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Can you Help? Fuel pump, Fuel Pump Relay?

  #1  
Old 10-08-2005, 03:12 PM
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Default Can you Help? Fuel pump, Fuel Pump Relay?

I have am having a reoccuring problem with my 96 Blazer. It will not start. I took it to the mechanic the first time and it cost me 1100 bucks because they had to replace the distributor, computer, module etc. I got it back and 3 days later back in again because the engine would not kick over. Took it back to them again and this time they tell me it is the fuel pump inside the tank ($700). Again repeat behavior of getting it back and made it 2 weeks came home from work didn't move and it would not start yesterday. I read the questions about the fuel pump relays and I purchased a new one and replaced it. Still no luck. Can someone tell me what I am not dong correct? Or can you shed some light as to what I can tell the next mechanic? All in all this is becoming way to costly....Thanks
 
  #2  
Old 10-10-2005, 01:05 AM
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Default RE: Can you Help? Fuel pump, Fuel Pump Relay?

What kind of battery does it have and how old is it?

When it doesn't start are you getting a security light on the dash? Ignition switch.



 
  #3  
Old 10-10-2005, 10:51 AM
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Default RE: Can you Help? Fuel pump, Fuel Pump Relay?

sorry I can't exactly help, but we might have the same prob - maybe we can find a solution together! My 96 blazer will crank but not start. HOWEVER if you spray some starting fluid in the intake, it will start and run fine. I replaced the plugs, wires, cap, rotor, air/fuel filters (and coolant, t-stat - unrelated). The engine now runs much better, but when the engine cools back down it will not start - only crank. If the engine is warm it may start with some protest, but will start. Let it cool down for an hour and then nothin'.

And yes I too was told I needed a fuel pump at the cost of $650. I have a hard time beliving this is the prob as the truck runs hard to 5K at WOT! I see that didn't fix your truck either - those bastards. Anyways I will post to this thread as I figure it out. Hope you will do the same. Thanks to anyone who can help these newbs out!!!

EDIT: read other post on fuel pump relay, I will check it tho. My fuel pump turns on fine. I laid under the truck and had a buddy turn the key on several times to check the fuel filter that I had just replaced for leaks and I heard the pump turn on and off like it's supposed to (on two sec or something then off) after five turns of the key to the on position - it barely turned on and then not at all. I assume this is because there was sufficient fuel pressure after it was done priming the fuel line and filter after the filter change?

Thanks again for any input! After doing a search, I see there's alota knowledgeable guys and gals on here!
 
  #4  
Old 10-10-2005, 11:36 AM
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Default RE: Can you Help? Fuel pump, Fuel Pump Relay?

More updates after more searches. I common theme among posts of our sort of prob is irregular fuel pressure. I thought fuel pumps either work or dont. We both need to measure our fuel pressure with a gauge. This can be done by hooking it up at the schrader valve behind the throttle body. I've read we need 55-60 psi consistantly or no start. The prob is either a weak f-pump or more commonly a bad line or connection of fuel line near the engine, I will check it out.
 
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Old 10-10-2005, 01:26 PM
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Default RE: Can you Help? Fuel pump, Fuel Pump Relay?

The first guy might not have a fuel problem.
First off, does your security light come on when you turn the key to run?
The security system will kill power to the fuel pump. A fualty ignition switch will be interpted by the computer as a security violation and your truck will not start, no power to the fuel pump. Your security light should be flashing on the dash when this happens, if the light bulb isn't burnt out or not functioning for some reason. Does it come on when you trun the key to run? Now if you wait 15 mintues and tray it again, ususally it will run. I had the fualty ignition switch replaced by the dealer on my '00. Still under warrenty at the time.

AC Delco batteries have a problem with the positive battery cable post. It likes to corrode inside the battery. I have seen the post literally fall out of the battery. The cable show no sign of corrosion. All the corrsoion happens inside the battery.

As for the second guy, yep you need fuel pressure in the 55-60 psi range. A fuel pressure testing gauge costs about $40. If its is starting with either, then you have a fuel problem. Check the Chiton/Haynes manual on a part called a Fuel Pressure REgulator. I am not sure if the S-series trucks have one of not, I do know it is a common problem in the fullsize trucks. They develope leaks and make it hard to start when warm.
 
  #6  
Old 10-10-2005, 02:56 PM
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Default RE: Can you Help? Fuel pump, Fuel Pump Relay?

Thanks HANR3! I will check out the fuel pressure regulator and buy the gauge - I've needed to have one for a while to t-shoot other cars too. Thanks for yor time!!
 
  #7  
Old 10-10-2005, 03:59 PM
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Default i am having the same problem

i am having the same exact problem

94 s-10 blazer

i get 38 psi in ignition on position and 55 psi at cranking

i have replaced the MAP, IAC and Spider assembly and it still wont fire

it cranks all day long and if i put gas in the throttle body, VWOOM fires and will run as long as i play with the throttle under the hood. but if i let it idle too long, it dies... i was thinking fuel pump, but i tested it at the shrader valve and it read as i have stated...

50-55 PSI all the time? if thats the case, then i can assume that the fuel pump is working under load, but no load it is not supplying sufficient fuel pressure, but at cranking it jumps to 55 psi, and that would be prefect to fire, but it wont fire


this is really starting to **** me off. i have spent so much money on this truck since i bought it 6 months ago.. rebuilt the tranny, new radiator, water pump,, cap, rotor, wires, plugs, power steerin pump, fuel filter, o2 sensor

and i replaced the spider assembly this past friday... at a cost of $350 bucks ( so now i know this is not the problem)

when i first got it i had to emissions test it here in tucson and it passed the Hydrcarbons by 8pts. which means it is running WAY TO RICH. it has also clogged the EGR valve about 5 times, until i finally removed the plenum about 3 weeks ago and got all the carbon out of it, and now that damned thing wont run at all...


it is getting spark at the cap, and at #1 plug, it has fuel because i turned the car on when i had the spider assembly out and fuel came out of the main fuel line inside the plenum.
compression is at 145 psi in #1 cylinder.
*frustrated*

please help
 
  #8  
Old 10-11-2005, 04:45 PM
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Default RE: i am having the same problem


I had a similar problem with my 96 blazer. 1st thing wrong was the fuel pump so I replaced it. The truck would still not start sometimes and if the dash lights ( i.e. airbag, oil, all gages ) does not come on it would start. If I turned the key to the one postion and waited a few seconds the dashboard would light up, I would hear a relay click on in the glove compartment and then the truck would start. I took it to the dealer and they found codes for ignition faults and it finally was the ignition module and wiring harness. This is a known problem with 1997 blazers but they have seen it on later 1996 (as mine was built near the end of the 1996 run before the 1997's was started ). Hope this helps

 
  #9  
Old 10-11-2005, 05:04 PM
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Default RE: i am having the same problem

I would like to add. The ignition control module can be shot and you will still get spark. The ignition control module controls the timing of the spark.

Have you ever replaced the cat? The computer kept adjusting the settings as the cat was pluggin up over time. Once you disconnected power to the computer it forgot thsoe settings and reverted to the base line. Now it is so far out of whack, it won't start.
 
  #10  
Old 10-12-2005, 01:36 PM
Join Date: Oct 2005
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stmanser is an unknown quantity at this point
Default RE: i am having the same problem

one thing i need to add.....

i have ZERO codes..... it flashes 12 all day long...


any way to test the ecu while it is in the vehicle..??



 

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