braggent

i have a 96 chevy 1500 with 305 engine automatic ,i was wondering if any know how to tell if a pressure regulator has gone bad or is weak. .is there a test to check it or is it not checkable? i have notice that when i fill up on an empty tank there is no air pressure release when i open the fuel cap before i would always hear it when i open it . i have change the fuel pump about a 8 months ago and the fuel fiter 2 weeks ago. i have notice that when i turn the truck off there is a release sound coming from the engine like if some kind of pressure was release. not like a vaccum leak but a pressure leak. the only thing that i do remember is that after i change the fuel pump my truck after runnning about 10 min lack power and the rpms drop it would not do it all the time but now it is. if anyone has advice let me know.

kcb37

I don't think you can check it. I have a 96 with a 5.7 (350) I have a Chiltons and a Haynes Manual. At the moment I don't know where my Haynes is, but the Chiltons only shows replacment. If it is not to much you may want to try it.
This is what is say's.
1. Disconnect battery
2. Relieve fuel pressure.
3. Remove upper manifold assembly. (should be intake)
4. Remove the fuel pressure regulator vacum tube.
5. Disassemble the fuel pressure regulator snapring retainer.
6. Remove the fuel pressure regulater assembly and the o-rings, filter and back-up o-rings.
Then put it all back together.

I don't think I have ever heard mine release pressure when I take the gas cap off.
Do you have a working air condisoner? That may explain the release of pressure when you shut off your pickup.
You might try some fuel injector cleaner. How many miles do you have on your pickup?
Have you gotten into the engine at all yet?
Is your engine light on? If so you will need to got to Auto-Zone or Advance, or another parts store in your area. I know the other two will check for free if they have the comp and offer the service.
It could be something like a throttle positioning sensor.
Let me know what you find out.

Nomad76lj

if you take off your filler cap and you hear that noise like air being sucked into or let out of the tank its not suposed to do that. it usualy means that there is a vent line pluged somwhere along the line. also i would say that if you have a leak somwhere that you would here it when the truck is running. that sound you here when you shut the truck off may be the return line from the gas tank releasing the gas from the injectors back to the tank. just some ideas i thought i would throow out for you to think about.

braggent

I feel like some of the problem has gone away . I change the fuel pump again and it has made a big difference. But now I think I am having a issue with the throttle has an one ever had a problem with a sensor or the body itself. The is on the same truck.

kcb37

What kind of problems is it giving you now?

braggent

Throttle is not sticking it feel like it loses power slowly then if I take my foot of the pedal and hit it again the truck picks up fine. The it starts to lose again power and feels as if the engine is slow low RPM s but if I take my foot of again it has power. The truck runs fine and has power. I don’t know if it can be a Crank Position sensor or Throttle Position sensor. I have no Check Engine Light, is there any way to check these sensors? The only thing I have notice is that at a stop light the truck has a misfire, but if the truck is at idle it runs smooth. I need to get a smog check and I don’t know if this will affect it. This is on that same 96 chevy 1500.

kcb37

That sounds like it could be your timing. That usually bogs down when you first hit the gas though.
If you get a book for it it should tell you how to check both of those sensors.
I really don't know what else to tell you at the moment.

braggent

the timing on my truck is not adjusteble accorring to the manuals i have. the PCM does the adjusting. it does not seem like it blogs down when i hit the gas it moves fine . it loses power when i have my foot on the gas. i have to let go of it then hit the gas again.

kcb37

You can adjust it, but it has to be done on the timing chain, the small adjustments are done by the comp, where older cars were done with the distributor.
I would check your TPS,MAS,MAP,sensors.

Nomad76lj

if its the cat most times you can smell a rotten egg smell coming from the tail pipe. try hitting the underside of the cat and see if it sounds broken up inside or very solid witch usualy means dcloged up.