I just purchased a '97 S10 Blazer with a 4.3 liter Vortec TBI V6/auto trans. The rig is in great shape and I got it for a great price. The person I bought it from says that his mechanic says it needs a new engine. I asked him what happened and he said that it over-heated and just wouldn't ever start again. His mechanic told him that it needed a new motor because the overheating caused the rings to lose their seat and that there's no compression. The only way to fix it would be to replace or re-build. I'm sure most of you on here can smell what I'm smelling about his diagnosis.

When I got home today after towing it 60 miles, I opened the hood to see what was going on. Well, first of all, there wouldn't be any compression because the spark plugs were finger-tight in their sockets. Second, the plug wires were unplugged and hanging there. Third, the fuse to the engine computer was pulled out and sitting in the ashtray. I feel bad for the guy I bought it from, but I really needed this vehicle.

The problem: After putting everything back together and in proper order, I attempted to start the motor. It turns over just fine, but won't start. I checked for spark at #1 and it looked good, though the plug was not the chocolate brown I like to see - it was pretty toasty looking. There is fuel in the line and appears to be plenty of pressure. I get fuel when I check the Schrader valve, and got squirted in the face with gasoline when I pulled the lines next to the throttle body. The battery is brand new, the fuses are all intact, and the starter is smooth and quiet. I tried starter fluid and even dumped about a quarter cup of fuel into the throat and still - no start.

I'm at a complete loss and need advice and guidance, please. I've heard of vehicles over-heating and then not starting until whatever sensor that caused it to shut off is cooled completely. As for which sensor? I'm at a loss. I'll start with the cheap, quick, and easy by replacing the spark plugs, but as I said before, there's a good, hot spark - at least at #1. Not enough fuel pressure? If that were the case, it would start of I primed it and die when it burned out the primer fuel. Fuel pressure regulator? Throttle position sensor? Something else entirely? I'm scratching my head at this one.

Any help, advice, or even ideas would be very appreciated. I'm a Scout Master and need to get this running by this weekend (10-12) to transport scouts to a weekend camping trip. Thank you so much in advance.

 

The best way to tell if have you have decent compression is to have a cylinder leak test done. A leak test is done with the piston at Top Dead Center with both the intake and exhaust vavles closed, then a metered amout of compressed air in force into the cylinder through the spark plug hole. If a cylinder is not holding air, it's leaking out from somewhere. A leaking head gasket will cause air to leak into cooling system, leaking valves will leak into either the intake or exhaust or both (if it's bad), and if the rings and cylinder are worn the air escape through the engine oil filler cap (or oil dipstick). A cylinder leak tester requires a constant supply of compressed air work, so you may have to take the truck a trusted repair shop to the have it tested.

Also, make sure your spark timing is good and not completely out of order. If the guy who was working on the vehicle didn't do the timing right; you could have cylinder no. 1 fire, when no. 4 should be firing. The firing order on a 4.3L is 1-6-5-4-3-2. The HEI ignition uses a traditional sytle distributor cap, while the EDI ignition uses a flat cap usualy what cylinders are suppose to be connected printed in small numbers on the cap.

 

Check fuel pressure and leakdown first. It's quick, easy and cheap, and it tells you the overall condition of the fuel delivery system. Most auto parts stores rent & sell fuel pressure testers. If you're planning on keeping this vehicle for a while, consider spending the $40 to put a necessary tool in your tool box. You'll use it more than you think

Ignition ON, engine OFF, fuel pump running: Pressure must be 60psi to 66psi and must remain above 55psi for at least 10 minutes after the pump shuts off. If it fails any part of this test, further diagnosis is necessary to pinpoint the problem in the fuel delivery system.

1997 has a known issue with the ignition switch that can easily cause symptoms like you describe, (has fuel and spark and no-start).

 

Thanks everyone for the responses and advice. I decided yesterday to just bypass all of the tests and tear into this motor's fuel delivery system after I took a look under the air-intake throttle. Once I got the intake manifold off, I was pretty sure I figured out why the truck wouldn't start, even though it had spark, fuel, and air. The injector assembly along with the interior of the manifold was covered in black gunk. When I pulled the injectors out of their seats, the butterfly handles broke off they were so brittle. It appears that these have never been changed and I theorize that they were not seated properly due to the amount of goo that covered everything - as in fuel spraying back into the manifold. I've got the injector assembly on order and will post here once I get it installed. Hopefully, this will solve most of the problems.

 

The black "gunk" is perfectly normal. When the EGR valve opens, the entire plenum is filled with exhaust & air. If there are areas where it appears to be "washed", (golden color) that would indicate a fuel leak.

 

what is this know problem your talking about i am having the same problem on a 1997 that i just put a new engine in and No start fuel spark and right timing ive redone the timing on it so many times

 

This thread explains: https://blazerforum.com/forum/articl...-switch-33465/

 

So I'm going to heed the last responder's advice and check the ignition switch. I don't have the money to throw parts at it until it starts, though I wish I did. One thing that has me curious that it may be the ignition switch is that the headlights don't completely turn off unless the key is turned off. They stay on dim (less than low-beam brightness) even when the light switch is turned off. I understand this also may be the headlight switch itself, or even the relay, but if it is the ignition switch causing this, could it be possible that it's causing the vehicle not to start, too?

 

There are probably a dozen wires to the ignition switch. This means it supplies voltage to a dozen main circuits. DRL's, (Daytime Running Lights) is one of them, ignition is another, so yes, it can cause both to operate incorrectly.

 

So, here's something interesting. It appears that the mechanic who looked at this before I bought it drained the coolant from it. Would no coolant in it cause a no-start situation? Additionally, it appears that the thermostat is stuck wide-open. He did say the thing overheated when it stopped running.