Engine/Transmission (1994 - 1998) Monitor Fuel Pressure on a 12V?

[VicR]

Does anyone monitor the fuel pressure on the 12 valves? I am a recent convert from the 24 valve section where watching the fuel pressure over there is a given, but I don't see much about it here. Is it worth it?



I wanted to put the gauge post filter so it would also watch for retriction. The 97 and my 99 take the same filter so I thought it would be easy and use the same test port on top of the cannister. Whoops! Same cannister, but no test ports? Where are you tieing the gauge in? If I do this, I'll use the westach fp gauge as it matches the combo and transmission temp.



Thanks,



-Vic

 

[VicR]

followup

So usually I am smart enough to 'search' before I post, but I was a little slow this morning. Now that I am educated, I have 2 followup questions:



1. I see that most tap into the banjo bolt at the pump. Why is that better then the bolt that holds the line to the filter? (I am assuming thats a banjo bolt too). Then I suspect I could use a Genos or other off the shelf tapped bolt.



2. It sounds like the normal operating range is right at the top of the Westach 30 PSI gauge. Anyone had problems running this gauge in this application?



Thanks,



-Vic

 

[illflem]

Main reason I use the injection pump banjo is that there is plenty of room, it's out of the way and you can still use your bleed screw after changing the filter.

It's best to use a gauge that mainly reads in the middle of it's range, pegging a gauge isn't good for it. My FP mainly reads about 26 psi but if the fuel is cold or going downhill with no throttle it will hit 35. 40 - 60lb gauge is best, but you may have trouble finding one, they tend to skip from 30 to 100psi. That's why I use just a simple water pressure gauge.

One big difference on 12 valve vs. a 24 it that you must use a snubber or needle valve ($4) to restrict the flow. The 12 valve lift pump pulsates too much, even if you can read the gauge the sender or gauge will be destroyed in short order. Plenty of room for a valve down on the injection pump.

 

[PUMPERDUDE]

If you're looking for a mechanical gauge,Northern Tool catalog has just about any range in any size you could need,back or bottom mount... . I put a 0-60 fluid filled on mine.

 

[Todd T]

i am in the works to build banjo's with Schreader valves on them. this way us 24V reverts can still use our test guages Briar help us build. I'll put one at the inlet of the pump and one on the overflow valve.



a new lift pump is in the mail to me now.

 

[Joe G.]

Vic,



If you decide to go with an electronic gauge, you can get a 40PSI gauge from Westach. You still need the snubber and needle valve as Bill says. Adjust the needle valve so the gauge barely works. Mine seems to be ok and I have put a lot of miles on it.

 

[QRTRHRS]

Banjo bolt part number

I stopped to pick up an extra bolt to drill and tap but they were out of stock. The parts man said there are two different bolts. Is the input different than the overflow? Anyone got the correct part number?

 

[Todd T]

well i chose against the schreader valves. i did it at the pump banjo and ran it through a needle valve like Illflem and others have said to. now i am chasing low pressure problems. i am changing parts one at a time to see if i can tell the culprit.



i can suck it down below 10PSI on WOT and it never shows above 20 under a load (driving) i can get 23 in the driveway @ 2500rpm's



i have a new lift pump, filter and overflow spring to install one at a time this weekend until i fix it.



then we go back into the pump for more power it may be time to get some bigger injectors and turbo too! uncle sam was good to me this year!

 

[illflem]

Todd, don't forget the pre-filter screen in the fuel heater http://dodgeram.org/tech/dsl/filter/pre-filt_clean.htm

 

[QRTRHRS]

I chanced upon some micrometer adjustment style needle valves with Swagelock fittings. The valves are made to be secured by threaded stem bodies. My plan is to drill through that triangular flat flanged area on the intake airhorn. I am going to use stainless tubing from the fuel inlet banjo to the needle valve. Then either stainless back towards the firewall before flexible or flexible all the way to the guage.



The valve is just a tad big to mount near the banjo but I don't think weighty enough to hurt the intake.

 

[PHaller]

Todd, I too had low pressures and installed a gauge and needle valve as Illflem indicated. I found that if you pinch the rubber portion of the fuel return line and the pressures spikes immediately to 40+ psi, your lift pump is ok and the fuel return valve needs replacing. If however, the pressure slowly rises to 50 psi your lift pump is probably bad or at least the check valves in the lift pump.

After replacing the return valve I run right about 24-26 psi and under wide open throttle maybe even 30 psi. That's a big difference from the 10-12 psi I started with.

-Paul R. Haller

 

[VicR]

Thanks

Thanks for the input. Westach has a 50 PSI that looks like it will match my combo and transmission temp. I'll probably go that route.



-Vic

 

[Todd T]

I got that too, Ill. just forgot to list it



it turned out to be the lift pump. my pressure was spuratic. at times it was OK, others it would run low. that in conjunction with the knocking sound, i pretty much new it was the problem. after replacing the lift pump, still on the old overflow valve, flilter and screen it smoothed out, and idled at 25psi. i then replaced the filter, put in the strainer kit and replaced the overflow valve.



i now have 28-30psi while cruising and it wont drop below 25 at WOT. i also noted it smoothed out the spikes on the guage some and is a LOT quieter. the knocking sound i could here from about 30 foot away, is gone.



i went into the pump this weekend again too. i was curious if my afc lever was reracting far enough to allow full travel of the rack. i put it on air with a regulator and guage and measured its travel at 38PSI then compared that with the rack travel. it turned out OK. i took 2 turns out of my initial screw and that helped out my high idler a bit. before i could hardly use it due to the engine reving real easy. i must have had it right on the bleeding edge of the plate. it apears to have cleaned up my smoke some too. over all it was good visit to the shop for "whitey"



althought the top or my hands look like i have been in a cat fight