WOT Fuel Pressure

[Linewalker]

I am running 20 pounds of boost and have 43 pounds at static pressure. I know this should equate to 63 psi
at wot, but I only am showing 61 psi at wot. Is this "close" enough or is my fuel pump headed south? Btw, my pump is hot wired, am running alky, and have 42 pound injectors with Eric's chip. My 02's are about 3 to the lean side, also at wot.

 

[Boost231]

That's good imop..

 

[QWKRTNU]

Do you have a separate ground from the fuel pump up to the negative on the battery? If not add that and I bet u get a little more

 

[dynoman]

Do you have a Scanmaster ? If so what are your WOT 02 #'s .....? 61psi doesn't sound to far off ....gauge accuracy ??

 

[Linewalker]

Do you have a Scanmaster ? If so what are your WOT 02 #'s .....? 61psi doesn't sound to far off ....gauge accuracy ??

I tune with a OTC 4000e revision D. My wot 02's are supposed to be between .88 and .92. Mine is between .84 and .86. That is what I meant by running a little lean. I have messed with fuel pressure, with no change. That's
Why I was asking if it might be time for a new fuel pump. I don't want to just start throwing parts at it. That logic has cost me more money than I care to admit in the past.

 

[TurboDave]

I tune with a OTC 4000e revision D. My wot 02's are supposed to be between .88 and .92. Mine is between .84 and .86. That is what I meant by running a little lean. I have messed with fuel pressure, with no change. That's
Why I was asking if it might be time for a new fuel pump. I don't want to just start throwing parts at it. That logic has cost me more money than I care to admit in the past.

NB O2's shouldn't be too heavily relied upon for reality. Your numbers could easily be good yet.
My WOT NB O2's run in the mid 700's (same as your 800's) but my Wideband tells me I'm actually safe at 11.4 AFR.


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[gusszgs]

You may be right at the edge. I'd watch the pressure very close if you turn the boost up any more.
What pump are you running?

 

[Ttype6]

I am running 20 pounds of boost and have 43 pounds at static pressure. I know this should equate to 63 psi
at wot, but I only am showing 61 psi at wot. Is this "close" enough or is my fuel pump headed south? Btw, my pump is hot wired, am running alky, and have 42 pound injectors with Eric's chip. My 02's are about 3 to the lean side, also at wot.

It looks like you have a fuel delivery problem. If this is true,you can be sure if you increase your base pressure to 46 and see what you have at WOT and 20 lbs of boost. If you still have 61,you have a fuel delivery problem. The first suspect should be the fuel filter.

 

[Boost231]

I would get a powerlogger and run a fuel pressure transducer on the rail and that will tell you what's going on

 

[forcefed3.8's]

I always add base pressure and recheck. Narrowband is useless. I had a car showing .800's, but it was actually in the 15s at wot. I have compared narrowband reading from different cars with the wideband readings from my portable lm2, and some showing .8xx are actually leaner than cars showing .7xx.

 

[Linewalker]

I am watching my fuee pressure. I have a gauge extended under the wiper. I'm getting zero knock. I increased static pressure to 46 and got 63 pst at wot. So it did increase. I'll keep a close eye on it. If it starts dropping too
much, I will know it's time to get a new pump. My fuel filter was changed about a month ago. Btw, I'm running a Walbro 240 pump. Thanks for all the replies
guys. You have really put my mind at ease.

 

[Ttype6]

I am watching my fuee pressure. I have a gauge extended under the wiper. I'm getting zero knock. I increased static pressure to 46 and got 63 pst at wot. So it did increase. I'll keep a close eye on it. If it starts dropping too
much, I will know it's time to get a new pump. My fuel filter was changed about a month ago. Btw, I'm running a Walbro 240 pump. Thanks for all the replies
guys. You have really put my mind at ease.

What fuel filter do you have?

 

[Linewalker]

What fuel filter do you have?

Purolator.

 

[Ttype6]

Purolator.

Now,more than ever,I think your fuel filter is the problem. Buy an AC Delco and see if it will allow more flow.

 

[Linewalker]

Now,more than ever,I think your fuel filter is the problem. Buy an AC Delco and see if it will allow more flow.

Ok, I'll give that a shot when time and weather permit. At least fuel filters are inexpensive.

 

[Ttype6]

Ok, I'll give that a shot when time and weather permit. At least fuel filters are inexpensive.

I'm not even sure,from day to day,if the AC filters are still the best. I do know that they were and that the Perolators never were and that you can still buy NOS AC Delco filters on ebay if the new ones aren't.

 

[Linewalker]

I'm not even sure,from day to day,if the AC filters are still the best. I do know that they were and that the Perolators never were and that you can still buy NOS AC Delco filters on ebay if the new ones aren't.

Thanks for the info. Just ordered one on ebay. We'll see if it makes a difference.

 

[Chuck Leeper]

Thanks for the info. Just ordered one on ebay. We'll see if it makes a difference.

Oooolld tests we did= Back to back, showed that the OEM Delco was the best flowing filter. Like many other parts, has Ho Chi Min got hold of them, and new they are junk??

 

[bison]

What is the max injector open time and RPM you are running? I highly doubt the fuel filter is the problem. I've worked on hundreds of these cars over the years and have only seen a few filters that were plugged. Plugged because the tank was rotted internally. Pump, proper connections on the pump hanger (submersible fuel injection hose) proper grounding of the pump, non kinked factory lines, proper alternator output, clean injectors, and accurate measuring equipment as Brent mentioned above.


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[Ttype6]

I've worked on hundreds of these cars over the years and have only seen a few filters that were plugged.

I can't speak for others,but I'm not saying that I think his filter is plugged with debris. I'm saying that installing a new Perolator fuel filter on a good running turbo Regal will create a great amount of restriction in the fuel supply line. If you're making enough power that this filter becomes a problem,replacing it with a new or used AC Delco will remove the restriction and allow a greater volume of fuel to move through the fuel supply line restoring the lost pressure and volume.