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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11380
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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1994 Chevy Blazer: Vortec..4.3L..The other night i filled up with gas

Resolved Question:

I have a 1994 Chevy Blazer with a Vortec 4.3L CPI. The other night i filled up with gas and went home. It was about -3 that night. In the morning I went to start the truck and it appeared the battery was low. Its only a 650 cold cranking amp battery and the battery light was flickering so I decided to give it a quick charge. It started after 15min of charging. The truck ran for a few minutes but had to be kept around an estimated 2500rpm. Too little throttle or not enough and the engine would slowly die. I brought the truck to my parents shop and tested the battery, alternator, air filter, spark from the plug wires, fuel filter and fule relays. Also replaced fuel filter, distributor cap, rotor, plugs and wires. The engine is reading code 54. Which could be the ecm, mixture control or the amount of power getting to the fuel pump. I am not sure what to try next. The truck has 250000km on it and has always ran decent. Any ideas?
Submitted: 4 years ago.
Category: Chevy
Expert:  Randall C replied 4 years ago.
Hello, did the check engine light come ? if so, did it come on after the battery jump or later when running poorly?
Customer: replied 4 years ago.
There has been no check engine light on. I just made sure that when the ignition is on that there is power going to the cpi, which leads me to beleive that the ecm is working and that the problem may be bad wiring inside, bad fuel regulator or damaged cpi unit. Does this make sense? It is my first time working with a cpi injected engine.
Expert:  Randall C replied 4 years ago.
So to understand, the code 54 could have come along at anytime since you did not get a light on may mean stored in memory. is this what happened?
Customer: replied 4 years ago.

It could been saved in the memory. I have had the vehicle 3 years and this is the first time i have used my code reader. The check engine light has never come on before during my time with the vehicle.

Expert:  Randall C replied 4 years ago.
Thanks. so its running but very sensitive as per throttle like not getting enough gas?
Customer: replied 4 years ago.

Will not start. Has fuel in the tank, fuel pump works, has spark at the plugs but will not start.

What could be the solution?

Customer: replied 4 years ago.

Would a lack of gas from the pump cause the engine not to run at all? Should a fuel pressure test be done?

Expert:  Randall C replied 4 years ago.

Unsure yet. we need to be sure the fule is getting from the pump to injetctors and that injectors are allowing fuel in the engine. To di this, a fuel pressure test is needed but you can try a couple things. The easiest is to gently spray some carb cleaner in the throttle body then try to start. If it starts, we have to go to fuel problem. ) injector drive, pump etc) If not, lmk./ The other thing to do but be very careful is to lay a towel around the fuel pump test port and while cranking, push the pintle in like letting air out of tire. Fuel may spray out so keep face clear and rag around the area. the lcoation of the test port is on drivers side of engine just bhind the intake and sticking up out of the fuel line. It may still have a black plastic cap on it. see below. #20 and #19 LMk thanks

 

 

graphic

Customer: replied 4 years ago.
I just went out and bought a fuel pressure tester. I also tried using carb cleaner but no luck. When I turn the key to start the truck it goes up to around 40psi for about a secound, then drops to zero.
Expert:  Randall C replied 4 years ago.
Youn have one or more poppets stuck open and the fule is going directly into the cylinders and the engine is flooded. If you pull osme plugs, you will find wet ones either 1 or more. You fule meter assy is bad. This was such a problem with his design and we have replaced many
Customer: replied 4 years ago.

I am going to pull off the intake manifold tuning valve assembly to see if there is leakage inside. I removed all plugs and had no gas leakage. Sould the fuel meter assemby be replaced? Check the fuel pump for proper power? Should the pressure from the pump be constant?

Expert:  Randall C replied 4 years ago.
The fule pump comes on initially with the key then stops, it then starts again while cranking. If it builds to 40PSI +/- and drops quick you either have a bad fuel. pressure regulator or one or more stuck poppets ( injectors) the regulator is part of the meter assy under the intake. Once you get the upper intake off, you could have fule laying on top of lower intake or fuel is getting into cylinders from bad poppets but may ne be showing on plugs. it did not start with spray. the pressure drops quick, it will not start. All this does add up to something with the meter assy ( injector assy). tyhe fule pressure should stay around 38-40 psi after you key on/off and hold there a good while
Customer: replied 4 years ago.

The fuel pump is working fine then. Could thick, very old and cold oil cause an engine not to start? I am taking off the intake manifold.

 

Expert:  Randall C replied 4 years ago.
Not normally. You did say a couple posts back the fuel pressure went to 40 then dropped quick. This is regulator or injector problem only. this would not be a bad pump. The pump is working to build pressure but systme is not holding it
Customer: replied 4 years ago.

When the intake manifold comes off what should I inspect? fuel regulator, cpi unti, leaking lines, stuck ploppets?

Expert:  Randall C replied 4 years ago.

You would need a special tool to block off the return line to confirm bad regulator, As far as poppets, you can do same thing but will have to have the poppets up and out of their seating . If there is raw fule laying on lower intake after upper is off, this is sign of bad unit as well

 

PROCEDURE

  • Connect fuel pressure gauge.
  • Block off (pinch) return line.
  • Power up fuel pump (engine "OFF") by applying 12 volts to fuel pump "test" terminal.
  • Verify fuel pressure is stabile and remains constant.
  • Visually inspect injectors for evidence of fuel dribbling.

 

Customer: replied 4 years ago.
Do you know where the fuel pump test terminal may be found?
Expert:  Randall C replied 4 years ago.
graphic
Customer: replied 4 years ago.

So i just hook up 12v power to the pump should start? does the connection need a ground?

 

 

Expert:  Randall C replied 4 years ago.
that is correct. the pump is already grounded. just jump wire from battery POS to test connector
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 11380
Experience: ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
Randall C and other Chevy Specialists are ready to help you
Customer: replied 4 years ago.
I just got the manifold off

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Randall C
Randall C
Chevy Mechanic
11380 Satisfied Customers
ASE Master, L1, 32 years, Diagnostic / Electrical Specialist