Outer Limits 4x4 Board

Hey peoples!! well i am currently putting a new motor in my 1991 sierra WT (was a 1.3 carby, now is a G16A 16 valve EFI). I have everything done, but i cant get it to fire up!!!!!! Grr!! So im starting to do a few tests to try and find out whats going on. So, qtn 1.. one of the wires going to the distributor is getting 11.66 volts with the ign on.. when i crank it, the power drops to 6.4 volts.. should the power be up around 12 V while cranking?? Also, the "cranking" power feed to the computer (have got this from the original 1.3L starter solenoid wire) is only pushing out around 8 volts while cranking.. is this also enough volts to get the computer working properly?? Thanks heaps!!!

It's not unusual for battery voltage to be in the 8V range during cranking - have you measured directly at the battery? So I wouldn't be too concerned about this.

Similarly, the line to the distributor is probably completely normal (depending on how the electronic ignition works.) The coil uses current to generate a magnetic field, which then "collapses" when the current is interrupted - the collapsing field is what ultimately creates the spark for the spark plug. The current is traditionally interrupted in the distributor, so it's not unusual to see around 6V on a wire going to the distributor - it's actually switching very rapidly between 12V and 0V, so 6V is about right, depending on "dwell". In an EFI'd vehicle there are often other signals generated in the distributor which may be "chopped" 12V, so the 6.4V is not necessarily a problem.

Unfortunately, to troubleshoot an EFI problem you really need some form of manual to tell you what voltages to look for where. However, some fundamental things I would be looking at:

Fuel:
Does your fuel pump run?
Do you have pressure in the fuel rail? I did an EFI conversion and managed to hook my electric pump up backwards. It was running, but trying to pump into the tank.
Are the injectors firing? At idle, I can just hear the injectors "clicking". Do yours make any noise?
Smell your exhaust. Does it smell like fuel? Do you have a leaking injector flooding your engine? (Unlikely, as I would expect it to only affect one cylinder - not all.)

Spark:
Have you tried an inductive timing light on a spark plug lead, to see if the spark is firing? You could pull a lead & use a known working spark plug to look for spark, but EFI systems typically create more voltage than older systems, and, if you don't ground the spark plug properly, you run a risk of damaging your EFI computer - that's not normally a good thing.
If you get a timing light working, is the spark firing at the right time? If so, are you sure it's firing TDC on compression, and not TDC on exhaust?

You could also try asking in the Suzuki section (if you haven't already) - this is a Suzuki-centric question, so any tips or tricks particular to the G16A are most likely to be answered there.

Good luck.

Thanks scott!! Wasnt expecting as answer quite like that!! (usually get the yes/no answer!!) I checked the fuel just to make sure, i disconnected it from just before the rack.. it pumped for the 2 secs or so while the ign was "on".. then it stopped. This is normal though isnt it? I then thought i would test the plug leads..
Results..
lead 1: 3.66
lead 2: 2.62
lead 3: 2.17
lead 4: 1.72

Is this ok?? I will make sure the timing light flashes when the timing mark is on TDC when my misses gets home (need her to turn the key!!)
Another thing, it floods the plugs up with fuel after turning it over for 15 secs or so. and the eng bay stinks of fuel? Thanks again matey..

Did you hook the fuel lines up the right way around?

chimpboy wrote:Did you hook the fuel lines up the right way around?

Best double check.. hehe you never know!!

Just checked the timing.. the timing light wont work!! I went and tried it on my ute.. worked fine. Went back up to the zook, tried it again, still nothing!! I tried it on no: 1 lead, then no: 2 lead. Both didnt work. I made sure the ign was on, had it hooked up to the battery correctly etc..

Gday mate just a thought,it is really common for these motors to strip the timing gear off the crank,pull the distributor cap off and check if its spinning when cranking i know sounds like a long shot,but has happened quite a few times at our w/shop. goodluck

4runner_boy wrote:Gday mate just a thought,it is really common for these motors to strip the timing gear off the crank,pull the distributor cap off and check if its spinning when cranking i know sounds like a long shot,but has happened quite a few times at our w/shop. goodluck

yup.. the rotor button does spin (thank god!!). Another thing, i just went up and played with the timing light again.. and it only flashes (once) when ever i let the key off the cranking position. When this happens, the motor tries to fire. So it still seems like the dizzy/coil isnt getting full power (untill that last split second when the key is released).

get it up there wrote:

4runner_boy wrote:Gday mate just a thought,it is really common for these motors to strip the timing gear off the crank,pull the distributor cap off and check if its spinning when cranking i know sounds like a long shot,but has happened quite a few times at our w/shop. goodluck

yup.. the rotor button does spin (thank god!!). Another thing, i just went up and played with the timing light again.. and it only flashes (once) when ever i let the key off the cranking position. When this happens, the motor tries to fire. So it still seems like the dizzy/coil isnt getting full power (untill that last split second when the key is released).

The signals to tell the ECU when to fire the plug are often generated inside the dizzy. My next guess is that this "signal generator" isn't working, but it's possible that a single pulse is coming through as you release the key.

Can you see which bits inside the dizzy are making timing signals? Mine has a series of tabs which move with the rotor, and pass through light barriers - if that helps? If yours is similar, and has crud in the light barriers, that could prevent generating a signal?

-Scott- wrote:

get it up there wrote:

4runner_boy wrote:.

The signals to tell the ECU when to fire the plug are often generated inside the dizzy. My next guess is that this "signal generator" isn't working, but it's possible that a single pulse is coming through as you release the key.

Can you see which bits inside the dizzy are making timing signals? Mine has a series of tabs which move with the rotor, and pass through light barriers - if that helps? If yours is similar, and has crud in the light barriers, that could prevent generating a signal?

Pretty sure i understand.. like the tabs that open up points (when the eng has points!!). I looked under the cap (under the rotor button).. it looks almost new. No stuff built up anywhere
I just hooked a wire from the battery, through a fuse to the + coil. While cranking, it improved the volts from 5/6 volts (without the wire), up to 8.8 volts (with the wire). But still no fire.