87 Chevy van runs but when given gas falls on it's face.?

Might be running to rich of an air/fuel mixture

Is this TBI? I assume yes, but the vans were always a bit of a different animal.

Does it have good plugs and wires? How is the cap and rotor? Have you made sure all electrical and vacuum lines in the engine bay are in good shape and connected? Does the check engine light work, and is it giving you any codes? Does it idle fine hot and cold?

Need some more info, with what little you have given us, it could be *anything*

Edit: Did you replace the fuel pump? Your problem sounds like a very common one on the early fuel injected vehicles, which is that the hose used to connect the pump to the sending unit (inside the tank) is rubber, and if older, is not designed for ethanol. The ethanol weakens it, and it splits. Normally runs a bit better with a full tank (as it provides a bit of pressure to keep fuel in the hose, TBI is only 13PSI max) but again, if the split isn't bad, they will normally idle ok, and stumble or die under any throttle.

A rudimentary test for this would be to watch the injectors while idling, then manipulate the throttle and see if the spray pattern gets worse when the throttle is opened. Obviously if spark/ignition is what is failing the injector may randomly stop firing, but the spray should still be a nice cone shape, even if irregular.

Check the fuel pressure. I don't know what's normal for your vehicle, but find out.

If that's good, ignition system is possible but I think sensor issue is more likely.

You might have a failure relating to the MAP sensor or MAF sensor (whichever it uses). It could maybe be the throttle position sensor also. Other sensors can also cause drivability problems but given the severity I'm most suspicious of the MAP or MAF.

Using a multimeter you can sometimes diagnose these sensors to some degree. You'd have to research exactly how they do their signaling so you know what to look for.

The throttle sensor should be easy to test, the ones I've tested on other GMs are just a variable resistor that changes according to the throttle opening. I remember the MAP being difficult to test with a meter, but I don't remember the details of it. I've never tested a MAF.

A bad sensor reading doesn't always mean the sensor itself is bad. For example a vacuum leak can confuse the MAP sensor, especially if it's in or near the hose that it's reading from.

Lack of check engine light doesn't rule any of this out. The conditions for setting a code on 80s GM ECMs are not very intelligent.

I don't know if it supports your van, but if you're computer-inclined, you might look into a program called WinALDL. You can buy (or make) an ALDL cable that connects this era of GM to a laptop - preferably an old one with a serial port. Then you can use the associated software to read all sensor values in real time. This can make bad sensor readings easy to spot.

Search the web on that if you're interested. I've found it useful on other cars, but I have no idea if your van's ECM is supported.

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RE:

87 Chevy van runs but when given gas falls on it's face.?

A new fuel pump was put on, new gas filter. when it sits and idols it runs fine, take it out on the street and if falls flat on it's face and won't go. Was running fine and broke down on hwy. Got it towed but just can't seem to figure out why it won't really move.

Check your fuel tanks!!! i have a '77 and '87 chevy C10 pickup, and both of them have leaky tanks. had to replace one tank, and just patched the one on the 87, good luck