Ok first off i'm new to this site.. i have a 99 2door zr2 blazer.. my truck won't start cold when the truck is warm it will start sometimes... but as soon as i put jumpers on it it will fire right up.. i think it's the fuel pump but i just did it like 4 months ago.. new batter new starter new filter i have a lot of new parts... i have also been told it's the fuel pump cuz of the fuel pressure that it needs 62psi to start and run ok but it's should have 65psi.. i have at least 10 people stumped on this and i really don't want to buy a new fuel pump and put it in if it won't fix the problem...

 

Welcome to the forum .

[ol][*]If the fuel pressure is less than 379kPa (55psi) at idle, it falls into the following 3 areas:[/ol][align=left]




[ol][*]-[/ol]
The pressure is regulated but less than 379kPa (55psi).The amount of fuel reaching the injector is sufficient, but the pressure is too low. The system will run lean, hard starting cold, no start, overall poor performance, and may set a DTC. Refer to Engine Cranks but Does Not Run [/align][align=left]



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A restricted flow causing pressure drop -- Normally, a vehicle with a fuel pressure of less than 300kPa (44psi) at idle is inoperable. However, if the pressure drop occurs only while driving, the engine will normally surge then stop running as the pressure begins to drop rapidly. This is most likely caused by a restricted fuel line or plugged filter. [/align][align=left]



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A leaking or contaminated pressure regulator valve or seat interface may not allow the regulated pressure to be achieved. [/align]Does the engine crank slowly if you don't give it a boost?
Maybe the problem wasn't the battery, maybe the starter is drawing to much power.

 

no it don't drag it just sounds like there is no fuel getting to the engine/ but as soon at you put jumpers on it and give it like 5 sec it will start right up with in two trys and two is pushing it

 

I have seen this issue on several vehicals. What it normally turns out to be is bad terminal connections. Try checking and/or replacing your's. Last one I fixed like this was a Honda Accord they switched to side post, but used used cables. Replaced them with new and it fired up every time with no problems.

 

My Roommates 03 does the same thing, Turned out to be a bad cell in the battery.

 

the cables are fine on the battery and the battery is less then a week old!!!

 

Maybe you got a defected battery...try switching it out with one out of a friends car . If it starts up fine, then return the battery. The cold may be affecting the battery if it is defective.

 

recheck the cables to the battery. they may look good but they can corrode on the inside. when put the jumper cables on it the may tighen up just a bit. question??? how are you attaching the cables when you jump it??? if it is done the correct way, ie last connection on the chassis (ground) and it works, look toward theground wire and corrossion either at the battery or the bond to the engine.

 

I have seen aftermarket and factory connections to the battery that were not the LEAD/COPPER mix that MFG's use. Lots of times these will cause faulty connections that will give you the same issues.

Try making sure you have FACTORY connections. If you do then check the power output to the hot side of the starter. If itdoes not match the Battery then you have a faulty cable. If it does then take your battery into any auto part store (even wal mart will do this) and have them LOAD TEST the battery. If it fails the load test then replace the battery.

If all of these check out then pull your starter and have AutoZone / Checkers or like place test it. Might be a faulty Starter Cyclenoid or Bendex.

If your starter checks out good then swap your starter Relay

Out side of that not sure what to tell you. Those are all the things about any shop would check for this issue.

 

it all been checked i now have 7 shops stumped...... but they all led to the fuel pump. becuz when it's idling it's at 50psi.....