Engine runs extremely rough, seems to be fuel related, new fuel pump & filter installed, pressure good, run 2 bottles of injector cleaner through. Can't get to stay running under load. 1998, chev. silverado pu w/ 5.7 lt. vortec

Many small things can cause this...dirty fuel, water in tank, fuel pressure regulator going bad, air filter clogged, throttle body dirty, clogged catalytic converter. First try fuel injector gas tank and line cleaner...least costly...use 2 bottles of STP concentrated injector cleaner...also add a bottle of liquid heet...to absorb any excess water or sludge in tank...worst cause could be low fuel pressure caused by bad fuel pump...Hope this helps.

The fuel pressure has to to 35 to 45 psi. And no low fuel pressure will not cause no injector pulse.The veicle sounds more like a idle air control problem why? because as you stated it runs rough when it does start.Get it to start sysle the key you will hear the fuel pump go on cycle it three times then start it up. when the vehicle warms up take the idle air valve out and clean it with carburator cleaner or even brake cleaner you may even want to do the throttle body itself this should help with the hard start up and rough running

Hi,
I'm assuming you added fuel injector cleaner to your fuel tank rather than using a direct pressure cleaner through your fuel injectors.
When a solvent/cleaner product is added to your fuel tank, carbonaceous deposits (basically the dirt and gunk accumulated over years) are flushed through the fuel system. This can cause major problems if the contaminants manage to enter your fuel pump and make their way past the seals. This can and has damaged good fuel pumps. Downstream of the pump is the fuel filter - once deposits reach the fuel filter, they may block it and reduce fuel flow. The next major problem areas are the injectors themselves (rather sensitive to dirty fuel) and the engine.
Fuel injector cleaner is not a product I would recommend using. Many major car manufacturer's have recently issued memos to repairers blacklisting the use of cleaner products due to the downstream damage that may potentially be caused by them.
You should replace your fuel filter once you've finished using the tank of injector cleaner. This is most likely the problem (and could have probably used a replacement anyway). I hope this solves your problem. Otherwise you should check your fuel line pressure to ensure the pump is supplying what is required. Failing this, your injectors are probably the next most likely culprit. By this stage, things are starting to get expensive so lets hope the problem is just a blocked filter!
On a related side note; pressure cleaning an engine can sometimes cause water and soap to push down beside the spark plugs in a spark ignition engine. Sometimes this will cause the engine to run a little rough until the heat of combustion burns the contaminants away.
Hope this helps, Sherwin

It could be the fuel, especially these days with the different suppliers and additives, not to mention the extreme moisture in the air & seeping into the fuel tanks at local stations.

If you know your car doesn't need a standard tune up, the air-filter, fuel filter, and spark plugs have been maintained and are working properly you may just need to have the injectors cleaned, or use a little fuel injector cleaner every few tanks of gas to clean them up.

I always fill my fuel filter & those I'm servicing with fuel injector cleaner when I replace them. (1/2 full) This has seemed to provide ample cleaning for most as I've never had an injector issue return to me.

Try some regular fuel injector cleaner available at wal-mart or any parts store. Not the expensive bottle that claims it will make your car perfect just the regular 2.99 a bottle stuff. When your car is at about 1/2 tank on the fuel gauge, add a bottle & drive that tank to 1/8. After refilling later & getting down to about 1/2 tank add another bottle. This should do some good if you're talking about hesitation & minor idle changes that don't trigger sensor problems.

Of course if any of the parts mentioned need to be replaced, this would be the time.

good luck

Long cranking indicates a problem with part of the fuel pump assembly or the need for an air filter / tune-up. A restricted fuel filter also reduces fuel pressure to the injectors slowing cranking.

High mileage? Try a few bottles of Gum-out with a tank of gas, not the expensive stuff, just the regular fuel injector cleaner, then repeat & see if it improves. If it does, that would indicate Injectors and or fuel filter.

good luck

hav u inspected the distributer system--also the ignition module-these things wear car is gitten up there! dont forget fuel delivery pump,injectors etc buy a haynes manual at a parts place

DO A LITTLE TUNE UP.CHANGE SPARK PLUGS.CHANGE FUEL FILTER.CLEAN FUEL INJECTORS.FILL FUEL TANK UP.AND ADD A BOTTLE OF FUEL INJECTOR CLEANER IN FUEL TANK.WHEN YOU DRIVE CAR AROUND.THE INJECTOR CLEANER WILL CLEAN OUT FUEL INJECTORS.IF CAR STILL RUN ROUGH IN DRIVE.YOU COULD HAVE INTAKE LEAK.

either the fuel filter is plugged or fuel pressure regulator is bad

i would start easy and run a bottle of injector cleaner through it. Good Luck

there is no such reset switch located in the car. First turn your key on and listen for the fuel pump to pressurize the lines. Then check to see if the fuel is leaking from the  filter. If it is you may have got the connection wrong. If thats the case your engine is not getting the proper fuel pressure to run. Hence its sucking air. If that does not work you might have a bad fuel pressure regulator sensor that is bad. Its located by the TBI. Reference a Haynes manual for replacement.
also if you did not fill the new filter with fuel then you have air in you system and engine will not run. so try taking it off and filling it with fuel and then replace it.
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turning ignition on removes air from fuel lines and primes the fuel system. filling fuel filter with fuel is irrelevent, as lines need to be clear of fuel upon installation. leave ignition on after installation for roughly 30 seconds-one minute. this will prime the fuel lines and remove air and most water from the system. if problem continues, fuel injectors. this is a common problem in 90-92 camaros. if cannot start car, you'll need to replace every injector, as it's not cost-effective to diagnose every injector. roughly 300 dollars in quality parts, roughly 4 man hours of labor. if rough start that requires push on accelerator (try this), run the car with fuel injector cleaner. this should salvage you injectors. if this helps proformance, starting, then for the next 3-4 full tanks of gas, add stp injection cleaner for every tank of gas. be careful, as this does not restore your injectors, but it helps clear away deposits which are common in multi port injectors.