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Truck wont start - ideas?

jteck10

jteck10

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this is for a 1990 Blazer w/350 TBI
so i tried doing some routine maintenance today and threw on a few small things
the truck was running fine when parked this morning, replaced the below list, and now nothing
i notice when i try to start the truck there is some gas on top of the block around the base of the throttle body
i tried to attach a video to this thread, but essentially i hear a loud thud and the truck wont crank

any ideas?

heres what i replaced :
- both fuel injectors/gaskets
- Fuel filter (yes its pointed the right way)
- blower motor fan and relay (im having some ac/heater issues)
- starter (once the truck wouldnt start)
- took the battery to get tested/charged with no issue

what i think could be the issue :
- throttle position sensor? i didnt touch it but maybe it was ready to go?
- map sensor? no idea why, but maybe the reason its flooded?
- new battery? (i had the current one tested and charged. they said it was good but its on its last quarter of life)
- timing chain? (unrelated but with the loud thud and no crank?)
- harmonic balancer or crankshaft pulley? (unrelated but with the loud thud and no crank?)

any help is appreciated. im stumped at this point
 

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Sounds like you hydro-locked a cylinder with gas. Pull all of the spark plugs out, disconnect the power to the ignition coil and pull the fuse for the fuel pump. I believe that it's ECM "B". Then you should be able to crank it over, BUT this is hazardous due to spraying gasoline out of the cylinders. Turning it over by hand is safer.

You probably had a seal issue at the injectors which dumped fuel down the intake when the pump primed the system.
 
6872xtc said:
Sounds like you hydro-locked a cylinder with gas. Pull all of the spark plugs out, disconnect the power to the ignition coil and pull the fuse for the fuel pump. I believe that it's ECM "B". Then you should be able to crank it over, BUT this is hazardous due to spraying gasoline out of the cylinders. Turning it over by hand is safer.

You probably had a seal issue at the injectors which dumped fuel down the intake when the pump primed the system.
Click to expand...
Got it, I read somewhere that could be a possibility.

How do you turn over by hand? And cranking is dangerous because of fire potentially flying out?
 
jteck10 said:
Got it, I read somewhere that could be a possibility.

How do you turn over by hand? And cranking is dangerous because of fire potentially flying out?
Click to expand...
You can turn it over with a socket and ratchet on the center bolt in the crankshaft pulley.
If you disconnect power to the ignition coil, then there won't be any fire coming out of the cylinders, just gas, but the starter will have high current going through it, so that could be a potential ignition source. I won't say that it hasn't been done before , it just isn't 100% safe. Of course, turning by hand could lead to some gas running done the side of the engine.
You may also end up with gas in the crankcase, which can be a hazard and also bad for lubrication of the bearings.
 
6872xtc said:
You can turn it over with a socket and ratchet on the center bolt in the crankshaft pulley.
If you disconnect power to the ignition coil, then there won't be any fire coming out of the cylinders, just gas, but the starter will have high current going through it, so that could be a potential ignition source. I won't say that it hasn't been done before , it just isn't 100% safe. Of course, turning by hand could lead to some gas running done the side of the engine.
You may also end up with gas in the crankcase, which can be a hazard and also bad for lubrication of the bearings.
Click to expand...
Ah got it. If it’s just gasoline flying out of the cylinders, that ain’t that bad it is?

So sounds like : disconnect the power to the ignition coil, pull the fuse for the fuel pump, then put the key in and crank it til it starts.

Should I turn it off soon as it starts, or safe to let it stay on a couple min?
 
You missed pulling the spark plugs out to let the excess gas out of the cylinders. Engines really hate trying to compress liquid. Breaks stuff.
After you purge the cylinders, it will be safe to put the plugs back in. Some are probably going to be gas fouled and need cleaning.

Fix the leak at the injectors or throttle body before you try to start it.
 
6872xtc said:
You missed pulling the spark plugs out to let the excess gas out of the cylinders. Engines really hate trying to compress liquid. Breaks stuff.
After you purge the cylinders, it will be safe to put the plugs back in. Some are probably going to be gas fouled and need cleaning.

Fix the leak at the injectors or throttle body before you try to start it.
Click to expand...
Oh shoot, that’s right. So

So sounds like : disconnect the power to the ignition coil, pull the fuse for the fuel pump, pull out spark plugs, then put the key in and crank it til it starts.

The fuel injectors are new, so I’ll keep an eye on them and the throttle body for leaks
 
It won't start with out plugs.
You need to purge the liquid gas in the cylinders. Then put the plugs back(cleaned or new) then start the truck. Keep a fire extinguisher handy. I lit mine on fire the last time I filled a cylinder with liquid gas. I was ready and no damage, it does happen.
 
Wes Harden said:
It won't start with out plugs.
You need to purge the liquid gas in the cylinders. Then put the plugs back(cleaned or new) then start the truck. Keep a fire extinguisher handy. I lit mine on fire the last time I filled a cylinder with liquid gas. I was ready and no damage, it does happen.
Click to expand...
How do I purge the liquid gas in the cylinders? If it’s been sitting overnight would that do the trick? Or remove spark plugs and let sit then put back?
 
you could let it sit w/o plugs over night, the fuel should evaporate. cranking w/o plugs is the most expedient way to clear the cylinders. If it sits over night with plugs in a few of the cylinders will have the valves closed, no evaporation. Worse the fuel will leak past rings slowly, and contaminate your oil.
 
Wes Harden said:
It won't start with out plugs.
You need to purge the liquid gas in the cylinders. Then put the plugs back(cleaned or new) then start the truck. Keep a fire extinguisher handy. I lit mine on fire the last time I filled a cylinder with liquid gas. I was ready and no damage, it does happen.
Click to expand...
How do I purge the liquid gas in the cylinders? If it’s been sitting overnight would that do the trick? Or remove spark plugs and let sit then put back?
Wes Harden said:
you could let it sit w/o plugs over night, the fuel should evaporate. cranking w/o plugs is the most expedient way to clear the cylinders. If it sits over night with plugs in a few of the cylinders will have the valves closed, no evaporation. Worse the fuel will leak past rings slowly, and contaminate your oil.
Click to expand...
so if I’m reading that right :
- option 1 : remove plugs, let’s sit overnight, reinstall plugs, crank as normal
- option 2 : remove plugs, crank to clear, reinstall plugs, crank as normal

Right?
 
Yes, be sure you solved the to much fuel issue before you try to restart.
 
If in Fact you have locked the cylinders with liquid gas. You have a problem. If the engine is cranking the liquid gas should not be able to build up enough volume to lock up an engine
 
Wes Harden said:
If in Fact you have locked the cylinders with liquid gas. You have a problem. If the engine is cranking the liquid gas should not be able to build up enough volume to lock up an engine
Click to expand...
Now I’m confused. So don’t try and unlock it with the above options?
 
No there should never be liquid gas in the cylinders should be mixed with air.

You must try pulling the plugs.
If you have gas that runs out one, or more, spark plug holes this Indicates another issue.

If no gas run out of any spark plug holes, turn the engine over.
Either by hand or with the starter motor.
If you choose the starter motor method. You must disable the ignition spark and the fuel pump.
 
All of my post are based on "hear a loud thud and won't crank"
If the engine is turning over.
Then it is not hydro locked.
 
Wes Harden said:
No there should never be liquid gas in the cylinders should be mixed with air.

You must try pulling the plugs.
If you have gas that runs out one, or more, spark plug holes this Indicates another issue.

If no gas run out of any spark plug holes, turn the engine over.
Either by hand or with the starter motor.
If you choose the starter motor method. You must disable the ignition spark and the fuel pump.
Click to expand...
oh got it, that makes sense.
ill take them out (and replace them) and try this later today or tomorrow - thanks for all your help!
 
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