We have a rough idle and trouble starting it in the morning!

When it is cool out unless i let the fuel pump run and click off it has trouble starting, i have checked the fuel pressure, it looked to be ablout 55 psi running, but the guage was fluttering! it also bleeds off after i shut the motor off, not imediatly but in a 30 minute time it leaks off!

The next issue developed today, we filled up at our local kroger and went north about 70 miles and on the way it began to idle rough at stop lights, it did this when we bought it and i tuned it up, new cap, rotor, plugs and wires, new air and fuel filter. Once the motor seen a tune up i ran a couple cans of b12 chemtool through it and it idled decently for about a year!

I added a can of chemtool and filled up at my normal gas station and didnt see a change in the idle. I suspect fuel spider of distributor play. I should add it has no codes! it also drove great on the interstate! the engine runs smoothe other than the idle!

Im looking for ways to narrow this down!

 

do another leak down test, When the pump is running, engine off, pressure must be 60psi to 66psi.
When the pump shuts off, pressure will drop slightly but it must remain above 55psi for at least 10 minutes.

 

I agree with newguy. No codes cause me to think it's fuel delivery.

 

Thanks for the replies! right now i have the valve cover off, tomorrow morning ill do another test and report back! so if it does leak down does that meen there is a problem with the fuel pump? or can the regulator leak?

 

could be either, test to tell that also .First lets see if it does leak down

 

OK so key on engine off it hits 60 psi then drops to 55 psi and slowly leaks down from there! It was not an imediate drop to zero but i would say within a half hour it would hit 0. Running it is 55 psi and the needle was fluttering.

 

so now its one of 2 things, pump or spider leaking. part down this page https://blazerforum.com/forum/2nd-ge...eakdown-88305/ are directions to make an adapter to hook to your filter to check your pump. If that checks out its your spider/regulator. You can also just take off the throttle bodt and look inside the plenum. Everything in there should be carbon black. If you see ant shinyness you reg/spider is leaking and will need to be replaced. good luck

 

Thanks! Very helpful!! How tough is it to take the plenum off??

 

Dont need to take plenum off unless needed. Should be able to see under the plenum once the throttle body is removed. I replaced the spider assembly once with no experience, took 3-4 hours start to finish. Most likely videos on youtube

 

Thanks, i tested the pump itself thanks to that link! it holds at least 55 psi for about 13 minutes, so according to that sticky my pump is good!

So basically that leaves the fuel spider?