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Fuel pump and engine wiring

Tiny
MIKE PAGAN
  • MEMBER
  • CHEVROLET BLAZER
I have '95 chevy blazer with4.3 and 189000 miles. The car has a check engine light on. It's been on for a while. The problem I am having now is the car shuts off on me. It usually happens when I am going over 50. I changed the fuel pump two months back. The mechanic says it is either the fuel pump or the wires t0 the pump. I think it might be the wires. If so, how much of the wires do I have to replace? Any info would be helpful. I cannot make a donation at this time, but will make one in the weeks to come. Thanks, Mike
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Wednesday, November 14th, 2007 AT 10:50 AM

10 Replies

Tiny
RAYT333
  • MEMBER
  • 27 POSTS
I doubt it is the wires, first make sure of the actual pump pressure. If it is too low then maybe the pump they used was substandard and isn't putting out enough pressure.
If pump needs replaced then use a AC brand pump and take a close look at the wires to make sure they are in good condition.
I had one blazer where the wire on the inside of the tank got brittle and broke and I changed 2 pumps before I found the problem.

As a side note, I now cut a hole in the floor of my own blazers (I have 2) to access the pump without dropping the tank, much easier and faster and you can cover the hole with a thin metal plate and put the carpet back mover it and you can't even tell it was done. Here are the engine wiring diagrams which include the fuel pump. Check out the diagrams (Below). Please let us know if you need anything else to get the problem fixed
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Sunday, November 18th, 2007 AT 4:06 PM
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Get the check engine light OBD code/s read and comeback with it.

Could be the fuel pump relay, fuel pump/oil pressure sending unit or a bad pump again. Electrical diagram for the fuel system see below


https://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_15.gif



www.eautorepair.net
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Sunday, November 18th, 2007 AT 4:33 PM
Tiny
BRAVESFAN2006
  • MEMBER
  • 1 POST
  • CHEVROLET BLAZER
1995 Chevy Blazer
2 door 4.3L Vortec V6
150,000mi

Hi, its a 1995 2-door 4.3L Vortec V6 chevy blazer w/ 150,000mi. When I start the truck, it was alright for about 5 seconds (this morning) and then I can hear clicking about every 3.5 seconds. On the 1st click, the engine throttles down from 700rpm to about 500, and about a half second to a second, (varies slightly) a second click occurs, and it throttles back up to 700rpm (all in idle state) When I am driving, it continues, and you can really feel it. I fairly certain it happens more often when you are rolling, but I haven't timed it.

I do generally have to tap the gas to get the truck to start, and wasn't sure if this would be related or not.

I've had this happen once before. It went away after a day or so, so I wasn't able to trouble shoot much. The last time this happened, and this time, the drivers window will raise, but not lower. When you try to lower it, the E-Brake light kicks on in the dash, and the rest of the internal lights dim (have not checked headlights).

Any suggestions would be greatly appreciated!
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
2CARPRO JACK
  • MECHANIC
  • 11,533 POSTS
Makes me wonder if the window motor is shorted and you are hearing the breaker kicking and feeling the alt load down the engine in response to the voltage draw. Try removing the silver circuit breaker in the fuse panel and see if it still does it. PM me back
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
PAPO2591
  • MEMBER
  • 1 POST
  • 1992 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 93,000 MILES
I just put a new fuel pump in and I'm not getting any power to the pump I traced the wire all the way to th relay but still nothing even changed the relay still nothing is there a fuse for the punp cause if so I can't find it please help
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Check the ECM B fuse-Nothing there could be the computer not energizing the fuel pump relay. See diagram below


https://www.2carpros.com/forum/automotive_pictures/12900_oil_sending_unit_and_fuel_pump_circuit_3.gif

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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
DARREN BILLING
  • MEMBER
  • 1 POST
  • 1995 CHEVROLET BLAZER
  • 4.3L
  • V6
  • 4WD
  • AUTOMATIC
  • 100,000 MILES
Will not start unless fuel or aerostart is poured in, then only until that is burnt off. New fuel pump, new relay, wiring check, direct jump wire to pump for checks bypass, pump is working, fuse and holder ok, fuel pressure with test gauge to spec and holding, no fuel smell anywhere, plenty of spark from coil and at spark plugs, no codes showing. So all seems good to manifold, however car did run and just stopped dead, now not starting at all. I have run out of ideas, can you please assist?
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
WRENCHTECH
  • MECHANIC
  • 20,761 POSTS
If it's not running at all then it shouldn't be hard to determine the cause.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
KDSHELLEY
  • MEMBER
  • 1 POST
  • 1995 CHEVROLET BLAZER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 18,500 MILES
Changed plugs, replaced coil, still missing sounds like has a fouled plug or plg wire off, checked wires & plugs not the problem
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)
Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
Misfires can be caused by worn or fouled spark plugs, a weak spark (weak coil, bad spark plug wire), loss of compression, vacuum leaks, anything that causes an unusually lean fuel mixture (lean misfire), an EGR valve that is stuck open, dirty fuel injectors, low fuel pressure, or even bad fuel.
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Saturday, September 7th, 2019 AT 12:47 PM (Merged)

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