When you buy a fuel pressure gauge. usually some manufactures don't give you vehicle specific instructions on where to put it!! does anyone know where the best place would be to tap into for the pressure sensor on a LB7?? and would this place change after i got a dual CP3? are there any open DIY threads, i haven't found anything on this topic?? Also what range in PSI do i want the gauge to be, what should it run normally?? Thanx! Bryan..

Can't help on the location but would have to search for it. I do not know stock CP3 max output. But it is the same or less than later generations. LBZ and LMM run upto around 26,000 max. All I do know is when they test the CP3 to 160mpa that is about a little over 23,000psi. So I say in the 30,000psi should cover you but suggest calling the makers of dual CP3 and see what they say they push out.

Brian

All the gauges that i have seen only go up to 100 Psi. HOW will that work???

That be useful if you had a lift pump to monitor fuel pressure after the fuel filter. But for main fuel rail pressure that will not work. PPE and Autometer make gauges to 30,000 psi.

Brian

i think with efilive they are reading it. i think modules for dual cp3's tap in to control fprv. for low pressure, suction/liftpump/filter side some connect to schraeder valve in front of engine. one member removed schraeder vavle and put AN fitting, another guy broke part trying to do same thing.

i think with efilive they are reading it. i think modules for dual cp3's tap in to control fprv. for low pressure, suction/liftpump/filter side some connect to schraeder valve in front of engine. one member removed schraeder vavle and put AN fitting, another guy broke part trying to do same thing.
Are there any pictures of where this might be??

If you have a lift pump, you can measure fuel system pressure prior to the CP3 by removing the OEM Fuel Filter plastic bleed screw, and installing an adapter in link below. If you don't have a lift pump, this won't work as the stock fuel system operates under vacuum.
http://www.merchant-automotive.com/fuelpressuregaugeadapter.aspx

I hadn't heard of anyone monitoring 23,000 PSI out of CP3 with a gauge.

If you have a lift pump, you can measure fuel system pressure prior to the CP3 by removing the OEM Fuel Filter plastic bleed screw, and installing an adapter in link below. If you don't have a lift pump, this won't work as the stock fuel system operates under vacuum.
http://www.merchant-automotive.com/fuelpressuregaugeadapter.aspx

I hadn't heard of anyone monitoring 23,000 PSI out of CP3 with a gauge.


Well thats cool and good to know! but i don't have any fueling upgrades or nothing! thats why im wondering where to adapt to and what PSI of gauge i can use??

I took off schrader valve at the front of engine. This is a test port for vacuum gauge. The threads into fuel system I believe were 16mm 1.5 I made on a lathe a metric to 1/8npt fitting to accept a vacuum guage. I leave it there all the time where I can check the vacuum. Vacuum pressure with new filter should be round 2 hg. As filter becomes restricted, or other restriction, the pressure will increase. At around 7 hg, it would be time to change filter or find restriction in fuel system.

You can check KennedyDiesel website and will show a picture of a lift pump on and off with some gauges they sell. I have only seen one 30,000psi electronic gauge in the pillar in one truck. I just perfer the data output off the ECM using the Dashhawk II to read fuel rail pressure. Or every now and then using EFILive to check balance rates and CP3 output at idle.

Brian

You can check KennedyDiesel website and will show a picture of a lift pump on and off with some gauges they sell. I have only seen one 30,000psi electronic gauge in the pillar in one truck. I just perfer the data output off the ECM using the Dashhawk II to read fuel rail pressure. Or every now and then using EFILive to check balance rates and CP3 output at idle.

Brian
What is your fuel pressure at the rail?? What im trying to get at is everyone else is putting on lift pumps or dual CP3's and they are all checking fuel pressure!! But i don't belive that there guages are readig 30,000 PSI. I thought rail pressure is where they tap in??? i don't want to have to put in a lift pump or dual CP3 just to check fuel pressure! or do I?? im just trying to fill up my guage pod with the same gauges as my other ones so they are all the same!!

If you read before the CP3 pump it is in vacuum since pulling fuel from the tank.
If a lift pump is installed then you read pressure like 15psi or less is all that usually is needed.
After the CP3 is the what I call fuel rail pressure and at idle is like 5000psi and can max out around 26,000psi at wide open throttle and depending on the tune.

You can add a guage with vacuum and psi scale and monitor the fuel filter whether it is nearing its useful life. Maybe some use it that way and when or if you do add a lift pump your covered.

To me monitoring the actual fuel rail pressure and not knowing what the ECM is commanding the desired fuel rail pressure too is of no use without both pieces of data to see an issue.

Brian

ok so if i want to use the gauges of lower PSI i should read it after or on the lift pump!! i don't think the gauge company that im using has a vacuum and psi gauge! so i shall wait till i get a lift pump then!!

If you want fuel pressure of what the lift pump is supplying, the gauge will have to be tapped in between the lift pump and the CP3. I will get a picture where I plumbed my 0-30 psi gauge on my filter housing using the lubrication specialist kit with a 1/8 npt male run tee to keep the shut off valve in the system.

Anything after the CP3 will be under very high pressure.

If you want fuel pressure of what the lift pump is supplying, the gauge will have to be tapped in between the lift pump and the CP3. I will get a picture where I plumbed my 0-30 psi gauge on my filter housing using the lubrication specialist kit with a 1/8 npt male run tee to keep the shut off valve in the system.
Anything after the CP3 will be under very high pressure.

This adapter from lubricationspecialist.com is simular to the adapter I mentioned above. Installing a tee with a bleed port/fitting will still leave an easy way to bleed your filter.


http://lubricationspecialist.com/front/shop.aspx?catid=10&parentid=0&curr_page=4
http://lubricationspecialist.com/front/shop.aspx?catid=10&parentid=0&curr_page=2

I found my male run tee at Fastenal for about a buck. I just threaded the male run tee into the adapter, then threaded the shut off valve into the top of that. I couldnt put the fuel pressure sending unit on until it was installed in the filter housing because it would hit the stock primer button. With the tee, its real close to hitting but I promise it will work ;)

I found my male run tee at Fastenal for about a buck. I just threaded the male run tee into the adapter, then threaded the shut off valve into the top of that. I couldnt put the fuel pressure sending unit on until it was installed in the filter housing because it would hit the stock primer button. With the tee, its real close to hitting but I promise it will work ;)
So did u get all your parts from lubrication speacialist, you said you paid a buck??? and you ran a fuel press gauge up to 30 PSI. whats the most you have seen, And obviously with this you can determine if your stock lift pump ever craps out?? what u get a new fass lift pump. will the PSI be higher??

Going to Kennedy Diesel site and looking for the gauges they sell. You will see with their lift pump on that it is almost 7.5psi. with it off like 2hg vacuum. I read in post stay under 10psi or you can start causing issues in the high pressure rail not a big issue just a different sound at idle. So 30psi is more than enough. Also no Duramax comes with a lift pump. It is all aftermarket item. For the Fass pump best to check their site and if no info maybe email or call. Yes can help to tell if lift pump is on or not.

For the parts the lubrication sells the bleed valve kit and goto the hardware store or plumbing supply house for the tee and if you need any pipe nipples.

Brian

Moved to Interior.

So did u get all your parts from lubrication speacialist, you said you paid a buck??? and you ran a fuel press gauge up to 30 PSI. whats the most you have seen, And obviously with this you can determine if your stock lift pump ever craps out?? what u get a new fass lift pump. will the PSI be higher??

I got the tee for a buck from fastenal, needed if u still want to have the ability to bleed the system with the shutoff valve. The rest of the stuff came from lubrication specialists bleeder kit.

With a full tank and good filter I will see about 8 or 9 psi on the gauge. I change my filters if it drops to 5 psi on a full tank. On my big tune, I can drop the psi under 5 at WOT, and normally drop it to about 5 psi on all my other tunes. As Tanc Crusher said, supply psi over 10 psi runs the risk of doing damage to your cp3. Most stock units come factory preset @ 10 psi (FASS and AD).

OK so i will get a gauge with a low PSI numbers and the plumbing from The lube specialties guys!!! Thanx a bunch guys!!

Anyone else sell this adapter? I got a bunch of filters to change this weekend and was thinking of relocating my sender to the fuel filter housing. Only problem is that I wouldn't get the adapter til next week. So who might carry it. I have all the parts stores, a Fastenal hub store, a Winner's Circle all near me.

You have to locate a metric straight thread to NPT taper pipe thread adapter. I do not recall the thread but 14mm seems like the bolt size. There are post on the exact thread size and number of threads here in a few.

Brian

You have to locate a metric straight thread to NPT taper pipe thread adapter. I do not recall the thread but 14mm seems like the bolt size. There are post on the exact thread size and number of threads here in a few. Brian

10mm X 1.5 parallel thread.
Because of the parallel thread, (straight threads, NOT tapered), you need the O-ring to provide the seal.

Thanks for the correct thread size. Just not a thing on the top of my head. always have to search to find it.

Brian

Thanks guys, I tracked down a couple in town but it would take too long to get them shipped. Figured I'd do install it next week so I ordered it from Merchant Auto. To my surprise with UPS ground it will be here tomorrow, which it should since shipping was $14.