Engine/Transmission (1998.5 - 2002) Fuel Pressure

[Desert Proven]

Hey Gents,



I need a little assistance. My gauge is registering 0 Fuel Pressure. It's a Di-Pricol mechanical gauge with the isolator in the Engine Bay. The mechanic put a manual gauge on the VP-44 and it reads 17 psi (I've got a Walbro pusher pump in line), so I'm confident that I have pressure.



There doesn't appear to be any fluid in the line coming from the VP-44 to the isolator. The line from the isolator to the Gauge is full of anti-freeze.



I didn't do the installation myself, so I'm not sure of what approaches I can take to resolve it.



1) What can I do to fix the isolator?

2) If I can't fix the isolator, where can I purchase the isolator unit itself?



Any other ideas or suggestions would be greatly appreciated.



thanks

 

[blacksheepdiesel]

You need to bleed off the line that runs from fuel supply to isolator.

Godspeed,
Trent

 

[DIESELWRKS]

maybe what I have done may help. I had have 2 isolators blow the gasket inside in 1 year due to hard pressure picked up from vp. I move my t fitting farther back from the vp next to the fuel filter housing MY t line to the isolator. prior to the isolater I installed a needle valve to help absord the impuses from the fuel hittlng the isolator. some use rad-fluid to the gauge. I have always used clear silicone in the isolator gauge side. plugged it that was it never worried about bleeding the line to the gauge I have never worried about bleeding the fuel to the isolater to me its not needed. the fuel pressure is always on 20psi. when my isolator gasket broke my pressure jumped up to 25 for a couple days and then down to 5ps I then replace the isolator seperate. and this is when I installed the needle valve to help make the isolater last longer. what size fuel hose are you using to pick up the fuel off with. are you getting your fuel from the filter housing our on off on a t fitting like mine. I have had alot of probs with dipricol guages and isolators since they always go out in warranty I keep getting them back. also readings that come for the oem fuel filter area are not going to be the same going into the vp. this is why I have mine there..... Vulcan Performance Products Home Page

has alot of fitting and line and all you would need to get a look at them if you need replacement items also check your small tube going into your gauge see if you have a milk shave looking stuff this is diesel getting past the isolater and hitting 50/50 rad fluid. then you would want to replace the line and fittings from gauge to isolater again. its probley not your guage. they are strong and tuff. you can take apart your isolater with the 4 screws and check the condiion of the gasket. or just look into one of the ends. hop this helps. let me know if you need anything I can help with what I can. eric at vulcan is great guy and good to talk to also. .





2002 HO 6-SPD LB 4X4 QC HTT 62/14 SB-FE TST PM3/*REVO-BETA*SMARTY MACH 4'S, RINGED AND STUDS, AFE/2 " 4"EXHAUST D/PRICOL GAUGES, FASS 150, VULCAN 1/2 DRAW-STRAW, 3/8 FUEL LINE, DSS-TRAC-BAR STEER-BOX, AIR BAGS,17'' KMC BLACK HOSS, 315/70/17 MICKTHOM MTZ'S 6" RCD LONG ARM LIFT AND DE-BADGED FOR FUEL MILEAGE. :-laf... THANKS RIP Source Automotive Performance Diesel - Home

 

[Geno's Garage]

Hey Gents,



I need a little assistance. My gauge is registering 0 Fuel Pressure. It's a Di-Pricol mechanical gauge with the isolator in the Engine Bay. The mechanic put a manual gauge on the VP-44 and it reads 17 psi (I've got a Walbro pusher pump in line), so I'm confident that I have pressure.



There doesn't appear to be any fluid in the line coming from the VP-44 to the isolator. The line from the isolator to the Gauge is full of anti-freeze.



I didn't do the installation myself, so I'm not sure of what approaches I can take to resolve it.



1) What can I do to fix the isolator?

2) If I can't fix the isolator, where can I purchase the isolator unit itself?



Any other ideas or suggestions would be greatly appreciated.



thanks

How long has the gauge been installed? Did it EVER work?



The first thing I'd suggest is to check for fuel to the isolator. Some of the earlier fuel lines we carried had a teflon seal in the schraeder valve end that, when overtightened, the seal could compress to the point that it blocks the inlet point and does not allow fuel into the line. If you have a pump-to-isolator hose like this, and the seal is crushed, you can remove the seal, and schraeder valve depressor with a pair of needle-nose pliers. Then, you'll have to remove the valve core from the schraeder valve. This will allow an uninterrupted flow of fuel to the isolator.



Hope this helps.



~Andy

 

[mhenon]

I would think that even with air in the fuel line you would get some pressure showing on the gauge. Both posts above are right IMO... you want a needle valve before the isolator and you definitely need to get the air out of the fuel line.

Once you've done all that you might want to pull the line going to the gauge and take a peek into the isolator to see where the diaphragm is sitting. I had a problem similar to your's with no pressure on the gauge. Turned out the diaphragm was mashed against the top of the isolator so it couldn't flex to relay fuel pressure. I pushed it back down with a blunt stick and filled that side of the isolator with anti-freeze. The gauge worked fine from then on.

Hope this all made sense. Just keep in mind what's going on inside the isolator. With zero pressure to the system the diaphragm should be flat (centered) with fuel on one side and anti-freeze on the other. Fuel pressure can then push the diaphragm and pressurize the anti-freeze to show on the gauge.

Good luck... . Mike

 

[Desert Proven]

thanks all. The gauge has bee installed for about 2 years. It has worked fine up until recently. When I originally noticed it, it started at zero and then slowly built up pressure. Now, after putting a manual gauge on the VP-44 and disconnecting the line, it just reads zero all the time.



I'm going to try the suggestions made and will let you know what I find.



thanks again

 

[RJWEST]

Isolators: 1 more thing to fail in a critical path.
Isolators BAD, Direct read pressure GOOD.

 

[Parks]

Isolators: 1 more thing to fail in a critical path.

Isolators BAD, Direct read pressure GOOD.

So what happens when the gauge starts leaking diesel fuel into the cab?

 

[Desert Proven]

FIXED !



Mhenon nailed it. I pulled the fuel line from the isolator and when I turned the key, fuel came out. So that ruled out problems with that line. I then disconnected the anti-freeze (cab side line) and looked inside the isolator. It appeared that the diaphram was a little closer to that side than the view from the other. I was careful to not pour any anti-freeze out, but simply pushed down on the diaphram with a small wrench.



I put it all back together, fired up the truck and viola, 16 psi in the cab.



Thanks again for everyone's help and input.

 

[RJWEST]

Parks: I don't know... .
In 20 + years of " direct reading Gages " I never had a leak.

Seriously, 1/8 inch line, I don't see a problem...

 

[Parks]

In my short 7 + years in this business. I have seen several mechanical diesel fuel pressure gauges fail due to diesel fuel being run directly in to the gauge. Whether they stop working completely or leak fuel in to the cab of the truck.



That's why most manufacturers (Isspro, Danin etc) do not recommend running diesel fuel directly in to the gauge and will void the warranty on the gauges if installed with diesel fuel running directly into the gauge.



Now to your point, I am sure that there are some direct mount gauges that will hold up to direct install. But I have yet been able to find a company that will say 100% without a doubt that their gauges will not leak with "direct install". And I am referring to the main gauge manufactures in the aftermarket diesel business.



That's my two cents.



Desert Proven,



I am glad you got the gauge working!!!



Brandon

 

[hsmith]

Don't run one at all now, after having two leak fuel inside the cab. Another good reason to have the needle valve installed. BTW, both were new units.

 

[telliott]

i had an isolater that never read pressure accuratly but i delt with it. plus it made the guage rattle something awful. Then it apparently got a hole in the diaphram so when the line to the guage crapped out i got fuel in the cab anyway.



I therefor now run fuel direct with a valve that is easy to access in case of leak.



I just figured why use an isolator if i am going to get fuel in the cab anyway.



I am much happier with the direct setup. I trust the pressure reading a lot more, and i dont have an annoying rattle.

 

[RJWEST]

no leaks, cheap, made for Diesel, Easy install



I'M CHEAP

[/IMG]#ad