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94 sonoma won't start

 
 
 
 
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Old 08-28-2006, 02:42 PM
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Default 94 sonoma won't start

My 1994 4.3 CPI won't start. It seems like it isn't getting fuel. I recently did a tune up and changed plugs, wires, pcv valve, cap, rotor, fuel filter. I also recently changed the EGR valve and the entire CPI unit and fuel injector. A gentleman at the auto parts store told me that my fuel pump will most likely fail after I change the CPI unit. Apparently he was right. Does anyone have any thoughts on this? I can hear the fuel pump when I turn the key, but that doesn't necessarily mean that it is working. My electrical connections seem good, and I don't have a blown fuse. I'm thinking that I need a new fuel pump. If anyone has any other ideas please share. Also, if it is the pump, does anyone have any tips for changing it? Thanks.

 
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Old 08-28-2006, 02:52 PM
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Default RE: 94 sonoma won't start

You're gonna want to verify the fuel pressure with a gauge before dropping in a new pump. There should be a shrader valve test port on the main fuel feed line at the back of the upper plenum. Does your pump turn on, then turn back off again (turn the key to 'run', but not 'start' and wait)?

For the cost of a fuel filter (~$4), you may want to try putting a new one on just to make sure that you didn't pickup a defective filter.

Other than that, check all of your lines for kinks. Maybe take a look at the plug wire placement to make sure that it's correct.
 
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Old 08-29-2006, 01:02 AM
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Default RE: 94 sonoma won't start

That parts guy is more then likely correct. What happens is the fuel pump is used to fighting the restrictions, and when you chnaged all that, she flowed to free and fried the pump.

Test the fuel pump. no doubt its not pushing enough fuel pressure. Like 54-60 psi for start up.
 
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Old 08-29-2006, 10:15 AM
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Default RE: 94 sonoma won't start

Yeah, he told me at the parts store that everything would be fine and that the truck would run great for about 4 or 5 months, and then the fuel pump would go. That's about exactly what happened. It just wouldn't start one morning. Luckily it happened in my driveway and not out on the road. I'm taking a trip to Canada fishing, but when I get home next week I'm going to test the pump and see if that's the problem. Thanks for your help. I'll keep you guys posted. Thanks again.
 
  #5  
Old 09-11-2006, 02:18 PM
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Default RE: 94 sonoma won't start

My truck is up and running. It was indeed a bad fuel pump. Cost around $80 at the parts store. 12 years of corrosion on the fuel tank straps forced me to remove the truck bed to get at the pump, but at least it's fixed. Thanks for your help guys.
 
 
 
 
 
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