Hello everybody, new to this forum and need some help with my sisters GMC Jimmy and Blazer. I know one is a 96 and the other is a 97, can't remember which is which though. Both are v6's with throttle body injection. The Blazer is not starting at all, just spins over. Tune-up was done early this year and consisted of plugs, wires, cap and rotor. Pulled coil wire out of distributor to check for spark, which is there is. Pulled plug also, spark there as well. Didn't check with meter though. Haven't check fuel pressure, but put a little gas into throttle body, but still no start, won't even try to pop. My nephew was in the middle of doing a cooling system flush when we were trying to get it going. Is there a sensor in the cooling system that won't allow it to start without fluid? On one of these vehicles, while it was running, sister took it to Autobone and they said it need a o2 sensor. Would that cause a no start? On the Jimmy, we attempted to put a tune-up in it at my house and broke off the spark plug in the middle cylinder on passenger side. Plug would just spin and spin and not come out. They drove it home that night and the plug ended up shooting out and just leaving the threads in the head. Tried to get it out this last weekend, no joy. Its located in the perfect spot to work on it, with nothing in the way after taking tire off and going through the wheel well. Does anybody know of any tricks short of pulling the head to get this out? I used a propane torch and heated the head up and used a easy out with 1/2 drive ratchet and extensions to get outside wheel well for some leverage. Ratchet popped, so I stopped, afraid of snapping off easy out. I should say this vehicle was hard to start before and after the tune-up. It would just spin over and over, but eventually start, now it won't. I know its possible/probable that the missing plug is the issue with this one, just looking for alternative things to check out. Do these vehicles have crank or cam positioning sensors? If so, how can I test it?
Sorry about the long winded post, I need to get these fixed for my sister.
Thanks,

Mike

 

So are all of these problems with just the one truck?

You have confirmed spark, but it may not be in proper time. We'll come back to that after some other testing.

After you poured fuel down the throttle body, did you reconnect the intake duct work? If not, did you disconnect the MAF sensor? If the intake duct is not connected to the throttle body and the MAF sensor is still connected, the PCM will not 'see' the air flow to the engine and may not operate properly.

I would still recommend going through the procedure of testing fuel pressure.

Could you take a picture of what you are dealing with concerning the #4 plug (center on the passenger side)? From the sounds of it, the center portion of the plug, including the hex has broken off and you are left with just the threaded portion in the head. Have you tried penetrating oil? What kind of EZ-out are you using? The spiral type or the straight fluted type? I tend to like the straight fluted type because they bite in without putting a lot of expansion pressure on the threaded piece that's stuck, but they aren't as strong as the spiral type.

BTW, the 96+ engines are SCFI (sequential central fuel injection), not throttle body injection.

 

Thanks for the quick reply swartlkk.
To answer your questions, So are all of these problems with just the one truck? Both are no starts, turning over and over without them even attempting to start. Both have had new plugs, wires, caps and rotors installed, the Blazer was done early this year by a garage my sis took it to and the Jimmy was done 2 weekends ago. After you poured fuel down the throttle body, did you reconnect the intake duct work? If not, did you disconnect the MAF sensor? After pouring gas into it, we did not hook anything back up and everything was unplugged/removed when this was attempted. Have you tried penetrating oil? Supposedly, my nephew hit it with PB Blaster one time, about a week before trying to remove it. What kind of EZ-out are you using? Spiral type and I agree with expansion pressure when using these. From the sounds of it, the center portion of the plug, including the hex has broken off and you are left with just the threaded portion in the head. You are correct, the threads and the L shaped piece attached to it are still in the head, the porcelain piece that runs down the middle of the threads and the metal tip that sends the charge to the L shaped piece on the threads came out when the plug blew out by the compression. Never seen that before. If I get a chance this weekend, I'll take a picture of both. I would still recommend going through the procedure of testing fuel pressure. My nephew put a new fuel filter on the Blazer and that's the one we poured fuel in, so I'm thinking this one could be fuel related. I had a Ranger that I replaced the fuel filter on and couldn't get it started until I put fuel down it. Turned out to be pump was weak, strong enough to keep fuel flowing, but not pick up the prime. If it is fuel delivery, wouldn't it try to start pouring fuel in with everything unplugged/unhooked? I told my nephew to take fuel line loose at filter, first doing side after filter to make sure new filter isn't plugged and then before filter to see if there is a visible difference in pressure. I know we should be gauging it for accuracy, where should this be done? Do you know what psi pump should be pushing? Thanks again for your help.

Mike

 

There are two main types of fuel delivery issues. #1 - lack of pressure. #2 - leak. You could have a leak inside the plenum causing a rich condition although it is rare on the SCFI engines.

The 96+ Fuel System Diagnosis link in my signature details the requirements of the system in both pressure and leak down.

Did the no-start on both of the vehicles begin after a common thing? Like both had the same work done at different times and ended up with a no-start?

 

swartlkk,

The Jimmy was tuned up by my nephew and me at my house, driven home and if I'm not mistaken, was attempted to be driven to work by nephews girlfriend when spark plug blew out. She turned around, brought it home and has been parked since. Before the tune-up, it was hard to start when cold, but once warm, would start easy. The Blazer, I believe, was being prepared for winter by my nephew. New fuel filter, coolant flush is all he did (I think). I will check out the fuel delivery this weekend and post back with the results. Thanks for the link and help.

Mike

 

have you checked the battery and connections? is the fuel filter installed in the correct direction?

 

Maybe take a look at IAC (idle air control) on the valve body. I've had mine carbon up on two of my vehicles. There may also be a calibration procedure for these. If it does not open enough you would not get enough air to start the vehicle cold, but it may be enough to start warm since you would require less air. One way to test that would be to try and start it. This will load some fuel into the cylinders. Then put the pedal to the floor and try again. Putting the pedal to the floor is sort of a 'choke' mode. If it fires, be ready to pull your foot off quick. If it tries to die right away and you are able to keep it running with your foot, that would be a good indication.

 

Thanks for the replies, guys.

Blazerpower, I believe they have been driving it since fuel filter was changed, but I will check that out to eliminate it being the cause. Also, battery post and terminals were cleaned and tightened up good, battery charged when needed.

TZFBird, I will add this to the list of things to check out this weekend. I believe we tried to start it that way, but will try again exactly how you suggest to do it.

Thanks again guys, I'll post back with the results.

Mike