Jon Ison
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 posted on 28/9/04 at 06:18 PM |
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Fuel pumps........
Idea's please........
Having probs getting enough fuel to carbs after a long full throttle run, problem was showing itself at Donnington after going down straight on full
throttle i was running out of juice before i wanted to brake, just tried a few things which haven't made things any better, pretty sure it is
lack of fuel, just been out on a couple of test runs/blasts, runs great runs out of fuel (i think) back off give pump time to catch up ok again ?
1) Do you think it is fuel pump related ?
2) Running standard pump but the tank is at very front engine is, as you prob know at rear, the pipe run is long.
3) Not sure a after market pump would do the job as to get the pressure down to suit bike carbs you have to regulate them and lose lots of flow.
4) It dont show under "road" driving conditions but only after continuous wide open full throttle runs.
5) What do you think to putting a 2nd bike pump and line in and feed 2 carbs with each pump?
Any body had a prob like this that turned out not to be fuel pump related, am i barking up the right tree ?
Ta Jon.
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Jon Ison
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| posted on 28/9/04 at 06:28 PM |
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oh, the fuel pump is 6" of pipe and a filter away from tank and pumping all way to carbs, would it work better nearer the carbs ?
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Peteff
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| posted on 28/9/04 at 06:53 PM |
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The twin pump idea sounds reasonable Jon. If they are like the one on my bike they should be o.k supplying 2 carbs each as it only has 2 carbs.(NTV)
Would gravity get the fuel to the pumps if you mounted them at the engine end? If so they might be better there and not have to work so hard.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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Northy
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| posted on 28/9/04 at 06:54 PM |
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quote:
Originally posted by Jon Ison
oh, the fuel pump is 6" of pipe and a filter away from tank and pumping all way to carbs, would it work better nearer the carbs ?
I think they push better than they suck.
Sorry not sure of anything else.
Graham
Website under construction. Help greatfully received as I don't really know what I'm doing! 
"If a man says something in the woods and there are no women there, is he still wrong?"
Built 2L 8 Valve Vx Powered Avon
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Deckman001
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| posted on 28/9/04 at 07:00 PM |
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Just a daft thought Jon, but would it help if you had your breather pipe 'fed' from the front ie pressurised by the air flow at high
speed, this might aid the fuel to the carbs, as to pump location, it depends on the type of pump, some need to be near the tank and others should be
near the carbs, no idea how the bike pump needs to work, but your suggestion about using twin pumps might work, you will definitely get double the
flow
Jason
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The Shootist
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 posted on 28/9/04 at 07:06 PM |
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Do a fuel pump volume check
Pull the line loose at the engine and pump fuel into a known size container.
Most engines use less than .5 pounds of fuel per horsepower per hour. Since you want a safety margine you might look for 1 pound of fuel per
horsepower per hour.
Sooo....
If you have 150 hp engine you would pump 150 pounds of fuel per hour, or @6 lbs. per gal for gas 25 gallons per hour, or .42 gallons per minute.(1.6
liters per minute)
I would think the factory pump for the engine would have enough excess capacity to run, even with the extra line length, unless the motor is
modified.
You may also want to check fuel filters, and possibly change to a high flow unit if not using one already.
If you use dual pumps paralell them at the tank with a "Y" on the inlet and outlet. The check valves in the pumps will regulate the flow.
If the pumps were split to feed the carbs seperately a single pump failure could starve 2 cylinders un-noticed.
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JoelP
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| posted on 28/9/04 at 07:07 PM |
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what about a one litre tank near the engine, filled by a low pressure pump, with a high pressure pump to send it the rest of the way? like a glorified
swirl pot.
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kipper
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| posted on 28/9/04 at 07:24 PM |
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fuel pump problems
I had a similar problem with a bike I used on track days, at cadwell it was ok untill I went down park straight.
We traced it, after loads of head scratching, to the vent hole in the filler cap. As the pump was sucking the fuel out a vaccum built up and stopped
the flow at full throtle. Hope this helps, good luck.
Kipper
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Jon Ison
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| posted on 28/9/04 at 07:30 PM |
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Cheers,
I have a non return in tank, will pull it off and give it a blast, could be stuck, not checked it,
Good point about 2 carbs running out of fuel with seperate lines.
Gravity will get it to rear of car, think i'm gonna pull breather off, if its not that move pump to rear, if that dont sort it maybe add a
second pump.
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marc n
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| posted on 28/9/04 at 08:01 PM |
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is the pump mounted so it is gravity fed by the tank, if it has run for a reasonable amount of time without a gravity feed they become lazy, i had
this problem on a freinds grass track car, a new pump would only last two / three meetings, once we made the pump gravity fed he has done 17 meetings
and no problems, when i asked honda about this they confimed that was the case.
Normally the bike pumps are ultra reliable
hope this helps
regards
marc
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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marc n
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| posted on 28/9/04 at 09:27 PM |
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just re read your post john, you need to have the pump as close to the fuel tank as possible and mounted below the feed from the tank to make sure it
is gravity fed
hope this helps
regards
marc
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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marc n
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| posted on 28/9/04 at 09:29 PM |
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[Edited on 28/9/04 by marc n]
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NOTE:This user is registered as a LocostBuilders trader and may offer commercial services to other users
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Hugh Jarce
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| posted on 29/9/04 at 04:39 AM |
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Bike fuel pumps are usually Mitsubishi pumps similar to those fitted to Subarus etc, but they differ in their delivery.
DO NOT try a gallons per hour test with these pumps. They are designed to run only intermittently or for very short times at full capacity (think how
a bike works). You'll burn it out quickly if you ignore this.
Mount it as close to the tank as possible as was mentioned above, pumps push many times better than they suck.
Do make sure it's gravity fed.
Do make sure the bore of all fuel lines and fittings are at least as big as the ID of the pump inlet and outlet.
If you've fitted an aftermarket free flowing air filter in place of the restrictive standard air box configuration, your engine may just be
seeking more fuel than the pump can provide, but I doubt it.
As already mentioned, a belt and braces solution would be to fit two pumps, but they should simultaneously feed all four carbs. You'll need to
fit one way valves in the fuel lines between the pumps and carbs to do this to prevent the pumps trying to pressurise each other and shutting down.
Bike pumps will shut down at around 1.5-2 psi, so it's not difficult.
The pay isn't very good , but the work's hard.
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Mk-Ninja
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| posted on 29/9/04 at 07:42 AM |
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Jon
Ive got a spare pump if you want to try two.
I'm sure I've got one, just don't know where I've put it
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Alez
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| posted on 29/9/04 at 09:54 AM |
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quote:
Originally posted by Mk-Ninja
Jon
Ive got a spare pump if you want to try two.
I'm sure I've got one, just don't know where I've put it
That post made your sig even funnier now.
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ned
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| posted on 29/9/04 at 10:40 AM |
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Jon,
how about a small header tank above the carbs that holds a small amount of fuel to allow for long open throttle runs when the fuel line might be too
long for hte pump?
Ned.
beware, I've got yellow skin
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locoboy
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| posted on 29/9/04 at 10:56 AM |
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Ned - would that be the same as Joels suggestion then 
ATB
Locoboy
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Jon Ison
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| posted on 29/9/04 at 07:21 PM |
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thnx for the input, got home to late to do anything tonight, will keep you posted what cures it.
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Jon Ison
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| posted on 30/9/04 at 06:14 PM |
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Just been a blast with non return removed, defo better but still there, bit o work on fuel pump next, the fact its better with non return took off
tells me it must be fuel flow related ? Wot u think?
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Mk-Ninja
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| posted on 30/9/04 at 06:26 PM |
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What size fuel pipe have you used. Most bike pipework is 10mm.
I'm sure I've got one, just don't know where I've put it
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Jon Ison
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| posted on 30/9/04 at 06:53 PM |
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smooth bore 10mm copper flexi easy bend stuff, think its just the distance its traveling, the pump i seem to remember came off a CBR600, they all look
the same, well this one looks exactley same as a blade pump, i wonder if they are all the same ?? anyone know ?
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Mk-Ninja
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| posted on 30/9/04 at 07:31 PM |
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Dont know if there different between units. As I said before Ive got a spare off a ZX9R if want to try it.
I'm sure I've got one, just don't know where I've put it
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The Shootist
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| posted on 30/9/04 at 08:20 PM |
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Did the car always run like this?
If so I would guess you need a bigger pump.
If not... do you have a screen on the in-tank pick-up? It could be clogged by trash.
Given the fact that removing the non-return made a difference, I bet you need a bigger pump.
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Hugh Jarce
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| posted on 30/9/04 at 09:19 PM |
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Jon, having 10mm bore fuel lines means nothing if the fittings reduce the diameter. As I mentioned before, the entire system must be larger than the
pump inlet and outlet. You may need to use rubber hose to connect the pump barbs to the copper line and don't use any brass or plastic unions
that could reduce the ID.
The distance from pump to carbs won't be a factor.
If the pump is off a little 600, then it may not be man enough for the job. I would compare pump part numbers at your friendly local bike shop and
then, if necessary, source the correct pump for your engine.
It may even be worth fitting the pump from a larger capacity bike. Just don't try a car pump with a regulator as the regulators won't
provide consistent low pressure as required by bike carbs.
The pay isn't very good , but the work's hard.
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Hellfire
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| posted on 1/10/04 at 11:31 AM |
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Jon,
why not get MK Ninjas fuel pump for ZX9R and try that in place of CBR600 pump as another alternative.
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