My fuel pump is not working correctly?

Hi,

The pressure is low. Have you checked the fuel pressure regulator? It is mounted on the fuel meter body assembly. The regulator may be the cause. It will have an engine vacuum hose going to it. First, remove the hose and confirm there is no fuel in it. If there is, replace the regulator. If there isn't, reconnect the pressure gauge and start the engine. Disconnect the vacuum hose from the regulator and the pressure should increase. If it doesn't, replace the regulator.

The first two pics below show what the regulator looks like and location.

Here are the directions for replacement. Pic 3 correlates with the directions.

______________________________________________

2000 Chevy Truck S10/T10 Blazer 4WD V6-4.3L VIN W
Fuel Pressure Regulator Replacement
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pressure Regulator Service and Repair Procedures Fuel Pressure Regulator Replacement
FUEL PRESSURE REGULATOR REPLACEMENT
Fuel Meter Body Assembly

Pic 3

REMOVAL PROCEDURE

TOOL REQUIRED
J 34730-1A Fuel Pressure Gauge

CAUTION: Refer to Battery Disconnect Caution In Service Precautions.

1. Disconnect the negative battery cable.
2. Relieve the fuel system pressure. Refer to Fuel Pressure Relief Procedure.
3. Remove the upper intake manifold assembly.
4. Remove the fuel pressure regulator retainer clip (13).
5. Pull and twist the fuel pressure regulator (14) in order to remove the fuel pressure regulator from the fuel pressure regulator housing using a shop towel to catch any spilled fuel.
6. Remove the regulator seal lower O-ring (18).
7. Remove the regulator assembly filter (17).
8. Remove the regulator seal upper O-ring (16).
9. Remove the regulator seal backup ring (15).
10. Cover the fuel pressure regulator housing to prevent contamination from entering the fuel system.
11. Discard the O-rings.

INSTALLATION PROCEDURE

IMPORTANT: If the fuel pressure regulator is to be reinstalled, inspect the filter screen for contamination. If the filter screen is contaminated, replace the regulator.

1. Lubricate the new O-rings with clean engine oil.
2. Install the regulator seal backup ring (15).
3. Install the regulator seal upper O-ring (16).
4. Install the regulator assembly filter (17).
5. Install the regulator seal lower O-ring (18).
6. Assemble the regulator with the vacuum tube pointing down into the regulator retainer clip.
7. Install the fuel pressure regulator retainer clip (13).
8. Install the upper manifold assembly.
9. Tighten the fuel filler cap.
10. Connect the negative battery cable.
11. Inspect for leaks.
11.1.Turn the ignition switch ON for 2 seconds.
11.2.Turn the ignition switch OFF for 10 seconds.
11.3.Turn the ignition switch ON.
11.4.Inspect for fuel leaks.

_______________________________________

One last thought. Before checking the regulator, remove the fuel cap and see if pressure increases.

Let me know what you find or if you have other questions.

Take care,
Joe

2 days ago it was cold i think it was -3 and the night before that my low gas light came on witch i was 1 block away from my house so i figured ill fill it up tomorrow. the next morning i woke up the car turned on, so i let it run so it can warm up. after 7 min the car turns off. i turn it on again and it tried to turn on but no luck. when i used to turned on i heard like a little motor sound from under the car just for 2 sec or so. since this happen i haven't heard the sound again. do you think its the fuel pump the went bad??

If fuel very low you may have sucked up water and debris from tank. Try putting some HEET and more fuel see what happens.

i got the Heet and put a whole bottle in there and i also put 3 gallons of the best gas, the same thing happens it tries but it doesn't start. I checked the fuel pressure today and it didn't have any pressure, it had a little bit of gas just drops dropped.

Try filter replacement first see if pump comes on after. If not need to drop tank and replace.

I replaced my fuel pump and now its running bad and leaking fuel and my service engine light is on

you probably left one of the orings out of the lines . recheck everything you did. scan the engine, most auto parts stores do this for free.

Its pouring fuel out only if the gas cap is on. I replaced all o rings and stuff

recheck your connections you may have the return line and the evap purgelines crossed. Also as you have dropped the tank check to see if the vent line going to the gas filler is crimped or kinked.

Ok cool i will let ya know. thanks so much!

Six cylinder four wheel drive automatic 150,000 miles.

The miles are on the chassis, mileage on engine is unknown (has been replaced). I am not getting any power to fuel pump. When this happened it was running fine and would not start back up after being shut off. I have replaced the fuel relay and oil pressure switch. Not sure where to look next except start tracing wires back.

Do you hear the fuel pump come on when key is at run position? If not check the ECM control relay circuit. Have you checked the fuel pump fuse?

Here are some fuel pump wiring diagrams and a guide to help us get started fixing the problem.

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

and

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

There is a year split on the location of the relay so I gave you both.

Please let us know if you need anything else to get the problem fixed.

Cheers, Ken

I did not see anything labelled as a fuel pump fuse, only the relay. I have checked all fuses in the engine compartment are there fuses anywhere else? The fuel pump does not come on when key in the on position. No juice getting to connector at fuel tank. All fuses are good ECM circuit is good. No power at fuel pump test connector(ALCL connector terminal G).

All you got is 2secs to look for power-Be at the fuel pump connector and hook up the voltmeter and have helper turn key to On-do you have power? If not track it back thru the wires and the fuel pump relay. See fuel pump relay below

BETTER IMAGE ABOVE

What you are showing me is the diagram of the fuse block.
The one that is labelled fuel pump is a relay (right?).
I am told there is also a relay up by the firewall on the right side of vehicle.
If this is true I have power going to this relay.
Which one is actually the fuel relay ?
If I look up fuel relay on parts stores web sites it shows me the 4 pin that is in the fuse box on left side of engine compartment.

It is the one in the under hood fuse/relay block.

I have a 2000 Blazer 2WD, my fuel pump works sometimes and does not other times.

I tested the ECM B fuse socket and found, there is voltage on both sides when the key is on (11.48 on left side towards front. 45 on right side towards firewall). The right side terminal slowly drains down after a few minutes.

Where is this "Terminal G" test connector located on the Blazer?

Check the ground, it is on the rear left cross member. There are two wires, one is for static discharge, and the other is the power ground. It is up on top of the little corner gusset.

Both wires need to be connected. I had the static ground connected only, no go. Connect the ground and runs excellent.

I forgot to connect it. Called the pump company Airtex, it was their suggestion. They said corrosion has been a big issue also.

This was my second pump in two years, wonder if I forgot it two years ago, and some how ran?

Will never know.

Driving then it quits like it ran out off Gass gauge says half tank checked pressure got none checked fuses good
Had no noise from fuel pump so I pulled and check pump , pump is good checked pump wires for power got none recheck fuel pump relay under hood checked elm fuse a and b good what other relays and fuses can I be missing ? Can you help

Have you checked for spark?

Under what conditions are you expecting the fuel pump to have voltage? Do you have the ignition switch on? Are you cranking the engine?

I have the key on and tried cranking still no power to pump

Dandy. The engine has to be rotating to have voltage going to the fuel pump. To run otherwise would pose a serious fire hazard if a fuel line got ruptured in a crash.

Have you checked for spark?

A failure in the ignition system is responsible for about one percent of "cranks / no-starts". A failure of the fuel pump is responsible for about another four percent of those no-starts. It's a loss of fuel pressure AND spark that account for the majority of the no-starts, but too many people get hung up on the first thing they find missing, and they don't check for other clues and symptoms.

Yes motor will start with starting fluid or gas until it burns out have used jumper wire from battery to pump relay and got power to fuel pump connector that way but when jumper is pulled no power when ING switch on and off no power when cranking no power so I know the wire between fuse block and pump connector is good I know motor will crank and run know fuel pump will run just don't know why when connected right fuel pump has no power can the oil pressure switch or oil pressure relay under distributor cause this problem if gone out ?

Before I forget, there is a common problem you should be aware of if you have a steel gas tank. The pump is grounded through it to the straps, then to the frame. If the tank gets rusty, that ground can be lost. You'll have that 12 volts on the feed wire, but a faster way to check for this problem is to use a simple test light. Ground it to a good, paint and rust-free point on the body, then place the probe right on the tank. If the test light turns on dimly, drill a small hole in the tank's flange, outside of the weld, then run a screw in there and attach a wire to it and to the frame.

At the pump's connector, you should have been testing on the gray wire for 12 volts. You should normally see 12 volts for one or two seconds after turning on the ignition switch, then again when you're cranking the engine. If you DO see 12 volts for the first couple of seconds, we know the relay and wiring are okay, and the Engine Computer has control of that relay.

If you don't see that initial 12 volts, we're going to have to test at the relay. Either you're going to have to gain access to the underside of the fuse / relay block, or you must find a way to test on the relay's terminals while it's still plugged in. You might be able to lift the relay just enough so you can poke the test light's probe in there, or you can insert little pieces of wire to use as test points. You have to be careful though to not put enough pressure on the terminals in the socket that they become stretched. That will cause them to make intermittent contact.

To start with, you can remove the relay completely, then test at each terminal with the test light. There should be one with 12 volts all the time. If you're doing this underneath, that will be on the orange wire.

Next, move the test light's ground clip to the battery's positive post so we can test for grounds. Probe the remaining three terminals in the relay socket. One will make a bright test light. That's the ground wire for the relay and is black. Now look for a second terminal like that. That is a green / white wire. The test light should light up but it will be relatively dim because you're also reading to ground through the pump motor.

If those three circuits are okay, we have to determine why the computer isn't turning the relay on.

Went to drive it and the battery was drained. I purchased a new battery. There is no sound coming from fuel pump. replaced fuel pump still nothing. I do not think it is getting power. thanks, Brian.

Did you check for power at the pump? Wire diagram attached.

There is no power at the fuel pump all the fuses are good. When the key is on there is power to three of the legs on the relay. There has been a couple of times when there was power back at the pump but only a few times. Tried adding a ground but that didnt help.Was wondering if the ecm may not be sending signal to the fuel pump?Kind of at a loss on this one.
thanks in advanced for your help

Hello ..thanks for the donation .. much appreciated ..

Is the security light flashing or staying on ? .. the PCM cuts fuel if there is a fault on the Passlock system ... if the PCM was not sending signal to pump the oil pressure switch would still start off the pump ? let me know

FUEL DELIVERY
Fuel Pump
An in-tank, electric fuel pump delivers fuel to injector(s) through an in-line fuel filter. The pump is designed to supply fuel pressure in excess of vehicle requirements. The pressure relief valve controls maximum fuel pump pressure.
On Central Sequential Port Injection (CSI) systems, pressure regulator is mounted to fuel metering body under upper intake manifold. On Sequential Multiport Fuel Injection (SFI), pressure regulator is attached to end of fuel rail. Pressure regulator keeps fuel available to injector(s) at a constant pressure. Excess fuel is returned to fuel tank through pressure regulator return line.
When ignition switch is turned to ON position, PCM turns on electric fuel pump by energizing fuel pump relay. PCM keeps pump on if engine is running or cranking (PCM is receiving reference pulses from ignition module). If there are no reference pulses, PCM turns pump off within 2 seconds after ignition is turned on.
Most models also include a second control path through the oil pressure switch which will turn the fuel pump on after the switch detects oil pressure. Cranking time will be longer if fuel pump does not receive current until oil pressure switch contacts close.

PASSLOCK(tm) SYSTEM
When mechanical key turns Passlock(tm) lock cylinder, a Resistance Code (R-Code), is created by a rotating magnet turning past a stationary Hall Effect sensor. R-Code is sent to the BCM. The BCM determines validity of R-Code within a preset time window, then sends a coded password over the class 2 serial data line to the Powertrain Control Module (PCM)/Vehicle Control Module (VCM), which then allows fuel injectors to operate normally.
If BCM sends a password that is different than learned password in PCM/VCM, the PCM/VCM will enter no start mode. During this mode, fuel injectors are shut off for 10 minutes and SECURITY indicator light will stay on. Engine may crank and temporarily start, but will soon stall due to fuel shut-off. If a large magnet is placed near Passlock(tm) sensor, a tamper signal will be sent to BCM. The system is continually self diagnosing certain functions. If a malfunction exists, system will store a Diagnostic Trouble Code (DTC). BCM does not illuminate Malfunction Indicator Light (MIL). If a Passlock(tm) DTC exists, BCM illuminates SECURITY indicator light.

Thanks Dave

With the key on and after its cranked the security light is not flashing or steady.Does the power go from the relay back to the pump or relay to pcm then to the pump?Cause I always have power on three legs of the relay but not always at the pump.

The PCM (computer) sends a signal to the RELAY which energizes the PUMP ...the PCM gets it's signal pulses from the IGNITION MODULE so if the MODULE is not working the PCM cut's power to the RELAY/PUMP after 2 SECONDS ... ALSO the OIL PRESSURE SWITCH will energize the fuel pump after it has reached the correct pressure, if the pump does not recieve a signal from the IGNITION MODULE/PCM/RELAY ... when you first sit in the vehicle .. make sure everything is turned OFF (radio/heater) in the car .. turn ignition to ON (no crank)... do you hear a 2-5 second buzz noise inside the vehicle .. try this a couple of times to see if you hear the BUZZ .. also could you let me know how you checked for power @ pump ..did you check the actual wires on pump ?? let me know ??

When ignition switch is turned to ON position, PCM turns on electric fuel pump by energizing fuel pump relay. PCM keeps pump on if engine is running or cranking (PCM is receiving reference pulses from ignition module). If there are no reference pulses, PCM turns pump off within 2 seconds after ignition is turned on.
Most models also include a second control path through the oil pressure switch which will turn the fuel pump on after the switch detects oil pressure. Cranking time will be longer if fuel pump does not receive current until oil pressure switch contacts close.

We started this project by thinking it was just a bad fuel pump replace pump and it did not work so then removed pump and check wires for power at the tank.

from relay orange wire/relay pin A6/C2 is HOT all times to PCM 12volts grey wire/relay pin F1/C3 is feed to pump dark green white wire/relay pin A10/C1 is fuel pump control signal from PCM which would then put power to grey wire/relay pin F1/C3 black wire/relay pin F7/C2 is ground could you tell me what color wires you have at the pump ... my diagram is showing.. grey .. relay feed wire, hot @ key on for 2 seconds then hot @ cranking and hot @ engine running .. then 2 black wires which are grounds .. and a purple wire going to the PCM which is fuel level signal .. if you are hot @ the relay you must have a break/short in the wire between relay and pump .. let me know ..

just installed a new fuel pump because i thought the old one was bad. when i try to start my truck im not hearing the pump come on. ive checked all the fuses and checked the filter to see if it was clogged. my pump is not working is all i can figure because there is no gas makeing it to the filter. ive heard that there is a low oil pressure fuel cut off valve on this model of blazer, could this be the problem?

Welcome to the forum, thanks for the donation. Did you check voltage circuits at the fuel pump relay? Voltage to load side of relay should be hot all the time. Voltage to coil side of relay goes hot for a few seconds, key on, and hot with engine cranking. Voltage to the coil comes from pcm. Can you check for codes?

I have power to one of the 4 fuse entry ports, but after that nothing with the key in the on position.

The green wire with the white tracer is voltage for coil side of relay, hot for a few seconds when you you turn key on, no crank. Engine cranking, should be hot all the time. If nothing there, take circuit loose at both ends, check for continuity, if no continuity, replace wire. If continuity ok, check for pin voltage for that wiring circuit at the pcm. It may not be 12 volts, it maybe 5 or 6? If no voltage when there should be, you need to check the pcm.

What is the PCM and where is it?

On your vehicle, it may be called vcm, vehicle control module. Under the hood,passenger side front. You need to do some testing, before replacing anything.

Do all of your dash lights and radio come on when you turn the key forward?

yes, i am getting power to my dash. but to let you know, i did get the thing running. After going back and checking all the fuses and relays, i found that a celnoid on my injection sustem was grinding and makeing a bunch of noise. I took the thing loose from the side of the injection system and cleaned it, put it back on and Bin-Go power went to my fuel pump and the truck fired up. Im going to replace this old celnoid with a new one. Thanks for your help. You got me headed in the right direction and the rest was just back tracking. Thanks again.