Fuel Pump Woes

So to do this gravity feed, you take out the line that goes from the tank, to the fuel filter, to the pump, and then to the carbs, and replace that with a short line straight from the tank to the carbs? And that should work just as well?

 

I am sorry, but I am a bit cofused. The other line is just supposed to hang there? It looks like it was meant to be a vent for the vacuum slide operation.
Mine comes up between the coils, but there is nothing for it to hook up to. I looked all over the place, thinking that it was supposed to attach to the air box somehow, although it is made of the same material as the fuel lines. I don't want to just leave it open to the atmosphere (and dirty air), so I stuck a small fuel filter on the end of it.
My bike runs fine and I was concerned that maybe it was supposed to be fed with fuel. I guess not.

 

That vent hose just hangs there. It doesn't do anything but vent over flow from the carbs if the get clogged and won't close. I don't think they suck anything in they just blow.

If your tank is rusty or dirty in anyway you should empty the tank add a little gas swish it around and pour it out. Do that several times until the gas looks clean coming out. Don't reuse the bad gas. But then your tank should be better and you will only need a inline filter to collect the remaining junk. That is what I am doing and it seems to be working fine. But I am still using the fuel pump though.

 

FWIW- I removed my fuel pump last night. I installed an inline fuel filter and opened the bowl drain on one of the outer most carbs to allow the fuel to flow and fill the line and new filter. No problems.
Thanks for the Tip!
Greg

 

That is why I am wondering why I cannot get my last gallon out also. I opened the bottom of the petcock, and unlike most that I have seen, the fuel goes through a strainer, and then must travel back up to the outlet. For the fuel to overcome gravity and travel upwards to the fuel outlet, there must be a certain amount of fuel pressure, either a certain number of gallons in the tank above or external suction from a pump. I would think that a gallon of gas would be much more than enough to provide that pressure, but maybe it's not and that's where the pump helps.

 

Actually, if the line ever rises above the level of fuel, it will not flow out unless you have enough line after that the goes below it to siphon it out. The weight of the fuel in the tank has nothing to do with it once the line goes above the fuel. Think of a swimming pool. Tons of water (in weight), yet if you put a garden hose in it, and hang it out the edge of the pool, no water will come out on its own. You can only siphon out if you can get enough water flowing to draw it out.

 

IOW The line should be below the fuel level so gravity will pull the fuel down and create suction on the rest.

 

I get this question a lot. Running gravity feed cannot cause this problem - the tank just doesn't work that way. If your tank will not drain all of the way then it most likely due to the cap not venting properly. I've seen a lot of caps with this problem, so it's not all that rare. Remember, all of the gas that goes out must be replaced by air coming in. The pump will not help if this is the case.

 

Ok, so I got the Interceptor running good with no pump. My problems were due to carb issues, and now that I have those ironed out, it runs fine with no pump. Thanks!!!

 

Congrats and welcome to the no-fuel-pump club!

 

Hi there everyone,

I recently got myself an 83 VF750F and I've had a couple of problems. Firstly some water in the fuel which was evident when draining the bowls. All seemed well, but when it started cutting out again I was forced to do some more searching - I didn't know these things had fuel pumps until I found one, and being so low it needs draining if there's still any water about - though my question is, when do they run? R1s GSXRs that I've owned pump momentarily when you switch the ignition on, but this VF one doesn't make any pumpy kinds of noises. Do they only run when the engine is running? Going pumpless sounds attractive, I guess the marginal pressure head when the fuel is low must have made Honda nervous enough to assist it, yet it seems like a lot of bother -no one has any trouble with gravity feed? My tank is full of crap, although I got rid of most of it, I wouldn't dream of going filterless.

Thanks.

 

If you turn on the key or the engine cut off switch you will hear a click sound. When it is turning over you will hear it click more. When it is running it clicks every couple seconds.

I noticed that when the bike is running it clicks a lot faster.

 

Thanks dlman,

there's a relay that clicks but nothing else, and my float bowls are empty so you'd expect to hear the pump clicking away until they are full (if it's anything like the Yamaha one's I've experienced). Should the pump be getting power as soon as the ignition and kill switches are both on? I've checked the electrical connection to the pump and there's nothing going on. Hard to see where those two wires come from though.

 

Sometimes you can hear the pump click, other times not. The relays are also known to go bad, so that could be part of the problem. The pump is only supposed to run for just a second when the key is first turned out. You can turn the key off and on really fast to prime a set of drained carbs. The pump is always powered when the engine is running, it only moves as necessary when the fuel is used.

If you are considering removing the pump (it sounds like you are) then you can always put a sintered bronze filter in the line. That will keep the big junk from your tank from getting into the carbs without restricting the flow.

 

If you turn the key on and turn the engine kill switch on and off waiting a bit between turning it off. You should hear the pump click. It takes a second. But if you are not getting gas even though you hear a click. I would check to see if the filter is clogged. Change the filter if you can't blow thru it. Cheap ones that will work fine are available but a bronze filter maybe what you need for the long run. Cheap filters can be throw out without worrying so I am using them until I have gone thru a few tanks of gas.

 

Thanks guys. I connected an inline bronze filter since the pump isn't doing the job, it seems like it's not getting power, so maybe the relay...but why bother? A quick test ride and I was disappointed to find it spluttering after a few minutes. Checking the forum I noticed the symptom in another post, and sure enough the fuel cap breather was blocked. I've heard of this problem before but never believed it really happened, after 24 years and 26 bikes I've never been introduced to this before. When I was rinsing the tank out I must have shaken some of the crap into the pinhole - there was tons of crap in there. Anyway, it goes now so I'm looking forward to ride the bike I used to lust after while I learned on my XR75, and my first V-four fourstroke. Thanks again guys.

 

Glad to hear that you found the problem. Don't worry, most people are skeptical about the tank vent until they try it.

 

I sprayed the pinhole in mine and a word of warning to everyone. The cleaner ate the paint and the clear coat around my cap. I put a towel down but it wasn't enough to keep the cleaner off.

 

Oh man is this thread ever going to help me. Im in the process of restring an 84 750, almost had her running but was dieng and not continuing to run. I suspect the fuel pump so am going to by pass. thanks for the info guys will report back ....

 

Going to try this out on my 750 also, I could use the extra space that deleting the pump will give me. Might put the CBRF4i fuse box down there...