Engine/Transmission (1998.5 - 2002) Connect FP sender to Inj Pump or Fuel Filter?

[WMeyers]

I think I've read EVERY post regarding installing fuel pressure gauges -- and have a few things (or more, on this subject only) I don't understand --



1) A lot of you are connecting to a tapped Ray's Banjo Bolt at the bottom of the fuel filter. Why elect to do this when it seems easier to get to the Schraeder valve on the injection pump?



2) I've read about a) removing the valve referred to as like a tire valve stem from the Schraeder valve and b) I also think someone posted about removing the Schraeder valve and replacing it with a tapped Banjo bolt. Assuming both are in fact possible, any preference reasons? Why not simply attach a female Schraeder?



3) Geno's Westach Fuel Pressure Sending Unit Discussion dated 1/29/02 (which came with my order from them) recommends that the sender be installed vertically with the fuel inlet hose at the bottom. I hadn't heard of anyone doing this but am curious if anyone has an opinion on the importance of it.



Thanks for any clarifications on the above you can offer!

 

[Briar Hopper]

Most of us, no matter what brand of gauge we use, are mounting our sending units remotely with a length of fuel line & fittings. And a snubber, to try to isolate the sending unit from pressure spikes.

I personally consider it a better option to hook to the injection pump at the Schraeder valve, rather than pre-filter. I'm trying to protect the injection pump, not the filter... . so I want to know what pressure I'm getting AT the injection pump.

That's how I have mine set up.

Dunno about the Geno's Westach instructions. 90 degree fittings can be found if mounting it vertically, but remote, is desired.

 

[High Voltage]

Hooked mine up at the Schraeder valve with a 18'' 4an line at the injection pump, works great. Also using the Westach.



15. 5 psi at idle

9-10 at WOT



Also working on my second lift pump.

 

[SEmerson]

Hooked mine to the injection pump inlet too. And for a snubber I cut the seal off the valve in the inlet fitting. It leak just enough to smooth out the pressure.

 

[Bigsaint]

Wayne, it comes down to what your fuel needs are or will be, in regards to the use of the modifed banjo bolts, Weber fittings, etc. I chose the Weber fittings as I upgraded to the braided line and wanted to run Aeroquip elbows for better fuel flow with the step 5 injectors. The same can be said for the modifed banjos, if you plan on a box or larger injectors down the road, the modified banjos will help you flow more fuel than remaining stock, although to a lesser degree than the Aeroquip elbows IMHO. I don't see why you couldn't just use a female Schrader if you are going to remain stock, but my preference for even a stock truck would be to remove the banjo at the outlet to the fuel filter and replace same with a tapped banjo. Your readings will be post filter and the short length of line from the fuel filter to the VP44 will cut down on some of the pulses from the VP44. I would still use a snubber line from the banjo to the sender, for good insurance. My SPA sender isn't mounted with a snubber at the fuel filter outlet, but I'm running a risk of a sender failure w/o the snubber. Just my $ 0. 02.



Don't beat yourself up over this issue, any FP gauge mounted pre or post filter is better than none at all. Choose the connection that you are most comfortable with and enjoy the truck. The bottom line is that a FP gauge provides you a baseline of how your lift pump is performing and how much fuel the VP44 is requiring. There are many ways to install a pressure port for the gauge, they even make a 3/8" barb to 3/8" barb to 1/8" NPT fitting that you could splice in pre-filter to watch the lift pump psi's. While that wouldn't be my first choice, it's yet another option.



Scott W.

 

[WMeyers]

Thanks for the help guys!

 

[dresslered]

This will probably cause a few people to disagree with me, but in my modest opinion, there is NO reliable way to connect directly to the Schrader valve. Using Ray's modified banjo at the bottom of the fuel filter is the best location for post filter readings. Then, run a line from this fitting to a remotely mounted sending unit. A simple line is an 1/8" NPT grease hose extension.



Many people are forcing the -4AN fittings on the end of the Schrader valve and have been having success. However, they are mixing 45-degree flanges with 37-degree flanges. Mashing them down seems to seal it in most cases. The part that concerns me is that there is not the proper surface area on the flange of the Schrader valve for a reliable seal. The Schrader fitting is designed to be used with a "temprorary" gauge which uses a rubber gasket.



Just my 2-cents as always.

 

[CFowler]

let me see if i got this right. use a banjo bolt on the bottom of the fuel filter housing,run up a18 inch grease gun hose to the sending unit. isa gauge snubber the right thing to add?or is it not really necessary?thanks. CFowler

 

[dresslered]

CFowler-

You have it correct. If you go with the rubber grease hose, you probably won't need any additional snubbing. I am using only a 1-ft grease hose, and I am seeing no fluctuations in the readings. The rubber gives enough to dampen the "water hammer" from the injection pump. Also, by running from the fuel filter you also take advantage of the piece of rubber tubing between the injection pump and the filter. It is short, but does dampen somewhat.



Make sure that you get a good quality grease hose that has "tapered" NPT threads. Some claim to be 1/8" NPT but do not have the taper so that it never properly seals.

 

[RBSOB]

good info

Wow, am I glad to see this timely thread. Thanks for some great info TDR Guys. Jim G.

 

[RustyJC]

I'm running a dual combo Westach fuel pressure gauge. I used Ray's tapped banjo bolts, one on the backside (firewall side) of the filter for pre-filter pressure and one on the bottom of the filter housing for post-filter pressure.



I plumbed from the banjo bolts to the firewall-mounted Westach senders with teflon-core, stainless steel braided hose and AN fittings. This hose is so stiff radially that it doesn't provide any dampening of the high pressure spikes from the VP44, and I lost two (2) post-filter sending units within 1000 miles of installing the FP gauge. I added a gauge snubber to the inlet of the post-filter sender and have had no problems since.



I imagine Westach is wanting the sender mounted with the inlet down in order to trap some air for dampening purposes. Mine are mounted with the inlets up, and since adding the snubber to the post-filter gauge, they work just fine. The pre-filter sender has never given a problem.



Rusty

 

[WMeyers]

Rusty,



It was Geno's instruction sheet, not Westach, that suggests that the sender be mounted vertically, but you may have the right reason. I thought it may be that their instructions for the 98 and 99s which had the sender mounted vertically on top of the filter worked well and they decided to be consistent. My current plan is to attach to a tapped banjo bolt at the bottom of the filter and run a hose forward to the cubby hole near the windshield washer fluid -- can't see much free space that's very easy to get at on my firewall (and I'm only going for ONE sender!). Just waiting for the snubber to arrive at this point.

 

[SEmerson]

I used a braded fuel line and snubbing was needed. Greese gun hose was probly cheaper too.

 

[CCahill]

My setup was to go to the bottom of the fuel filter, install one of Ray's threaded bolts, screw in the Westach sender , reinstall the stock fuel line... then wired up the gauge... Seemed EZ enuf' and it's pre pump-post filter ,so I belive I'm getting a correct reading.





Colin

 

[Snow man]

definetely hook it up under the filter housing,not at the pump. I first hooked my SPA up right at the pump,directly on the banjo bolt,the Fp readings were all over the place,I then used a 24" peice of rubber fuel line hose,and 2 1/8 fittings to remote mlount the sender to the inner fender,but still had the banjo on the VP44 inlet,this way ti was bettermbut still fluctauted. When i moved it to under the filter housing,the guage settled down perfectly,and i get the same exact readings i got at the pump inlet,just get them without so much fluctuations.

 

[SEmerson]

I think I will move mine to the filter. I had even wraped my line to cut down pump noise.

 

[redneckdr]

another point of view

i have the Isspro mechanical gauges. i installed all five of Ray's banjo bolts. i tapped into the VP44 intake for my hose, which i had made at a local hydraulics shop. 10 feet of 300 PSI hydraulic hose to the gauge, and no fluctuations. i plugged the banjo pre filter. future plans call for a tank switching valve to be installed, and feed the gauge from the outlet, and hook pre and post banjos to the inlets. with a simple SP/DT switch, i should be able to switch vfrom pre to post filter to read the pressure.

 

[CAM]

Great information,anyone w/ pictures.

Mike

 

[Hohn]

Originally posted by dresslered

This will probably cause a few people to disagree with me, but in my modest opinion, there is NO reliable way to connect directly to the Schrader valve. . .

Many people are forcing the -4AN fittings on the end of the Schrader valve and have been having success. However, they are mixing 45-degree flanges with 37-degree flanges.

Dresslered: I was aware of the difference between the 37° and the 45° flares when I did my install. I *did* connect directly to the Schrader, and it has been reliable. What I did was run a fitting that was REGULAR #4 tube (NOT A/N) female and 1/8" NPT female. That gave me a double-female adapter to my grease gun hose. I even have a little capped-off tee in the line so I can bleed it if I need to without disassembling it.



The only problem a I see it is that the stock VP fitting has an extended portion on the end that isn't threaded. This means that your tube adapter is only hanging on by 2or 3 threads. The fittings aren't deep enough otherwise. It's reliable as long as you don't go too tight. Just tighten it gently and rely on thread sealant more than torque and it will be fine.



HOHN

 

[jjohn]

W

I went pre filter on on the fuel filter on my 02. The link has a pic of the SS fuel line and 90 degree fitting. I also added a test port to use my test gauge to check pre and post (at vp44) pressure across the fuel filter at oil changes. fuel line and fittings