99 blazer 4.3L no spark

[Tgibson_br]

I have a 99 blazer 4.3L vortec. Just recently my blazer died on me, i noticed for about a week that it was hesitating starting in the morning, only in the morning it seemed but during that period, it was humid out and moisture content was high, so i assumed moisture was getting into the distributer area. All of a sudden, it doesn't want to start. I've checked for spark from the plug wires and also from the ignition coil. Decided to replace the ignition coil, and distributer cap and rotor. Still no luck. I also decided to replace my crank sensor and with that done, it still does not want to start. Any ideas on how i could check this or know what could be wrong. I've scanned the vehicle and no codes came up. Any help would be greatly appreciated. Thank you.


Tim

[82Stang]

Is it getting fuel and can you hear the fuel pump when turning the key on?

[Tgibson_br]

yeah, the fuel pump will turn on when you turn the key, activates for a few seconds as it should, then shuts off again. I also can hear the relay clicking on and off when this all happens also.

[82Stang]

Okay, if the fuel pump is working then lets move forward from that point. How about the fuel filter? It will cause stalling at lights and slowing down when getting clogged and even a no start condition when really clogged? I'd make sure the fuel filter is recent and not the problem.

Hope this helps.

[Tgibson_br]

yeah, i just replaced the fuel pump and the fuel filter around spring time. april/mayish, in there. my fuel pump went completely dead on me. But i will have to check it out. Thank you.

[Tgibson_br]

ok, i replaced the fuel filter today, and still no luck on the starting. If anyone knows, what is the psi that the fuel pressure should be at for my vehicle? when i bought a pressure gauge yesterday, it tested out to be at 44-45psi when the pump would activate and slightly held and dropped a few psi over time. Is that a low count? If so, i'm guessing that my pump is screwed up. Oh well, any feed back would be helpful, and any info on how i could test this b4 i drop the tank and take the pump out. Thank you.


Tim

[MT-2500]

Fuel pressure is way low.
Jumper the fuel pump or bump the ign a couple of times to prime up fuel pump to full pressure.
But that does not explain the no spark.

If you have crank sensor signal or rpm signal and the coil is good check ign module.
MT

Do you have a scanner to see if the pcm/vcm is getting a rpm signal or crank sensor signal?
Any remote start or add on anti theft?

[82Stang]

I agree with MT, an ignition module could also be the culprit. But first I'd get it scanned for any codes. Most auto parts stores will do it free.

[Tgibson_br]

what type of scanner are we talking about? is it just the one that you plug into the OBD 2 port to scan the computer? or is it scanning the sensor itself somehow that i'm not aware of? I bought a scanner the other day and got no codes from my vehicle computer. As for the ignition control module, i did replace that.

[Tgibson_br]

also, how would i jumper the fuel pump? I know i read about it somewhere, but not sure if what i read was the right thing. I did try to prime the pump a few times. Turn key to start, let it run. shut off. waited, then turned key to start. Didn't seem to be working. Would having the low pressure cause a nostart/no spark type situation? Thanks for the help

[old_master]

In the underhood fuse box, find the fuel pump relay. About 1/4" in front of the relay is a single, recessed, open terminal, (nothing connected to it). That terminal is connected to the fuel pump circuit, (grey wire). Connect a fused, (10amp) jumper wire from battery positive to that terminal and the pump should run until you remove the jumper. With 45psi fuel pressure, the engine will not start, guaranteed!

[Tgibson_br]

ok, i'm trying to test my fuel pressure from my filter to the pump, by using the pressure gauge i have, only to find out that i can't get the darn thing to thread on. i think my gauge might be just a hair to small than what i have on. any other ideas on how i might be able to test the pump. my pressure seems to still be low in the mid 40's and i would like to find if it's the pump causing the pressure loss. any other ideas?

Thanks

[old_master]

There are two special tools: Each tool has a shut off valve, a service port for the fuel pressure gauge, and fittings on each end that attach to the fuel lines. One tool is installed in place of the fuel filter, and the other in the return line. The tools are used to isolate each component in the fuel system to determine where an internal leak is. The tools come in a set and are quite expensive. The alternative is go to your local hardware store and procure the necessary fittings to adapt your fuel gauge to the pressure line. If you're really creative, you can make the tools yourself. I made both of the tools for around $65.00 total, (A little more than the cost of a fuel pressure regulator). If you're serious about DIY, (do it yourself) not GIY (guess it yourself), the tools will save you some money in the long run. GM used different configurations of fuel line connections over the years, so another model year may be different than yours. Bottom line is you need to connect your pressure tester to the pressure line from the pump, then briefly energize the pump and check maximum pump output. Less than 75psi means time for a new pump. Another way to check max output is to slowly restrict the fuel return line and watch fuel pressure. That procedure is risky. If pressure is allowed to rise above 75psi, it can permanantly damage the fuel pressure regulator.

[Tgibson_br]

alright everyone. i want to thank you for your help and support during this time, i don't know what i've done. but i managed to get my blazer started back up. i think it was a combo of different things. but i did replace alot of parts, and even my fuel filter. i now have another problem, it seems that my blazer is now misfiring. using my computer that i have, i let it run for a bit b4 scanning and got this code. P1351....manufacturer control ignition system or misfire. Any ideas on what this code could be talking about? i'm gonna do some research on it, but if anyone has had any experience with this code, could you let me know what you did to take care of it. Thank you all once again. I really appreciate the help.

[old_master]

What parts did you replace? It may be related to the DTC. If you did anything with the plug wires, recheck the firing order. On the passenger side, front to back on the distributor cap are cyls 2, 4, & 6, in that order. Driver side front to back is 3, 1, & 5.