16v blue top no injector pulse

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

16v blue top no injector pulse

Postby Hyrev86 » Fri Mar 24, 2017 8:40 pm

Hey guys,
So i have a rebuilt bluetop that i just dropped in, it cranks fine but i couldn't get it to start. Sometimes it sounds like its about to turn over but then it just keeps cranking. I have both spark and fuel. Fuel pressure is 35psi at the rail. I measured the voltage at the injector connectors with the key on and i get 12v on one side and about 100mv on the other, which there should be 12v on both sides right? So i checked the manual and it says to check the ecu for 12v on 2 terminals:
pics in the link
http://imgur.com/a/ErBe2

Im getting 100mv at those terminals so i follow the flow chart and inspect my fuses and ignition switch and they all are fine. my grounds seem to be connected too.

would the problem be my ecu or is there something else that i could try and do? Any help would be greatly appreciated.
Last edited by Hyrev86 on Wed Apr 05, 2017 11:32 pm, edited 1 time in total.

Disable adblock

This site is supported by ads and donations.
If you see this text you are blocking our ads.
Please consider a Donation to support the site.


User avatar
jondee86
Moderator
Posts: 2125
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: 16v bluets no injector pulse

Postby jondee86 » Fri Mar 24, 2017 9:16 pm

Have you got these brown wires on the ring connector bolted down ?

Image

These are your ECU grounds and the ECU can't fire the injectors if these are not
bolted down. They hang out of the engine harness at the rear on the intake side.
Easy one to miss when doing an engine swap ;)

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v bluets no injector pulse

Postby Hyrev86 » Fri Mar 24, 2017 10:14 pm

yeah i thought for sure that was my problem but they were bolted down.

User avatar
jondee86
Moderator
Posts: 2125
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: 16v bluets no injector pulse

Postby jondee86 » Fri Mar 24, 2017 11:43 pm

OK... if we are to follow the steps in the link you posted, then you do this (key ON)...
1. Check for 12V to ground on the body side plug of the injector resistor pack.
2. Check for 12V to ground on the two output wires from the resistor pack.
3. Check for 12V to ground at the injector plugs (both sides 12V).
4. Check for 12V to ground at ECU pins 10 and 20 (back probe connector).
You can probably skip to No.4 if you have already done some testing.

If you have 12V all the way to the ECU pins, and the ECU grounds are bolted down,
then your injector circuit is good. When the engine is cranking/running the ECU
momentarily grounds the injectors to make them squirt. Here we are talking only
a few milliseconds, so a normal multimeter is not quick enough to pick up the
pulse.

If you use a stethoscope, long screwdriver to your ear or a finger on the body of
the injector, you should be able to hear/feel the injector "clicking" while cranking.
If it clicks but no fuel gets into the cylinder (check the plugs after a cranking
session) then you possibly have blocked injectors.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

Disable adblock

This site is supported by ads and donations.
If you see this text you are blocking our ads.
Please consider a Donation to support the site.


jinx
Club4AG Expert
Posts: 203
Joined: Fri Jan 11, 2013 10:20 pm

Re: 16v bluets no injector pulse

Postby jinx » Fri Mar 24, 2017 11:57 pm

r the injector contacts 'clean' ?
one side is +ve 12V constant, while the ecu -grounds- the other termainal 12V to fire
ez to set cam timing out 180º. Won't start

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v bluets no injector pulse

Postby Hyrev86 » Sat Mar 25, 2017 7:55 pm

jinx wrote:r the injector contacts 'clean' ?
one side is +ve 12V constant, while the ecu -grounds- the other termainal 12V to fire
ez to set cam timing out 180º. Won't start

contacts are good and I'm getting 3 ohms per injector. I'm only getting 12v on one side of the connector and the other pretty much nothing with key on.

jondee86 wrote:OK... if we are to follow the steps in the link you posted, then you do this (key ON)...
1. Check for 12V to ground on the body side plug of the injector resistor pack.
2. Check for 12V to ground on the two output wires from the resistor pack.
3. Check for 12V to ground at the injector plugs (both sides 12V).
4. Check for 12V to ground at ECU pins 10 and 20 (back probe connector).
You can probably skip to No.4 if you have already done some testing.

If you have 12V all the way to the ECU pins, and the ECU grounds are bolted down,
then your injector circuit is good. When the engine is cranking/running the ECU
momentarily grounds the injectors to make them squirt. Here we are talking only
a few milliseconds, so a normal multimeter is not quick enough to pick up the
pulse.

If you use a stethoscope, long screwdriver to your ear or a finger on the body of
the injector, you should be able to hear/feel the injector "clicking" while cranking.
If it clicks but no fuel gets into the cylinder (check the plugs after a cranking
session) then you possibly have blocked injectors.

Cheers... jondee86

key on and back probing to the resistor I'm not getting 12v to any of the 3 terminals. theres millivolts but not the full 12. I'm getting 12 volts to the positive terminal if i unplug it though, could it be just a bad resistor thats causing the eco to no control the injector ground?

User avatar
jondee86
Moderator
Posts: 2125
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: 16v bluets no injector pulse

Postby jondee86 » Sat Mar 25, 2017 8:18 pm

Right.... let's not worry about the resistor at this point. If you can get 12V at the
injectors it is pretty safe to say that the resistor is OK. When testing stuff, it can
make a big difference to the readings you get if the item is plugged into the wiring
or unplugged. When tracing wires and looking for a possible break, you are always
going to be testing with one probe on the plug and the other one on a clean piece
of metal that is grounded to the chassis.

With the injectors, all four are connected together on the power supply side. That
means that with the key ON you should be able to find 12V to ground on both sides
of the injectors if you back probe them with the plugs on. If you disconnect ALL FOUR
injector plugs and test them, you will only find 12V to ground on one pin. The other
pin will be dead. On the ECU side, the injectors are wired together in pairs. So if
you pull only one plug off, you will find 12V on both pins. Trust me... it took me a
long time to get my head around this :)

What you need to establish is if there is an electrical circuit all the way from the
power supply thru the resistor, thru the injectors and reaching right up to the ECU
pins. And basically you can prove that if you have 12V to ground on pins 10 and 20.
If you don't find 12V at pins 10 and 20, work your way backwards towards the power
supply and find out where the 12V stops.

Cheers... jondee86

PS: If you really do have spark and fuel to the rail, check to see if you have gas on
the plugs after a cranking session. If the plugs are wet, and the engine sometimes
kind of coughs and sounds like it wants to start, then most likely your ignition timing
is off.
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

jinx
Club4AG Expert
Posts: 203
Joined: Fri Jan 11, 2013 10:20 pm

Re: 16v bluets no injector pulse

Postby jinx » Sun Mar 26, 2017 6:02 am

if plugs not wet.... injectors 'sitting' unused for a long time may stick. Common prob
i always keep a spare pigtail handy to energize the injector (tap accross battery terminals, direct 12v)
u should hear a solid click. Sometimes they're stuck and only heat up/spark when tapping battery terminals
most r freed up if hitting on the injectory body, with a 3/8 ratchet extention -while- pulsing 12v
but some r too dead and needed replacing. All injectors removed for above procedures

BEFORE u remove inj, u can crank til u have rail pressure with inj clips -off-, then pulse each inj with spare pigtal
try cranking again, should fire up immediately(only breifly tho) IF injectors r good AND timing correct
no start & wet spark plugs = timing problem(cam or ignition)

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v bluets no injector pulse

Postby Hyrev86 » Mon Mar 27, 2017 12:36 am

cool thanks for all the info guys. i won't be able to test until next week but ill post back when i can. i did use my old injectors that were sitting for a while, figured i could still use them since i just had them cleaned before i removed the engine. ill try to energize the injectors and see if they clear up.

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v bluets no injector pulse

Postby Hyrev86 » Wed Apr 05, 2017 12:16 pm

Update.....
I went to go chase down the wires in the loom for a short, started cutting the loom and tested for voltage on the yellow and green wire going to the ecu. I guess I must have shook something cause now I'm getting 12v to pins 10&20 at the ecu.
I'm still not getting an injector pulse though. Checked with a noid light and got nothing
I checked my plugs and they were all dry but smelt like fuel. Swapped out my injectors for brand new ones I sent out to get cleaned a while ago.
When I went to first started it coughed a little like it was about to turn over. Checked my timing again to make sure it was on point and it looked good. I'm completely stumped at this point

jinx
Club4AG Expert
Posts: 203
Joined: Fri Jan 11, 2013 10:20 pm

Re: 16v bluets no injector pulse

Postby jinx » Wed Apr 05, 2017 7:13 pm

that's the CAM timing u checked ?
My GTS is hard as heck to start if I don't "pulse" the cold start injector (single one hi up on side of plenum). Use the same pigtail
Mine fires right up after that. iirc the COR pulses it automatically on startup. Just not got to sorting my own yet

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v bluets no injector pulse

Postby Hyrev86 » Wed Apr 05, 2017 8:44 pm

jinx wrote:that's the CAM timing u checked ?
My GTS is hard as heck to start if I don't "pulse" the cold start injector (single one hi up on side of plenum). Use the same pigtail
Mine fires right up after that. iirc the COR pulses it automatically on startup. Just not got to sorting my own yet

yup, cam timing is all lined up correctly with the crank and distributor is set as close as i can guesstimate to point to no1 cylinder at tdc compression. previous owner grounded the COR so the fuel pump would stay on for some reason, i was going to check that later on but it shouldn't affect my injector pulse right?

User avatar
jondee86
Moderator
Posts: 2125
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: 16v bluets no injector pulse

Postby jondee86 » Wed Apr 05, 2017 9:23 pm

I'm picking you might not be getting enough fuel into the cylinders. Grab a can of engine
start fluid and try spraying a bit of that into the intake before cranking. If the engine fires
and runs off the spray for a few seconds, that eliminates ignition and timing problems. You
can then start focussing on the fuel supply side of things.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v blue top no injector pulse

Postby Hyrev86 » Wed Apr 05, 2017 11:43 pm

I just realized that my ecu temp switch and cold start thermo switch are not connected because they used to be at the front of the radiator water neck near the thermostat. I had to put those switches in the back so now the connectors aren't long enough to reach the back. will reconnecting them have any significance?

User avatar
jondee86
Moderator
Posts: 2125
Joined: Fri Jan 11, 2013 10:21 pm
Location: Wellington, New Zealand

Re: 16v blue top no injector pulse

Postby jondee86 » Thu Apr 06, 2017 1:02 am

Hyrev86 wrote:will reconnecting them have any significance?

YES !!!! A truck load of difference :) Trying to start a cold engine without the cold
start injector functioning is difficult. Trying to start it without the cold start injector
AND without any cold enrichment from the ECU is almost impossible.

All engines need a lot of extra fuel when starting from cold, and those two things
that you have disconnected are what trigger the extra fuel. No trigger.... no extra
fuel... no start ;) So get busy with some extra wire, crimp connectors or solder and
heat shrink. Extend the wires and hook up the sensors.

Cheers... jondee86
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.

Hyrev86
Club4AG Enthusiast
Posts: 62
Joined: Wed Jan 09, 2013 4:50 pm

Re: 16v blue top no injector pulse

Postby Hyrev86 » Fri Apr 07, 2017 1:22 am

Thanks guys those 2 sensors i hadn't plugged in worked! it fired up within 3 cranks. lol i should've plugged them in the first place, i thought i could get it started for a while with out them and then worry about re-wiring later. good learning experience. thanks again for all the help jondee and jinx

Disable adblock

This site is supported by ads and donations.
If you see this text you are blocking our ads.
Please consider a Donation to support the site.



Return to “TECH: 4A-GE ENGINE”

Who is online

Users browsing this forum: No registered users and 7 guests