rattlehead

What can cause injectors not to deliver the fuel?

I've cleaned and checked the injectors on my 87 t2 to see if the function and they do. I've also checked to see if they get the right voltage and they do but the fuel still doesn't get in the engine could they also be easily clogged by debris in the gas tank?
Any other possibilities for them not fuctionong right

satch

iTrader: (1)

What injectors are you checking and how are you checking them. The B/Y wire powers them, but the other wire is the trigger wire from the ECU. The primary injectors work basically all the time while the secondary injectors are activated when under load.

rattlehead

I checked them with a volt meter and by pulsing them rapidly with 12v
I know my car has the resistor pack whichh I think is what also makes them work as for the one on the ecu idk what it is my ecu just came hooked up to the harness without the 3 plug ins ,without any other extra outer wiring
I also have noticed in the ecu there is a burnt blue resistor could this also be a problem and how can I a dress this? Bad grounding

rattlehead

If I have to get new ones because of the process I did that's no problem but that's how I've seen others clean their injectors

satch

iTrader: (1)

Not sure what " as for the one on the ecu idk what it is my ecu just came hooked up to the harness without the 3 plug ins ,without any other extra outer wiring " means.

Take a pic of the ECU that you believe is damaged and hopefully someone can chime in what is wrong.

When the ECU is plugged in and the key is turned to start the ECU will pulse a ground signal to the primary injectors to activate them. The wires are in he smallest ECU plug. The primary injector wires are Light Green for the front primary and Light Green/Black for the rear primary. Taking an LED light and placing one wire end to the back of the plug where one of the above two wires resides and the other wire end to pin 3I (same plug, Black/White wire) and the light should flicker which tells you the ECU is attempting to pulse the injector into firing fuel.

rattlehead

i guess i must have seen someone add external parts to their ecu
anyways

would a volt meter work, i dont have the LED light but i can go get one later

i noticed 3 green cables one with a strip do they all go to the same thing?

inside the ecu the red arrow points at the resistor that looks burnt, does it affect injectors?



and the second image thats is how my ecu is placed in the car
the arrow points to a connections thats capped

satch

iTrader: (1)

The smallest plug houses the four Green wires for the injectors and the two noted above are for the primaries. You need an LED light as the ground pulse is too fast for the meter to recognize. Also, the plug near the ECU is not for the ECU as it only houses three Yellow plugs (speaking of the ECU here). Not sure about the plug you speak of especially w/o the wire colors of the wires contained within the plug. The FSM has a wiring diagram just in case you wanted to play "what's that plug." And I'm not familiar with the inner components of the ECU thus you'll have to rely on others insight as I have none to offer.

You might want to message "sonic rat" as he is well versed w/ECU's.

rattlehead

ok so ill get the LED check those out
and ill see about the other components

also would debris block the injectors completely from working if there is stufff in the gas tank?

and thanks for the info

satch

iTrader: (1)

Yes, they could be clogged.

rattlehead

ok then ill have to take out the tank and clean it

any easy effective way to clean the lines from the injectors to the tank?

satch

iTrader: (1)

I'm not familiar with the exact process but I'm sure the internet has this info. And it would be a good thing to have the injectors professionally cleaned and flow tested.

rattlehead

ok thanks
i plan to get new ones eventrually

what kind would i have to get and do you have any recommendations on where to buy them?

satch

iTrader: (1)

You need not replace them but just get them professionally cleaned as that would likely be the cheapest route taken.

rattlehead

alright then cool then that is better

Evil Aviator

99% of the time the problem is the fuel pump, not the injectors or ECU. The pump is typically dead or receiving very low voltage due to grounding problems.

In rare cases, the problem is the AFM, usually due to a loose electrical plug.

Although I assume it does happen, I have never heard of an engine with two completely clogged primary fuel injectors. Usually clogs create a bad spray pattern or lower output as opposed to no fuel whatsoever.

rattlehead

I'll have to check fuel pump voltage but the fuel pump is new and so is the afm

satch

iTrader: (1)

If you splurge and spend $2 at Radio Shack and buy an LED light you will be able to test the ECU to see if it's sending the proper signal to the primary injectors. If that tests out well then you know the CAS, AFM and ECU are good. If that were the case then that narrows down your possible causes. Okay?

rattlehead

ok ill be sure to get one and test the ecu

how would i go about dealing with the CAS anything in specific? or should i not mess with that?

satch

iTrader: (1)

" buy an LED light you will be able to test the ECU to see if it's sending the proper signal to the primary injectors. If that tests out well then you know the CAS, AFM and ECU are good."

And you never stated which injectors you tested, which was asked earlier in the thread.

rattlehead

i havent had the chance to go get one and will probably have time to do all this on friday
oops my bad, but i tested them all

satch

iTrader: (1)

And one thing you definitely want to check is the voltage on the Brown/White wire at the boost sensor w/key to on and it should read 5 volts.

rattlehead

Well that adds to the list of problems as mine doesn't have it a previous owner must have removed it, they installed a boost controller
Is it located in the back drivers side near the flywheel area?
I've only seen the pressure sensor in the front passenger side

satch

iTrader: (1)

The pressure sensor is the boost sensor.

rattlehead

Oh I thought hey we're the same then I do have it
Is it suppsosed to be hooked up to the blow off valve and the upper intake manifold?

satch

iTrader: (1)

Yes, the vacuum hose is connected to the UIM. It has 4 wires: B/W, Br/R, Br/W and Black.