Relay

[Channing]

Originally Posted by Gary RVRoamer

Are you trying to make a distinction between an electric vs an electronic one? Or just wondering if you have an electric powered pump. If its a simple electric power question, the answer is Yes, you have an electric pump. Mechanical fuel pumps have been obsolete for decades.

It's a 1987, so it is decades old. It does have a mechanical fuel pump on the right side front of the engine controlled by a push rod that is controlled by the camshaft. Some of these p30 chassis motorhomes between 1985 and 1990 used both a mechanical fuel pump and a electrical fuel pump in the tank. Some of the Bounders did I know for sure but there are other models also I need to know if my Holiday rambler aluma lite XL 27 footer is one of them. Here's my conundrum. I HAVE A CARBURETOR (Rochester Quadrajet) I HAVE A REALLY SWITCH. It's under the engine cover on the firewall left side next to the engine which clicks when I turn the key I have no ECM and I have no TBI I know something mechanical does not run off of something electrical for instance a mechanical fuel pump cannot be controlled by a electrical relay switch. You can't just turn it off unless you turn the engine off. I understand all that. I don't understand why I have a relay switch. I have changed the mechanical fuel pump put on a new one and it's the same results no gas to the CARBURETOR. I cannot get one to turn on in the tank when the key is turned there's no sound I'm in a situation where it's going to be very difficult for me to drop the tank is there a way to tell without having to hear it turn on in the tank or having to chase down a wire.?

[Channing]

Originally Posted by dieselclacker

You are confusing “electronic” fuel pump with a simple electric fuel pump. Carbureted engines like your 454 only require 8-10 psi to feed the carb. The electric pump runs all the time the ignition is on. Electronically controlled pumps are usually higher pressure pumps for fuel injected engines, and are computer controlled by an engine computer. The fuel pressure regulator is usually located in the fuel line between the mechanical pump and the carburetor, it sometimes has a fuel filter and site glass in conjunction with it.
I don’t know what kind of in tank pump you have, but your engine driven
mechanical pump will pull fuel thru most electric pumps. Make sure the fuel line between this pump and the tank is good, with no cracks in the flexible parts. It must be air tight in order for the mechanical pump to operate.

I'm confused? How can you say I'm confused between an electric fuel pump and a mechanical fuel pump when all I want to know is if I have both of them? There's no confusion here. I explained how both of them worked more than once just so you would know that I know the difference between the two I know the difference. I WANT TO KNOW IF I HAVE BOTH OF THEM, 2 TOTAL 1 ON THE ENGINE AND 1 IN THE TANK 2, 2 OF THEM DOS, 2. NO CONFUSION. Some of these motorho mes between 1985 and 1990 not all of them just some of them have both electric and mechanical fuel pumps y'all are the ones that are confused it's a simple question. I came back to fix this because I read it wrong you weren't talking about mechanical pumps at all but I'm not confused between electric and electronic either I couldn't have been because to be honest I didn't know the difference (but I do now) so I don't see how I could have been confused about it like I said I'm just want to know if I have a mechanical and electric or electronic whatever fuel pump do I have two pumps one that runs mechanically and one that runs electricity. You know what nevermind I think it'll be a lot easier if I just figured out for myself and a lot less time than trying to explain this over and over again. One or two pumps a mechanical pump or a mechanical pump and a electric pump.... Easy.

[Channing]

[QUOTE=amosnandy;5813440]No, an electric fuel pump is self regulated. When it reaches pressure it shuts off.

And yes, your chassis has an electric fuel pump in the tank and a mechanical on the engine. Get rid of the mechanical pump. Take it off and put a cover over the whole.[

/QUOTE]
Well if you can't adjust them then they must sell eletric fuel pumps that are for carbs under 10 psi. Guessing someone needs to be careful when shopping for one. Wouldn't want to get one for a throttle body or fuel injection.

I have one more 2 part question....
If I left the one in the tank as it is (not working) would my mechanical pump be able to pump the fuel through the one in the tank (assuming it has to) then also up to the carb and then of course the return to the tank? If so, then can it do it after everything has been taken off to be cleaned, checked, or changed? Lines and filter are dry and fuel free.

[dieselclacker]

Originally Posted by Channing

I'm confused? How can you say I'm confused between an electric fuel pump and a mechanical fuel pump when all I want to know is if I have both of them? There's no confusion here. I explained how both of them worked more than once just so you would know that I know the difference between the two I know the difference. I WANT TO KNOW IF I HAVE BOTH OF THEM, 2 TOTAL 1 ON THE ENGINE AND 1 IN THE TANK 2, 2 OF THEM DOS, 2. NO CONFUSION. Some of these motorho mes between 1985 and 1990 not all of them just some of them have both electric and mechanical fuel pumps y'all are the ones that are confused it's a simple question. I came back to fix this because I read it wrong you weren't talking about mechanical pumps at all but I'm not confused between electric and electronic either I couldn't have been because to be honest I didn't know the difference (but I do now) so I don't see how I could have been confused about it like I said I'm just want to know if I have a mechanical and electric or electronic whatever fuel pump do I have two pumps one that runs mechanically and one that runs electricity. You know what nevermind I think it'll be a lot easier if I just figured out for myself and a lot less time than trying to explain this over and over again. One or two pumps a mechanical pump or a mechanical pump and a electric pump.... Easy.

Channing,

Sorry, I was not meaning to insult you, but rather to inform you.

You should go back and carefully re-read my response to you in post #14 of this thread.

[Ljwt330]

[QUOTE=Channing;5813689]

Originally Posted by amosnandy

No, an electric fuel pump is self regulated. When it reaches pressure it shuts off.

And yes, your chassis has an electric fuel pump in the tank and a mechanical on the engine. Get rid of the mechanical pump. Take it off and put a cover over the whole.[

/QUOTE]
Well if you can't adjust them then they must sell eletric fuel pumps that are for carbs under 10 psi. Guessing someone needs to be careful when shopping for one. Wouldn't want to get one for a throttle body or fuel injection.

I have one more 2 part question....
If I left the one in the tank as it is (not working) would my mechanical pump be able to pump the fuel through the one in the tank (assuming it has to) then also up to the carb and then of course the return to the tank? If so, then can it do it after everything has been taken off to be cleaned, checked, or changed? Lines and filter are dry and fuel free.

Again, a general response and not specific to your chassis.


If you have two pumps, an electric "transfer" pump in the tank and a mechanical pump on the engine that feed the carb, the answer to your question is a resounding, "maybe."


Once the fuel line from tank to carb is full and the carb bowl is also full, the mechanical fuel pump will likely be able to pull fuel through the lines without the assistance of the tank pump. I say "likely" because putting under heavy load, like rapid acceleration or pulling a grade, could cause some fuel starvation to the mechanical pump and engine miss would occur. However, your system may be designed to work is such a way so this is not cast in stone.



If there already is air in the fuel line, due to a disconnection for carb cleaning for example, the mechanical engine pump may not be able to draw out the air and start pulling fuel because the engine is not running and the pump is only turning at starter motor speed. This is typically why a tank pump is employed, to pressurize the fuel lines and guarantee a fuel supply to the mechanical pump and carb bowl.


If your rig does have two pumps like you suspect and the tank pump is not working, a work around would be to install a small aftermarket electric pump in the fuel line, in an accessible location close to the tank. You should be able to find one that provides the correct psi, and also does not need a return line back to the tank. If you can identify the wire from the relay to the tank pump, that's the one to use to power the added pump.

[Argosy]

Originally Posted by Channing

even though the relay switch clicks when I turn the key, could the relay switch be bad?

Happens all the time. The relay might have a schematic on the side, if it does check the voltage out on the plug.

[153stars]

If not mentioned dual pump set up also helped prevent vapor lock from what read here before.

[Channing]

Originally Posted by dieselclacker

Channing,



Sorry, I was not meaning to insult you, but rather to inform you.



You should go back and carefully re-read my response to you in post #14 of this thread.

I miss read the first part of your response I thought you were telling me that I was confused between a mechanical and an electric pump I also apologize it was pretty frustrating day

[Ljwt330]

Originally Posted by Channing

I miss read the first part of your response I thought you were telling me that I was confused between a mechanical and an electric pump I also apologize it was pretty frustrating day

As a member of this forum and follower of this thread, I appreciate and applaud your response, quoted above.

[Channing]

Originally Posted by dieselclacker

Relay could be bad, or could have a blown fuse that is preventing power from getting thru the relay to the load (fuel pump). Easily checked with a test light or voltmeter. Look closely at the relay, the terminals are numbered either on the relay case or more commonly next to each terminal on the relay.
Commonly used numbers are:

#30 is the fused circuit to the power source
#87 goes to the load, in this case the fuel pump
#85 goes to 12 volt source when ignition is on, should be fused
#86 is ground.

If you can hear it click, or feel it click, I world first check terminal #30 for power using test lite or voltmeter.
Next if 30 has power and the relay is good, you should have power to terminal 87. Power at 87 indicates your problem is either wiring between relay and pump, or the pump is bad.

The above is assuming your rig is equipped with a standard 4 terminal relay.

unfortunately I do not have the standard four terminal relay which I am familiar with. What I do have is a five terminal relay part number15528707. That is prone to go bad and their unavailable. But apparently there is a another one that's off of p32 chassis that I could use.
It's not square shaped. The terminals are in line, and labeled 1 2 3 4 5 in order. Not really sure about this, but I think maybe the fifth terminal is for a timer inside of the relay which allows the pump to turn on for only 5 seconds before the ignition is turned to the start position. (I don't know kind of sounds like a diesel to me where you have to wait after you turn the key on before you start it.) But anyway still trying to figure out which wires are which so I could test this thing. Going to clean it first and put it back in and try it. It's amazing how much oil and dirt got down in this thing as tight as it fits into the plug. It's like airtight, and it's on the sidewall not even on the engine how the heck did he get all that gunk in it. Definitely makes me believe that this is my problem. We will see.

[Argosy]

Chev Fuel pump relay 15528707 - Topic

[Channing]

[QUOTE=Ljwt330;5814060]

Originally Posted by Channing

Again, a general response and not specific to your chassis.


If you have two pumps, an electric "transfer" pump in the tank and a mechanical pump on the engine that feed the carb, the answer to your question is a resounding, "maybe."


Once the fuel line from tank to carb is full and the carb bowl is also full, the mechanical fuel pump will likely be able to pull fuel through the lines without the assistance of the tank pump. I say "likely" because putting under heavy load, like rapid acceleration or pulling a grade, could cause some fuel starvation to the mechanical pump and engine miss would occur. However, your system may be designed to work is such a way so this is not cast in stone.



If there already is air in the fuel line, due to a disconnection for carb cleaning for example, the mechanical engine pump may not be able to draw out the air and start pulling fuel because the engine is not running and the pump is only turning at starter motor speed. This is typically why a tank pump is employed, to pressurize the fuel lines and guarantee a fuel supply to the mechanical pump and carb bowl.


If your rig does have two pumps like you suspect and the tank pump is not working, a work around would be to install a small aftermarket electric pump in the fuel line, in an accessible location close to the tank. You should be able to find one that provides the correct psi, and also does not need a return line back to the tank. If you can identify the wire from the relay to the tank pump, that's the one to use to power the added pump.

I got a external fuel pump. It says it's good for 4,6, and 8 cylinder carburated engines. I haven't mounted it, because it looks like it's going to be a real bear putting it back by the tank. So, what I did to test it was put it into my line further up towards the carburetor (much easier) probably about halfway. Is that why it won't pull gas up from the tank? Because I would like to mount it there. Or, Is it because It has to pull the fuel through the old in-tank pump? Or, is it because I still have my return line in? Or, because my mechanical fuel pump is still in and may be bad? I'm sure if the mechanical pump was still good it would be fine it would help right? Would a bad mechanical pump be the same as not having one at all or worse? I do not have a fuel pressure gauge, or the money to buy one right now. The ones I've looked at need a primed system to work correctly anyway. I have blown through the feed line and the return line with no problem with my own lungs, so I'm assuming it's not clogged. Any ideas?

[Channing]

[QUOTE=Argosy;5817077]Chev Fuel pump relay 15528707 - Topic

[/QUOTE*]
Which wire goes to the fuel pump the p-30 manual says tan and white that would be #5 but when I follow it it just goes straight down under the left side next the engine and just dead ends into the top of a cross member I can't see the end but it feels like rubber and it doesn't come back out like a ground wire.