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Express & G-Series Vans Offered in both a full size van, or a large box truck, the Express is the modern GM workhorse

Chevrolet Express
Platform: GMT Van

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  #1  
Old 01-22-2011, 10:02 PM
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Default 1990 G20 Losing power when going up hill?

I looking for some ideas on what my problem could be. I have a 1990 5.0L G20 Sport Van. When I'm going up any hills it spudders like it is starved for fuel. It started when I was driving on a small hill and almosts sounded like it was back firing multipal times at the same time. I had about 4 gallons of gas at the time. I then tried to make it home which was up a bunch of big hills. I finally pulled over and it would run fine in park but then die in gear. I then replaced the fuel pump and put 4 more gallons of gas in. That was enought the get me home about a mile away up hill (still was spuddering the whole way). I then replaced the fuel pump and made sure there was no water or debree in the tank. That didn't help anything. ANY SUGGESTIONS?
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Old 01-23-2011, 12:21 AM
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Default I'm new to this.

Am I doing something wrong, because I've had 39 views and ZERO replies.
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Old 01-23-2011, 05:10 PM
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Vacuum leak. Check your vacuum hoses and replace dry, cracked and rotted hoses.
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Old 02-04-2011, 02:23 PM
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i doubt if the solution just b4 my post is of any help. coz those are not related.
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Old 02-05-2011, 01:45 PM
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its not? why is that?

an increased engine load like going up an incline reduces engine vacuum. The wider the throttle is the lower the engine vacuum. If your engine has cannot maintain vacuum it will stall. And this is most easily to demonstrate at low speeds when climbing a hill. If you are climbing a hill at 20mph the engine has to work harder to move the mass up the hill, so you have to hold the pedal and keep the throttle open wider decreasing engine vacuum. Now if the hose is plugged, rotted or collapsing on itself the car will stall because of an extreme change in vacuum.

When the car is off you should have 30mmHg of vacuum.
At idle and partial throttle you should have 15-21mmHg of vacuum
At wide open throttle vacuum should be near 0mmHg.

Is this wrong?
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Old 02-05-2011, 02:15 PM
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fuel filter, same thing happened to my friend just yesterday, he limped it home and burned out the fuel pump, of course he changed the filter first, then he went to start it and the pump was now shot, filters are cheap
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Old 02-05-2011, 04:49 PM
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the dude said he replaced the pump 2x.
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Old 02-13-2011, 05:49 PM
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So I've replace the fuel pump, fuel filter, cap, rotor, plugs, wires and some worn vac hoses. None of this has helped, I'm now thinking a timing issue. when I replace the cap the destributor was covered in rust.

Does anyone know where the timing is supposed to be on a chevy 305. when I checked at idle it was at 0, then moves to after a bit while raising the rpms. At 3 rpms it goes to 8 before. This doesn't seem right.
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Old 02-14-2011, 07:52 AM
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Same problem with 97 Tahoe!! Also dies on me when braking. Have replaced computer, MAF sensor, cap and button, fuel filter, air filter which helped drastically for about 3 weeks. Giving a code for o2 sensor. Gonna replace that today. Really don't think that is gonna be it though. Don't feel that it is the fuel pump. Starts back up every time. Gonna try the vacuum hoses I guess. Any more ideas would be appreciated.
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Old 02-14-2011, 08:03 AM
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best thing is to graph or monitor the O2 sensors after motor gets warmed up. you should see volts fluctuating constantly,(youll need a scanner for this) if you see steady or no volts at any of those sensors then they are bad. another possibility is a clogged catalytic converter. look for a blackish powder coming from the tailpipe.
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Old 02-14-2011, 08:03 AM
 
 
 
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93, astro, avalanche, bog, caprice, chevy, dies, hill, hills, loses, losing, power, spudders, van, whats, wrong


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