 9 psi and 15 psi so it is not a lot ... even with Walbro 255 L/min pump the pressure regulator will always regulate close to 15 psi or just a bit higher if it is adjusted a bit (some mods exist on the TBI forums)

Hot exhaust could really explain why they did not route at the back :D - it is so obvious now I feel bad in my tuna brain cwm3

I was thinking about using an old or new fuel filter for the quick coupling function. I think it may be possible to cut them on a filter and adapt them to a temporary T connection with a gauge onto it.
This would allow easy connection at the very place of the filter to do a pressure reading. After that one just re-install the filter and drive ...
 

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I have also considered using a fuel filter to adapt a fuel pressure gauge. It becomes a problem when you try to test drive the car. You need about 10 feet of hose to get the gauge in a position where you can see it while driving/operating the car. Another issue is that the wall of the fuel filter is thin, and may not work well when trying to attach the fitting for the gauge.

You could make a hose to hose adapter for use after the fuel filter. It would also require the lengthy connection to position the gauge for viewing while driving/operating the car.

If you are inclined to make a "quick disconnect" adapter to install between the hard and nylon connection, the "help" section in your local parts store has both ends of the quick disconnect. The issue is the length of the unit when assembled. To assemble an adapter, it becomes about 4 inches long. There is not enough room to hook it up at the hard/soft line connector unless it is flexable. You are back at a similar issue you have with the adapter which screws into the TBI unit.

I have tried cutting the metal fuel line at the front of the engine by the thermostat, but was not happy with the arrangement. You could use either a flexable rubber fuel line with a "Y" tap, or a compression "Y" fitting in the line. The problem arises when you try to get everything back together, because the lines are clamped together and there is no room for the fitting without bending the lines. There really is little room for the assembly in general at the front of the engine as well. I tried this with an electric gauge, and the hookup was not a pleasant sight. I am not reallly fond of cutting the metal line either. It was a lot of work and I ended up replacing the cut line with another uncut one for the safety factor.

If I decide I need a gauge again in the future, I am going to take an inlet fitting from the TBI to a machine shop (or do it myself) and have a 1/8 pipe thread tapped into one of the flats.
 

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The CFM Tech adapter looks much easier than the one I have, it replaces the adapter in the regulator assembly so it wont be such a tight fit. I wish I'd seen this one before I bought mine.........:( guess I better try one.
Also, I still think I may try to replace my metal lines completly. I may try an NPT to barbed an- adapter at the nylon line end and a barbed NPT fitting at the TB end...........
 
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