fuel cut-off relay question

[turabaka]

Well guys I've got a slight problem. Hoping somebody here can help me out, so here goes.
Put a Holley blue fuel pump in it about a year ago, and everything's been running fine up until now. About a week ago the fuel cutoff relay went out. I ran up to Schuck's and replaced it. The part lasted about 3 hours and died again. Put another one in it, and it lasted a bit longer, but still died. Put a napa one in it, and it works fine, but doesn't cut off the fuel like it's supposed to.

I'm thinking I'll just save myself the headache and use a general purpose 30 amp relay instead of the factory one. I looked through the Haynes manual though, and it doesn't tell me which pin on the stock relay goes to what.

If anybody can tell me what pins goes to what on the stock relay, or has any idea what's wrong with the electrical system to cause this I'll give you a nice cookie or something.

[2ndGenGuy]

I think you should bypass the stock wiring if you're going to use a Holley pump. The amperage draw seems to be greater than stock. When I hooked my Holley up to the stock wiring, I noticed mine ran all the time. Does yours do that too?

[turabaka]

It didn't used to run all the time. But it does with the napa relay. Now if I turn on the key to prime the pump it'll keep running instead of shutting off after a second.

so what's the pinout on the stock relay? That way I can just solder a new relay onto the pins of my broken stock relay.

[2ndGenGuy]

Does the stock relay have 85, 86, 87, 87a, and 30?

[turabaka]

Apparently I'm a tard. Opened up the relay, and it's marked on the damned board what goes to what. So the far left is ignition, then -, +, and fp.
What's FP mean?

[lostforawhile]

you don't want to get rid of the relay, it turns off the pump if ignition pluses stop,such as if someone hits you and you are trapped in the car. you need to install a bosch relay at the back that is controlled by the safety relay. Fp is the 12 volts out to the pump, install the relay in the line where the wires run down the floor near the drivers side. the power into the pump now would go to one of the coil terminals. the other coil terminal to ground, then switched ignition power into the relay and out to the new pump. why are you running a hollet pump anyway? I was going to replace my pump until I found out how much volume it can produce, it's really not bad at all. In a carb setup you don't need pressure, you need volume. If you are running a weber, you only need 2 psi. anymore and you may damage the needle valve and cause the carb to flood.

[lostforawhile]

Apparently I'm a tard. Opened up the relay, and it's marked on the damned board what goes to what. So the far left is ignition, then -, +, and fp.
What's FP mean?

in the relay ignition goes to the negative side of the coil, thats what tells the pump to come on, it's listening for dizzy pulses from the module, - is ground, + is power into the relay from ignition, and fuel pump is out to the pump

[turabaka]

you don't want to get rid of the relay, it turns off the pump if ignition pluses stop,such as if someone hits you and you are trapped in the car. you need to install a bosch relay at the back that is controlled by the safety relay. Fp is the 12 volts out to the pump, install the relay in the line where the wires run down the floor near the drivers side. the power into the pump now would go to one of the coil terminals. the other coil terminal to ground, then switched ignition power into the relay and out to the new pump. why are you running a hollet pump anyway? I was going to replace my pump until I found out how much volume it can produce, it's really not bad at all. In a carb setup you don't need pressure, you need volume. If you are running a weber, you only need 2 psi. anymore and you may damage the needle valve and cause the carb to flood.

I didn't intend to get rid of the relay. I intended to replace it with a beefier relay.

what you're saying is that I should wire up another relay inline between the fuel pump and the stock relay? Mind making me a diagram of what you mean?

[lostforawhile]

I didn't intend to get rid of the relay. I intended to replace it with a beefier relay.

what you're saying is that I should wire up another relay inline between the fuel pump and the stock relay? Mind making me a diagram of what you mean?

well i don't have a way to draw one, on here,i'll do one in a bit and try to take a picture. the fuel pump relay really isn't a relay, it's a safety switch to turn off the pump in an emergency, you really can't just put in a regular relay, I'll try to explain, you know how to hook up a regular relay right? all you do is take the existing power going to the pump at the back, and use that 12 volts to turn a regular bosch relay on and off. then you need a 12 volt ignition switched source going through that relay for the pump. just leave the safety relay where it's at. and hook everything up at the back of the car.

[turabaka]

well i don't have a way to draw one, on here,i'll do one in a bit and try to take a picture. the fuel pump relay really isn't a relay, it's a safety switch to turn off the pump in an emergency, you really can't just put in a regular relay, I'll try to explain, you know how to hook up a regular relay right? all you do is take the existing power going to the pump at the back, and use that 12 volts to turn a regular bosch relay on and off. then you need a 12 volt ignition switched source going through that relay for the pump. just leave the safety relay where it's at. and hook everything up at the back of the car.

kk. I'll do that. So if I'm understanding this correctly, this setup makes it so that the fuel pump draws amperage through the beefier bosch relay, and not through the stock cutoff relay. But the cutoff relay still functions as factory, and shuts off the pump if the car stalls.

This is kinda my first foray into relays, so I'm pretty much lost.

[lostforawhile]

kk. I'll do that. So if I'm understanding this correctly, this setup makes it so that the fuel pump draws amperage through the beefier bosch relay, and not through the stock cutoff relay. But the cutoff relay still functions as factory, and shuts off the pump if the car stalls.

This is kinda my first foray into relays, so I'm pretty much lost.

actually i'm lost lol. let me try to find a bosch relay diagram online. you got it right, the stock relay only controls the bosch one so it's not pulling a bunch of amperage. it functions as stock. best way to explain is the factory "relay" isn't a relay at all, but an rpm sensing module that can turn the pump on and off. the 12 volts out of it are what will turn the pump relay on and off

[lostforawhile]

here's a diagram,think of the switch as the fuel pump cut off relay and you should be able to make sense of it.

[turabaka]

Thanks dude. That helped a ton. I assume I only need a 4 prong relay and not a 5 prong. Correct?

[lostforawhile]

Thanks dude. That helped a ton. I assume I only need a 4 prong relay and not a 5 prong. Correct?

right you only need a relay that makes contact when power is applied to the coil ,look at the upper one, just think of the switch allowing positive current as the original relay

[Oldblueaccord]

Think of the Fuel Pump Relay as a latch. Its a logic circuit that if the motor is running(spark) then the fuel pump needs to run. The other relay you are talking about is to help with the load(voltage) to the pump. it is possible the Holley pump does not like a relay on its motor I would double check with Holley on that one.

EDIT:
I'm a sweathart and looked it up for you. It can use a relay.

http://www.holley.com/data/Products/...199R7914-3.pdf

p.4

I would switch to positive esp on a 12 volt automotive system. Its very easy to "find a ground" were as its hard to find a 12 volt signal on a car cuircuit and thats a good thing. You dont want a short to ground making your fuel pump run all the time.

Sorry I dont write Relay logic. A old time electrician could write one up for you real quick.


wp

[carotman]

You nailed it right Tim.

Installing a BOSCH Relay will do the trick. You can't get rid of the fuel cutoff relay or the carb will flood or the pump will fail.

[lostforawhile]

Think of the Fuel Pump Relay as a latch. Its a logic circuit that if the motor is running(spark) then the fuel pump needs to run. The other relay you are talking about is to help with the load(voltage) to the pump. it is possible the Holley pump does not like a relay on its motor I would double check with Holley on that one.

EDIT:
I'm a sweathart and looked it up for you. It can use a relay.

http://www.holley.com/data/Products/...199R7914-3.pdf

p.4

I would switch to positive esp on a 12 volt automotive system. Its very easy to "find a ground" were as its hard to find a 12 volt signal on a car cuircuit and thats a good thing. You dont want a short to ground making your fuel pump run all the time.

Sorry I dont write Relay logic. A old time electrician could write one up for you real quick.


wp

The fuel pump relay uses a triac I believe to switch on the pump, it's only designed to handle a certain amount of current, holley pumps are bad about a lot of inrush current, thats probably whats knocking out the relay, thats why you need the bosch one. I still don't see what's wrong with the factory pump, It's capable of producing more gallons per hour then just about anyones setup on this site requires. A lot of people get confused on carbs, they are the opposite of FI, you need low pressure and high volume. I was going to run an aftermarket pump too, then after finding out about the factory pumps GPH capability, it's not needed. the main issue with the pumps are the cheapo aftermarket ones out there to repalace the factory one, I think with a bosch pump, it will handle any carbed setup you can put on this car. the bosch are supposed to have the metal impellers vs. the plastic ones.

[turabaka]

The reason I ended up switching pumps is because my factory pump wasn't holding 3 psi all the time. I think the best I ever got out of it was 1.5 or 2 at idle, and then almost nothing at full throttle. So I figured I'd get a good aftermarket pump instead of another stock in tank pump.

[lostforawhile]

The reason I ended up switching pumps is because my factory pump wasn't holding 3 psi all the time. I think the best I ever got out of it was 1.5 or 2 at idle, and then almost nothing at full throttle. So I figured I'd get a good aftermarket pump instead of another stock in tank pump.

1.5 to 2.00 psi is good that's within range according to my book are you running a webber? thats the recommended pressure for one. I have a regulator on mine to keep it at 2.00 psi, thats also the pressure needed for the SU's. a pound off is no big deal to a carb, as long as it's on the low side, you want volume, that's what keeps the float bowl full. if the pump can keep filling the float bowl, ahead of the engine you are good.

[turabaka]

I had problems with fuel starvation at 5000 rpms.

[lostforawhile]

I had problems with fuel starvation at 5000 rpms.

thats strange, are you sure the pump wasn't worn out? some of the aftermarket pumps are garbage. I'm going to replace mine with the bosch pump when it's ready to go, I think it's the same as factory. there are a lot of advantages to having the in tank pump, one is constant pressure on the inlet side of the pump. one of the junk pumps that come to mind is the carter, and all the other pumps it's rebadged as, you don't even want to get me started on that. the hanger isn't even right, I was having fuel starvation problems and the pump kept burning up, the hanger forces the pump against the internal baffle in the tank. I compared a stock hanger to the carter and you can see how far off it is. they are so bad Oreilies quit carrying the brand because they kept coming back. I can't remember what i've got now but it seems like a ggood pump,probably no good though from sitting. i have to clean and seal the tank anyway.

[turabaka]

the pump was going bad. That's why I replaced it. I just figured I'd go with a nice Holley pump instead of some other OE type aftermarket pump.

[lostforawhile]

if you ever have problems with the holley,after looking for years, I finally found a pump that was suited to our cars with both stock and aftermarket carbs plus it's dry lift, so it can pull fuel out of the tank, and down to the pump without damage. I would look at the the FRD1 or FRD2 , just scroll down. the FRD 2 is ten gallons per hour, but for a four cyl engine, thats plenty of fuel. http://www.autoperformanceengineerin.../fr_pumps.html

[turabaka]

Cool. Thanks man. If I get any more problems with this Holley I'll see about getting one of those to replace it.

[lostforawhile]

no problem, I hear people say al the time I want a 30 gallon per hour pump bla bla bal, figue it this way, a six cyl aircraft engine which is horribly inefficient and practically sends fuel out the exaust, running at cruise might burn 8 gallons per hour, our far more efficient engines that run at maximum load only on acceleration , are going to go through far less the that . that's with the aircraft engine running under constant load near it's rated output horsepower