wasp

can this be run into your hood say as a readable gauge? or would you need to extend the hose and use a different gauge? also what is the clear tube on the button?

Benm109

I'd say it would be just fine to use while driving to check fuel pressure at WOT (wide open throttle) every now and then. But, I personally would not leave it permanently installed. It's just not designed for permanent use. I understand the problem though, the hose is just not long enough to run up to the windshield for WOT test (common trick on most other EFI engines, especially since the shraeder valve is usually fairly close to the firewall and the gauge can be routed outside the car and taped to the windshield).

If you want a gauge to show you fuel pressure all the time, than just look at what gauge companies like Autometer, Cyberdyne, etc. offer. They all make both mechanical and electrical FP gauges that will work on our cars.

The clear tube is just to bleed off the fuel pressure. Like if you were going to work on the fuel system and needed to relieve the fuel pressure, you would just hook up the gauge, drop the clear tube in a container, and press the button, and the excess fuel would flow into the container and relieve the fuel pressure. It's really not needed, though, for TBIs. Just taking off the gas cap and waiting a minute or 2 will relieve the fuel pressure enough to work on it.

wasp

can that "t" be left in and a different gauge hooked up to it later on? would it need to capped or anything if so?

wasp

id like to mount it in a cup on my dash , do i need a liquid filled one or not for this? , which is more accurate , mechanical or electrical?

Benm109

You can leave that brass T-fitting in. It won't need to capped because it has a shraeder valve in it that keeps fuel from coming out unless the pintle is depressed (just like tire valve stems).

If you want a fuel pressure gauge in your dash, I would highly recommend an electric FP gauge. If you got a mechanical FP gauge, you would have to run a fuel pressure isolator. Mechanical gauges have to be hooked up physically to whatever your testing. If you ran a mechanical FP gauge in the dash, then you would have high-pressure fuel running in the passenger compartment, which you absolutely do not want. The solution to this is a fuel pressure isolator. It's basically a diaphragm. you would hook up a fuel line to 1 side of the isolator, and then run a line from the other side to your mechanical gauge. That other line would be filled with some kind of inert liquid (can't remember what they recommend). That way you don't have high-pressure fuel running in the passenger compartment, although there is still a risk of bursting the line that holds the liquid.

Something else to keep in mind is that mechanical FP gauges are affected by heat. The hotter it gets, the lower FP it reads. A lot of people have hooked up mechanical gauges into the stock fuel feed line under the hood and left it permanently installed there (I am one of them). Once the engine heats up, the gauge doesn't read correctly. It goes from about 11 PSI at 100* to about 7 PSI at 220*.



A much easier way (but not the cheapest, honestly) is an electric fuel pressure gauge. Electic FP gauges just use a sending unit that attaches to a fuel line. All you have to do is hook the sending unit up inline with the fuel feed line, and then run the wires up into the passenger compartment and hook them up to the gauge. Much simpler, and much safer than trying to hook up a mechanical FP gauge.

Just to back up what I said, take a look at what Autometer has to say about running a mechanical fuel pressure gauge:
http://www.autometer.com/tech_faq_an...px?sid=1&qid=1

Also, Autometer has instructions for all of their gauges on their website. You can get a good idea on what it will take and what other parts you might need to install a FP gauge however you choose to do it.

wasp

yeah i see the electrics area bout $200 , but id rather spend the dough and be safe..............so the sending unit could be put in place of this "t" for the testing gauge? basically id only have to cut the line once................

Benm109

You would still need some kind of a T fitting, but you won't necessary need the one that comes in the Actron kit.

I took a look at one of the instructions for an electric FP gauge, this one: http://www.autometer.com/download_instruction/665H.pdf

It says the fuel pressure sending unit has a 1/8" NPT male fitting. All you need is a 3/8" fuel pressure gauge fitting adapter. Both Summit Racing and Jegs sell them (although it looks like Summit is out of stock of both T fittings until Sunday):

http://www.jegs.com/cgi-bin/ncommerc...58&prmenbr=361
http://store.summitracing.com/partde...=KeywordSearch
http://store.summitracing.com/partde...tt=SUM%2DG1710

I used that Summit Racing adapter when I hooked up my fuel pressure gauge.

wasp

if im going to be setting up a gauge on my dash i wouldnt need any of the parts in the actron kit then correct? i plan on getting the atm-7163 from summit, then all i need is the adaptor?

Benm109

You are correct. You are not going to need anything from the Actron kit. There is no need to buy it.
Yes, from what I can tell, the electric FP guage will come with everything else you need.

And, this is just my opinion, but a 0-100 FP gauge might be a little hard to read at times, especially since TBIs usually don't see much over 20 PSI (on modified TBIs). Autometer offers 0-30 PSI FP gauges, but not in the C2 series. But, like I said, it's just my opinion.

wasp

i agree, however why would it be hard to read? 0-30 is fine but i liked the look of the c2 , i didnt think id have a problem reading it , am i wrong? i plan on setting up a bottle later on , i was going to put fuel pressure and bottle pressure side by side in cups on my dash..............water temp, trans temp and air/fuel ratio in a triple pod on pillar......i figured with the 2 important ones on the dash id be able to read them easy at high speeds

Benm109

It's really not that it would be hard to read, just take a second or 2 longer to determine exactly where the FP is at.

For example, say your fuel pressure is 12 PSI. It's not hard at all to tell exactly where 12 PSI on this 0-15 PSI gauge:


But on this 0-100, 12 PSI is just a little bit harder to determine as fast:


There are pros and cons to both gauges. For example, if you ever swapped out that TBI engine for a TPI, LT1, etc., that 0-100 PSI gauge would still work just fine, while the 0-15 would have to be changed out. That 0-15 is only going to work on carbed and TBI engines.

But, like I said, it's just my opinion. I think that 0-100 gauge will work just fine, I just thought it might be a little harder to read.


No matter what you decide though, I would love to see pictures of your set-up once it's done. I don't think I've personally seen pictures of an electric FP gauge hooked up on a TBI engine.

wasp

i see , also the 0-100 is in increments of 2 instead of 1............thanks for the heads up.................

wasp

well i got the gauge and the fitting, it says not to use teflon tape on the threads of the sending unit? why and what do you guys use? would black rtv be ok?

Benm109

I'm not sure how true this is, but I have heard that gasoline eats away or dissolves teflon tape. That might be why. I used teflon tape before I knew that when I installed my mechanical fuel pressure gauge and have had zero problems with it so far.

You could try thread sealant, which you can get at any auto parts store. Most places also sell liquid teflon paste which may work.


EDIT: Found the answer in the Tech Tips section of my Autometer catalog. They suggest not using teflon tape for 2 reasons, one because a lot of people accidently use too much of it, and it gets trapped in front of the opening on the back of the gauge/sender, causing it to read incorrectly or not at all. The other is that if using an electrical sender (like what your using), it will prevent the sender from making a groud contact.

They just suggest using a small amount of liquid Teflon sealant on the threads.

wasp

makes sense to me, ty much , well i searched for liquid teflon on both autozone and advance sites, only thing that came up was this in advance


http://www.partsamerica.com/ProductD...rtnumber=59214


is this ok to use? where can i find this liquid teflon?

Benm109

Any hardware store or place like Wal-Mart with a hardware/plumbing section will have liquid teflon sealant.

http://www.homedepot.com/prel80/HDUS...4+3116&pos=n06
http://www.lowes.com/lowes/lkn?actio...d=C070308&bc=l

I think regular thread sealant will work just fine.