fuel pump problem 2000 Chevy S10


lbonde
12-25-2005, 09:07 PM
I have a 2000 Chevrolet S10 pickup 5-speed V-6 4.3L, and am having problems with the fuel pump not running. I have power to the fuse box under the hood, but i don't have any power at the fuel pump. I have replaced the fuel pump and a few fuses which give power to the pump. I am running out of ideas, if anyone knows what else I could possibly try please let me know. (could it also be related to the security system, and how might i check it?)

unbe
12-25-2005, 09:21 PM
I have a 2000 Chevrolet S10 pickup 5-speed V-6 4.3L, and am having problems with the fuel pump not running. I have power to the fuse box under the hood, but i don't have any power at the fuel pump. I have replaced the fuel pump and a few fuses which give power to the pump. I am running out of ideas, if anyone knows what else I could possibly try please let me know. (could it also be related to the security system, and how might i check it?)
Check your fuel pump relay

MT-2500
12-25-2005, 10:28 PM
Check ecm b fuze for power. check for 12 volts power to fuel pump relay at orange wire.
Check for 12 volt out put to fuel pump on the gray wire or gray primer wire on key on pump prime or crank.
If no 12 volt power jumper a fused 12 volt jummper to the gray wire and see if fuel pumps runs.
If not go to fuel pump or fuel pump connection and test there.
Do you have spark at 2 or more plug wires when cranking engine?

If not repair spark before trying to get the fuel pump to run.
MT

Floyd_ODB
12-26-2005, 12:15 AM
you may want to check if the fuel pressure safety switch is working if your vehicle has one. GM combines this switch with the oil pressure sending unit most of the time. this is a safety feature in case your in an accident the fuel pump will stop running with a loss of oil pressure

lbonde
12-26-2005, 08:42 AM
Check your fuel pump relay
ok but i am not sure where the fuel pump relay is located in my truck. If it is located in that fuse box under the hood then i have replaced it, otherwise i don't know where it is. do you know?

MT-2500
12-26-2005, 11:33 AM
Lbonde
Go to this link for a pdf on your fuelp and relay wiring.
http://members.troublecodes.net/crunch/00s10.pdf
Print it off and look it over.
There is a fuel pump prime a gray single wire with a plastic connector close to relay.
For your fuel pump to run you have to get 12 volts on it or the gray wire running to fuel pump.
There is no fuel shut off switches used on gm.
Some older models used the oil pressure switch for a helper if the fuel pump relay quit.
Like I posted before check for spark to plugs.
Do you have spark?
If so go to fuel pump relay and check for power at orange wire and then for power on gray wire to fuel pump on key on eng. prime or engine start.
If no power on gray wire jump a 12 volt fused jummper to it and see if fuel pump runs.
Post back results.
MT :feedback:

Floyd_ODB
12-26-2005, 03:11 PM
There is no fuel shut off switches used on gm.
Some older models used the oil pressure switch for a helper if the fuel pump relay quit.




I wonder what these are?
http://www.partsamerica.com/ProductList.aspx?parttype=417&searchfor=Oil+Pressure+Switch%2fSender&ptset=A

those are for a 2000 and I know my pump would not run without one other than the first 5 seconds of 'Key on' and I can tell you that even if the oil pressure side of the switch works(pressure on guage)doesnt mean the switch is good.

MT-2500
12-26-2005, 05:41 PM
Floyd
Your 85 S-10 Blazier is a long way from a 2000.
If it would not run without one then you had a fuel pump relay or pcm or wiring or fuse problem.
The ones that do have a oil pressure switch for the fuel pump only use it as a saftey switch to keep the fuel pump running in case the fuel pump relay quits.
The old oil pressure switch running the fuel pump is a old wives tale started by people that did not know what they were talking about..
It is not a saftey shut off switch and is only along for the free ride if the fuel pump relay is working.
Look at the wiring I posted for the 2000 S-10 4.3. It does not even have a oil pressure switch for the fuel pump.
That on line parts place might even sell a chocolate cover doggie drop for all I know or care.
But it will not fit on a 2000 S-10 4.3.
Show me where it is at in the wiring diagrams?
MT :lol: :grinyes:

Floyd_ODB
12-27-2005, 09:11 AM
a helper switch? come on, PM inbound

Floyd_ODB
12-27-2005, 09:26 AM
relays are used to keep amp draw down. running wires brom the battery to the back of the vehicle would draw alot of amps and would require large diameter wire. so they use a relay.
so if the relay goes bad the switch takes over? and your smiling at me :loser:

NoSpudsInIdaho
12-27-2005, 10:09 AM
Floyd, the switch you are pointing to at partsamerica is an oil pressure switch - only. It is designed to shut down your ignition system if oil pressure is lost in order to prevent engine damage. It does not directly shut down your fuel pump. After initial prime, your fuel pump requires an ignition signal to the computer to continue running. Since lbonde has no power at the pump at all, your oil pressure switch is a very unlikely suspect. MT's diagnostic procedure is the correct course of action.

MT-2500
12-27-2005, 07:08 PM
Floyd_OBD
Like NoSpuds said the switch on the online parts place is some kind a of aftermarket device.
The 2000 S-10 4.3 does not even use a oil pressure switch for or with the fuel pump wiring.
I was not Laughing at you.
But I fail to see your point in posting about the switch.
Tell us what your point is or what you are trying to tell us all.
We all all ears.
MT

Floyd_ODB
12-27-2005, 07:11 PM
actually it is a helper switch. I would have never beleived MT. when I put my 4.3 in I could here the pump for the first three seconds but wouldt start until I checked and change this switch. prbly a corroded wire or something, I dont know. and the only link to the ignition system is through the puter. check diagrams here>
http://www.photodump.com/viewer/Floyd_ODB/scan0010.html
http://www.photodump.com/viewer/Floyd_ODB/scan0009.html
http://www.photodump.com/viewer/Floyd_ODB/scan0008.html

so I guess this means that I need to wear a fire suit :icon16: :screwy:

MT-2500
12-27-2005, 10:47 PM
Floyd_OBD
In the pictures of wiring diagram that you posted shows the oil pressure switch has a switch in it that feeds 12 volts to the fuel pump or gray wire to fuel pump. When it has oil pressure.
But it is not a safety shut off switch or is it designed to run the fuel pump.
Only fords have the safety shut off switch or inertia switch that shuts off on an impact or when the little lady starts slamming her door or trunk lid while putting groceries in the car.
On a GM the oil pressure switch is only on there as a safety feature to keep the fuel pump running in case the fuel pump relay quits.
If yours blazer would not run the fuel pump until you replace or repaired the oil pressure switch it had a problem with the fuel pump relay which is designed or supposed to run the fuel pump.
The oil pressure switch only takes over when the fuel pump relay quits or fails to turn on fuel pump.
I am not sure what year or engine system that the pictures you posted are for but that system was used on a lot of GM. Light trucks and blazers.
Cars do not use the oil pressure switch that I know of except a few real early 80s.
But if you look at the 2000 wiring PFD I posted for the 2000 chev S-10 you will see that the 2000 has done away with the oil pressure switch for the fuel pump.
I guess it got tired of being along for the ride!!
Now some early 80-model gm cars had an oil pressure switch that did power the fuel pump when the oil pressure was up. If it quit the car died on the spot. I think they had a primmer on start system but not sure.
Also way back in the 60s when they started putting in tank electric fuel pumps on HD gas trucks. They were run off of the oil pressure switch plus a primmer button to get them primed up and started before oil pressure came up.
And a lot of trucks use an oil pressure kill switch to kill the engine if they lose oil pressure.
And also some if they get to hot have a tempt kill switch.
But there is nothing that shuts off the electric fuel pumps that I know of.
The oil pressure switch for the fuel pump is misunderstood by a lot of people.
It is not designed to run the fuel pump and is only there to take over and power the fuel pump if the fuel relay or engine computer and fuel pump relay system quits.
If the fuel pump relay is working right you could pitch the oil pressure switch in the trashcan and the blazer would never know or care where it went.
MT

MT-2500
12-27-2005, 10:56 PM
One other thing to think about on the oil pressure switch for a back up fuel pump power is the fuse that powers the oil pressure switch also powers the fuel pump relay.
If it blows they both go dead.
MT :lol2:

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