Engine/Transmission (1998.5 - 2002) Fuel pressure gauge acts like Tach.

[FBeuthien]

New one on me, fuel pressure 14lbs at start up, 12lbs cruising. Next the pressure goes to 7lbs at idle and will increase as the motor is revved in neutral..... Any idea what kind of gremlin this is?

 

[Casey Ray]

Check your grounds, make sure you have nice connections, and separate grounds for the sending unit as well as the guage itself.



Casey

 

[Bandit2]

Is your gauge elect. or mechanical? From what I read here the mechanical guage is far more reliable.

 

[SCox]

I have a mechanical fp gauge, its doing just about the same thing... replacing lp tomorrow. Not sure if this is the problem. I'll know tomorrow.



Steve

 

[TMWeber]

I'm getting similar readings on my gauge (Westach electric). The instructions said to ground the gauge and sender together. Should they be seperate?

 

[Casey Ray]

I'm getting similar readings on my gauge (Westach electric). The instructions said to ground the gauge and sender together. Should they be seperate?

TMWeber,



Yep, separate them. You will notice a difference, been there done that.

Found out from Geno's after calling and describing the problem.

Casey

 

[TMWeber]

Will do it. Thanks.

 

[Graphic man]

I have a mechanical fp gauge, its doing just about the same thing... replacing lp tomorrow. Not sure if this is the problem. I'll know tomorrow.



Steve

bleed the line, if there is any air in the line the gage will go nuts

turn the key on bump the starter and the L/P will run for about 30 sec. , crack the line at the gage and get all the air out of it, do this a few times, make sure you have a few rags handy, you should see a huge difference.





Scott

 

[SCox]

Thanks Scott, I'll try that before I change out the lp, might just have a spare lp now!

Steve

 

[FBeuthien]

Thanks for all your help. I will know more on Friday.

 

[HChojnacki]

low Fuel pressure gauge readings you might try this.

just installed fuel pressure gauge in my 2002 24 valve I am getting 28 to 30 lbs. at cruse and 25lbs. at ideal. With foot into it, it goes to 20 lbs. Two things you might try if you haven't all ready 1# installed a inline LP kit coast is about 265$ to help the trucks main LP. #2 If your gauge is a macanical pressure gauge you might have air in the line. air is compressible and will give a false reading bleed the line by undoing hose at gauge and starting truck until fluid starts coming out have large rag ready for the mess. reattach hose (the fluid is noncompressable and should give you a better reading at the gauge) hopes this helps H. J. C.

 

[RAJohnson]

I was having fluctuating fuel pressure on my truck as well. I have a electrical fuel pressure gauge (Auto Meter) tapped in to the shradder valve right at the VP44 with a 18" flexible line, so I installed a snubber valve at the sender. This help take alot of fluctuation out of it but not all of it. So today I relocated the sender and flex line to the bottom of the OEM ff with a tapped banjo bolt. Rock solid now I think the shradder valve is to close to the VP44 and it see's alot of fluctuating pressure from the VP44.

 

[FBeuthien]

The Rest Of The Story

Checked the pressure at the diaphragm and found 16 lbs on both sides. This gauge set up has fuel on one side of the diaphrgm and antifreeze on the other. Added fresh antifreeze and no difference, the needle moves like a drunken sailor. So, looks like the gauge is "toast". :{