also check your tps gives .54 idle and around 4 or 5 volts dc wide open throttle. Good luck 
fuel preasure
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 31
Likes: 0
fuel preasure
Hi guys im here to throw another one at ya :P I was out in the vette tonight when all of a sudden it started cutting out really bad under load.I managed to make it home and put my fuel pressure gauge on it to see if maybe the pump or filter was gone to crap. When doing so i got a pressure of 40psi at idle and if i hit the throttle it shoots right up to near 50psi. Does this seem like the problem cuss my manual is saying 34 to 39 for my 87. I thought it was starving for fuel not loading up with fuel. Any help would be great.
Burning Brakes
Joined: Aug 2010
Posts: 833
Likes: 1
Sometimes pressure issues don't show up till the engine is under load. Go for a drive with the gauge taped to the windshield and see how it acts. Also check for any vacuum leaks and check plugs, wires and dist. components.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
re fuel pressure
Hi
Standard a vette has around 30-35 psi fuel pressure.
If the vacuum hose is disconnected(from the fuel pressure regulator) it will go to around 40 psi. even with the car idling.
You may have a adjustable fuel pressure regulator?
Follow the vacuum hoses from the right side of engine, one will go to the fuel pressure regulator if it has a screw on it its adjustable.
If its a standard regulator the return to your tank may be restricted?
Any way the vette should run fine at 45-50 psi. I had mine at that pressure for years before petrol prices rose to $1.50 a litre here in Australia. Hovers around $1.40 per litre
Hope this helps you
Standard a vette has around 30-35 psi fuel pressure.
If the vacuum hose is disconnected(from the fuel pressure regulator) it will go to around 40 psi. even with the car idling.
You may have a adjustable fuel pressure regulator?
Follow the vacuum hoses from the right side of engine, one will go to the fuel pressure regulator if it has a screw on it its adjustable.
If its a standard regulator the return to your tank may be restricted?
Any way the vette should run fine at 45-50 psi. I had mine at that pressure for years before petrol prices rose to $1.50 a litre here in Australia. Hovers around $1.40 per litre
Hope this helps you
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 31
Likes: 0
Is there any harm in blowing air through the return line back into the tank? It also has new wires new coil new plugs and i just replaced all the injector seals a couple weeks ago cuss i had vacuum leaks around them.Car idles perfect but as soon as you touch the throttle it feels like you pulled 3 plug wires off.I'm really fed up with this car,I's been one thing after another since i got it 2 years ago.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
re fuel pressure
Hi
Do the following to check the injectors are working ....
from cold start the car and run for a few seconds,
then check your headers if any cylinder is cold ?
I had this fault with my car, turned out to be the injector electrical connector on cylinder 2 injector... takes just a few secs to confirm that you are getting fuel to all cylinders,
Good luck
Do the following to check the injectors are working ....
from cold start the car and run for a few seconds,
then check your headers if any cylinder is cold ?
I had this fault with my car, turned out to be the injector electrical connector on cylinder 2 injector... takes just a few secs to confirm that you are getting fuel to all cylinders,
Good luck
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 31
Likes: 0
I checked and all cylinders are firing and getting hot i'm now replacing all the fuel filters including the sock on the pump but i dont feel that is the problem cuss they all seem free flowing.
might be a good time to strike a match while there is all this gas around hehehe.Any other good ideas????
might be a good time to strike a match while there is all this gas around hehehe.Any other good ideas????
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
re fuel pressure
Hi
you have plenty of fuel pressure, the standard injectors can have problems but saying that. I had my vette running 45 psi with standard injectors before i installed bosch 111 injectors and a blower.
I would look at the throttle position sensor, set 0.54 volts dc at idle or off ign on (top two wires) the lower one goes to ecm.
if that is good the only other thing, if you have a corvette buddy swap the mass airflow sensor to fault find.
(i have spare ecm,maf,tps,iac,burn of module and injectors) you can pick them up real cheap on ebay, good to have spares to eliminate stuff quickly. (you need to have spares in Australia as when you mention i need a ??? for my vette the spares guys see $$$$ LOL)
There are very few vette experts in Australia.
Remember most of us have had something so annoying wrong with our vettes and after months found it to be a simple fix.
If it gets too much, walk away and return a month or so later and you may spot the problem right away. As we all know ... when the vette runs great it gives you plenty of smiles per mile
you have plenty of fuel pressure, the standard injectors can have problems but saying that. I had my vette running 45 psi with standard injectors before i installed bosch 111 injectors and a blower.
I would look at the throttle position sensor, set 0.54 volts dc at idle or off ign on (top two wires) the lower one goes to ecm.
if that is good the only other thing, if you have a corvette buddy swap the mass airflow sensor to fault find.
(i have spare ecm,maf,tps,iac,burn of module and injectors) you can pick them up real cheap on ebay, good to have spares to eliminate stuff quickly. (you need to have spares in Australia as when you mention i need a ??? for my vette the spares guys see $$$$ LOL)
There are very few vette experts in Australia.
Remember most of us have had something so annoying wrong with our vettes and after months found it to be a simple fix.
If it gets too much, walk away and return a month or so later and you may spot the problem right away. As we all know ... when the vette runs great it gives you plenty of smiles per mile
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Race Director
Joined: Dec 2000
Posts: 17,551
Likes: 26
From: El Paso Texas
If it's flaky now, it will fail altogether soon. Given your description and the results of your fuel pressure test, I don't think you have a fuel delivery issue. I would start testing ignition / emissions components.
Racer
Joined: Dec 2010
Posts: 302
Likes: 0
From: delancey new york
Is there any harm in blowing air through the return line back into the tank? It also has new wires new coil new plugs and i just replaced all the injector seals a couple weeks ago cuss i had vacuum leaks around them.Car idles perfect but as soon as you touch the throttle it feels like you pulled 3 plug wires off.I'm really fed up with this car,I's been one thing after another since i got it 2 years ago.
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 31
Likes: 0
I tried unplugging it at idle and the first time it shut right off like you turned the key off. So i tried it again and the next time it stayed going but still behaves the same as if it was plugged in.Darn car really has me pissed
Thread Starter
Intermediate
Joined: Oct 2009
Posts: 31
Likes: 0
A few months ago i started getting code 34 when i started it when it was hot but that went away after i replaced the bad o rings on the injectors.Then this whole crappy running problem started after about a week of fair running out of it. But now i see the code 34 has returned and im trying to see if its related again or if its something else thats crapped out on it.I'd hate to throw another 250 bucks at a guess if its not the MAF.I was at a car show today and there were a few cars there with the same motor and they dont even have the MAF on them so how are they making them work?I dont understand how guys can make an old rat rod work by throwing them together and i cant even get a bone stock vette work with all the part where they should be I'm gonna need glasses after all the reading ive been doing lol
I'm gonna need glasses after all the reading ive been doing lol
Burning Brakes
Joined: Aug 2010
Posts: 833
Likes: 1