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Discussion Starter #1
I just replaced my broken fuel pressure gauge yesterday with a liquid filled one from summit. I'm running a Holley blue electric pump along with a regulator. I started the engine, checked all around the gauge checking for leaks. The gauge was reading 2 psi. I adjusted it to around 5 1/2. Let it idle a few minutes then gave it a few gooid revs. The fuel pressure gauge started dropping down to about 4 psi. Any thoughts? I'm guessing my fuel pump is on it's last leg. What else would cause a drop in fuel pressure?
 

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I have about the same guage from Jegs. I have the same effect. You may not be dropping pressure at all. When I called Jegs about mine doing that , the guy told me it was the nature of this kind of guage. I believe he said the oil warms and then reads less than it really is.( I asked why do you sell them if thats the case. He just said "cause you asked for it" go figure) I checked mine with another dry type and it checked out ok. Buy the way I have the same fuel pump as you . Good Luck.
 

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O.K thats interesting. I'll go drive it around some, get it all warmed up then check the gauge and set my pressure where I want it at. Thats crazy how it floats around like that though.
 

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i have the same problem i set mine higher so it comes down to where i want it im going to relocate mine soon so i can see what its doing as im going down the track :yes:
 

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Yeah, I would have bought the cheaper non liquid filled gauge if I knew they were like this. I just thought the liquid filled one was better. I really cranked on my regulator to get it to 5 1/2. I wonder how much it's off by?
 

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I had the same problem with my gauge. there is a rubber stopper on it, pull up the corner of on watch your gauge, jump back up. Your basicially burpping it. I finally just drained it, works much better.
 

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I had the same problem with my gauge. there is a rubber stopper on it, pull up the corner of on watch your gauge, jump back up. Your basicially burpping it. I finally just drained it, works much better.
Thanks for the advise. I'll definately give it a try.
 

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When this first happened to me it drove me nuts. I now run an Autometer gauge!!
which one liquid , mech, electric.... i want to use the 2-5/8s autometer ( procomp) and mount it on my cowl some where under my 4'' cowl hood opening using a braided a/n line does that make since :yes:
 

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The only time a liquid filled gauge should be used is in the cockpit. The glycerin is put in the gauge to keep the lens from fogging up but absolutely isn't meant to be used in any environment where they will see extreme temperature changes.:no:

Just get a GOOD mechanical gauge and start tuning.

Nitrous tuners run into this type of problem all the time and it has cost a good number of pistons. It's not uncommon to see/hear them say "I've got the flowing fuel pressure set to X on MY GAUGE.".. That's because they know it's more important for the gauge to read CONSISTENTLY than on any specific number. As long as it's consistent you can use it as a reference to make adjustments. Otherwise it's just there to look pretty and plug a hole.
 
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