Engine/Transmission (1998.5 - 2002) Install FP gauge - what is needed

[canblue]

Read a few post about FP gauges failing. What is the correct method for installing one, either mechanical or electric? The posts implied that the shock waves from the VP damaged the electric sending unit. Can this be prevented? If so how? I want to install a gauge with some likelyhood of surviving for a few years.

I was planing to install and electric one to reduce the chance of fuel leaking.



Thanks.

 

[dresslered]

Here's an old reprint of some instructions that I had previously sent someone. Start here:





The fuel pressure gauge is very easy to hook up once you've figured out the correct method. I can give you all the details of all the various methods or just get to the point. I ended up going with the Autometer 4361 Ultra-lite gauge. This is a very high quality gauge with the only drawback of it costing nearly $200 (from Summit Racing). The install would be similar to other electrics.



If you haven't read by now, the waterhammer effect from the injection pump, as well as the engine vibrations are extremely hard on the very sensitive pressure transducers. Because of this, I think that all sensors should be mounted remotely. Additionally, some sort of snubber should be used to take out the pulses from the injection pump.



I think that the method that I used is extremely simple and it is very reliable (do not replace the Schrader valve with a -4AN fitting like some people have--these are not compatible with each other even though by forcing them on, they appear to be working for many people). The method that I used replaces only the stock banjo bolt located at the bottom of the fuel filter. It also retains the fuctionality of the Schrader test ports. Substitute in one of Ray's tapped banjos (available now thru Geno's garage). If you're careful, you can reuse the two O-rings from the OEM banjo bolt. The new banjo will have an 1/8" NPT female thread in the bottom of it. I then screwed in a good quality rubber grease hose (male 1/8" NPT threads on both ends) into the tapped banjo bolt. The rubber hose will flex enough to take out the pulses from the injection pump (acts as a snubber). The rubber hose was then run up to my remotely mounted sender which I mounted on one of the brake master cylinder bolts via a custom bracket. With a female-to-female 1/8" NPT coupler, the sender was joined to the rubber hose. I chose to leave a little extra air trapped in the hose to act as additional snubbing. The rest is just electrical. The gauge has worked flawlessly for over 30,000 miles and has already identified my first ailing pump. Good luck with the install,





EDIT: Just noticed that you have a '99 so you might already have the 1/8" NPT threads on your fuel filter saving you the trouble of getting the tapped banjo bolt (make sure that you tap the post filter side).

 

[canblue]

David. Thankks for all of the valuable information. A rather simple question> Did you fill the flex hose manually to ensure that there was an air gap? Can't

wait to order the parts and get it all installed. Oo.

 

[dresslered]

A mechanical engineer that I know who builds experimental airplanes said that he always leaves air in the fuel pressure lines. Personally, I don't know how important it is, as it might just adventually get absorbed by the fuel over time. Basically, all I did was not bleed the tubing during the install--it will not effect your readings in any way.



As an added note, some people (including myself) have purchased cheap grease gun hoses in which the ends weren't true NPT threads (they weren't tapered), thus they never seated properly (i. e. watch out for those cheap inports!). Make sure that they seat before bottoming out.



If you PM me your email, I can send you some pictures if desired.

 

[moremph]

where would you get a high quaility grease gun hose at? Thanks Travis

 

[Bob Wagner]

Originally posted by moremph

where would you get a high quaility grease gun hose at? Thanks Travis

Home Depot under 6. 00

 

[jerrethomas]

i understand the idea of leaving the air in the line to help to absorb vibration and what not, but doesnt' air compress and the fuel doesn't. if this would be the case, wouldn't it give you a little bit of a false reading due to it compressing the air in the line a little bit. just wondering.

 

[JFinke]

No, the air will compress to the same pressure as the fuel pressure. It will equalize as fast as the guage can respond. Also as a side note, fuel does compress, just that is almost an unmeasurable amount, something like . 000001%.

 

[2ndgen2500]

ive had my electric gauge on for over a year, not one issue, reads accurate and no isolator, for me it was the best choice.

 

[dresslered]

My electric gauge is still running flawlessly. It is now identifying its second ailing lift pump at 56,000 miles.

 

[jerrethomas]

i knew someone would straighten me out, anyhow. what electric fuel pressure gauges are you guys using that are holding up so well?

 

[dresslered]

I'm using the Autometer 4361 Ultra-lite which has it's own sender while other gauges often use the Stewart Warner sender. I think that as far as the reliability goes, it all boils down to how you mount it. You need to get the sender off of the engine and provide proper snubbing and it should hold up just fine. If in doubt, go with the mechanical. I think that the mechanicals are great but just a little more difficult to route the lines.

 

[CFowler]

guys, im not trying to change the subject but i have a fuel pressure guage related question. please tell me if im doing this right. i have one guage hooked to the taped banjo on my fuel filter housing and presume im getting the pre-filter press. reading now i have bought the grease gun hose from genos ,guage & sender and another taped banjo,just in case. can you guys help to get me going in the right direction with the installation?do i just screw that hose to the fitting on the pump?or should i use a taped bolt? sorry i just dont want to do it wtrong. thanks,carl.

 

[Thomas]

If you retained the banjo with the schrader at the filter and replaced the other banjo at the filter with a tapped banjo, I believe you're already monitoring post-filter. If I'm wrong, David will jump in and set me straight.

 

[CFowler]

o. k. now im thinking that i might havnt made this clear. i only have one guage hooked up right now. to the bottom of the fuel filter housing. all along i have been thinking that i have been getting pressure readings pre filter. and i want to install another guage post filter. help is going to be needed here.

 

[Thomas]

You can use tapped banjo bolts at both the inlet and outlet of the water separator/fuel filter to monitor both pre and post filter. The inlet (pre-filter) is at the top-rear of the filter and has the Schrader valve (test port). The outlet (post filter) is at the bottom of the filter.



I monitor both full time and have done it this way. I'm keeping the electric sending units for my dual fuel pressure gauge away from the VP44. I use tapped banjo bolts at both locations. I got rid of the Schrader valve.

 

[CFowler]

thanks. all along i was watching post filter readings and thinking that it was pre filter. . now if i got it right all i have to do is remove the schrader valve at the top rear of the fuel canister,screw in a taped banjo bolt and put my 18" rease gun line to it?