K5 Blazer 1969-1994
While this model ended its run, it is not uncommon to see them on the road or off, years after production end.
Platform: Truck, GMT 400

1994 K1500 Blazer - New Engine w/ 50 miles same exact problem previous engine had.

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Old January 20th, 2018, 11:02 AM
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Default 1994 K1500 Blazer - New Engine w/ 50 miles same exact problem previous engine had.

Truck will start, idle, and even drive smoothly (if you drive like a sane person, which I do sometimes.) Has no miss, and doesn't have an issue starting (2-3 cranks and engine is running)


When going up a hill, merging onto a highway, or passing someone I have no power.

The engine will rev up to the desired RPM at 3/4 throttle, but have a popping sound from exhaust and fall flat on its face. Letting off the throttle brings back the power. If I let off just a *little* bit, I start increasing speed. Transmission is also holding. If you go into the upper RPM range slowly, without going past 3/4 throttle, it makes power all the way up. I have no tested this phenomena in park/neutral as the engine is brand new and doesn't deserve that kind of abuse.

This morning, engine runs and idles perfectly. When put into gear it dropped to 200 RPM, also does this when turning wheel or AC is turned on. Previous engine didn't do this, I'm still suspecting fuel pump.


tl;dr Engine will rev up to any desired RPM, but once you get past or at 3/4 throttle, has no power, if you let OFF the throttle even just a tiny bit, the power comes back EVEN if its still in the high rpm range. Engine also pops.

**I should also mention, the previous engine also had this issue. I got rid of the previous block 1 month ago, but I thought it was just a tired engine** I was planning on getting this jasper for better towing anyway. So no loss there.


Things that have been done:

* New longblock, Jasper 350

* New fuel filter

* New injectors OEM (tbi unit)

* new plugs, wires, cap, rotor

* engine has been timed

* new air intake

* dual flowmaster 10s with no cats

* new water pump

* oil pump new

* new intake manifold gaskets, tbi gaskets, heads, valve covers, gaskets everywhere are new.

* New temp and oil sensors (both sending and sensors)



My mechanic is thinking EGR, TPS, Fuel Pressure Regulator, or Fuel Pump. As both engines had the same issue, and this engine has been timed. I am not aware of how to time this particular engine, and since it is under warranty I do not want to mess with it.

Anything else I can try? I am renting a fuel pressure gauge and going to test that myself, but what about fuel volume?

Otherwise, the engine runs FANTASTIC and it definitely has 4x the power my previous engine had, as long as you stay under 3/4 throttle, which isn't possible when passing/merging in this big *** tank of a truck. The engine REALLY wants to make the power, but can't..




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