Have a problem getting gas to the engine. Fuel pump seems to be working normal. It cycles normal when you turn on the key. Shuts off after about 3-4 seconds. Problem is when I check for fuel at the pressure check valve I only get a small drip. Doesn't seem to have much pressure. I'm going to change the fuel filter first to see if it was clogged up. If that does'nt seem to fix the problem my question is can the fuel pressure regulator cause what seems to be a lack of fuel in the rails?

 

Something in these links may help:

http://forums.corvetteforum.com/c4-t...m-i-think.html

Multi search results:

http://www.google.com/search?q=1985+...=safari&rls=en

 

You need to test the fuel pressure (see below). Remove the hose off the regulator and check to see if there is fuel in the line. If there is, the diaphragm in the regulator is broken.

••••• TESTING FOR LOSS OF FUEL PRESSURE

... Here are the sure fail tests for the fuel system to save you time and money.. Take a fuel pressure gauge attach it to the Schrader valve.. Turn the key on and off a few times to build up the pressure in the system... If you are having starting trouble the pressure will probably drop as soon as it hits 38 or 40 and the pump turns off it will probably leak back to zero within a few minutes. Ok now right after you prime the system pinch off the return line near the tank if the pressure drop stops it is a bad fuel pressure regulator.... Next pinch off the feed line if the pressure holds then the leak is before the point where you pinched the line IE fuel pump check valve..hole in the metal line on the sending unit caused by it rubbing on the inside of the tank you should visibly be able to see this if you pull the pump and the sending unit...(this was my problem) or the pulse dampener which is the piece between the pump and metal line on the sending unit.. the diaphragm tears.. and last if you pinch both the feed and return line near the tank and the leak down of the pressure continues then a fuel injector is your problem.. This is the GM test.. saves time and money..
•• disconnect the vacuum line from fuel pressure regulator and plug the line with something like a golf tee when you test the pressure.

 

Okey this morning I changed the fuel filter to see if that would be the problem. It started right up and ran well so I had my wife take it around the block. Ran like it was getting enough fuel except it would stumble when you pressed in gas pedal. It would take full throttle and didn't seem to be starving for fuel. We let it run trying to figure out why the stumble and then it started to run very badly again. Almost feels like it's starving for fuel again. Don't have pressure guage but checked fuel out shrader valve and got plenty of fuel and pressure. Not sure what's going now. My thought is that it's the fuel regulator. I did pull vacuum line off and found no fuel but I did notice that when I pulled the line off the engine did'nt seem to change running. When I was doing this on the 95 the engine speed veried a bit then changed when I put it back on. Should that have happened? My thought is that the regulator is not working is the engine did'nt change. Any thoughts cause I want to do the fuel regulator if that's the case.

 

Can't say for sure. I would think you may have a broken regulator or a vacuum leak on the regulator hose. Because at idle you run roughly 38 PSI with vacuum, as you raise the RPMs, you have less vacuum to the regulator and that PSI increases to 43.

So, if there is a vacuum leak on that hose, you may have 43 PSI @ idle, and as you try to accelerate you are flooding the engine with too much fuel, and then the O2 sensor corrects for it, provided you are doing this after it is warmed up and been running for a while. I would start there with fuel pressure.

 

Is this a new car for you ....so you really don't know the past history?

I would suggest that if you can fish out the old fuel filter from the garbage that you cut it open to see what you find. If you find that it is full of rust and particles then you need to look toward the tank. It could be that the tank is rusted and the sock filter on the pickup tube has come off and your sucking crap into the fuel line.

I would check that out first. You might have to get a new sock (press on) filter for the tank and also replace the in-line filter again.

Go to Autozone or another parts house and borrow one of their fuel pressure gauges to see what is happening.

 

I had a similar problem with my 85. Turned out to be the pulsation dampner (as mentioned earlier in this post) and my regulator wasn't getting the job done. I bought an adjustable reg from jegs and by passed the dampner - got the pressure back up and no more issues.

 

This is ChevetteMan's wife, reporting back. Thank you everyone, for all of the help. The car is back in action again, running well. It turned out to be the fuel pump. The car would start seemingly fine after sitting for quite some time, then quickly return to the sputtering and stall with any attempt at acceleration. As advised, we got a hold of a fuel pressure gauge so we could get a much better picture, rather than assuming the pump was fine just because there was fuel at the valve. Well, when we tested, the pressure was very low - 6 lbs with the ignition on (no engine running) and 12 lbs at idle. Seems that it was enough to start from a cold start, but certainly wasn't enough to keep it going or to handle acceleration. With the new pump and sock (and the new fuel filter) everything is back to good again. We sure appreciate everyone's help. The great write ups here on the forum about how to change the fuel pump sure came in handy, as well.