1993 gmc Vandura sputters

Pinky317 · April 21, 2015

I've had this van for 8 years, 3 of which it wasn't driven due to the rear end going out. It had the same issue before being parked for those 3 years, so the issue isn't related.

It fires right up with no problems, but once it's put into gear, it will die. It is possible to drive it, just takes some skill with the accelerator (too much and it will bog out).

Once it's been driven above about 55 mph it runs absolutely fine with zero issues. I've tried googling what could cause this and I keep hitting dead ends.

I have recently put new plug wires, plugs, and fuel filter in an attempt to fix this issue. My son and I race motocross out of this van so reliability is key.

Any leads or just pointing me in the right direction would be amazing.

Thanks in advance,

Alex

Pinky317 · April 22, 2015

It doesn't matter if I let it sit and warm up for 30 mins, I still have to follow the "pumping of the throttle" ritual to get it to move in any gear, however, if it's in park or neutral, I can pump the gas with no hesitation. Like I said, once I've driven it through all gears, it'll run fine. I know the issue is related to fuel/air, and that the mixture isn't correct, but with so many sensors it feels like this is a never ending journey.

Is there a way to see if the choke is sticking open, if that's even possible.

I don't recall seeing anything connected to the air filter assembly. When I checked the air filter, I unbolted the cover and pulled it right up and out.

Thank you for the assistance. I appreciate it.

Pinky317 · April 21, 2015

Cap and rotor as well as air filter are next on my list. After it warms up and has been driven for 5 mins, it doesn't have a miss or anything, which makes me want to rule out "out of time." I would think it would be a constant issue rather than one that goes away.

Doug_Scott · April 22, 2015

There is no choke on a EFI engine. But, that does not mean it does not need the effects of having a choke. I was told back when EFI started being commonplace that you should simply treat it the same as if it were carburetor equipped. All those sensors simply replace the analog devices carb'd engines had. For example, the ambient air temp sensor/coolant temp sensor replaced the choke, throttle position sensor and manifold absolute pressure sensor replaced the accelerator pump, etc.

If you can get yourself to understand what the sensors are reporting, then you can apply that to what you would have done with a carb'd engine. This does not work 100% of the time, but it sure beats lifting the hood and saying "it broke" to the dealership.

Doug_Scott · April 21, 2015

If your bike ran this way, where would you look? 4 stroke engines are 4 stroke engines regardless of the implementation. Does not matter if fuel injected or has a carburetor. Troubleshooting still follows the same logic.

Note that "cold" does not mean winter, it simply means not at operating temperature.

You are describing an engine that does not like to be driven when cold. Towards the end of the carb years, engines were all having a tough time being driven when cold, unless all the various manufacturer hacks/fixes were in place. Most common issue was a missing or disabled heated air intake system. This was the sheet metal wrapped around exhaust manifold, with a stove pipe connecting it to the air horn on the air filter assembly. Disable that system on a GM 8 cylinder and you would be smacking your nose into the steering wheel if you hit that gas hard at 10mph after the first cold start of the day. The initial fuel injected engines still used that system. For whatever reason, GM was effected the most by this.

Issues when cold only are almost always related to fuel/air. EFI has sensors that must be working correctly in order for the PCM to control fuel properly.