antfarmer2

I would take a much closer look at that hose we are missing something here. Are you sure the filter is not in backwards and clear?

1stVetteFinally

I don't know how I could look at it any closer than I did without an MRI machine. I removed the complete assembly and looked at it very closely. I'm 99.99% sure the hose is good.

As for the filter, I remember making sure the filter was put in correctly. That thing was a serious pain in the *** to change. Why would they put it in such a tight spot? Looking inside the tank, I don't see trash in the bottom of the tank. Since the filter is less than 6 months old, I doubt it's clogged already. It could be, but I doubt it. Besides, as long as there is no fuel leak at the filter, how could it be the cause of the loss of fuel pressure? If the filter was the cause of the pressure loss, wouldn't it be leaking fuel also?

antfarmer2

Well it pumps up fine from what I hear it just can't keep up when running a cloged filter will do this without leaking. They are not that bad to change if you do it right. Clamp off your fuel line then take the line off the back of the filter and disconnect the return line next to the filter. Then go up top and release the lines you need a tool for this but just a cheap piece of plastic. Then pull the lines out with the filter change the filter and reinstall. your looseing pressure but not fast enough to keep it from running imho.

1stVetteFinally

I understand what your saying, but that wouldn't account for losing 35 PSI of fuel pressure in 10-15 seconds of the the pump shutting off, would it?

antfarmer2

No but think it would still run doing some looking might be the icm it tells the puter what to do after starting. And looseing that pressure was without the clamps right. Most fuel pumps don't have the cheack ball system the original had for the goverment

antfarmer2

If it's not the filter. I have been doing some reading for you and might be the puter itself this is past my pay grade do some reading and ask others that know.

antfarmer2

Take a look at the icm clean connections and the ground

1stVetteFinally

icm??? How can I test it?

correct

well that just completely screws my line of thought I had going.

1stVetteFinally

will do

1stVetteFinally

thanks for your help

antfarmer2

Wish I was closer hard to do without seeing but think we are getting close.

antfarmer2

Look on youtube to check for codes with a paper clip

antfarmer2

Found this might help



I have a 1992 Corvette that isnt gettign fuel to the fuel injectors, pushed the check valve on the rail and nothing, took the line to the filter loose, no fuel.

I would liketo check the fuel pump relay before I just automatically assume its the fuel pump, but cant seem to locate the fuel pump relay. Anybody care to chime in with a few ideas/suggestions?
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Old 06-13-2013, 09:59 PM #2
seabright
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May help (?):

http://www.digitalcorvettes.com/foru...d.php?t=131407
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Old 06-13-2013, 10:14 PM #3
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helped a little as to how to systematically trouble shoot an issue but I'd still need to know where the fuel pump relay is as I dont believe it is on the firewall on the 92, mine runs along as you continue to spray starter fluid in the intake.

But did test pressure on the shrader valve by the injectors and found none.
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Old 06-13-2013, 11:00 PM #4
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still need to know where the fuel pump relay is
Fig 23

Click the image to open in full size.
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Old 06-14-2013, 06:28 PM #5
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Getting to the Fuel Pump Relay is a PITA (ask me how I know this). Putting the whole mess back in place is also a bit on the dificult side.

In the LT1 equipped C4's the fuel pump is powered in one of two ways - 1) during start the PCM turns on the fuel pump via the fuel pump relay - and runs it for about 2 sec (or when cranking). 2) when you have oil pressure, the oil pressure switch sends power to the fuel pump. Personally - I think it's a lot easier getting to the oil pressure swtch at the upper back of the motor. I believe the orange wire (Pin C) is the power feed, and the red wire (Pin D) is connected to the fuel pump. (I beleive you can also jump power to the fuel pump though the 10 Amp Fuel Pump Fuse - which the FSM shows as After the oil pressure switch and Fuel Pump Relay - but I'm not 100% sure of that).

Do you hear the fuel pump run when you turn the Ignition to "ON". Normally you can hear it - if you can't you may well be looking at a fuel pump replacement.

GOOD LUCK !!!
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Old 06-14-2013, 09:06 PM #6
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Getting to the Fuel Pump Relay is a PITA (ask me how I know this). Putting the whole mess back in place is also a bit on the dificult side.

In the LT1 equipped C4's the fuel pump is powered in one of two ways - 1) during start the PCM turns on the fuel pump via the fuel pump relay - and runs it for about 2 sec (or when cranking). 2) when you have oil pressure, the oil pressure switch sends power to the fuel pump. Personally - I think it's a lot easier getting to the oil pressure swtch at the upper back of the motor. I believe the orange wire (Pin C) is the power feed, and the red wire (Pin D) is connected to the fuel pump. (I beleive you can also jump power to the fuel pump though the 10 Amp Fuel Pump Fuse - which the FSM shows as After the oil pressure switch and Fuel Pump Relay - but I'm not 100% sure of that).

Do you hear the fuel pump run when you turn the Ignition to "ON". Normally you can hear it - if you can't you may well be looking at a fuel pump replacement.

GOOD LUCK !!!
I think this is a better approach. The relays really don't go bad very much. It is easy to pull the pump or just check for power if necessary by getting to the connector of the pumps power in the rear of the car. Four screws for gas cover and remove rubber and there's the connector.
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Old 06-14-2013, 09:32 PM #7
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did a little work in the garage today, tested the fuel pump and relized it was bad, repalced it but the new one still isnt getting power(only works hot wired) the sending unit(purple wire) is getting power but not he fuel pump wire(gray wire)
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Old 06-14-2013, 10:01 PM #8
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Re-check fuse #14. Then makes the checks purple92 suggested. It's possible you blew a fuse under the hood in fuse block 1 but it's doubtful.

Are you sure no power is going to the pump. Just a double check to make sure the pump has a good electrical connection and is grounded. Just a suggestion.
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Old 06-15-2013, 08:50 AM #9
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Re-check fuse #14. Then makes the checks purple92 suggested. It's possible you blew a fuse under the hood in fuse block 1 but it's doubtful.

Are you sure no power is going to the pump. Just a double check to make sure the pump has a good electrical connection and is grounded. Just a suggestion.
yes the gray wire at the pump harness is showing no currrent, but I will check the fuses, the pump works if you apply direct current to the gray wire
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Old 06-15-2013, 09:38 AM #10
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If you check for voltage at the gray wire you will not have it if the engine is not running. It is only there for the first 2 seconds when the key is turned to the ON position. So you have to monitor as you turn the key to ON.

Once the engine starts, the relay is held closed by the ECM and voltage is also sent to the pump from the switch which is activated by oil pressure (redundant power).

Another simple test to try is to connect your voltmeter to the gray wire and crank the car. You should be able to build up enough oil pressure to close the switch. Might give you additional information and a clue.

Another interesting test is to run the pump with external power. Then try to start the car and see if it runs. At the same time monitor the gray wire with a voltmeter and see if voltage appears on it. If it does, that might mean the oil switch is working and the problem is in the relay circuit.

If no voltage appears on the gray wire when the engine is running, then I would check the fuses under the hood in fuse box 1.

You get the idea.
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Old 06-23-2013, 06:14 AM #11
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thanks for all the input everybody got the fuel pressure issue addressed, had to replace the fuel pump, and after a few on & offs of the switch finally got itfired up, now I have to address the idle but I'll do another post for that

antfarmer2

Sorry more than I wanted but look where the oil pressure takes over bet this is it

1stVetteFinally

pulled codes, module 4, code 15 and 55

TLS_Addict

Coolant temp sensor and lean condition?

antfarmer2

That coolant sensor on the water pump is connected to a lot of things might be on to something. Becarefull not to get your opti wet don't want to start more $%$#

Cliff Harris

The oil pressure doesn't normally "take over". It is a BACKUP for the fuel pump relay. It only "takes over" if the fuel pump relay fails.

You can force the fuel pump to come on by disconnecting the oil pressure switch and connecting the orange and red wires together in the connector.

1stVetteFinally

so what would you people suggest my next course of action should be?

antfarmer2

I would try Cliffs trick.