97 TB no start

[97blazer]

Hi everyone,

Bear with me a bit please. I'm attempting to help my daughter with her 97 TB. Did a little searching but decided to just post and ask.

This a long distance thing, she's in Washington and I'm in Cal. Yuk. Anyway 97 TB, 4.3 V6, that won't start. However it will run if they pour gas in it so it has spark. The have replaced the fuel pump. I just talked to them and suggested they have the ign module tested (in the dist, thinking it may not be firing the inj's). I'm somewhat familiar with 91 S-10s (I have a Syclone) but not 97's so I'm having to guess a bit hence my joining and posting here.

FYI I'm rather mechanically inclined but they aren't which adds to the fun.

Any suggestions appreciated and thanks!!

Don

 

[Wooluf1952]

Welcome Glad you found us.

In case you haven't heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/

I understand they changed the fuel pump, but did they check the pressure? Change/check the fuel filter?

 

[97blazer]

Welcome Glad you found us.

In case you haven't heard:
http://gmtnation.com/f5/welcome-gmtnation-com-heres-story-226/

I understand they changed the fuel pump, but did they check the pressure? Change/check the fuel filter?

Yes, just read that in my welcome note that I received after joining. Interesting because I'm a member (was?) at Trailvoy because I have an 05 TB. No difficulty at the moment but I did get some useful info on changing the t-stat.

RE your question. I've talked to them about checking fuel pressure. They're gonna try to do that. Do you know the correct pressure? And yes, they did change the fuel filter.

Thanks

 

[Wooluf1952]

Yes, just read that in my welcome note that I received after joining. Interesting because I'm a member (was?) at Trailvoy because I have an 05 TB. No difficulty at the moment but I did get some useful info on changing the t-stat.

RE your question. I've talked to them about checking fuel pressure. They're gonna try to do that. Do you know the correct pressure? And yes, they did change the fuel filter.

Thanks

My '92 Chevy Astro with the 4.3 ltr. and CPI called for 54-62 PSI. The 4.3 with TBI was only 9-13 PSI. I don't know about the '97.
There could also be a problem with the Fuel Pressure Regulator.

 

[JB100]

On the 97, it sounds like there is no injector pulse. The 97 has an fuel injection "spider" under the upper intake plenum. You can check the inj pulse at the connector. If memory serves it requires about 50 LBS of fuel pressure. There is a pressure test port on the back of the intake where you can check it. Another thing that dies is the fuel pressure regulator they are known for causing a no start condition. Another thing to check is the camshaft position sensor on the distributor, this provides a signal for the injectors to fire. You can also goto www.blazerforum.com they specialize in the s10 platform.

 

[97blazer]

On the 97, it sounds like there is no injector pulse. The 97 has an fuel injection "spider" under the upper intake plenum. You can check the inj pulse at the connector. If memory serves it requires about 50 LBS of fuel pressure. There is a pressure test port on the back of the intake where you can check it. Another thing that dies is the fuel pressure regulator they are known for causing a no start condition. Another thing to check is the camshaft position sensor on the distributor, this provides a signal for the injectors to fire. You can also goto www.blazerforum.com they specialize in the s10 platform.

Good info thanks! I check the link as well.

 

[MAY03LT]

Gotta check the fuel pressure first. Key on engine off should be 60psi. Further diagnosis can go a variety of ways and which way to go depends on knowing if there is pressure or not.

 

[97blazer]

Gotta check the fuel pressure first. Key on engine off should be 60psi. Further diagnosis can go a variety of ways and which way to go depends on knowing if there is pressure or not.

OK, thanks. Just called them with your info and they're gonna run down to Harbor Freight and pick up a gauge. They have a kit that looks like it should work.

Meantime what fires the injectors? Is it a pulse from the module in the dist? Is there an easy way to test that? Apparently in the Syclone they will sometimes fire the coil but not the ECM so there's no inj pulse.

 

[NJTB]

OK, thanks. Just called them with your info and they're gonna run down to Harbor Freight and pick up a gauge. They have a kit that looks like it should work.

Meantime what fires the injectors? Is it a pulse from the module in the dist? Is there an easy way to test that? Apparently in the Syclone they will sometimes fire the coil but not the ECM so there's no inj pulse.

There is always 12V to the injectors. The ECM provides the ground so they fire.

 

[MAY03LT]

Is there an easy way to test that?

Based on the first post, I think there is pulse.

I have used this method before for a fast go/no go test.

-hook up a fuel pressure gauge
-short the coil wire to ground
-turn the key on (don't start), the pressure should go to 60psi
-unplug the fuel pump relay
-crank the engine and watch the pressure gauge. It should drop in small "steps", which verifies pulse

Of course this test can only be done if the pressure can get to 60psi.

 

[JB100]

I was looking at this thread again something jumped out at me.. You said they replaced the fuel pump. If they put an Airtex or one of the cheap junk pumps in it it will not last long. I had one in my 96 that went bad. It was an airtex pump and the fuel gage never worked properly. I replaced it with a OEM pump from a 97 and never had an issue with it again. The gas gage worked properly and that awful whine went away. Maybe the connecter came loose? The fastest way to see if the pump is running is to open the fuel door take the cap off and listen for it running. The OEM style pumps are very quiet and the cheapass chinese ones are VERY noisy. Also check the fuel pump relay.

On the S10 series trucks like this the PCM will command the pump to run, when there is a key on, it expects to see a start condition, if not it will turn the pump off after a few seconds.

Hope this helps a bit.

Hope you can get it up and running.

 

[97blazer]

There is always 12V to the injectors. The ECM provides the ground so they fire.

Same as the Syclone, interesting.

I'm gonna combine all the info in the latest posts and give them another call.

Thanks everyone.

 

[Mooseman]

I do have experience with these trucks. Had an '00 Jimmy with the 4.3. One question that has not been asked yet: When the key is turned to ignition but not started, do you hear the fuel pump run for a second or two and then off? The fuel pressure test will also confirm this. If no pressure and no noise, then something is not sending power to the pump. Whether it's an Airtex or even a CCC pump, it should work if it's new. Check the fuses, relay and connections to the pump. If it's been a while since it was replaced, it could have failed.

And here's an obvious one... is there gas in the tank? It is quite possible that they think there is gas but the gauge is either showing low or is not working properly.

 

[JB100]

Mooseman has a good point. My 96 would run out of gas at 1/4 tank. I learned that one the hard way. Once I replaced the fuel pump/sending unit assembly it worked great.

 

[NJTB]

OK, thanks. Just called them with your info and they're gonna run down to Harbor Freight and pick up a gauge. They have a kit that looks like it should work.

Meantime what fires the injectors? Is it a pulse from the module in the dist? Is there an easy way to test that? Apparently in the Syclone they will sometimes fire the coil but not the ECM so there's no inj pulse.

There is also a tool made called a 'noid' light. It has the same connectors as the fuel injectors. They're cheap (as I remember), ~ $10-15.
Un plug the connector from one injector, plug in the noid light and crank the car. If it flashes, the injectors are pulsing. Steady on, look at wiring, ECM.

 

[97blazer]

Little update and a thanks for all the suggestions. They were finally able to get an occasional start out the thing and get it to a shop. He discovered that the MAF was in very bad shape. $80.00 later it was clean and ran. Sort of. They get it home and next morning no start. Now everyone agrees it's the fuel pres regulator. The shop wants 400 for a complete tuneup including the FPR so skip that. The thing ain't hardly worth that. They're gonna try to get one the friend/mechanics to change the FPR and sell the thing.

So. a) I didn't want to leave this thread hangin'. (One of my pet peeves.) and b) post the results so you folks van add MAF to your "why won't it start" check list.

Cheers and thanks again.