Question about timing...

General Bellett, Gemini 75-98, Piazza 81-93, Bellel, Florian, 117 Coupe, Minx, Aska technical discussion.
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Post by impulsive » Wed May 09, 2012 4:45 am

Cheers, mate!!!

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Post by impulsive » Thu May 10, 2012 1:32 am

Well, all I can say is last night I fiddled with some stuff, had the dizzy out and I was checking my timing again, and I have everything back together and I am back to where I was 4 days ago. She cranks all day but will not even start.

Back to the basics again I guess.

:rolleyes: Bart
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Post by wedgenut » Thu May 10, 2012 4:39 am

I guess I don't need to say that if you have fuel pressure, spark, air delivery and compression it WILL start providing everything is happening at the right time.

Sort out/check the mechanical side first, it isn't variable. So compression check. Cam timing check, again it isn't variable. Ignition timing, once set can't change. If all okay are you getting a fat reliable blue spark at the plugs? If yes it comes down to fuel/air delivery and pressure. That is everything from AFM to injectors. Check fuel pressure at static and during cranking. Check all vac hose condition and routing. Check all wiring and earth connections secure. If necessary remove the injector rail assembly and see if they are firing fuel during cranking (disconnect coil LT leads to prevent sparks of any kind anywhere). You need to check all connections, even the plugs into the back of the ecu, are they clean and secure? I find it frustrating not being able to stick my own filthy paws in there for you.
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Post by impulsive » Thu May 10, 2012 4:50 am

Thanks, wedge. Part of my problem is getting the time right now also. I just finished putting her together, and now I have family in town and other stuff going on so I get about 30-60 minutes a day to work on stuff, and with no help to do simple stuff, it gets frustrating.

Could a bad ground cause the car to not start? I notice I get a nice shock from the door when I get out now. I was thinking it is just static but maybe its a bad ground.

I know I will sort it out, it just sucks donkey dick sitting here at work (especially when it's slow) when I know I could be at home sorting out the car. But hey, I got a job. ;)

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Post by wedgenut » Thu May 10, 2012 5:21 am

We all got that JOB problem, except those refugees the governemts give a house, car and income to without working. A bad or missing ground wire can certainly stop things happening. Check the security of the ground wires on the front lower plenum. There are two or three wires that all have to be firmly grounded there and also the ones from the fire wall to the stud on top of the VALVE cover (see amorica speak). There is another earth point on the inner FENDER (enough already) close to where the horn relay is attached. There are a few under the dash as well and one on the console bracket behind the head deck position. Even these inside ones are important. The one behind the console links back to the start relay which in turn links to the fuel pump relay. That is why I suggested powering up the fuel relay direct from the battery so that you KNOW you have an active fuel delivery at all times.
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Post by impulsive » Thu May 10, 2012 8:02 am

wedgenut wrote:A bad or missing ground wire can certainly stop things happening. Check the security of the ground wires on the front lower plenum. There are two or three wires that all have to be firmly grounded there and also the ones from the fire wall to the stud on top of the VALVE cover (see amorica speak).
Yup, I am 100% positive those are grounded good.

wedgenut wrote:There is another earth point on the inner FENDER (enough already) close to where the horn relay is attached.
Right-o, I got that one too. There is also one from the coil to the spot on the plenum.
wedgenut wrote:There are a few under the dash as well and one on the console bracket behind the head deck position. Even these inside ones are important. The one behind the console links back to the start relay which in turn links to the fuel pump relay. That is why I suggested powering up the fuel relay direct from the battery so that you KNOW you have an active fuel delivery at all times.
Well, I did not mess with any of the wires behind my dash, so I think those should be good. I wonder if the main ground from the battery to the block is not grounding good through the painted engine?

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Post by wedgenut » Thu May 10, 2012 1:57 pm

Thats a good point make sure metal on block is bare and on some models the earth cable also bolts to the body so check that as well. If it has a separate earth to the body check it, the little earth wires up on the firewall to valve cover are not good enough for main engine to body ground.

It is a gradual process of elimination and by going through all the first basics the target will become smaller. If it was running before as you said at high revs then it indicates your compressions must be good enough or it wouldn't have started in the first place, same goes for valve timing I guess and ignition timing on its own wouldn't make the engine race so something has changed or is playing up since it did run last.
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Post by impulsive » Fri May 11, 2012 2:14 am

Yeah, I'll figure it out. Being stuck in the cube here is my only issue right now. I need a solid weekend of dedicated work.

As for grounds, would it be prudent to run all of my grounds directly back to the negative post on the battery?

I am going to take my wire wheel to the painted spot on the block and reattach the ground there.

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Post by wedgenut » Fri May 11, 2012 4:26 am

No need for that just make sure they are all clean and tight on bare metal. I once had one that wouldn't start and I suspected fuel delivery, I pulled the injector rail back just enough to see if it was firing fuel, and being super clever I left them pointing into the manifold holes so that gas wouldn't go everywhere and I cranked it over. This is why I said disconnect the LT leads from the coil....I didn't. The fuel was squirting in just fine but with them being out it was taking air in as well and the damn thing started. It hit about a gazillion RPM before I managed to kill the power, with all that unrestricted air entry it was like having the throttle stuck full open. When I put the rail back in it once again wouldn't start so I knew it was air related. That's when I discovered the faulty IAC solenoid. Turns out it was fine but the wiring terminal had fallen off because the stupid little wire clip was missing, so it was like trying to start a carb style car in in cold weather with no choke.
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Post by impulsive » Fri May 11, 2012 6:14 am

I've been thinking about temp sensors also. Particularly the one at the bottom of the radiator. If that sensor is bad or wrong, could it cause the car to fail to start? Could not having enough coolant in the system circulating cause it to fail to start? I have 2 gallons of coolant in the system right now.

As for the air regulator, I checked my plug there and it was connected. I seem to remember though, the connector for it and the connector for the knock sensor are similar. I can't remember if they are the same, but damnit I wonder if i have them reversed.

Thanks for the tips.

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Post by wedgenut » Fri May 11, 2012 4:12 pm

Don't lose focus, the temp sensor on top of the manifold is for temp gauge only and not relevant to starting. The one under the manifold is for signalling the ecu but again has no bearing on starting. Same applies to the one in the bottom tank of the radiator. None have anything to do with start circuit so ignore those. The knock control wiring plug is nothing like the IAC plug on any car I have seen. Knock control has a wire with a free hanging tubular female connector to connect to the male from your harness. The IAC has a square spring clip connector identical to the standard injector connectors and is part of the same harness. Some later models have a different electrical fast idle where as up to '86 I'm sure they still had the slow opener under the manifold

Depending on model you may have an anti theft system but if that was faulty it normally wouldn't even crank over. What manual do you have? Is it a factory Impulse manual or one of those nasty Chiltons crap things? The factory manuals give a good schematic of the starting circuit and what's involved in it.
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Post by impulsive » Sat May 12, 2012 3:12 am

I have a factory Isuzu 1987 Manual, shows both the G200 and the 4ZC1-T. I am very much a novice when it comes to electrical stuff and wiring diagrams, but I have been learning and muddling through stuff.

I am confident I will get to the bottom of this soon.

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Post by wedgenut » Sat May 12, 2012 6:00 am

Thats cool, best you can get, I have a 1987 Impulse manual as well, probably the same edition as yours but some things may be different if your car is an 86 model sold in 87
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Post by impulsive » Sat May 12, 2012 6:57 am

wedgenut wrote:Thats cool, best you can get, I have a 1987 Impulse manual as well, probably the same edition as yours but some things may be different if your car is an 86 model sold in 87
My car was manufactured in December of 1986. I was 11 years old.

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Post by wedgenut » Sat May 12, 2012 7:30 am

My 86 was manufactured in July and I was already past my best before date! :weedman:
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