Ok I have a kid at work who has a 87 project that has turned into his daily driver anyway were marines so he is poor and im trying to help him out with this problem.

He took the car to the barraks to see some other guys and when he came back out to start the car it would turn over and no start.

Im used to the fuel pump being the problem so I sujested that, He changed it today brand new pump and guess what nothing im not one to assume the old and new pumps are bad and looking at the circuit Im pretty sure its the fuel pump relay but I went over there without any tools (only had the 87 shop manual) I couldnt put power to the pump itself i guess you can take a wire from the positive bat terminal and hok it to the G pin in the aldl conector to get the pump power?

Im pretty sure its that relay, its a auto or I would have swaped the 4+3 relay to see if it would work but I want to rule out wiring.

Also the conector for that relay was nasty exposed wires almost like they have been pulled out I dont like the way it looks but maybe its some good old GM engineering thats almost 20 years old :LOL:

any sujestions on checking this thing and also are these relays available at like autozone?

im going to check just wondering on your experience.


thanks

johnny

 

If the relay is bad, the back up power supply(oil pressure switch) should have fed the pump power. Applying 12 volts to terminal "G" will send power to the pump as long as the fuse is good. Did he test for fuel delivery and spark ??
The shrinking wire insualtion is VERY common on the older C4's. Shrink tube should make it safe again.

http://members.shaw.ca/agent86/Fuel%...elivery-8A.pdf
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf

 

As Agent 86 suggested, when powering terminal G it sends power to the fuel pump circuit as long as the fuel pump fuse is good. This should tell you if the relay is bad. You can also use a short wire and insert it in the first prong and last prong on the fuel pump relay connector. This will bypass the relay and send power from and too. Also when the terminal G is powered you can use a test light on the fuel pump fuse and/or on the fuel pump connector. The test light should light up at either place while the terminal is powered. The oil pressure switch is the backup for the fuel pump relay and if it is good it should start the engine after extended cranking time. Hope he wired the pump correctly before bolting the assembly down..but not a big dead, just have to remove it and do it again.

Check for spark while cranking by using a spare spark plug in each wire and touch the exhaust manifold. There should be spark on all 8 cylinders.

They these things and see what you come up with. Use shrink tubing and a hair dryer or liquid electric tape on the fuel pump relay wires that are exposed.

 

well in not even worried about spark becasue there is no fuel pressure at the fuel rail..

what fuse is it for the pump ?

 

10 amp fuse in the passenger side fuse panel.

 

ok finaly got togeher with this guy and tried the relay jumper had spark there so it has power but didnt get the pump running.

so I went to look for the fuel pump fuse and all of thw writing on his fuse panel is worn off so I dont know what is what.

can anyone post a picture of the fuse panel and what locations are what??

thanks

johnny

 

when you're looking at the fuses it's the second one from the right on the lower row.

 

I'd replace the fuse even if it looks good (trust me, it's cheap), and manually excite the relay on the driver's side firewall with some alligator clips and the key in the "ignition" position. Use your ears, and the fuel port test schraeder on the passenger side fuel rail to verify fuel pump operation and pressure (with a gauge preferably). If the pump still doesn't work, get out the good old test light and follow the wiring. Good luck!!

 

Mine is the bottom/right corner =10 amp fuse

 

Try this.

 

ok riddle me this how do I get 12 volts to terminal G

do I kjust ground it to terminal A?

because I tried that and nothing from the pump

I need it broken down barny style im a mechanic not a wire chaser

 

What I did is use a speaker wire (16ga) and tie into the positive terminal on the battery and stick the other end into terminal G. This should power the fuel pump circuit if everything is correct. It will send 12v until the jumper wire is removed.