Hi. I have a 1995 Chevy Blazer. I replaced the original motor with a 1992 Blazer vortec motor 4.3. It ran great for two weeks with no problems at all. Then it would just cut off and not restart until it cooled down. Now it starts when cold, revs good, never stalls in neutral. As soon as you put it in drive and give it gas it wants to die.

I’ve replaced- fuel pressure regulator on pass. Side, (the driver’s side was good), EGR screen (there was build up in valve), cap and rotor, wires, plugs, fuel filter, air filter, battery, ignition module.
All 6 plugs (new) are black and shiny on only one side. (AC delco #1) The other side is clean.

I don’t have an ohmmeter to check the coil. Does anyone know what color the spark should be if the coil is good? Can I check the coil without the ohmmeter using insulated pliers?

Could it be the O2 sensor? Any other ideas? I can’t keep replacing parts.
Any help is greatly appreciated. This is getting old. I need this truck to run!

Thanks in advance,
Sam

Wow. I BET you can't keep replacin' parts - not many LEFT to replace... Hope you didn't spend too much on all that stuff. See if you can swap some of them on an ohmmeter. Serious.

So lets do some free tests: fuel pressure to start with. Static (motor off), idle with vacuum off of FPR, idle with vacuum ON FPR, and pedal down (gauge taped to the windshield). See how long pressure holds after shutdown too, to test for leaking injectors.

Post back the numbers.

Does it lope at idle when warm?

Wow. I BET you can't keep replacin' parts - not many LEFT to replace... Hope you didn't spend too much on all that stuff. See if you can swap some of them on an ohmmeter. Serious.

So lets do some free tests: fuel pressure to start with. Static (motor off), idle with vacuum off of FPR, idle with vacuum ON FPR, and pedal down (gauge taped to the windshield). See how long pressure holds after shutdown too, to test for leaking injectors.

Post back the numbers.

Does it lope at idle when warm?

Thanks for the response. I woked on it some more last night. I knew there was no pressure because when I took the line off, there was no spray.

I listened to the tank. I heard the fuel pump whining and could even feel it.

I took the gas tank out, took the sending unit out with pump and screen. The rubber hose connection with the two metal clamps was deteriorated SO bad. The rubber on the fuel pump deteriorated too and the pump was shot.

If the rubber connection from that fuel pump loses it's tightness, you're going to lose pressure. I put my new connection on as tight as I could get it and will hope for the best. Bad design. It should have a metal connection like a brake fitting instead of rubber.

As far as the other parts, I know I needed the EGR valve gasket screen because the carbon was building up and getting stuck in the valve holding it wide open and flooding it. The regulator was bad on the pass. side so I know I needed to replace that. I could see where gas was leaking out of the pressure regultor valve at the top. It washed the black off clean.

I usually work on antique cars. I am new at working on these "new" fangled vehicles. All the sensors and wires are too much!

Now I have to get the "service engine soon" light off. I don't know know if that means something is still wrong or it just needs to be reset. The truck is running great. Starts on first crank. Idles great. Has incredible power...the damn tires are spinning. I really hoped it would work out. I like this little truck. It's going to be better on gas than my 69 Sport Utility was. It is a learning experience though and I know I have a lot to learn about it. This is a great site for that!

Thanks.
Sam