Who Has Removed Fuel Pump And Done Direct Feed To Carbs?

[JIMLARCH]

Has anyone done the above, removed the fuel pump and done a direct feed to the carbs. If so, what exactly did you do, and did it work efficiently. Any help would be appreciated.

[mk2davis]

I've heard of people using a simple gravity feed system to the carbs without issue. I have not done it. They ran (I believe) just from the petcock - filter - carbs. Since it can be done, it makes me wonder why Father Honda put a fuel pump in. but mine still works.

[gll429]

yes i have !

on more than one!!

the best way to do it.

.buy 2 feet of new gas line. an inline gas on/ off valve. add a filter in the middle.,

and run a nice smooth arc where the pump would normally be.

the down side.. if you are running over 100mph the bike will bog down like its about to run out of gas in about 10 to 12 min..

just back off to 70 or so for a minute.

i routed my on off switch so i could turn it buy removing the seat.

the other one i used 3 feet of line and mounted it just inside the fairing for easy access.

[Audigier]

The fuel pump is to provide a fast and steady fuel flow to the carbs.

If its for testing purposes go ahead. If not I'd suggest to find a replacement and leave it the way it was designed

[V4 Rosso]

I once had to as the pump died the evening before a trip. It ran fine, no problem whatsoever, not even when doing a lap on The Nürburgring. Then again, I did not let the fuel level get below a quarter, topping up about every 200km.

[YoshiHNS]

I ran it for a while while troubleshooting a fuel pump issue. Keep the petcock and fuel filter and run it straight down.

[VIFFER93]

I have never run a direct line but I have been considering this. The logic I can not resolve for myself is this.

The Japanese scrutinize everything when manufacturing products in order to keep costs low, quality and reliability high. With that in mind, why would the engineers include an item that increases the cost of manufacturing and provides a potential point of failure.

I keep coming up with two reasons;

- Safety, the fuel pump is tied to the fuel relay so if the bike tips the fuel pump shuts off

- Making the full capacity of the fuel tank available. If gravity feed only allows you to utilize 3-4 of the 5 gallons of fuel and 1-2 gallon of fuel weights more then a fuel pump then why would you do this?

These are just my opinions and they are worth exactly what you are paying for them. LOL

[gll429]

I have never run a direct line but I have been considering this. The logic I can not resolve for myself is this.

The Japanese scrutinize everything when manufacturing products in order to keep costs low, quality and reliability high. With that in mind, why would the engineers include an item that increases the cost of manufacturing and provides a potential point of failure.

I keep coming up with two reasons;

- Safety, the fuel pump is tied to the fuel relay so if the bike tips the fuel pump shuts off

- Making the full capacity of the fuel tank available. If gravity feed only allows you to utilize 3-4 of the 5 gallons of fuel and 1-2 gallon of fuel weights more then a fuel pump then why would you do this?

These are just my opinions and they are worth exactly what you are paying for them. LOL

he has a 95. meaning external pump, and no tip switch.

the bike will run fine . i had the same bike and ran it with no pump for 5 years..

ditto for and 86 700 . i ran that one with no pump for 20 years.

as for fuel. every single drop can be used until it empty.. you just cant go 150 mph on 1/4 tank but you can do 65

[YoshiHNS]

I think the point is that you CAN run without the fuel pump if you have to. Still recommended to run with the pump. Part of the problem is that if your pump does ever go bad, a replacement is expensive, and aftermarket ones are questionable.

[JIMLARCH]

Thanks for the replies guys, helped me a lot. I couldn't see any reason why gravity feed wouldn't work, but wanted it confirmed. The reason I ask is that I took my bike out of storage yesterday. I always drain the carbs, and it normally only takes a few seconds for the pump to prime and the bike start.

On this occasion it took about 15 tries on the starter before the bike started, and it only started after I rapped the pump. I don't know if it is normal but the pump is not giving a constant smooth feeling but seems to lurch every so often. After I switched the bike off there was a strange noise coming from the inside of the tank and bubbles could be seen rising to the surface. The bike still ran fine on idle and being revved up.

My concern was that the pump is on it's way out and I might be stranded on the side of the road. Obviously that will not be the case as I can just do direct feed.

[gll429]

in that case.. by some tubing and keep it under your seat..

and the right size tube connections (2)

this way you can bypass your pump in an emergency without removing the tank.

[rangemaster]

There is a set of points (like an old distributor-I know, I'm dating myself) under the cover of the fuel pump. I lightly file 'em once a year to keep them flat and corrosion free.

[JETS]

I'd be a little worried that you might start running lean as the fuel level drops. Don't you think that is what's happening when the bike won't hold speed under full load? Valves burn, etc. not buying a pump might be a poor economy.

[Guest]

Interesting topic, my project 93 VFR needs a new pump and I was going to run tubing from the tank too and skip a new pump. I guess it's in the design but all the old cradle frame GSXR750s were gravity feed only - no pump. I remember motorcyclist or cycle world doing an article on the redesign for the first water cooled GSXR's in 92 and still not using a fuel pump. My 93 GSXR has no fuel pump. Might be the petcock placement and shape of the tank.

I guess I'll be hunting down a pump.

[Guest]

My experience with this is that it runs rich at low and mid rpms and lean at high rpms.

You got a lot of pop on overrun andeven some flames at times....

But that is my bike with custom, short and high flow 2-into-2 exhaust system.

Around town it is fun, but i couldn't ride it like that on the highway because any throttle position more than 3/4 and you make the engine starve for gas.

[apexandy]

You guys convinced me to keep the pump on my naked bike project... I know some have done away with it but really it isn't that big and there must be some good reason Honda put it there. At least that's what I'll tell myself.

[Dutchy]

on my naked bike project...

[apexandy]

I know... I know. The bike is nearing completion, it has always been my plan to post up a thread of the project when I'm done :) I want to ride so bad!!!

[TheHound]

Direct fuel feed Old thread but on topic.

I removed the fuel pump. In it's place I ran a piece of fuel hose that had a pre bent 90 in it, from the fuel filter line back to the carb intake line. This formed a nice even curve where the pump used to be. I rode with no ill effects for hours. Over a Hundred, up, down, then it happened. With about half a tank left climbing a descent hill it started to run out of fuel dogging with each turn of the throttle. I coasted to a flat spot were it died and after 15 minutes she fired right up. Rode to a gas station filled up and all was well until I was at about half a tank again. Riding 65mph at 6K for 4 minutes and she slowly died. Rolled to a stop waited 10 minutes for the fuel to refill the bowls and I was off to the gas station again. 80 miles home with no problems.

So maybe if you ran the line straight down through a filter to the carbs I can see this working. From what I saw on this ride, using the stock lines connected with a looped fuel hose, below half a tank you will have issues. The bike doesn't run the same either. I had to turn the idle up a little, it sounds different not as throaty, low. I wanted people to now, as I am now in the same boat buying a cheap pump. Stashing the hose under the seat.

 

  

 

  

[JZH]

In case it helps someone, I recently found some really nifty stainless steel fittings in the correct size for 3-4th gen VFR fuel lines (5/16" -- 8mm) at Beverage Factory in California--including a tight u-bend that is perfect for replicating the 180-degree bend in the OEM fuel line (from the tank).

I use polyurethane clear tubing (a Tygon-type) for my fuel lines, but it should work with conventional rubber fuel line as well.

 

[Edit: I should have said, some of the VFR's fuel lines.  The fuel pump takes the larger 3/8"  --  10mm size, but the hose barb on the tank petcock is the smaller size.  I have forgotten what size the lines at the carbs were originally (mine is currently 8mm), so, as always, best measure before buying!]

 

Ciao,

[YoshiHNS]

I run direct with the F2. Petcock through inline filter to carbs. The only issue I had was when I forgot which way was the prime and reserve positions. Never put more than 1/2 tank of gas in. 

[Terry]

All stock VTR1000's run a simple gravity feed to the carbs, with  a vacuum petcock to shut off the fuel when stopped. The fuel lines are pretty big (10mm??), one to each thirsty carb, and they never starve the engine. The only filter is a strainer on the tank outlet.

 

I think the real reason for fuel pumps on the carbed VFR is the relative height of the float bowls vs the tank outlet. You are going to need a reasonable amount of fall to ensure some flow otherwise the carbs will run dry when the tank level is low. 

[Dutchy]

6 hours ago, Terry said:

All stock VTR1000's run a simple gravity feed to the carbs, 

 

"All VTR's are equal, but some VTR's are more equal than others..."

-George Orwell

 

 

 

 

 

 

 

 

(U know, I know, stateside they are RVT's........)

[Terry]

 
"All VTR's are equal, but some VTR's are more equal than others..."
-George Orwell
 
 
 
 
 

 

 
 
(U know, I know, stateside they are RVT's........)

Ok just don’t get me started on camchain tensioners!


Sent from my iPhone using Tapatalk

[JZH]

22 hours ago, Terry said:

All stock VTR1000's run a simple gravity feed to the carbs, with  a vacuum petcock to shut off the fuel when stopped. The fuel lines are pretty big (10mm??), one to each thirsty carb, and they never starve the engine. The only filter is a strainer on the tank outlet.

 

I think the real reason for fuel pumps on the carbed VFR is the relative height of the float bowls vs the tank outlet. You are going to need a reasonable amount of fall to ensure some flow otherwise the carbs will run dry when the tank level is low. 

 

That reminds me...there is no vacuum diaphragm on the 3rd gen, so if it is converted to gravity feed and a float sticks open or something...you better hope you don't park in an enclosed space--particularly not one with a water heater or other open-flame device!  Filling one's crankcase with gasoline is bad, but blowing up one's garage/house/neighbourhood is worse...

 

These bikes do have three-position petcocks (on-off-res).  Even the US-spec bikes have it!  (They are fitted with plastic knobs that prevent the "on" position from being used, but the petcock is otherwise the same part as the ones used on the ROW bikes with the remote petcock controls.)  But it's the "off" position you need to use when you go gravity feed.

 

Ciao,