Symptoms of a Bad Fuel regulator?

[scot w.]

I have a question. I know and have seen where peoples fuel pressure regulators went bad but I never seen what the symptoms were.

What are the symptoms of a bad fuel pressure regulator?

Scot W.

 

[wile87]

a problem i had was leakdown caused by a bad diaphram. the diaphram was riped and it was not holding pressure and the car was a pain in the ass to try and start.

 

[Quick6'n'-K.C.]

bad regulator symptoms could be, no change in fuel pressure when trying to adjust it. If you always have high fuel pressure, then there could be oring debris in the return at the regulator.

If the car has a double pumper, make sure the check valves in the pumps work, or else static fuel pressure from one will flow past the other and you wont have much fuel pressure (constant leak back to tank) when using a double pumper.

BW

 

[scot w.]

Thanks guys!!

Here is what i'm seeing. When I got the car I test drove it, It drove just fine, WOT fine No knock @ 18lbs boost with a TE-44..

Get the car home and during my checks I notice the (fuel pressure @ 20 line off!) Is what I say! So I set it @ 40 line off. This saturday I took it to put air in the tires and drive it a tad and went WOT and ended up with 1.7 knock, Second time went WOT had 1.9 knock! So I pull it in the garage and look at the fuel pressure (line off) and it read 40lbs (just where I set it before) So I figure, HUH Okay i'll just add a few more to get rid of that little knock I had so I put it @ 42 (line off) this time.
Well my wife & I went to the local pizza place tonight and we went WOT and got 4.7 knock!!! I'm like, WTF!!! So I Went WOT again just to see if it would do it again and it went to 6.6 knock.. Now i'm pissed!!! It's going backwards !!

Well we eat and when he left (guess what I did!) Yep, I went WOT again and it showed 795 o2's & 0.0 knock!! The next time I went WOT it showed 800 o2's & 0.0 knock!!! Now i'm baffled..

My guess the fuel pump is picking trash up and it's not delivering fuel when that happens. OR The regulator is bad.. It's a Acufab regulator and a Walbro 340 pump. I have NO IDEA how new these are because the old owner had no clue either.

I guess it would be cheap insurance to just get a RED's XP pump...

Scot W.

 

[Quick6'n'-K.C.]

I would think that with the higher outside temperature, and the hotter your fuel gets, the higher the fuel pressure reading will be. Once it cools off, then the pressure is lowered. Fuel will expand and does give different readings with different temperatures.


Now after dinner the car isnt heat soaked, the fuel is cool, and its less prone to detonation.
Sounds like you were hot dogging it on the way to dinner and the car was just heat soaked, afterwards with the cooler temps, all is good.

Welcome to heatsoak :biggrin:

Let the car cool off, check the fuel pressure, check the volume of the fuel pump or replace it, and then upgrade the cooling system
BW

 

[scot w.]

I would think that with the higher outside temperature, and the hotter your fuel gets, the higher the fuel pressure reading will be. Once it cools off, then the pressure is lowered. Fuel will expand and does give different readings with different temperatures.


Now after dinner the car isnt heat soaked, the fuel is cool, and its less prone to detonation.
Sounds like you were hot dogging it on the way to dinner and the car was just heat soaked, afterwards with the cooler temps, all is good.

Welcome to heatsoak :biggrin:

Let the car cool off, check the fuel pressure, check the volume of the fuel pump or replace it, and then upgrade the cooling system
BW

BW, It was just out of my air-conditioned garage and cool when leaving my house on the way there and it detonated on the very first WOT pass just about 2miles from the house! So at that time there shouldn't have been heat soak! And the heat soak theory wouldn't count then, (I wouldn't think) and we were almost home when we done the last WOT blast and it had 0 knock... There is deffinetly something more funky going on here than the weather or heat soak.

BTW: The car never get's above 180*, The car has the G-body parts streched s.l.i.c...

Scot W.

 

[GNVYUS 1]

You're going to have to see what the pressure is doing while WOT, if it moves 1:1 then the reg and pump could be fine.

A lot of guys are getting fake 340's and the pumps are dying fast. If anything, get an electric fuel pressure gauge and make sure. With all the 340 fakes and dying pumps I'm considering this to keep on eye on pressure at all times.

 

[scot w.]

You're going to have to see what the pressure is doing while WOT, if it moves 1:1 then the reg and pump could be fine.

A lot of guys are getting fake 340's and the pumps are dying fast. If anything, get an electric fuel pressure gauge and make sure. With all the 340 fakes and dying pumps I'm considering this to keep on eye on pressure at all times.

That's what i'm leaning towards! But I won't go back to a 340. Iv'e NEVER had any problems with a RED's XP pump and that's what i'll be going with this time too.. I was told they are nothing but a 340 with the letters ground off but iv'e never had problems with his.. Who is selling the fakes?? I think we should know so rest of the buick members don't go blowing engines up cause of this garbage!!!

Scot W.

 

[wile87]

i picked up a 340 from full throttle. i would think they would have the real deal,due to not wanting to f-up thier reputation. jmo

 

[scot w.]

i picked up a 340 from full throttle. i would think they would have the real deal,due to not wanting to f-up thier reputation. jmo

I would like to know who is selling the BAD WALBRO's that people had to return!! So the rest of the buick members don't buy them and won't end up hurting there engines! This is a serious part and can cause alot of damage if they are junk and fail..... This can be a serious problem!!

Scot W.