Okay, so sometimes I do things the wrong way....

Posted previously as my 95 LT1 starting running like complete crap. Checked the obvious - Coil (replaced) - Optispark (original replaced), checked all plugs made sure everything is firing.

Car still completely ran like crap, and shuttered at idle.

Even died a few times driving around the block after those replacements...

Then sat back and though. The car started acting up after I put in fuel treatment / cleaner, and progressively got worse. Even to the point where it died a few, times and was a pain to start.

DUH I said to myself, Fuel Filter.... Replaced that, the original was so clogged I looked like a trumpet player trying to blow air through it.

Started up, is running much better, but still has quite a hobble to it when I put it in gear. Also dies like I am losing fuel again.

Going to get a fuel pressure gauge to see what the pressure is. What is the normal pressure I should see?

Is there anyway to check the injectors without removing from the car? Could I remove the electrical connection to see if I get a worse or same idle scenario to help determine what is going on?

I think that this fuel injector cleaner cleaned some crap in the tank, and pushed it through the filter, and is causing havoc.

Any Suggestions?!?!

Thanks



Not sending any codes, and is going into closed loop.

 

You should see around 42 PSI on the fuel pressure. A few pounds either way will not make the car do what yours is doing.

My guess would be if there is that much crud in the filter, there would be some in the injectors. I personally would pull the inectors off and get them cleaned. Obviously this car is old enough it is time to do these kinds of services anyway even if done before.

Pulling injectors is extremely simple and worth the small effort that way you know for sure fueling is not the problem.

Additionally, I agree that if that car has sat, it had crud in the tank that the cleaner let loose. I would change the filter again after a few thousand miles. Make sure you know the particle size of the filter (microns with lower being better)

 

The fuel pressure needs to be measured the correct way.

At idle, remove the vacuum compensation line from the fuel pressure regulator (plug the line, so there's no vacuum leak ). Pressure should be 43.5psi (3 bar) with GM specs accepting anything from 41-47psi. Reconnect the vacuum line, and pressure will drop proportional to intake manifold vacuum. An 8psi drop from the "no vacuum" pressure would be normal with a stock cam, and less drop with a more aggessive cam with less vacuum.

Then take it out on the road, max RPM/WOT and it should hold at least 40psi. Typically there's very little vacuum at WOT, so the closer it is to 43.5psi, the better.

 

Anyone know of a decent fuel pressure gauge out there? Would prefer something that I can either bolt on directly, or use a tube to extend it from the shrader valve to somewhere where I can see it.

Would it be necessary to prime the fuel pressure after changing out the fuel filter?

 

Do you want a "test gauge" or a permanent install? The typical test gauge comes on a hose, with the correct -4AN connector, and a pin to depress the core of the Schrader valve so you can get a pressure reading. To run the test gauge on the road, you have to pull the hose up through the opening between the cowl and the hood, and tape it to the windshield.

For a permanent install, I believe Accel makes a small gauge that screws directly on to the Schrader valve. You could get the correct fittings and run a braided SS hose from the Schrader valve to a gauge mounted somewhere under the dash. I can give you the fitting descriptions if that's of interest. For a dash install, you need to use an electronic gauge, so there's no fuel line running into the interior. I have an AutoMeter electronic gauge, which is easy to mount in a dash vent in the Firebirds.

http://www.injuneer.com/images/photos/DCP04239a.jpg

You may have a little air in the system after changing the filter, but the fuel system is "recirculated", so the pump should push the fuel through the system and force the air down the return line.

 

Okay,

Just tested the pressure, I am seeing around 48psi with the vacuum line removed, and 38psi with the vacuum line attached.

I am at my wits end right now trying to figure this dang thing out.

Maybe it's just that it doesn't like the fuel injector cleaner I used? Anyone else have problems with that?

It is weird how it started acting like this after I put that stuff in it..

 

I'd pull the injectors out and have them cleaned. Four bolts, eight clips, and they're out. Just make sure you dislodge the upper and lower o-rings and don't leave them behind.

 

That's about what I am thinking right now...

 

if its a pain to start sometimes, it may be the injectors are leaking/dirty

my 95 started like crap warm, but good cold

I had good fuel pressure, however when i went to change my plugs they were all completely soaked in fuel

I changed the injectors with some new 26# Accel's (24# being stock)

Starts and runs MUCH better now

if i were you, have a look at em, and make your decision to replace them or not

I paid i think just over $200 with shipping from Summit for the set

 

Did you have the PCM reprogrammed for the 26# injectors? If not you're dumping 8% more fuel than what the PCM thinks.

 

Adding larger injectors to an engine that appears to be running rich already, and not programming for them, seems counter-intuitive. But then they're Accels, so who knows.

 

Pressure is not the problem.

What did you use to clean the injectors? Why did you put it in? Was it running poorly before and that's why you tried it? Did the cleaner create the problem?

Is it O2 safe? Have the O2s ever been replaced? They are tune up items.

Why don't you simply pull the fuel rail up and see what each injector spray pattern looks like when someone cranks it over?

Do you have any way to see what the O2 readings and the fuel trims are?

 

Using free scan, the o2 sensors vary in closed loop. Don't recall the fuel trims right now, will have to hook the laptop up later.. What should they be?

Thanks

 

If you are running FreeScan, do a data log, and let us take a look at it. You have to post it on an FTP site.

 

How long of a sample of data would you need?