I have a early 86 vette with a fuel pump problem and was wondering if any one could help. My vette had a fuel leak in the rubber hose of the fuel feed line and would not crank. I replaced it and I also replaced my fuel injectors about a week ago. The car had been sitting up for about a year and a half do to replacing the fuel line. When everything was fixed I went to turn the ignition over and I noticed the fuel pump did not prime for the 1 or 2 seconds that you can hear. The car turned over fine and back fired an time or two but that is all, it will not crank. I have read up on the fuel system and have checked the fuse and relay. I am not getting any power the the fuse and the fuse is good. I tried to run a hot wire from the G terminal under the drivers dash connector to the relay and nothing. I tested the relay and it has 4 wire going in and only one (orange) is hot. I think that the wiring goes from the ignition to the fuse panel to the relay and then to the fuel pump but I could be wrong. The wiring does not look to be in bad. I also tested the wiring at the fuel pump (tan w/white, pink, and black(ground) and nothing. I also tested the wiring on the back side of the fuse panel and traced it to the ignition and tested, nothing. I think I might replace the relay but would like to know if anyone has had to deal with this problem. I would like to know how to fix it, is on my last nerve. Thanks

 

The ecm triggers the fuel relay to send power to the fuse then the pump. The oil pressure switch will suppy power to the fuse when a few pounds of oil pressure is reached (back up power if relay fails)
The ecm will only power the relay for a few seconds and then again when it receives reference from the distributor.
Heres some good reading from my 86 factory manual.
http://members.shaw.ca/corvette86/Co...0View%2086.pdf
http://members.shaw.ca/corvette86/En...ButWontRun.pdf
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
http://members.shaw.ca/corvette86/Fu...l%20System.pdf

 

Your symptoms are fairly common, however there can be several causes. Before you can make much headway, you're going need a couple of tools. One is a fuel pressure gauge, to verify just when, if ever, the pump pressurizes the system and at what times. The second is a factory service manual. It would appear that you have some sort of guidance. Terminal "G" of the ALDL is indeed connected to the fuel pump wiring. Why did you happen to run a wire to the fuel pump relay and to which terminal? Applying 12 volts to terminal "G" should make the pump run. Although the fuel pump is electric, nothing in the fuel pump circuitry should keep the engine from cranking. "I have read up on the fuel system and have checked the fuse and relay". With a little more studying you will realize that the fuse only receives power when one of the sources is powered up to run the pump. Get some tools, a DVOM, a manual, and a fuel pressure gauge.

RACE ON!!!

 

should have been running 12 volts to terminal G to check or run fuel pump.Have you checked your fuses? No cranking, are you
sure your battery is fully charged? and I'm wondering about a possible
vats problem-hope you get the service manuals-they're well worth the
few $$ they charge.

 

My battery is new, my fuses are all good, and there is gas in the tank. I would not need a fuel pressure guage unless my car was running, no pump no pressure. I ran a 12 v wire from the battery to G terminal and no pump noise. I also ran a jumper wire from the hot wire on the relay to the one next to it (should turn on pump) and nothing. Strange because the car ran before the fuel line cracked. If the wiring is ignition, relay, fuse panel, then pump, It is probably my relay! Thanks for the suggestions.

 

The battery was suggested because rarely does, "a fuel leak in the rubber hose of the fuel feed line" cause "and would not crank"


A pressure gauge could detect pressure from a pump that runs, but that you can't hear.


Maybe the new battery is defective.


It is...and it isn't. A factory service manual would spell out out for you and help you find the true cause. Why would it be "probably my relay"? We are trying to help, here, but you rebuff all the valid information. Good luck.

RACE ON!!!

 

Hey guys, thanks for helping. I am going to get my hands on a service manual. I tried the battery in a different car and it worked fine. Someone told me that I could push the valve where you check fuel pressure and it should spray a little gas, tried it and nothing, don't now if it should or not. The only reason I mentioned the relay is what agent 86 said about the ingition going to the relay then to the fuse panel. Only one hot wire going in and no hot wire coming out. I just don't know, so I will purchase a manual.

 

RRT Where are you located?. if you are near north jersey I have original factory manual.

 

That is part of what AGENT 86 said. I didn't click on them, but AGENT 86's .pdf files didn't help? Once you've had a chance to study your new manual, let us know if there are any details we can help you with. When you get a chance to study the manual, it will be a lot clearer.

RACE ON!!!

 

I never said the ignition went to the relay, the ecm sends power to the relay. The 12 volts you see is direct power from the battery through a fusable link. That is the 12 volts that the relay sends to pump. The ecm sends 12 volts to the coil in relay so it can inturn transfer the battery 12 volts to pump.
Read the pdf's, there is good info in there

 

It sounds like a dead pump, but there's still a chance the relay is bad.

If you have a 4+3, swap plugs with the overdrive relay, they're exactly the same.



Everything you've attempted so far is still trying to power it through the relay. Even the ALDL plug goes through the relay. Unplug the relay and short wires A and E of the relay harness together. This will send 12V to the fuel pump fuse and to the pump.

If that doesn't turn it on, then you've got a dead pump or bad wiring to the pump. Some have had issues with the wire connector right above the fuel tank. You have to remove the gas door and rubber boot to get to it.

 

At the back of the block next to the distributor,drivers side ,You will see a plug going into a oil sending unit .Pull off the 2 wire connector and put a paper clip into the connector contact both terminals and turn on the key see if you get fuel to the rail or hear the pump humm.

 

Hey there, I live in Lousiana as of now. I will try to use a jumper wire from wire A to E at the relay connector to see if that will work. I will try the paper clip trick at the oil pressure connector too and I will also check my junction box beside the battery to see if all wires are connected. I bought a new relay but haven't tried it yet. I have checked the connector under the gas door and everything looked good. Seems to me if I can't get power to my fuse panel for the fuel pump then it won't power my pump. The fuse panel on my car says FR and I would guess this is the fuse for the pump(#10 fuse). Also the fuse next to it says INTS and it is dead also(#3 fuse) and both are located at the bottom right on the panel. I will have time this weekend for these. If I can get power to the pump I will let you guys know. If there are any other suggestions I am all ears. Thanks for all the good info. I will get it running one way or another.

 

if the fuel pump is good, even if the relay were bad the fuel pump
would work after cranking caused the oil pressure to reach 4 pounds.
the valve you're refering to is the schrader valve, and yes, if the fuel
pump is actually working you should be able to depress the valve and
have gas come out.I suspect the fuel pump-or the wiring to it.Just
my 2 cents though.BUT-a bad fuel pump or relay will not impede the
engine from cranking! You need to be able to trouble shoot the cranking issue first.

 

My car will turn over fine but not crank. There is no pressure at the Schrader valve. I checked the oil sensor with a paperclip, and jumped A and E on the relay connector. When I do this I hear a click next to the battery but not fuel pump charge. I replaced the relay but with no luck. I wonder if the ecm needs to be checked? Like I said the car sat up for over a year with out being cranked. I have had the car for about 5 years now and only drove it about 25 miles. I hope the service manual can lead me in the right direction.

 

If you are jumping the correct terminal on the correct relay than you should be able to see some power at the fuse. If you now have power at the fuse and pump is not running than you have a dead wire going to pump or the pump is dead.

 

Hey it worked, I jumped a wire from the hot wire on the fuel pump relay to the last wire on the relay and I got power to the fuse. I didn't hear the pump come on but I will try to crank it. I wonder why when the new relay is on it want power up the fuse? I have to run to town now but I will try shortly.

 

Your fuel pump is dead, or the connector is junk.

 

I pulled my fuel pump today and I was wondering what kind to go back with. Will any fuel pump do or is there one that would be better. The car has minor upgrades. Also I have the jumper wire in the A and E terminal of the relay harness and am getting power all the way to the pump now. When ever I go to crank the car the fuse blows. If I unhook the fuel pump connector and try to crank it the fuse is still good. Could a bad pump cause the fuse to blow? Thanks for the help looks like I will have her cranked soon and that gremlin out of my car.

 

I went with a NAPPA fuel pump, sock, and filter. But before you go out and buy new components-check where the fuel pump electrical connections where you attach the new pump are clean and
corrosion free-some here on the forum have reported problems in this
area.