alliance12364

I'm going to replace my fuel pump regardless but I would just like to know what my pressure should be. My pressure as of right now is 40 psi (primed) 35psi (idle-at 1800rpm) and 42psi (WOT) all with vacuum still attached. What should it be at normally? I am aware that it shouldn't be idling that high and I'm workin on figuring that out. Thank you

shoebox

Your pressure is within normal limits.

http://shbox.com/1/4th_gen_tech2.htm...essure_testing

Try looking for a vacuum leak.

alliance12364

Ok so from my understanding from your site, is that my pressure seems to be alright, I'm gona go ahead and replace it anyway cus I have a pump just sittin in my room. I'm sure I have a vacuum leak somewhere I just need to find it. And I'm pretty sure the car is running rich due to codes 15 and 21 (I herd they can cause richness) and code 43 knock sensor messin with spark. But if there a vacuum leak wouldn't I be getting high fuel pressure like wot. (Like when u pull the hose off the regulator?

shoebox

No, because it does not directly affect the regulator. There will still be plenty of overall vacuum.

I don't know why you would replace the pump if there seems to be nothing wrong there.

calaban

Yeah that's a PITA job. Unless you have a problem, I wouldn't do it.

alliance12364

I wana change it cus the car is old and sat for most of its years so I figured y not. It could maybe fix my problem now or prevent future problems and headaches. I tryd starting it last night and it would start and immediately die. It did that 3 times. I cycled the key twice and it started and idled at 2000-1800 rpm and car started to die. Rpm would drop to as low as 400 and go back up. Leading me to think fuel cus the opti is fairly new and so are the wires. It has a brand new icm and coil. I cleaned both ends of the harness that goes to opti and code 36 went away. There no fuel leaking from the regulator so that seams good. I'm going to test my tps today and then change spark plugs.

alliance12364

Yea I agree it is a pain. I'd rather just get it over with cus if it does go I don't want it to be stranded . Especially if it happens in the town I work in. Very very bad place lol. I'm gona wait it out and work on everything that could cause this besides the pump. The pump will be the last thing.

Injuneer

Why don't you fix the codes so you can rule them out as part of the problem. DTC 15 for the coolant temp sensor - low temp indicated - can elevate the idle speed (although not to 1,800rpm) and cause it to run rich. DTC 21 indicates a problem with the TPS (signal voltage high). DTC 43 for the knock sensor causes almost constant knock retard.

I don't know how anyone could even attempt to drive the car like that. And to waste time replacing a fuel pump that is not a problem makes even less sense.

alliance12364

Lol i am fixing the problems i have a new tps that im gona put in, thermostat, and 2 temp sensors. My local auto parts store ordered me a knock sensor i just have to pick it sometime this weekend. I was juat wondering if my fuel pressure was correct so i would know that that is not something thats adding to my problem. And iwana change my pump jusy so it doesnt become a problem with that later on in life

Injuneer

How do you know the DTC 43 code is due to the knock sensor? Did you check the circuit with a multi-meter? A loose wire could set the code. Why two coolant temp sensors - does your dash temp gauge also not work? The code is only for the sensor in the water pump.

RamAir95TA

What Fred is saying is that you're just throwing parts at the car in the hopes that doing so will fix your problems. More often than not, that's not the case. Many times it's just a loose connector, broken pin, grounded out or exposed wire, etc. You should rethink your diagnostic procedures, unless you've got money to burn.

I also vote for leaving the pump alone. If it ain't broke, don't fix it. Many LT1s last 200k+ miles on the original fuel pump.

alliance12364

Cus that's what it says in my service manual. No I haven't checked the circuit yet but I'm going to along with other sensors and plugs and what not. I haven't even taken my multimeter out of the box yet. And yea my dash temp gauge dosnt work. It did at one time but not anymore.

He is 100% right and I do hope it fixes my problems but I know its not. I bought the sensors and stuff just to replace anyway. Example- Like the sensor for my water pump. Test the connection find the problem fix it and replace the sensor. That way its fresh and don't have to worry about it. Sensors aren't that much money and on top of that I have an account at the auto parts store and I get a big discount

1slow93z28

get the multi meter out of the box meathead.... you where gonna check the tps and get back to me via txt... still waiting..

mike