TPI fuel pressure dropping

[wichitacorvette]

Ok, guys....... before i get to whats wrong, ill let you know whats new.

fuel filter, 2 weeks old
fuel pump, 1 months old
TPIS fuel reg., 6 months old
fuel lines, 6 months old

the regulator vac line is connected, fuel pressure set to 48psi (only place it works with my motor) and for the past 2 weeks ive had no drop in pressure.

now the problem. idles fine, correct pressure. touch the throttle, the pressure drops about 5-10lbs.

Now it has alwasy climbed when i hit the gas, what could be some causes for this?

Thanks
Tony

 

[Ken]

I don't have a definitive answer to your question, but there are cases where the part malfunctions shortly after purchase. It happens to me all the time. :eyerole

 

[wichitacorvette]

up and down

ended up the sock in the take had gotten clogged but now the a/f gauge reads very rich and ive taken my pressure down to 40lbs trying to get it..... still, black unburnt fuel smoke from the exhaust. i know it cant be too big of injectorsbecause it was fine a week ago??? help!!!!

 

[Ken]

If it's running rich, you are obviously getting excess fuel. It could be due to one or more of your injectors leaking. When I installed brand-new Accel injectors last year, one was bad immediately; it was stuck in the open position, and I actually discovered it when I was breaking-in the cam. Not a good time to discover something like that. Luckily it didn't wash the cylinder clean and ruin my new build. :eyerole

Check your injectors (each one).

_ken

 

[wichitacorvette]

how should i do that? the good ol "ohm" check? or some other way?

since my af gauge is stuck on rich, could 1 cylinder do that? and the black shoke comes from both sides... very thick...... its white soft smoke(which im told is pretty normal) but when the throttle is touched it turns thick black.......

 

[8388]

Hook the gage to the rail and purge the system. see how long it takes for the pressure to drop with the pump off. If it drops quickly, you have a leak. You can pull the spark plugs and see which if any are soaked with fuel. If they are dry, you just may be running rich by having too much pressure.

 

[wichitacorvette]

i have a permenant autometer pressure gauge mounted since the accell unit broke (made way too cheaply). The pressure doesnt drop at all really, maybe 5 lbs over a 10 min time. plugs look fine, some carbon that i cleaned off but nothing bad or wet. I have my pressure all the way down to 40lbs? the screw on the regulator looks likeits about to come all the way out?

 

[8388]

Aftermarker FPR are generally pos. The best luck I've ever had is modifiying the factory regulator.

 

[wichitacorvette]

how do i do that?? id love to do that, this screw in, screw out thing frankly ****es me off, the plenum smashes against it when i mount it down anyways....

 

[8388]

Drill a hole at the top of the regulator hat, braize a nut on it. find a small hex head bolt, cut it so that you have about 1/2" travel inward. I've used a slug the size of a quarter polished smooth. Also the very tip of the bolt that makes contact with the slug needs to be filed smooth with a polished tip. I have found better control of the fuel pressure this way. With some of the aftermarket ones 1 full turn for for1 psi increase then 1/2 a turn and you have 5 psi increase not very accurate.

 

[wichitacorvette]

sounds fairly easy, where should i set my psi? approximately....

 

[8388]

sounds fairly easy, where should i set my psi? approximately....

A bad MAF, or one going bad can also cause a rich condition while driving.

 

[wichitacorvette]

i have a MAP system, do those go bad like that as well?

 

[8388]

i have a MAP system, do those go bad like that as well?

They can, check your vacuum line 1st.