# Fuel Inj. Guys help



## hondarecoveryman (Feb 28, 2009)

Ok this I am not sure about a FI 750 comes in the shop today and it will only run for about 2 secs then dies, you can let it sit for a sec turn the key back on and it will run for 2 secs again... I checked the fire going to the pump , It gets hot when you turn on the key for a sec or so then kicks off , Is there a fuel pressure switch or something that cycles the pump??? pump is new , has good pressure on initial start up but the pump dosent kick back on ?? just need a little help with this one :thinking: Thanks in advance guys


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## phreebsd (Dec 16, 2004)

the fuel pump kicks on and pressurizes the fuel rail then kicks off.
pressurizes to 43psi 
I think it kicks back on once the motor starts. download the manual if you dont have it already. it has an extensive DFI troubleshooting section.


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## hondarecoveryman (Feb 28, 2009)

The manual just tells me to replace the pump. the stealership has already done that at his expense , out of frustration he brought the quad to me . there is a simple problem somewhere I just have to find it .....


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## sandman7655 (Feb 18, 2009)

possible ground issue or fuel pump relay


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## phreebsd (Dec 16, 2004)

there's a fuel pump relay at the very back. perhaps it's bad.
below i drew diagram of rear of bike. D is the one. u can try swapping c and d to test.

______ 
A RO B 
c d 

a = starter control - neutral
ro = roll over switch
b = starter control - brake
c = fan relay
d = fuel pump relay


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## phreebsd (Dec 16, 2004)

here's a pic









in this pic, swap B and C


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## Bootlegger (Dec 18, 2008)

Steve is the Man....that is a GREAT idea...try that.


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## 650Brute (Dec 18, 2008)

Brute Knowledge.....


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## 08GreenBrute (Jul 13, 2009)

It sounds like it could be a problem with the relay


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## jakedogg (Aug 14, 2009)

ISC valve controls the idle. However these are the reasons it lists for engine stall. A lot of these are under the Unstable/rough idling as well... 

Engine stalls easily:

Fuel pump trouble--- Inspect (see chapter 3).
Fuel injector trouble ---Inspect (see chapter 3).
Throttle sensor trouble ---Inspect (see chapter 3).
Fuel pressure too low or too high--- Inspect (see chapter 3).
Inlet air pressure sensor trouble--- Inspect (see chapter 3).
Water temperature sensor trouble ---Inspect (see chapter 3).
Inlet air temperature sensor trouble ---Inspect (see chapter 3).
Fuel line clogged ---Inspect and repair (see chapter 3).
Fuel pressure too low or too high--- Inspect (see chapter 3).
Fuel pressure regulator trouble ---Inspect fuel pressure and replace fuel pump (see
chapter 3).
Crankshaft sensor trouble--- Inspect (see chapter 16).
Ignition coil trouble---Inspect (see chapter 16).


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## hondarecoveryman (Feb 28, 2009)

it will idle for a sec. or rev for abou 3 secs. the relays have been swapped , I dont understand why the fuel pump is only getting fire on the initial ingnition , but not when you start the engine , what cycles the pump??? On most FI cars it is a pressure switch , but dont see one on the breakdown in the manual, does the crank shaft have a sensor on it for the FI ?


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## phreebsd (Dec 16, 2004)

yep, there's a crankshaft sensor that comes into play. that's chapter 16


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## Metal Man (Dec 17, 2008)

Have you checked the ECU yet? Might not be the problem but its easy to try if you have access to another ECU.

Swap it out with a known good one. You can swap them around in less then a minutes time.


PS
My VDI was giving me a bad crank sensor code a while back. turns out the bottom of the relay plugs were getting wet and causing it. After i dielectric greased them the problem went away. 

The problem was on the fan sensor relay.It controls more then the fan. If you unplug it the bike will not run at all.


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## hondarecoveryman (Feb 28, 2009)

Thanks for all the suggestions .....I am off to the shop see what happens, I will give updates this evening


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## hondarecoveryman (Feb 28, 2009)

Ok got the brute to crank and idle fine , revs fine when in N but when you ride it it spits and sputters and runs like crap at anything over 1/4 throttle , kinda like its really lean...:thinking:


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## drtj (May 3, 2009)

Trash in gas tank? When its not moving running fine. But when moving trash is getting in fuel?
Just an idea


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## Hogchain (Sep 14, 2009)

Sounds like the same thing mine is doing. http://www.mudinmyblood.net/forum/showthread.php?t=2875 Idle is fine, but any throttle pressure it pops, spits, pukes and dies.


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## walker (Apr 5, 2009)

goin out on a limb what about the fuel filter


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## Masher (Jan 16, 2009)

Check the sock and swap injectors. Sounds like trash in the injectors.


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## Masher (Jan 16, 2009)

I would also pull the tank and clean it out.


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## hondarecoveryman (Feb 28, 2009)

I thought it was getting lean ,so i checked all the boots and stuff for any air leaks , so that is eleminated from the cause, anj, valves and changed plugs, .....still no change., oddly enough when you cor the snork up about 3/4 of the way it clears up for a few secs .?? , I will take he pump out and clean the sock, it seems to do fine until about 1/2 throttle then begins to spit and sputer and backfire(lean?)


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## Masher (Jan 16, 2009)

Have you swapped in good injectors yet? If the sock is dirty try it for sure. Could also be keeping the line pressure if clogged a bit.


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## hondarecoveryman (Feb 28, 2009)

I am going to try that in the morning after i check to sock , makes sense...If the inj. are clogged, it will act like its lean right ? still getiing air , but not all the fuel..= lean :thinking: FI is fun to trouble shoot :aargh4:


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## phreebsd (Dec 16, 2004)

it will act that way when the pump isnt putting out enough either.
Did you check the fuel pressure? should be 43 psi. also the volume test?
the pump should output 1.7 oz (50ml) or better in 3 seconds of operation (that initial run at key on)


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## hondarecoveryman (Feb 28, 2009)

The pump is Brand new from dealer, it was installed 1 week before warranty ran out,witch was 2 weeks ago now, so I havent checked it for pressure ... I just assumed that the pump was operating correctly, it is running for 3 secs and puting out the right flow.maybe Ill check for pressure too


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## phreebsd (Dec 16, 2004)

that must not be it then.


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## hondarecoveryman (Feb 28, 2009)

This one is kickin my butt , LOL when I get it figured out I will know the FI system by heart:haha:


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## Masher (Jan 16, 2009)

What burnt the fuel pump in the first place? I've got a sneaking suspicion their is garbage in the injectors. When they changed the pump they probably took care of the sock if they are worth their salt.


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## hondarecoveryman (Feb 28, 2009)

I found a few bad o- rings when I dissasembled the pump today, I am going to replace them in the morning and try that, I took out the injectors,and cleaned them, along with everything I could find today that was FI related , It would run great for a few mins then would loose pressure on the pump ....:thinking:


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## walker (Apr 5, 2009)

maybe them o rings gets to a certain pressure it gotta go somewhere


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## hondarecoveryman (Feb 28, 2009)

thats what i think walker . We will all know tomorrow evening


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## walker (Apr 5, 2009)

i've seen an o ring that looks brand new leak like all get out.. simple things will make you think the most..... hope that fixes it


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## Masher (Jan 16, 2009)

We saw what happened to the Space Shuttle with a faulty O ring.


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## hondarecoveryman (Feb 28, 2009)

no luck:nutkick:It drops volume and flow when ypu pressurize the system.....lookin like the pump


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## hondarecoveryman (Feb 28, 2009)

O.K. guys here is what I am going to do , buy a universal, high pressure in tank pump,( about 100 bucks) and a fuel pressure regulator ( about 20 bucks) , I just cant see payin 500 bucks for a fuel pump


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## phreebsd (Dec 16, 2004)

Im interested in seeing how that turns out


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## 650Brute (Dec 18, 2008)

Keep us posted


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## hondarecoveryman (Feb 28, 2009)

In theory it will work fine ....Parts should be here by next monday


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## Metal Man (Dec 17, 2008)

Did the dealer already replace the old pump with a new one?


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## hondarecoveryman (Feb 28, 2009)

Yes they replaced the pump , but they didnt clean out the tank so the trash that killed the first pump would get the second one too ...I guess it finally did LOL


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