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Truck no Start

twiget

twiget

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I got in my truck this morning to go to work and it would crank, but it would not start. It's a 90 Suburban with a TBI 454.

My keen troubleshooting skills :rolleyes: have lead me to the conclusion that the injectors are not opening when I try to start the truck. I have verified the fuel filter is ok, and I have verified fuel to the injectors. After trying to start it a couple times, the injectors are bone dry, and there is no indications of fuel in the bowls.

I doubt both injectors would fail at the same time, so this leads me to the conclusion that the injector controller might be having some issues. I tried to trace the wires back from whence they came, but no luck. I inspected all the connectors and vacuum hoses that go to the injector assembly, and everything looks in order. Even after all this TLC, the truck still wont start. :mad:

Any thoughts on where I can find the injector controller, and/or what might be causing my issue?
 
Ignition module is a likely suspect.

Hook a "noid" light up to one of the injector connectors. The ECM grounds one of the wires when the engine cranks, and the other wire is ignition 12V, so you have to use both wires on it.

If the light doesn't flash, more than likely an ignition module issue.
 
dyeager535 said:
Ignition module is a likely suspect.

Hook a "noid" light up to one of the injector connectors. The ECM grounds one of the wires when the engine cranks, and the other wire is ignition 12V, so you have to use both wires on it.

If the light doesn't flash, more than likely an ignition module issue.
Click to expand...


I agree with dyeager. As well, if you have someone crank the truck you should be able to see very easily a nice cone spray from the injectors. If you see fuel spray then cheeck spark. But those ignition modules are known for going out, in fact the cheapy kragen one I bought is going back for a gm original as it has been acting finicky as of the late.
 
Best advice thus far...shouldn't assume the easy stuff has already been checked. :)
 
Very true. I'll check the fuses when I get home from work.

Where is the ignition module located, in case it is not the fuses?
 
It's under the distributor cap. Need to check for spark/injector pulse before even considering it though.
 
So a quick run down of todays events:

Fuse: Check
Spark: A-Ok
Noid Light: Dead as a Doornail

Looks like I'm getting a new ignition module. And since the distributor is coming out, might as well do a tune up with new wires, plugs, and distributor.

Any advice on how to turn the motor so that the #1 piston is at TDC?
 
Once you get all the plugs out put a socket wrench on the crank pully and spin it clockwise till you are at TDC on the timming mark. When the plugs are out it is piece of cake! That is if you can get to it.
 
Slow down just a hair. You confirmed that you have 12V to each injector connector with the key in run? Just want to make sure something didn't happen to that wiring after the fuse. I'd guess on TBI the two injectors to be run off the same 12V source. Just in case. Easy to check.

#1 TDC is pretty easy if your timing tab is marked/accurate. Pop the #1 plug out, rotate engine with socket wrench on crank with thumb over spark plug hole. Once you start to feel compression, bring it up to "0" on the timing mark.
 
Isnt that what the noid light did? If there was 12VDC at the injector, the light would have turned on. The light did not turn on, which indicates that 12VDC is not making it to the injector.
 
Incorrect.

"The ECM grounds one of the wires when the engine cranks, and the other wire is ignition 12V, so you have to use both wires on it. "

With the key in run one wire should always have 12V, with no ground path until the engine starts turning over. Thats ONE of the things the ignition module does, send a signal to the ECM that the engine is turning over, start pulsing the injectors by grounding the other wire on the injector lead.
 
It's unlikely a problem, just would hate for you to find out later that isn't the issue, when it's simple to test. :)
 
So changing the ignition module did not fix the issue. Still cranks, but no gas from the injectors. Is there a fitting on the fuel line where I can check fuel pressure?

I know the fuel pump is running, and it's pushing some fuel, but perhaps it is giving up the ghost and cant meet the pressure requirements?
 
I know this may sound a bit odd but check the cap for a good seal. Some injector systems are gas cap sensitive on the preasure. Another thing like you said the pump may be pooped! If not I would start disecting the system to see if you have a clog or loss of pressure. Tank to Filter, Filter To Pump, Pump to Injector Rail, Injector Rail to Injectors. Just a thought!
 
The fuel filler cap is in good condition, and it is tight. I've already checked the fuel filter, it looks brand new, and I've got fuel to the injectors. Unfortunately, there is no schrader valve on the fuel line, so I dont have an easy way to check the fuel pressure.

Apparently, when I said the spark was ok, I was wrong. I just double checked it, and I've got nothing. I even checked from the ignition coil to the distributor, and nothing. So, what do you think? Ignition coil?
 
That more than likely is the culpret! Before you replace it make sure your getting 12VDC to the cap. Not sure of your type of dist. but I assume it is HEI and there should be two wires to the cap 12VDC on the left from the ing. and optional wire on the right for the tach. Might as well get new rotor and cap if they are not too new!

Look on the bright side least you don't have points!!!!!!! I rip my points dist out and put in an HEI. Let us know.
 
So the ignition coil did not do the job. :mad:

Lets do a little review.

The problem:
Truck cranks, but does not start.

Stuff I've checked:
All the fuses good
Gas cap in good condition and tight
Fuel filter looks brand new
Fuel to the injector rails
Fuel pump runs
No fuel from injectors
Noid light indicates injectors are not being pulsed
There is 12VDC on each injector, as it should be
Replaced ignition module, still no fuel from injectors
Checked spark from ignition coil to center of distributor cap, no spark
Replaced ignition coil, still no spark
Visually inspected distributor cap, rotor, electrical connections, spark plug wires and boots. Everything looks good. I didnt see any corrosion, or damage on anything.

Anything else I should look for?
 
Do a search on here for problems people have had with the pickup coil. Only thing I can think of for spark, assuming all the new stuff you have works.
 
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