simpsons721

Hi

Got a dune buggy built it and the last thing i put on is the gas tank
it looks like we put is together right but there is this vacuum nipple that has nothing going to it and we think that is our problem

check out the vid and please help this is the only place i know will solve the problem

[YOUTUBE]http://www.youtube.com/watch?v=NvTJFDncmm4[/YOUTUBE]

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chrisbnaz

What is that at the very end? It almost sounded like it started for a second?

simpsons721

its the engine shutting off,
i know i thought it sounds like it starting to

simpsons721

please help

corax

looks like a pretty large nipple, probably for a brake booster which I'm pretty sure you don't have - just plug it off.

Also, just because you have spark doesn't mean it's sparking at the right time - is that DIS or does it have a Dist?

stepside trd

looks like an intake manifold vacuum nipple generally used for brake booster, if so, listen to corax. also might want to check fuel press. and/or regulator. Might have to purge the (fuel) line of air being that you just hooked up the tank. Do these things and if still no luck, go from there, check fuel inj., comp. signal, timing, etc.... Good luck, nice rig....

bpayne88

how about timing? or injector pulse. just cause you have fuel presure dosen't mean its getting to the cyl. see if your plugs are wet with fuel. that could be cam sensor or computer issues if its a newer style engine.

Matt16

The huge vacuum leak probably isn't helping anything (can't tell if your plugging it or not). Give us a little info on the engine, carbed or FI?

iamsuperbleeder

wth motor am I even looking at?

simpsons721

motor is 1000 cc efi engine

question - what is that black cylinder canister? because i ran a line from that to the gas tank and

should their be a line coming from the fuel tank just sucking air

stepside trd

With efi motors, you must have a main feed line AND a return line to and from the tank. It helps circulate the fuel and keeps the fuel temp. cooler for better atomizing and burning. You should find the info on what type of efi system you are using. It is a fairly easy system to understand, just that there is a lot to know in order to diagnose. When dealing with it, there is pressurizing, purging, dealing with vapor lock, matching your injectors to your throttle body, adjusting your fuel pump to your injectors, so on and so forth... Look to your manuel or tech sheet for the schem. of your syst. and the proper psi settings

simpsons721

thanks for the help

we have mechanic looking at it right now we think we dont have good pressure in the fuel tank

bigt

post pics

abecedarian

1000 cc efi engine out of a what? GZ1000 suggests a suzuki motorcycle, correct?
That noise at the end sounds like maybe the radiator fan or maybe starter motor is spinning but not engaged.

Having fuel pressure means little more than the pump and regulator are working. What the pressure is can help narrow things down a bit, but likely not much. I'd be more interested in knowing if the injectors are pulsing- having all the fuel pressure you need means nothing if the injectors aren't opening.

Judging from what I see, on top of the throttle is the idle speed control valve and below that is the throttle position sensor... no problems there. Given it's efi and the air filter is directly on the throttle body... got me . Presuming the air filter assembly is what it's supposed to be- open, without a MAF, between the filter and throttle body, and it is a motorcycle engine, it's possible the port you're concerned with could be to a MAP sensor.

In all honesty, we need more information to help: what is the engine from; what FI system is being used (the one from the vehicle the engine is from or aftermarket?); ANYTHING you can tell us about the setup.

EFI generally consists of a few things:
1) fuel circuit: fuel pump, pressure regulator, injectors: pump and regulator maintain a constant pressure at the injectors so a known amount of fuel is injected when the injector(s) are opened. The regulator opens when the pressure exceeds a certain amount, allowing fuel to return to the tank. Conveniently, this setup nearly eliminates vapor lock on an EFI system.
2) air circuit: air flow meter, mass air flow, or manifold absolute pressure sensors; throttle position sensor; sometimes intake air temp sensors. The ECU needs some way of calculating how much air is entering the engine hence the need for one of the first three sensors. In the case of afm or map sensors, air temp is also necessary to determine density of the air charge. The tps is used to determine how far the throttle is opened and at what rate it's opening or closing. The ECU uses this information to: in case you are applying throttle, enrich the mixture before the air sensors react; in case you are releasing throttle, lean the mixture out to help emissions and the "engine brake" effect; in case you are wide-open, to ignore most feedback systems (such as O2) in order to keep the engine at the safest fuel mix (tends to be rich under acceleration).
3) ignition circuit: distributor (if so equipped); cam / crank position sensor; ignition coil(s). Pretty self explanatory.
4) engine temperature: plays a significant role when determining the fuel ratio- like how a cold engine needs more fuel (choke on a carburetor) than a warm engine.
5) feedback systems: O2 sensor for instance. Allows the ECU to fine tune the mix during part throttle operation for better economy.

abecedarian

I should add that with the air circuit, having a closed system after the air has been metered is imperative. Any vacuum leaks after that point (afm/maf/map) mean that air is entering the system without being measured and will throw the fuel mix calcs off. At part throttle, if the leak is small enough, the O2 sensor will catch the lean mix and the ECU might be able to enrich the mixture to compensate. Most issues with vacuum leaks show up at closed throttle / idle and and wide open throttle since the ECU tends to ignore the O2 at those two throttle positions.

space-junk

iTrader: (1)

hmm... seems as if this thread is a little bit in the wrong section...