Van sputters and pops when gas is pressed

gmc
safari

#1

My 97 GMC Safari Van starts up fine but as I step on the gas it sputters and pops and then dies. The fuel pump has been tested and has pressure. The throddel sensor has been tested and it’s fine. I should also add that about 3 years ago I was told by my dealership that there was a small crack (I believe it was in the block) and that if over time it grew larger that water could get in and it would be the end of the engine. Could it be water mixing with the fuel? What do you think is wrong?



Thanks,




#2

Water cannot mix with the fuel so that is out but a few questions.
Has the van been scanned for any codes? If not, drop by an AutoZone, Checkers, etc. and have this done. It’s free of charge.

Does the van idle smoothly?

Usually a problem like this points to a fuel delivery (weak pump, clogged filter), clogged catalytic converter, or very possibly a faulty MAF sensor.

I wouldn’t put too much faith into that cracked engine block diagnosis. While things like this can occur it is very seldom the case even though it may have been diagnosed as such.
Let me put it this way. I’ve been a tech for over 35 years and have yet to see a cracked engine block other than the one in a pickup that a friend bought. In that case it was a 1953 GMC truck that had been sitting in a farmers field for 15-20 years and I could actually see the crack in the side of the 6 cylinder engine.
He’s an ace welder, the crack easy to get to, so in a few minutes he had that cured.


#3

Thank you so much for your response. I will definately have them checked!


#4

I’d follow OK4450’s advice.

But I’d add to his list the MAP sensor. That senses a huge rise in absolute pressure (drop in vacuum) in the intake manifold when you open the throttle, and I’d put it in the list as a high probability among possibilities. I’d be inclined to put the cat converter lower on the list. A plugged converter won’t usually respond to the change quite that immediately, it’ll more typically manifest itself as simply inability to gain power.

A farmer’s field for 15-20 years, eh? Ice in the water jacket? It’s amazing how much force ice can exert.


#5

Thanks for your time. I appreciate it!


#6

IIRC, the fuel system on your engine is the Central Port Fuel Injection system. This involves a central injector/pressure regulator located under the intake manifold. Off this central injector are tubes that go to each cylinder. At each cylinder these tubes attach to what are called poppet valves. This whole injection system is called the spider assembly.

Because this fuel injection system relies on the fuel pressure in order to operate correctly, it’s a high pressure system. The fuel pressure spec for your vehicle is 60-66 PSI. If it’s at all below this the fuel injection system won’t operate correctly.

Tester