Starting/Running Issues... no spark

bigd9247 · Oct 30, 2007

My truck is a 1989 Toyota Pickup with 3.0L... My truck has just started doing this within the last three days and it is getting worse.

It first started out just being hard to start, then I would have to crank on it multiple times to get it to start, and now it will turn off when I'm driving down the road. The weird thing though is that it is totally random... sometimes it'll start right up on the first crank but other times I'll have to try it multiple times. One other strange thing is that if I have been cranking on it and it wont start, it will start if I compression start it.

So I started trying to figure out what was wrong. First I loosened the bolt on the fuel rail to make sure I was getting fuel... which I was. Then I pulled a spark plug to check for spark. I attached the spark plug wire, grounded the threaded part of the spark plug, and had my girlfriend crank over my truck... no spark. I grounded the plug in multiple spots and made sure the plug wire was fully on the plug... still no spark. Did I do this test wrong or am I really not getting spark? The spark plug isn't dirty, in fact they are all almost brand new.

What could be causing me to have no spark? And for that matter, why would I get spark sometimes (because my truck runs sometimes like I said before) but not always? The distributor cap is new, the spark plug wires are new, and the plugs are new.

Toyotanut · Oct 30, 2007

possibly the coil going bad

bigd9247 · Oct 30, 2007

Toyotanut said:
possibly the coil going bad

Is there any way to check the coil to see if it's good, or do I need to just go buy a new one?

angelfly · Oct 31, 2007

go to carquest bro put it in runt it for like a couple hrs if that doesn't fix it pull it out and return it they will take it back as long as you have the reciet!

Happy B-day by the way

Pat · Oct 31, 2007

Check the battery. I've experienced exactly what you described more than once with Hondas. Both times it was a weak battery, computers are funny like that.

bigd9247 · Nov 3, 2007

Battery reads 12.2 volts sitting and 14.1 running. Truck cranks over just fine so I don't think that could be the problem...

I replaced the coil and that wasn't the problem. I've narrowed it down to something having to do with power to the ECU or the ECU itself. When you turn the key to the "ON" position, normally the Check Engine light will turn on until the truck is started. But with my truck, the Check Engine light doesn't always come on. When it's off the truck won't start, but when it comes on the truck starts right up. When I turn the key to the "ON" position, the the light doesn't light up, I can sit there and wait and the light will usually turn on eventually without me touching anything... any ideas of what to check next?

TreeClimber · Nov 3, 2007

I've no formal training on this application, but I'd be checking all the ground connections from the motor, body, computer, etc.

The ECM is essentially a 'switched-ground-circuit'.

Pat · Nov 3, 2007

Other than the fact that it died while driving down the road, I would still think it could be the battery. Just for the sake of starting with the simplest things first, did you load test it or just volt reading? Mine also cranked over, had lights, radio, etc so I thought no way it could be the battery- must be something like ignition coil or ECM. Turns out my battery had volts but not enough amps to make the computer function properly, hence the no spark and intermittent running issues. I'm NOT a professional mechanic but I've learned to start troubleshooting with the simplest things first, before throwing money at it.

bigd9247 · Nov 3, 2007

I only volt tested it. Tomorrow I'll take my battery down to the auto parts store and have them test it for me to see if it's good or not. I just can't understand how it would die driving down the road, because the battery shouldn't matter at that point. Oh well it's easy enough to test it so I might as well.

bigd9247 · Nov 6, 2007

I took the battery down and had it tested... it is fine. The truck is still doing the same thing, but luckily it hasn't turned off on me recently while I was driving it.

I'm thinking that the problem has got to be one of the things listed below:

-a relay somewhere... which one though?
-the ignition switch
-the ECM
-a bad ground... but i wouldn't even know where to look for that. the grounds inside the engine compartment are fine.

anyone else have any ideas? i have a buddy that has an extra ECM so I might try switching that out this weekend...

where is the "Main Relay" on a 1989 Toyota pickup with the 3.slow V6? The manual says it should be with the fuses under the hood but the only two relays there are the starter relay and the headlight relay... or is the starter relay the Main relay?

GaryTJ · Nov 12, 2007

The EFI relay is in the main fuse panel. It powers a few things besides the ECM.

Very common problem is the 02 sensor shorting or wiring grounding causing the ecm voltage to go below threshold and turn off the ecm.

pin 12 of the check connector is power from the relay. It is a white wire with red tracer. Put a voltmeter on it when you driving around.

bigd9247 · Nov 13, 2007

Hey GaryTJ, I will take a look at the 02 sensor wiring and i will also check the voltage of that wire. Thanks for the ideas.

One other thing that I've noticed... When the key is turned on, I can here the starter relay click (like it should) and then I hear a second relay click nearby and then the truck will start... if I don't here the second click, then the Check Engine light doesn't light up and so it doesn't start. Where is this second relay?!?!?! I can't find it, but where-ever it is, it has to be in the engine compartment or nearby because i can't hear it inside the truck... In the fuse panel under the hood there are only two relays, the starter relay and the healdight relay... could both clicks be from the starter relay (like a double throw type relay or something like that)?

SnoFalls · Nov 13, 2007

The other "click" could be the fuel pump relay ... I don;t recall exactly but I think that relay is behind a kick panel.

GaryTJ · Nov 13, 2007

bigd9247 said:
One other thing that I've noticed... When the key is turned on, I can here the starter relay click (like it should) and then I hear a second relay click nearby and then the truck will start... if I don't here the second click, then the Check Engine light doesn't light up and so it doesn't start. Where is this second relay?!?!?! I can't find it, but where-ever it is, it has to be in the engine compartment or nearby because i can't hear it inside the truck... In the fuse panel under the hood there are only two relays, the starter relay and the healdight relay... could both clicks be from the starter relay (like a double throw type relay or something like that)?

you have a curcuit opening relay that is a dual relay. One side is trigger by the air flow meter. it turns the fuel pump on when it senses air flow and if the temp is cold it also triggers the cold start injector.

next time it won't start, leave the key on and check power to the injectors. (blk wire - red tracer) they are fed direct from the switch. If you have no power there, look for a bad ignition switch. If you have power at the injectors, look for power at the check connector as I said before. That will tell you if the efi main relay is working. (or bad wires to it)

If you have power there, then check all powers and grounds to the computer. Let me know if you need pin numbers/wire colors for them.

bigd9247 · Nov 20, 2007

Ok I have found the problem!!! Thanks, GaryTJ for your help. I started by checking out the things you said and that helped me narrow the possibilities down. Turns out there is a bad connection at the black relay in the fusebox in the engine compartment. It's the only relay besides the headlight relay. I know it's either the starter relay or the main relay. But either way, if I "wiggle" it then it will work like it should. I tried using needle-nose pliers to crimp the connectors inside the relay mount tighter... but that hasn't solved the problem. I'm thinking it's a bad connection under the relay mount, but I haven't had time to take the fuse box apart and fix it. Either way, at least I know what the problem is now!

Thanks again to everyone for their help.