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Fuel pressure gauge install

9K views 20 replies 6 participants last post by  jleedog 
#1 ·
Going to be adding a fuel pressure gauge to the truck soon. Isspro installation manual recommends a "snubber" to be used before the pressure sending unit. Do I have to add this part? Anyone not using it? Will it hurt the gauge or cause it to be to erratic. Any input is appreciated.


From the Install manual: Install Snubber kit R78828 with the 7/16 SAE O-ring adaptor threaded into the test port on the fuel bowl.
 
#2 ·
The snubber is for fuel pressure spikes keeps from damaging the sender . I don’t run one on my 7.3 and have had a gauge on it for ten years and only replaced one gauge sender do to damaging it wile working on the engine.


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#3 ·
Same here. Over 100k on my ISSPRO sending unit attached straight to the back of the fuel bowl. Never had a problem.


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#4 ·
Did you guys both mount the sender directly to the bowl, or a remote location because of vibration?
 
#5 ·
#6 ·
Help please, Finished install today with the pressure sending unit installed on the passenger side port of the fuel bowl. Fired the truck up and it reads 25 psi steady. Have yet to drive it yet, the truck runs fine. Shouldn't I have at least 40 PSI at idle? Any suggestions? I have a new Bosch pump that I have been meaning to install. Does the sending unit need to purge out the air by driving? Or is it possible I have a bad gauge/ sending unit. I figure Isspro would be a good brand.
 
#7 ·
ISSPRO is a great brand. Air clears out almost instantly since fuel goes past the regulator and back to the tank. You either have a supply issue (pump / clogged filter in the tank) or a regulator with a weak spring or bad seat. See what happens when you accelerate aggressively.


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#8 ·
OK spoke with an isspro tech today and we did some tests with a voltmeter with the gauge and sending unit. Everything checked out fine. The Tech told me that he has an pre 99 7.3l that has the same pressure when running. He suggested a new fuel pump or rebuilding the fuel pressure regulator. So im going to start with a new fuel pump and see what happens. Will update when I know something.
 
#9 ·
You should be able to narrow it down with the test I suggested. If it is a supply issue, when you accelerate, the pressure will plummet. If it is a regulator issue, it won't change.
 
#10 ·
So I installed a new Bosch fuel pump and I gained 5psi on the gauge. 30psi and it drops 3-4 psi when I accelerate heavy. So I ordered a fuel pressure rebuild kit and housing from dieselorings. Thank you for your help. Will update soon
 
#11 ·
I think you’re on the right track. Be uber careful with the regulator housing- the threads snap off easily. Bob has a billet replacement if that happens.


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#12 ·
In anticipation of snapping off the fitting, I ordered the new billet housing and replacement nut and bushing as we as the rebuild kit. Wondering what spring I should put in when I do the work?
 
#13 ·
The silver should be fine. 60 psi is your ideal pressure. I’ve never seen a benefit of going higher. Just more work for the pump.


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#14 ·
Ok, so I rebuilt the entire fuel bowl (thanks Dieselorings.com) Including the new housing for the pressure regulator and new poppet and seat.. New fuel filter (thanks Amazon). Fired up the truck and I now have 75psi at idle. WOW! I did not take RTs advise and use the silver spring. I used the gold one. I am planning on upgrading injectors soon, and I wonder if I might need that extra fuel pressure for them. Should I keep it at 75psi or should I take RTs advise and put the silver spring in and drop it down a few PSI to save wear and tear on the pump. Isspro gauge seems very stable even at WOT. Pressure got as high as 78PSI on the gauge when test driving. I swear the truck seems a bit more responsive now and may have a few more HP. I cant wait to tow and see if will improve my EGT.
 
#15 ·
Take RT's advice.
 
#17 ·
Ok switched out for the silver spring and pressure has dropped but not very much. Getting 70psi at idle and around 65 on WOT runs. Maybe it will come down a bit when I get some hours on the pump.
 
#18 ·
Well I'm at a loss now. I started the truck today and the pressure is now 100psi at idle. It dropped to 90psi when driving around. *** is going on, I dont understand. How can it change after sitting a week or 2. I'm tempted to install the old pump to see what happens. Gauge was bouncing slightly I noticed, last time it was very steady and smooth. I guess I can contact isspro again to rule out a sender issue. Any input is appreciated. Thanks
 
#19 ·
I’m running the Hewitt fuel pressure gauge with the transducer in a remote location due to vibration (I don’t have regulated return), still the original fuel bowl, needle stays rock steady, and gauge purges air super fast when fuel system is opened. ? I’m not sure how the pressure could increase if the pressure relief valve is working— strange
 
#20 ·
Yes I really dont understand how my pressure went up. I'm sure I installed the spring properly in the regulator, and it was fine when I tested it last time.
 
#21 ·
Started it today and my pressure is back to 70 again. Not really understanding what is going on. Maybe I had air in the sender that was compressed and giving a higher reading. Will be calling isspro to talk to tech to see if problems are gauge related. Update to follow
 
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