Surging?

[big83diesel]

I have an 83' k-5 blazer with a 6.2 c code engine. Yesterday the strangest thing happened. All of a sudden my engine seemed to have tons of power, it would take off like a rocket when i was just cruisin'. After I stopped at a light, and went about a hundred feet it stalled. After a few cranks, it started again and still seemed to have more power then usual. I have recently changed the lift-pump, injectors, and fuel filters but they seemed to only give me a little bit of power. What is causing the truck to surge? i like the power increase, but the stalling sucks. Any suggestions?

[DmaxMaverick]

Could be a number of things. Anything from "is that all" to "OMH".

Start with the simple things first. Check the fuel cap. If the vent has failed closed, the pressure in the tank (early in the warmer season), it would prevent a free flow of the return to the tank. This causes timing advance (HPCA), and additional fuel being temporarilly distributed, and ultimately, a stall due to an internal inj. pump pressure balance (no pressure to injectors).

Try that, and check for the common leaks, mechanical binding, etc.

Good luck.

[britannic]

Check the CDR valve is functioning correctly (search the forums for CDR), if too much engine oil is getting into the intake, it can cause the engine to take off. The worse case scenario with a faulty CDR, is an engine runaway that revs itself to destruction.

[big83diesel]

I found the problem, a pin sized hole in my main fuel line. I dids everything in the reference section, found out it was air in the lines, pressurized the tank and there it was. Thanks for your help guys! I did find an oil leak under my CDR valve though. Do you guys know where i can find the rubber piece that goes under the CDR and connects it to the intake? How will I plumb the CDR when I install my turbo? It is a GM-7

[gavio]

My van had some problems with erratic behavior similar in many ways to what you are describing. Eventually got so bad I couldn't drive it. It sat for a while as I tried everything I could think of, including poking around in the injection pump. fuel lift pump, throttle cable and all kinds of other groovy stuff.

Finally a grueling session of isolating the fuel system one section at a time revealed the problem to be the fuel filter. Why that would cause the engine to surge and run away is something i cannot quite explain, but the evidence was obvious.

Why hadn't I thought of that first, you ask?

Because that filter had just been changed only a few hundred miles earlier :eek:

Apparently a bad batch of fuel had been the culprit. I have a new approach now: ALWAYS try the filter first!

It's been running fine since.

Just a thought...

[big83diesel]

I had the same problem with my Blazer. I had to change the fuel filters four times within two months. Apparently, the HESS station by me had a bad batch of Diesel. Too bad it is the only place within 25 miles that sells diesel, Thanks again!

[wthif]

Originally posted by big83diesel:
I did find an oil leak under my CDR valve though. Do you guys know where i can find the rubber piece that goes under the CDR and connects it to the intake? The dealership can help you find the rubber piece. I bought one at one point and it didn't cost too much. You should also replace your CDR while you are at it.