f/p regulator Q & A

[bison]

No..... you have gotten confused....

Line off is 0 psi..... which is 43.....
Line on...idling.... is actually sucking on the diaphram....instead of pressurizing the diaphram (which adds 1 lb FP to 1 lb boost) .. the vacuum has the opposite effect of boost on the fuel pressure... so when you plug the line up.... it lowers the FP...... again... this is vacuum which is not the same as 0 psi boost..... soooooooo .... if you were going to 24 psi boost...... you would need (as compared to 0 boost) 24 additional psi in fuel pressure just to keep up.....

so 43 (line off) +24 = 67 psi fuel pressure .......

HTH

All this assuming the boost and fuel pressure guages are accurate. Regardless they should still be 1:1. Ive seen a lot of $hitty boost guages.

 

[1 RARE T]

So it would appear that I do not have enough f/p.

New pump, filter, regulator, voltage checked at pump, (14.1) alt. checked,.......now what?

If the lack of fuel is actually causing the problem?

Remember the post about brown plugs on one side, grey on the other. No one has a theory on that?

 

[Squid4life]

Maybe not enough fuel pressure, like you said. Maybe fuel is available on the one side, but not so much on the other side. Too bad you couldn't have a fuel pressure gauge on both sides of the rail under boost, would be interesting to see.

What are blue tops rated at @100% duty cycle? How old is the regulator? Have another to try out?

 

[Blazer406]

So it would appear that I do not have enough f/p.

New pump, filter, regulator, voltage checked at pump, (14.1) alt. checked,.......now what?

If the lack of fuel is actually causing the problem?

Remember the post about brown plugs on one side, grey on the other. No one has a theory on that?

Just my $.02 .... fix what is obviously a problem first.. and then re-evaluate. You know you have a fuel pressure problem......

Either you have pump problems (possibly could troubleshoot by pinching off return line and see where the pressure goes..... this is all the pump will put out.... regardless..... (at that pump voltage)

You could have a bad FP regulator.... or maybe a leak in the vacuum/boost line (or anything up on the manifold that would not let full boost down the vacuum line) that is feeding the regulator.

Do you have a scan tool? It might be worth checking that BLM's are where they need to be.... and that IAC's are where they need to be... this could tell maybe if you are having some sort of vacuum leak.....

HTH

 

[Blazer406]

.......


Noise is there as soon as boost goes past 20 and almost sounds like valve float. Don't think it is because the R.P.M. is low when it starts and continues all the way through.

That scares the $hit out of me...... Do you have an audible knock detector? .... if not I highly recommend you get one..... it just might save your engine..... I bought a Caspers..... solders to a few wires near the ECM.... works great.....

Also need a scantool if you don't have one already....

 

[1 RARE T]

I've have been unable to find any vacuum leaks at all and would love some advise on the best way to test/pressurize the t/b to try and find the leak.

My blm's usually are at 116 at idle hot. I asked Eric about this and he said that was ok.

As soon as you lean into the throttle they go right to 128.

If it was that lean should'nt it knock?

 

[1 RARE T]

Is it poss. that the relay on my hot-wire kit is bad and not delivering 14= v.?

Did notice today that my scanmaster is only showing 13.5- 13.8 for voltage under w.o.t.. Where does it take that voltage reading from?

Had the alternator checked last week and was told it was perfect.

Starting to think maybe voltage issue at the pump might be the problem.

Can you run the hot -wire any other way or is it best right off the alternator?

 

[Razor]

First thing is to make sure your FPR isnt leaking air. It is very common for leaks to happen through the screw hole or the nipple to body connections. Obviously the more boost you run, the greater the leak.

You can buy a tool called a "Mity Vac" at autoparts stores.. and make sure it holds vacuum. Also you can put air pressure on the nipple and make sure it raises past the number.

Other places of interest are the gasket on top of the TB, the metal tube not having a breach from the TB to the reg, the rubber hose from metal tube to reg, and lastly the regulator itself.

Pumps when going south will lose flow ability, but will comeup on pressure until they start dropping off when the injectors open up.

Turn the boost down on the car until its figured out. Leaning out one of these motors is bad news. And that alky can only go so far covering up..

And... make sure your guage is properly working At 17 PSI you should have 62 with 45 base.

 

[1 RARE T]

Put air to the reg. and f/p goes right up to 100.

Put air in the boost sensing line at the t/b, f/p goes right up.

Re-checked voltage at the pump, 14.0 at idle.

Already changed the gasket on the vacuum block.

Reset the chip to 10% W.O.T. fuel. Re-checked f/p and it seems to be almost 65.

Noise still there.

Could my denatured be bad? It's from last year.

 

[1 RARE T]

A little update for those watching this thread.

Found a leak in the boost line going to my alky kit. Was bleeding a little boost and not supplying the regulator all 24 psi. Fuel pressure is now 70 ish.

That's the good news.Unfortunately the problem did'nt go away.

Did turn it down to 18 psi. of boost and it runs clean all way from idle to 100mph.Anything over 20 and it's doing it again. It would seem even at 50 psi of f/p I still have a lean condition/misfiring cylinder.

Bad injector?