On Engine Fuel Pressure Gage - Schrader Valve Adapter
06-20-2009 | 02:48 PM
#1
Thread Starter
Gold Member
Joined: Sep 2005
Posts: 1,987
Likes: 0
From: Missouri
On Engine Fuel Pressure Gage - Schrader Valve Adapter
My 496 MPFI fuel rail has a schrader valve connection point for attaching a fuel pressure test gage. I want to permanently install an on engine fuel pressure gage on this schrader valve. Fuel pressure gages seem to all have a NPT male fitting. Ideal would be a fuel pressure gage with a female shrader valve connection that would screw directly onto the fuel rail's male schrader valve. Second best would be an adapter fitting with a female schrafer valve connection for connection to the fuel rail schrader valve leading to a male NPT connection that the gage could screw into allowing the fuel pressure gage to be hard mounted to the fuel rail.
Anyone know where to get such hardware?
Anyother ideas on how to accomplish the FPG to fuel rail mounting?
I currently have a fuel pressure gage and hose tester permanently attached to the fuel rail's schrader valve. I would like to replace this with a nicer looking setup.
Anyone know where to get such hardware?
Anyother ideas on how to accomplish the FPG to fuel rail mounting?
I currently have a fuel pressure gage and hose tester permanently attached to the fuel rail's schrader valve. I would like to replace this with a nicer looking setup.
06-20-2009 | 04:29 PM
#2
Registered
Joined: Aug 2005
Posts: 1,491
Likes: 0
From: sint maarten
well... two things. first , the direct answer to your question is that those threads are 1/8 npt and any good fuel press gage you buy will have those threads so if you have room for the gage, you can just use a little teflon tape and screw it in...
the second is that it is a very dangerous thing to do on any boat or car that takes a lot of shock load or vibration. those mechanical gages are just bits of flat copper tubing inside that have the fitting soldered to it. if you rigid mount that and hang it out in the breeze, you stand a better than average chance of just having it shake itself to pieces and fill your engine bay up with fuel... which will lead to an interesting newspaper article and everyone here saying " gee remember when that guy asked about that ?"
the right way to do it is with a couple of fittings and a short piece of flex line... -3 or -4 aeroquip ... doesn't have to be braided. it can be the neoprene push lock which is good to 200 psi. then just mount the gage inn a convenient place nearby.
that way no newspaper article.
the second is that it is a very dangerous thing to do on any boat or car that takes a lot of shock load or vibration. those mechanical gages are just bits of flat copper tubing inside that have the fitting soldered to it. if you rigid mount that and hang it out in the breeze, you stand a better than average chance of just having it shake itself to pieces and fill your engine bay up with fuel... which will lead to an interesting newspaper article and everyone here saying " gee remember when that guy asked about that ?"
the right way to do it is with a couple of fittings and a short piece of flex line... -3 or -4 aeroquip ... doesn't have to be braided. it can be the neoprene push lock which is good to 200 psi. then just mount the gage inn a convenient place nearby.
that way no newspaper article.
06-20-2009 | 07:45 PM
#4
Thread Starter
Gold Member
Joined: Sep 2005
Posts: 1,987
Likes: 0
From: Missouri
well... two things. first , the direct answer to your question is that those threads are 1/8 npt and any good fuel press gage you buy will have those threads so if you have room for the gage, you can just use a little teflon tape and screw it in...The problem with that approach is that there is no 1/8NPTF on the fuel rail to screw the gage into, only the male schrader valve that I referenced initially
the second is that it is a very dangerous thing to do on any boat or car that takes a lot of shock load or vibration. those mechanical gages are just bits of flat copper tubing inside that have the fitting soldered to it. if you rigid mount that and hang it out in the breeze, you stand a better than average chance of just having it shake itself to pieces and fill your engine bay up with fuel... Good point that is on my mind as well though I was thinking of the oil filled gages that claim to be more resistant to that issue but granted still an undesirable risk.which will lead to an interesting newspaper article and everyone here saying " gee remember when that guy asked about that ?"
the right way to do it is with a couple of fittings and a short piece of flex line... -3 or -4 aeroquip ... doesn't have to be braided. it can be the neoprene push lock which is good to 200 psi. then just mount the gage inn a convenient place nearby.Ok, but how do I connect to the schrader valve on my fuel rail and then to the gage? Where can I get the necessary fittings to accomplish this gage connection from schrader valve to 1/8 NPTM? I guess that I could just leave my current fuel pressure test gage attached to the fuel rail schrader valve and mount the gage to the bulkhead. Will not look pretty but a little better than the current coiled snake of hose and fuel pressure gage tie wrapped to the top of the coolant resevoir that I have now....maybe.
that way no newspaper article.
the second is that it is a very dangerous thing to do on any boat or car that takes a lot of shock load or vibration. those mechanical gages are just bits of flat copper tubing inside that have the fitting soldered to it. if you rigid mount that and hang it out in the breeze, you stand a better than average chance of just having it shake itself to pieces and fill your engine bay up with fuel... Good point that is on my mind as well though I was thinking of the oil filled gages that claim to be more resistant to that issue but granted still an undesirable risk.which will lead to an interesting newspaper article and everyone here saying " gee remember when that guy asked about that ?"
the right way to do it is with a couple of fittings and a short piece of flex line... -3 or -4 aeroquip ... doesn't have to be braided. it can be the neoprene push lock which is good to 200 psi. then just mount the gage inn a convenient place nearby.Ok, but how do I connect to the schrader valve on my fuel rail and then to the gage? Where can I get the necessary fittings to accomplish this gage connection from schrader valve to 1/8 NPTM? I guess that I could just leave my current fuel pressure test gage attached to the fuel rail schrader valve and mount the gage to the bulkhead. Will not look pretty but a little better than the current coiled snake of hose and fuel pressure gage tie wrapped to the top of the coolant resevoir that I have now....maybe.
that way no newspaper article.
Last edited by Rage; 06-20-2009 at 08:03 PM.
06-20-2009 | 07:52 PM
#5
Thread Starter
Gold Member
Joined: Sep 2005
Posts: 1,987
Likes: 0
From: Missouri
Real time/full time fuel pressure monitour would be best but I just want to be able to spot check the fuel pressure for deterioration periodically since I have an adjustable fuel pressure regulator and who knows when adjustment may drift. I want a mechanical gage versus electric for accuracy and do not want to run a fuel line up to the dash.
Last edited by Rage; 06-20-2009 at 08:10 PM.
06-20-2009 | 08:39 PM
#6
Registered
Joined: Aug 2005
Posts: 1,491
Likes: 0
From: sint maarten
you just unscrew the schrader valve. if it is like 99 % of all those installations it is screwed into the fuel rail with the same 1/8 pipe threads... you just uncrew it and replace it w/ your fitting. all the mechanical gages are made the same way. flat curled up piece of copper tubing w/ a needle attached to it and the fitting soldered to the other end. the oil filled gage you are describing is just an oil filled face that damps the needle movement for smooth operation. in fact that would be a worse deal because it is considerably heavier and the inertial forces on it much greater... but either way...
i admit that , like earlier mentioned , im not sure why you want it there but assuming its for some reason like i have a mechanical oil press, water temp and fuel press gage set in my engine bay so that i can confirm any anomolous reading on the junk electric gaffrigs that are in the dash, all i am suggesting is that you reconsider the rigid mount.
its just asking for trouble.
i admit that , like earlier mentioned , im not sure why you want it there but assuming its for some reason like i have a mechanical oil press, water temp and fuel press gage set in my engine bay so that i can confirm any anomolous reading on the junk electric gaffrigs that are in the dash, all i am suggesting is that you reconsider the rigid mount.
its just asking for trouble.
06-21-2009 | 09:05 AM
#7
Thread Starter
Gold Member
Joined: Sep 2005
Posts: 1,987
Likes: 0
From: Missouri
you just unscrew the schrader valve. if it is like 99 % of all those installations it is screwed into the fuel rail with the same 1/8 pipe threads... you just uncrew it and replace it w/ your fitting. all the mechanical gages are made the same way. flat curled up piece of copper tubing w/ a needle attached to it and the fitting soldered to the other end. the oil filled gage you are describing is just an oil filled face that damps the needle movement for smooth operation. in fact that would be a worse deal because it is considerably heavier and the inertial forces on it much greater... but either way...
i admit that , like earlier mentioned , im not sure why you want it there but assuming its for some reason like i have a mechanical oil press, water temp and fuel press gage set in my engine bay so that i can confirm any anomolous reading on the junk electric gaffrigs that are in the dash, all i am suggesting is that you reconsider the rigid mount.
its just asking for trouble.
i admit that , like earlier mentioned , im not sure why you want it there but assuming its for some reason like i have a mechanical oil press, water temp and fuel press gage set in my engine bay so that i can confirm any anomolous reading on the junk electric gaffrigs that are in the dash, all i am suggesting is that you reconsider the rigid mount.
its just asking for trouble.
Bill
