CIS basic no fuel from injectors

[ArsenicPants]

I'm not entirely sure what issue i might have, although I think it's 1 of just 2

I have fuel coming into the FD, fuel going to and from the WUR, going to the CSV, and there's at least enough fuel in the fuel injector lines that they spray fuel when I crack them on the fuel distributor. but the fuel injector aren't spraying when I crank

if i trip the fuel pump relay and do an injector test, they all spray just fine

so, could my problem be that I don't have enough fuel pressure to open the injectors up at startup?
or could it be that I have some kind of MAJOR air leak and there isn't enough pressure to pull up on the air metering plate?

i'm running 4 throttle bodies with a custom made intake, and i've checked all over to try and find somewhere the air might be escaping. but even if there's a small air leak somewhere, you would think there would still be enough vacuum to at least make the car sputter? when I pull the spark plugs they're bone dry and so is the piston face

[ArsenicPants]

I should mention that I was using the same FD before swapping in the 4 throttle bodies and it worked fine
new fuel filter too
different WUR, different, older style injectors (it a 16v, I took the stock ones out so that I could use older style fuel lines with a coarser thread in the connectors)
same CSV

[WaterWheels]

if i trip the fuel pump relay and do an injector test, they all spray just fine

so, could my problem be that I don't have enough fuel pressure to open the injectors up at startup? or could it be that I have some kind of MAJOR air leak and there isn't enough pressure to pull up on the air metering plate?

i'm running 4 throttle bodies with a custom made intake

When you say they spray when doing an injector test, do you mean that you are raising the air sensor plate and they then do spray? Have to ask to be sure and not do any guessing.

No, fuel pressure does not seem to be the problem if you are doing the injector testing by raising the air sensor plate. If they open and spray then, the injectors, then they should also open when starting when the plate lifts a little. Yes, you could have a leak in the intake system which is allowing air to by-pass the air sensor plate and not allowing it to lift as it should. My major question before making any real comments or guesses is the throttle body statement. Are you saying you have 4 (four) factory throttle bodies installed or do you mean something like individual throttle bodies?

[ArsenicPants]

When you say they spray when doing an injector test, do you mean that you are raising the air sensor plate and they then do spray? Have to ask to be sure and not do any guessing.

No, fuel pressure does not seem to be the problem if you are doing the injector testing by raising the air sensor plate. If they open and spray then, the injectors, then they should also open when starting when the plate lifts a little. Yes, you could have a leak in the intake system which is allowing air to by-pass the air sensor plate and not allowing it to lift as it should. My major question before making any real comments or guesses is the throttle body statement. Are you saying you have 4 (four) factory throttle bodies installed or do you mean something like individual throttle bodies?

yes, I'm raising the sensor plate and they and they all spray without any problems
I'm using 4 GSXR individual throttle bodies in place of the single standard throttle body
I have a lot of worm gear clamps, with rubber connectors on either side of the throttle bodies. I realize there very well could be a slightly open connection in any one or a few of the clamps, but even if there were a few, wouldn't the engine still at least sputter a little bit?
I'm going to try lifting the plate manually tomorrow with someone else cranking it to see if it makes any difference. although I guess if the "injector tests" works, then the car should at least sputter and sort of run if I tried it this way. so I guess it wouldn't really prove anything...?

[ArsenicPants]

the system goes like this:
head to intake manifold, to rubber connectors, to 4 throttle bodies, to rubber connectors, to plenum manifold, to adapter plate, to single rubber connector, to spiral-wire based hose, to intake boot, to fuel distributor
i've checked for leaks from the fuel distributor to the plenum, but not anything further. i'm not entirely sure how without compressed air...

there's a vacuum port of the top of each TB, all connected together, and connected to the brake booster
there's smaller vacuum ports on each TB as well all connected together, with 1 connection going down to the intake track pre throttle bodies. so it should be closed.
the air shroud port on the intake manifold is capped off. the injectors don't have the hats on there, that are supposed to "seal in" the air shroud system. but i've read that that shouldn't matter as it will only slightly decrease fuel economy
each injector has a new O-ring, but because of the slightly larger connectors on the older style injector lines, with the coarser thread in each connector, the "clamp" spring things that attach to each fuel injector to push them into the manifold aren't connected, but the O-rings are well seated and look like they're sealing.

[Glegor]

the spiral tubing CANT seal very well, being that there is always going to be a spot where the spiral wire runs under the clamp.

and the engine doesnt really intake much air at idle, or cranking.. so it wouldnt take many vacuum leaks for the fuel dizzy to not see any vacuum at all while cranking...

im thinking that you have too many rubber/clamped connections between the intake port and the fuel dizzy..

[ArsenicPants]

the spiral tubing CANT seal very well, being that there is always going to be a spot where the spiral wire runs under the clamp.

and the engine doesnt really intake much air at idle, or cranking.. so it wouldnt take many vacuum leaks for the fuel dizzy to not see any vacuum at all while cranking...

im thinking that you have too many rubber/clamped connections between the intake port and the fuel dizzy..

I thought the same thing, but I've tested the hose from the intake boot to the plenum by sealing off one end and blowing my own breath through it, and none can escape
You're right that having so many rubber connectors can't be beneficial though

Maybe I can take the whole assembly off of the head, seal up each port, and do the same air-blowing test to try and find leaks somewhere in those connections
It's a pain in the ass, but it'd give me a better idea

[ArsenicPants]

I made up a quick vacuum test using electrical tape over each of the manifold ports, and a household vacuum connected to the fuel distributor end

www.youtube.com/watch?v=hyD2lEhaD8E

I'm going to try using a hair dryer next to try and find any pinhole leaks. But I don't think vacuum is really my problem given how quickly the hose sucked up, and how difficult it was to pull up on it while the vacuum was turned on

[WaterWheels]

I think you are going to have to figure out the "why" part of this one as nobody can do any hands on for themselves. It is basically simple if the information so far is correct, but the exact reason has to be discovered. If the injectors will open and spray fuel with the pump hot wired and the air sensor plate raised then you have to find out why this does not happen by itself.

Here are a few places to look or ideas you can play with.
~ False air as has been stated. It only takes the total area of say the size of a Bic pen to allow enough air to by-pass the air plate and keep it from lifting.
~ Air sensor rest position. You said the fuel distributor was being used before, is the air sensor also the same and were they seperated? To low or to high a rest position can cause a no fuel/no start.
~ Air sensor stuck. Moving it around you may have bumped it enough to now hang on the side of the air cone. Or if it sat for a long enough time the plunger in the fuel distributor could have gummed up. Wrong air filter or a rats nest in the filter box to hold the sensor open. Anything which blocks the sensor plate either open a little or closed or fixed and can't move.
~ Operate it yourself. A little un-filtered air will get into the engine if this bothers you, but you can remove the mixture unit from the filter box base and operate the sensor plate yourself to see what happens. Just don't expect to be able to "run" the engine for more that a few seconds this way. But if it starts and runs for a few seconds you know air intake is your problem.
~ The bike throttle bodies. Just a thought but it could be that the air "signal", pull against the air sensor plate, is too weak with four throttle bodies? With EFI and individual throttle bodies it is different. But with using the CIS injectors it starts to get more interesting I think. Are the throttle blades open a little to allow some air to be drawn in? You seem to have no cold start valve to give the engine that initial kick, maybe installing one will fix things?

[DjBij099]

Can't really help with your question, but just wanted to say this looks like a pretty cool setup you got goin on

[ziddey]

It's because you don't have a timing belt!


Have you tried flooring it while cranking? May draw that little bit of extra air needed.