Fuel pump relay?

Tiny
BADASSTRUCKOWNER
  • MEMBER
Ignition switch tested good
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
GEORGEWALDROP
  • MEMBER
I have this almost exact scenario, with the addition of when the situation originally manifest the fuel gauge began reading hard over past full. I have not replaced the pump/relay as yet, but in testing both appear to be working when forced (by bypassing segments).
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
HMAC300
  • EXPERT
If you can't scan for codes then it won't run if you don't know what is wrong.
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
ASEMASTER6371
  • EXPERT
Good afternoon.

Can you clarify your issue?

In the first sentence, you stated power back to the pump and then you state there is no power to the pump.

Can you clarify?

Roy
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
GHOSLEY
  • MEMBER
  • 1991 CHEVROLET SILVERADO
Electrical problem
1991 Chevy Silverado V8 Four Wheel Drive Manual

My problem is that the fuel pump is not getting any power when plugged into the wire harness at the pump. When unplugged I test that there is a full 12 volts going directly to the pump, but when plugged back in it cuts down to 0 volts. I have replaced the pump and the fuel pump relay. The pump fuse is good as is the grounding at the fuel tank. I have come to a dead end!
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Have helper crank engine over and recheck the power.
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
GHOSLEY
  • MEMBER
I tried that a couple times, testing all wires in the pump relay harness

Could it be the ignition switch?
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
2CEXPT
  • MEMBER
The computer energizes the fuel pump relay-when the engine fires up-the oil pressure sending unit powers the fuel pump


https://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_66.gif



Check the inline fuse 20amp see item no.15 below


https://www.2carpros.com/forum/automotive_pictures/12900_fuse_7.jpg

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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
2CARPROS-ARCHIVES
  • MEMBER
  • 1993 CHEVROLET SILVERADO
  • 78,000 MILES
I have no spark and no fuel spraying out of the tbi and fuel to the tbi. I have changed the coil, cap, rotor, module, and fuel pump relay. Thinking it may be the computer not sure.
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
Some testing is required and you would need a testlight or DVOM to start with.

Was anything done prior to this occurring?
Did you check for trouble codes?
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
MUNCH3MAN
  • MEMBER
No spark check your Ignition Control Module
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
DIABLO63
  • MEMBER
  • 1991 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 220,000 MILES
Looking for information on 1991 Chevrolet C1500 V8. Need the voltage readings, with ignition 'ON' and 'OFF', for Fuel Pump & Fuel Pump Relay connections.

The fuel pump does not turn on when you first turn the ignition key 'on'. Checked fuse and relay at the firewall, both are good. I brought and installed a new fuel pump with strainer.

Engine runs fine when fuel is poured down the TBI throat, so I know I have spark condition. Just not getting the fuel to TBI is the problem.

Any help/suggestions would be greatly appreciated.
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
KEN
  • ADMIN
Hello, it sounds like the system is not getting power, remove the fuel injector connetor, with the key on check for 12 volts on one side of the connector and get back to me.
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Tuesday, June 23rd, 2020 AT 5:30 PM (Merged)
Tiny
STICHSR
  • MEMBER
  • 1993 CHEVROLET SILVERADO
Where is the relay or fuse located on my 1993 silverado for the electric fuel pump
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)
Tiny
BMRFIXIT
  • EXPERT
On right side of firewall it has fuse and a relay for the fuel pump
some times its covered with a plastic shield
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)
Tiny
CHEVY MAN 22
  • MEMBER
  • 1993 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 228,000 MILES
Ok, here is the deal the other day I went to start my truck up. First try didn't start thought it was odd usually it starts on the first try. Second try started right up, drove it to work and parked it, later when I got off work went to start it and would not start up. At first I figured the fuel pump went out. So I had to tow it home, next day I replaced the fuel pump motor and strainer only, along with the fuel filter. Hoping it would start, It didn't It turns but will not turn over to stay on. I then sprayed the TBI with starting fluid and it started but was Idling real bad, none the less I stepped on the pedal to give it some gas when I would let go of the gas pedal it Idling bad still, I could see the gas shooting from the TBI into the carb but it was shooting in spurts not a constant flow. I thought that was strange. After awhile it would shut off and would not start on its own again. It was getting late so I figured I would work on it the next morning. Next morning I went and tried to start it once again, and to my suprise it started on its own when I turned the key. No problems at all was Idling perfect as if nothing had happend. I left it for awhile while warmed up, I then peeked into the carb again and I could see the TBI was shooting gas into the carb with a constant flow no interruptions at all. I thought maybe it would be back to normal again, then I decided to take it on a test drive down the freeway, drove it at around 65-70mph for a ways no problems up and down. When I came to a stop light after getting off the free way I felt a jerk like it wanted to shut off, but it stayed on good thing I was close to home. When I pulled up to my house it just died on me no shaking no jumping just dead in drive. I then tried to start it up and it started but then it would die when I would put it in gear. Now I'm stumped. After a bit the temp gage went up close to 210 while the truck was off. That too was odd because I had changed the radiator a few years back to a larger one and it never got hot past 120 not even on hot summer days above 100 degrees especially when I would shut it off. So that was weird I thought. Then I tried to start it and it would not I looked into the carb and I'm not seeing any fuel coming from the TBI anymore bone dry. I checked the codes and at first I got code 54 which according to the repair manual it states "Fuel pump Circuit (low Voltage) what ever that means. I don't have a clue on it. Then I read somewhere about maybe the fuel pump relay switch which I replaced and still no luck, I ran the code test again and now I get codes 22 and 54. 22 is for Throttle Position Sensor (TPS) circuit signal low voltage. Again no clue what it means. Can someone please point me in the right direction as to how I can fix my truck. I really need it for work and I'm running out of options or clues. I'd can't really afford to take it in to the shop. That would have to be last resort. This just all happened out of the blue no signs of it going bad nothing. Also I've heard mentioned something about the fuel pressure, How do I check it where do I look for it? Any and all help is greatly appreciated. Thank you!
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Do you hear the fuel pump come On for 2secs? If so do a fuel pressure check the readings should be 9-13psi then comeback with the actual readings this is where we start-

Also measure the resistance of the injector should read 1.3ohms-I'll be waiting. The TPS can be a problem with the stalling too.
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)
Tiny
CHEVY MAN 22
  • MEMBER
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)
Tiny
2CEXPT
  • MEMBER
Next time it refuses to start do below something has to give between the fuel and ignition system

Get a carb cleaner and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light.

Fuel pump/Pressure Regulator and Injector/s checks out-start checking the ignition system-power to coil, coil/s itself, distributor pick-up, control module, Cam and Crankshaft sensors.

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)
Tiny
CHEVY MAN 22
  • MEMBER
Ok, I think I may have found the problem, after replacing the IAC along with everything else I have mentioned before. The other day it started up just fine. Idle was fine left it running for about 30min then when I went to put it in gear it shut off again. Started right up again then tried putting it in gear again and shut off. After about the third try it would not start up, it just would crank but not turn over. I was curious to see if I was getting any spark to the plugs so I pulled one of the wires and had someone crank it while I checked for spark. Nothing no spark present, I tried a different wire and still no spark. Finally it donned on me It must be the IC ignition control module. So I went out and replaced it and it started right up. Still a little weary of it maybe shutting down on my I was reluctant to test drive it. So I let it warm up for about 20 min or so then got the courage to take it around the block and hope it didn't shut off on me. The only question I have now at this point is when I put my truck in gear what should the rpm be at? When it's in park it's around 1000k but when I shift it into gear it drops down to like 250-300rpm. And if I turn my steering wheel at that moment it sounds like it wants to shut off. I'm wondering if my idle in gear is set too low. Maybe when I put the new TPS I didn't set it right. Is that even possible? And if so If I adjust the TPS a little will that do the trick I wonder. If you can tell me what the rpm should be at when the truck is in gear that would help me out. And if you think that by adjusting the TPS will do the trick. Please advise Thank you for all your help. Very much appreciated.

Mike
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Tuesday, July 7th, 2020 AT 1:35 PM (Merged)

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