So, I think I destroyed my fuel pump

[barmanvarn]

Apologies for the long post....

Late last year I decided to start work on my '69 C15 that had been sitting for around 10 years. It took a lot of work (and a lot of help from the forum) but I finally got her running. (No brakes, so she's not going anywhere. Was just happy to get the engine to run). I haven't worked on it since early spring so this weekend I decided to do some maintenance before winter hits.

One item on my list was a fuel tank. Obviously the stock tank is toast so I've been running a line to a portable gas can just as a temporary measure. I was wanting to set up something so that I wouldn't have to haul out a gas can every time I need to run the engine. I settled on an outboard fuel tank that I could sit in the bed of the truck. This way my Dad (the truck is behind his shop) could go out and start it every once in a while so it doesn't go downhill again.

Anyways I hooked up the new tank, filled it with gas and Stabil and tried to start the engine but it wouldn't crank. I pulled the fuel line off the tank to check for pressure in the line, but when I remove the line from the tank, gas came gushing out of the tank. I then checked for pressure in the line and got nothing. Even checked the input line at the pump and still got nothing. At this point I'm pretty sure the pump is toast.

After some research, I think I found that this marine tank doesn't have a manual vent but has some kind of automatic one. The gas gushing out when I removed the line tells me the tank was pressurized meaning the pump was trying to suck out gas from the tank but was unable to since there either is no vent or the vent isn't working. I'm thinking this put too much stress on the pump and basically ruined the pump.

Does this sound about right to you guys?

I'm going to replace the pump (which is obviously toast) but I guess I need to figure out what went wrong w/ the gas tank. Again, I"m guessing it's a venting issue but wanted to see what you guys think.

EDIT: I did some more research on the fuel tank I'm using and am a bit confused. It appears to not have a manual vent (due to new EPA regs). It has what they are calling an "automatic vacuum valve" in the gas cap. What confuses me is that it appears to release pressure when the tank expands, but I'm not seeing any way that air gets in when the pump is trying to suck out gas, thus the issue that I encountered.

[cdowns]

if you have the original hose on that marine tank it will not flow cas unless it is connected to the original type of fitting that goes on the outboard engine// I think that is where your problem is

[barmanvarn]

Originally Posted by cdowns

if you have the original hose on that marine tank it will not flow cas unless it is connected to the original type of fitting that goes on the outboard engine// I think that is where your problem is

The tank didn't come w/ a hose. I added one myself.

I went back to where I got the tank (since the truck is an hour away) and did some testing on a tank on the shelf. Looks like it'll let air in if I unscrew the cap just a bit but I can see myself forgetting to do that and ruining my fuel pump again.

Are there any affordable options for my installing some kind of temporary tank? I'm not going to be driving the truck anywhere. I just want my dad to be able to go out and start the engine from time to time without his having to do any extra steps.

[RustyBucket]

What's the outboard tank made out of? I put a non vented cap on '69 Nova I had and the fuel pump sucked the factory steel gas tank flat... TWICE before I figured out what I'd done. I thought my Son backed over something & squashed the tank. If it didn't deform the boat tank it you had a bad pump anyway. Put a pump on it and stick the fuel line in through the cap hole. Run it awhile and then let it run the carb. dry if it not being driven anyway.

[barmanvarn]

Originally Posted by RustyBucket

What's the outboard tank made out of? I put a non vented cap on '69 Nova I had and the fuel pump sucked the factory steel gas tank flat... TWICE before I figured out what I'd done. I thought my Son backed over something & squashed the tank. If it didn't deform the boat tank it you had a bad pump anyway. Put a pump on it and stick the fuel line in through the cap hole. Run it awhile and then let it run the carb. dry if it not being driven anyway.

The pump was virtually brand new. Put it in at the beginning of summer and it worked like a champ. The outboard tank is made of whatever heavy duty plastic they use for gas tanks now.

The pump couldn't suck any gas out since the tank had no venting, so I'm betting it gave up the ghost when it couldn't get any gas out of the tank. Kinda like trying to suck a McDonald's milkshake through a straw. LOL

I'm still working on the truck sporadically. It took me SO much work to get it running I just want to make sure it stays that way so I've asked my Dad to go out and start it every once in a while. I just wanted to have gas hooked up to it full-time so all he has to do is go out and turn the key.

I'll likely just go with unscrewing the cap just a hair so that air can get in so the pump can suck the gas out. That should work until I can get around to pulling the old tank and putting a new one in.

[cdowns]

you know I don't think you can just hook a hose up to a marine tank and get it to flow fuel without having the interlocking fast disconnect on the fuel hose as they cum from the factory

[barmanvarn]

Originally Posted by cdowns

you know I don't think you can just hook a hose up to a marine tank and get it to flow fuel without having the interlocking fast disconnect on the fuel hose as they cum from the factory

I did see a kit I could get that was some sort of quick disconnect kind of attachement to the tank. Not sure if that's what you're talking about.

Outside of my current failed attempt, any suggestions for a way I can have gas hooked up full time so that I don't have to drag a gas can out every time I need to start the engine?

[BrianG]

It doesn't at all sound like an issue with the tank to me, but rather an issue with the fuel line. You said that the tank was pressurized and gas came out when you unhooked the line. That would tell me that the tank isn't the issue. Try moving it right next to the motor and see if it will run the motor. If it will, take a look at your fuel line. Maybe its plugged or too long for the size you are using. Could it be collapsing maybe? Those tanks work just fine for an outboard, and although they probably don't use fuel as quickly, the same principles apply. If it needed some sort of extra vent then it would need it for any application.

[barmanvarn]

Originally Posted by BrianG

It doesn't at all sound like an issue with the tank to me, but rather an issue with the fuel line. You said that the tank was pressurized and gas came out when you unhooked the line. That would tell me that the tank isn't the issue. Try moving it right next to the motor and see if it will run the motor. If it will, take a look at your fuel line. Maybe its plugged or too long for the size you are using. Could it be collapsing maybe? Those tanks work just fine for an outboard, and although they probably don't use fuel as quickly, the same principles apply. If it needed some sort of extra vent then it would need it for any application.

thanks for the feedback.

I checked the lines from the tank to the pump, and from the pump to the carb and they are all clear. There is no pressure at the pump so I know for sure that it's hosed. I have a new one on order and will install as soon as I get the chance.

I'm definitely stumped on the tank as to how a pump is supposed to suck out gas when the tank has no vent to allow air in to replace the gas that is leaving.

[71swb4x4]

You are stumped about the pressure yet you tell us it was pushing gas out. So it had outward pressure, not inward pressure. If it's pushing gas out how would that prevent the pump from pulling the gas in?

[barmanvarn]

Originally Posted by 71swb4x4

You are stumped about the pressure yet you tell us it was pushing gas out. So it had outward pressure, not inward pressure. If it's pushing gas out how would that prevent the pump from pulling the gas in?

Assuming the pump was working (at first), I'm assuming the pump was trying to pull gas out of the tank, but since there was no way for air to get into the tank, the pump simply failed.

When I disconnected the line from the tank, that's when gas just poured out of the tank, to release the pressure that had built up. The gas line itself was completely dry.

I'm not trying to act like I know for certain what happened, just throwing out my non-expert theory.

[BrianG]

I think that those tanks let air in but not out. If they didn't then they wouldn't work on a boat. I suspect maybe it was just a bad pump...OR... Maybe because the tank gets pressurized as it did, maybe your pump can't handle that. If that's the case then make sure that you disconnect it when you are not using it and just cap off your fuel line. I always do that with my boats. I've seen those plastic tanks really swell up when they sit in the sun. I disconnect them because I've worried about the excess pressure that must be exerting on the fuel pump, although I've never actually seen it become an issue on my boats.

[BrianG]

Also on the boats there is a primer bulb that gets fuel up to the pump before you try to start it. Adding one should make sure that your fuel pump isn't starving for fuel as it tries to send fuel to the carb after sitting for a while.