Hello,

I have a 1992 Rallysport with a 350 that I converted over to a holly 650 Carb, but I am still using the intank fuel pump. Well today while I was driving down the road it shut off. Here is what I have concluded,


1: I have spark
2: It runs but no gas is being pumped to the carb, it will run with gas in the fuel bowls, so it is something with fuel delivery.


When I wired up the fuel rely I did not use the red or green/white stripe wire of the rely, and it work fine(10,000 Miles). I am using the oil pressure safety switch in the circuit, no blown fuses or fusible links, and I replaced the oil pressure switch. What else am I forgetting or any input would be helpful. Thanks Chris and I posted this in the carb section.

 

Are you using the stock Fuel Pump Relay? It's possible the relay went bad. Do you have a 'current' testing light?

Have a buddy sit in you're car, while you get underneath by the fuel tank. When you're buddy puts the key in the 'on' position..... listen for the electric fuel pump, it should start operating immediately.

If it doesn't, run a seperate 12 volt lead to the fuel pump's 12 volt wire, and if the pump doesn't go on then.... the pump is bad.

If the pump does go on, then you'll need to test for current within the pump relay. Sure, it might be receiving voltage..... but it might no be transferring it, which would mean a bad 'switch' within it. Whether it's bad or not, just pop for a new one anyway, their only $15 bucks.....

If you have you're set up running through the stock (non-hooked up) ECM, then check the ECM's fuse.

The test light is the key though....

BTW.... what kind of regulator are you running? Check for leaks.

 

I have you're wire schematics right in front of me.... tell me what wire you have where, but more importantly, which wire are you using for the 12 volt supply from the relay.... and where is it hooked up to, what source?

 

I am using the Mallory 3 Pt return style and there are no leaks, what get me it was working fine tll a couple of days ago, I put a new relay in it, yes I am using the factory one. I can apply 12 volts to the green/white stripe wire and that will turn the pump on and send fuel. I can't hear the pump when I turn the key but when I put 12 volts to the green/white wire it works. Are the fan and fuel pump relays the same?

 

When you made the swap, did you disconnect the ECM and it's sensors entirely? Or are you still running current through the ECM..... even though it's not 'hooked' up to the fuel injection.

What type of distributor did you change to?

Lemme know....

 

If the ECM is not being used, but it is still in its place..... it's imperative that you bypass it (if the ECM fuse has been removed). That Green/White wire from the relay goes to the ECM (which means it NEEDS that ECM fuse to be in the fuse box to provide 12 volts).....

If you're car ran fine for ten thousand miles, then suddenly stopped supplying gas.... and this was the wire you were utilizing the entire time (through the ECM), then it's probably just the ECM fuse, it might have blown....

 

I don't know anyhting from experience but I have heard that stock high pressure pumps tend to blow up when they are regulated to carb pressure levels. Shrug might be time to get a pump for a carb.

 

I took the whole harness out, I am also using a GM HEI 2 wire distributor. What's the red wire for on the relay?

 

Make sure you're looking at the Fuel Pump Relay connector..... and not the MAF Power Relay Connector. From right to left, tell me what colors the wires are on the pump relay (i want to make sure you're looking at the Fuel pump relay, as the other two relays share a blue wire.... make sure you're relay that you're looking at has NO BLUE WIRE)...


DOH!!! I forgot you have speed density LMAO.... forget about the 'blue' wire!

The red wire is you're load.... TO the fuel pump. Give me the color codes from left to right.....

 

Green White Stripe- hooked up to nothing

Black White Stripe- Grounded

Orange- Hooked to 12 volts tied in with the oil pressure sender switch

Red- Nothing

Gray- Hooked to oil pressure switch

Now this all worked till 2 days ago, now I went to the car tonight and it turned over and ran, checked the fuel pressure gauge and it ran at 6PSI never a problem, what gives? Thanks for the help

 

You're Green/White 'should' be hooked up to a 'key on' 12 volt source....

You're Black/White is grounded, good.

You're Orange (which is shared with you're oil switch) SHOULD be to a constant 'hot' source....

You're Red goes to the Electric Fuel Pump....

You're Grey (which is shared with you're oil pressure switch) goes to the Fuel Tank Unit....

The way you had/have you're set up, are you actually able to get a reading for you're fuel level???

Are you sure you removed the ECM harness, cuz some of those wires are connected directly to the ECM.... and there's no way (if the ECM was pulled), that those wires (the green/white and the black/white) could be left alone. They had to be either cut, or removed from the connector....