Is this normal?!

Troyphoon

New member
Re: Is this normal?!

Can anyone make any suggestions on this? I replaced my fuel filter and no change. My ty is all stock with a couple mods I added 41k miles so I'm thinking it's the pump going out. Any suggestions?
 

Don W.

Stab it and steer it
Re: Is this normal?!

Questions. What happens when you jump the FP with the engine off? (using FP test connection near the dist) Does hold steady then? When you disconnect your jumper wire does the pressure hold?

Unless I missed it somewhere those answers will help isolate the issue. IMHO it should not be doing that. At least to that extent.

Not much of anything to stick inside the FPR but who knows. It's also conceivable that there is a restriction in the return line.
 

Troyphoon

New member
Re: Is this normal?

Re: Is this normal?

Questions. What happens when you jump the FP with the engine off? (using FP test connection near the dist) Does hold steady then? When you disconnect your jumper wire does the pressure hold?

Unless I missed it somewhere those answers will help isolate the issue. IMHO it should not be doing that. At least to that extent.

Not much of anything to stick inside the FPR but who knows. It's also conceivable that there is a restriction in the return line.

I know for me if I power on the ty without starting my f/p jumps and holds to around 41-42 but when I start it up the guage goes crazy. Also if I jack up the truck with it running and touch the fuel rail I can feel it pulsating is that normal??
 

Don W.

Stab it and steer it
Re: Is this normal?

Re: Is this normal?

I know for me if I power on the ty without starting my f/p jumps and holds to around 41-42 but when I start it up the guage goes crazy. Also if I jack up the truck with it running and touch the fuel rail I can feel it pulsating is that normal??

IMHO that is not normal. When you you jack up the truck and touch the fuel rail are talking about one of the fuel lines underneath? Because where the injectors attach is commonly called the fuel "rail". If it's a line then which one? The pressure line is the one with the filter. Which, BTW, this brings up a point. If the fuel filter is clogged could this be what's happening?
 

Slyclone

Well-known member
Re: Is this normal?!

Filter installed correctly?

Don brings up a good point. Is it clogged? I removed mine and puffed a toot of air in opposite end and it blasted out a bunch of dirt and shit into a clean towel. I changed it out. But me puffing a toot of air into it was a extra measure for whatever reason? To replace it. The book reccomends to change the fuel filter every 15,000 miles I believe. Some have probably never ever been changed??
 

Troyphoon

New member
Re: Is this normal?

Re: Is this normal?

IMHO that is not normal. When you you jack up the truck and touch the fuel rail are talking about one of the fuel lines underneath? Because where the injectors attach is commonly called the fuel "rail". If it's a line then which one? The pressure line is the one with the filter. Which, BTW, this brings up a point. If the fuel filter is clogged could this be what's happening?

Yes I'm talking about the fuel line with the filter attached. I changed the filter and its on correct and it didn't help. So I'm thinking it has to be the pump going out.
 

conlyn

New member
Re: Is this normal?!

Changed the fuel injectors and with the cheap ass harbor freight gauge it only moves about 2 psi back and forth. Issue resolved.
 

Troyphoon

New member
Re: Is this normal?!

Changed the fuel injectors and with the cheap ass harbor freight gauge it only moves about 2 psi back and forth. Issue resolved.

So bad injectors huh??? I just installed 2 walbros in the tank what a pita! My fuel pressure guage it still acting up so I guess I'll be ordering some 60 injectors. Thanks for your input!
 

It's just a six

Super Member
Re: Is this normal?!

My Syclone has always done this, with the stock pump & a HP pump. With stock injectors & aftermarket injectors.
I have a cheap FP gauge & it does not have a small fixed orifice. That small fixed orifice is what will dampen the oscillation of the needle.

I just added a 4 ft section of hose to the gauge ( so I can read FP on a pass taped to the windshield)
When the added hose has some air in it, it will dampen the needle on the gauge & read steady, when the hose is full of fuel the needle will bounce.

My Sy runs great, never had any issues by having the fuel pressure gauge needle oscillating.
 

Troyphoon

New member
Re: Is this normal?!

My Syclone has always done this, with the stock pump & a HP pump. With stock injectors & aftermarket injectors.
I have a cheap FP gauge & it does not have a small fixed orifice. That small fixed orifice is what will dampen the oscillation of the needle.

I just added a 4 ft section of hose to the gauge ( so I can read FP on a pass taped to the windshield)
When the added hose has some air in it, it will dampen the needle on the gauge & read steady, when the hose is full of fuel the needle will bounce.

My Sy runs great, never had any issues by having the fuel pressure gauge needle oscillating.

My only problem is my autometer fp guage worked fine when I first installed it and it just started acting crazy.
 

Don W.

Stab it and steer it
Re: Is this normal?!

I have the Autometer gauge that works from about a 14" hose on the rail to a sender. Readout is rock solid. Maybe the sender dampens things? For a system like ours to function correctly fittings, hoses, connections (o-rings), pump(s), filter, regulator and injectors must all be functioning correctly. A problem with any of these components can/will lead to issues.

The Corvette direct injection motor operates on 2,000 lbs of fuel pressure. Imagine attempting to work on that system...

http://www.corvette-web-central.com/LT1Directinjection.html

These pressures have long since passed the point where fuel will penetrate the skin.
 

Troyphoon

New member
Re: Is this normal?!

I have the Autometer gauge that works from about a 14" hose on the rail to a sender. Readout is rock solid. Maybe the sender dampens things? For a system like ours to function correctly fittings, hoses, connections (o-rings), pump(s), filter, regulator and injectors must all be functioning correctly. A problem with any of these components can/will lead to issues.

The Corvette direct injection motor operates on 2,000 lbs of fuel pressure. Imagine attempting to work on that system...

http://www.corvette-web-central.com/LT1Directinjection.html

These pressures have long since passed the point where fuel will penetrate the skin.

Wow that's pretty sic! On my Autometer gauge I connected from fuel rail with steel braided hose directly to gauge. It worked great for a awhile. It just started acting up?
 
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