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  #1  
Old 10-01-2010, 12:26 PM
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Default Still need help with stalling/cutting out.

OK I'm coming back because everytime I think I've got this fixed I find out it isn't. I have actually been finding other little things that were bad and also needed fixing but haven't found the original problem.

I'm having a problem with my 95 Jimmy with the 4.3 vortec cfi vin w. When I have to take off fast from a dead stop or (and this is the important one) when I make a hard left the truck dies. No ignition. If I wait 3 seconds it'll start back up. Or if I'm on the road and take a hard left and keep going after the truck cuts out, if I keep my foot on the gas it'll sometime (SOMETIMES, Not always) will kick back in on it's own. But when it does totally kick out all I have to do is throw it in N and start it back up and go (after about 3 seconds, which is the time it'll take to kick back in if I'm rolling too). And it seems to do it only when the truck is hot. Not when I start out first thing in the morning.

Now while doing this I've had a fuel pressure guage hooked up and sticking up out of the hood and I can see that the truck is still getting 56psi fuel UP TO the intake. So it is NOT the fuel pump, or the relay. Now I've replaced the iac valve, the map sensor, pcv valve and the plugs are new last year and I checked them a few months back and they look fine (no bad deposits). I also had to replace my egr valve again when my new one BROKE at the base.

I don't know if it's related but also my heater core hoses developed leaks (now replaced) and one was spraying the distributor.

I have also replaced the fuel pressure regulator as I KNOW that WAS bad. I had the whole half the intake was clean and the other was dirty thing going on. Now it's got uniform deposits in the intake.

Oil is Full and so is tranny fluid.

The only thing that comes up is sometimes (And I mean SOMETIMES, and very infrequently) does it give a code saying MAP sensor low voltage. (I think it's code 0380) Can't remember. It's not there right now. (it is one of the OBDII models)

It's coming down to I have a feeling my spider injector is failing. And I'm planning on replacing it in January. (Maybe sooner if extra cash comes in). I'm planning on taking the plenum off Monday and doing some spot tests on it. But This is the kind of thing that if it IS the injector I won't know short of replacing it. $$$$$ My suspicion is that the injector is getting worn and the piston inside is failing when it's warm or possiby the connector is getting warped when it's warm.

I could really use some input. And can answer any followup questions to get this thing figured out.
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1995 GMC Jimmy SLT 4x4
4.3 V6 Vortec
over 200k miles and still purrin
  #2  
Old 10-01-2010, 12:45 PM
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Have you tested the fuel pressure yet? Specifically leak down after the pump shuts off?
  #3  
Old 10-01-2010, 12:47 PM
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OK Just a little follow up. Yes I do have the hole issue with it kicking in the but when it shifts from 1st to 2nd. I think this is a completely separate issue and it's not really that bad for me and it doesn't seem to be doing any other wonky things with the tranny so that's not an issue.

Now One other thing which is making me think that it is the injector. OK I've already said that when the truck cuts out (dies) it still has 56psi fuel pressure. But it will drop off. Just like if I test it by turning the key to on without starting it. The fuel pump will kick in like normal. The fuel pressure will jump up to 56psi. And when the 3 seconds for the fuel pump to cut out again the pressure will drop down to about 10psi. Now I've had the plenum off to check this once before (after replacing the fpr) and I have no VISIBLE fuel leaks. Like I said above. I've got uniform deposits on the inside of the intake now.

But this is why I'm going to take the plenum off Monday to get a look in there and do some more invasive tests. I'm not really inclined to taking the injector out altogether. But I'm going to really dig into it this time, not just cursory spot checks. It just seems weird how it'll stall when making hard LEFT turns. I've never heard of this happening to anyone else. If I can get this figured out I think my truck will be good to go for another 200k miles.

Heh: you were apparently reading my mind.
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1995 GMC Jimmy SLT 4x4
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over 200k miles and still purrin
  #4  
Old 10-02-2010, 09:10 AM
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So before I dig in on it on Monday. Are there any other little checks I can perform to try and nail this down. My plan is to unplug each injector poppet 1 at a time and turn the truck on (not start, just on) and see if there is fuel flowing out any of the poppets.

Here is my suspicion. I have a feeling that the injector is wearing out and it is not completely closing after each cylinder sprays and as it get's warm it also isn't opening fully. Basically a complete loss of function the warmer it gets. I know the unit itself is not serviceable. It's just up to this point I've been trying to isolate this issue and it keeps coming back to the injector. But the only way to know for sure it to just replace it which is an expensive resolution. In and of itself isn't a problem. I just don't want to throw cash at this and find out it is something else. But honestly I can't think of anything else that could be causing this that hasn't already been tested.

So I've pretty much done all the tests already in the fuel system diagnosis and just wondered if anyone has any other little tips or tricks to try before I tear into it Monday.
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1995 GMC Jimmy SLT 4x4
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over 200k miles and still purrin
  #5  
Old 10-04-2010, 08:06 PM
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OK Here is my follow up. Today I got my hands on a replacement injector. No, not new. But it doesn't matter because even with replacing the injector the problem is exactly the same. No change whatsoever.

Hard left turns will cause the truck to stall. Jack-rabbit starts will also cause it to stall. This is not an issue first thing in the morning but when it gets warm it gets more pronounced. And when it gets hot it even starts to hesitate while driving. And to add, The temp is staying steady at 175 degrees. It is NOT overheating.

And sometimes when it starts to hesitate it'll pull a 0710 code, map sensor low voltage.

Now I know what it is NOT. now I'm trying to find out what it IS. There are a couple other details. When I was disassembling the intake I found that the plugwire that goes to the coil was terribly corroded inside the boot. Specifically on the coil side. But it is cleaned now. Also, It still has the fuel pressure drop down. It will maintain 56psi fuel pressure, but once the truck turns off it drops back down to 10psi.

I have a feeling that I'm dealing with multiple issues. The pressure drop down doesn't seem to be a cause of the stopping. This is because I've had the fuel pressure guage plugged in and monitored it when it does stall. And during both the jackrabbit starts and hard lefts the pressure doesn't drop until like normal. It doesn't drop when the stall happens. And When it does stall it takes a few seconds to restart. And when I check the pressure comes back (56psi) but doesn't start right away. Takes about 5 seconds to get it to restart.

Now the whole fuel pressure drop-off I feel is somewhere in the tank, in relation to the fuel pump I replaced. It's working fine but I feel that something didn't go right with the replacement. So I'm going to look into that later, as it doesn't seem to be a cause of the stalling. Oh and new fuel filter.

Now the fuel pressure is good up to the injector and the injector is working as it's supposed to. And there are no air issues. New air filter good tubes. And my vaccum is steady at 19.5psi. So now I'm suspecting an ignition issue. I'm wondering about the coil or the circuit on the coil bracket. But I'm wondering if the distributor could be suspect. I'm looking for something that would cause stalling while turning left hard as I think that is where the main problem is. Could this also be in the tank?
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1995 GMC Jimmy SLT 4x4
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over 200k miles and still purrin

Last edited by cage47; 10-05-2010 at 09:23 AM.
  #6  
Old 10-06-2010, 12:45 PM
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OK Guys, come on I really need some help with this as it's really stumping me.

Now new coil. New plug wires. Pulled the plugs. All look good. But symptoms are unchanged.
When it's hot, not when it's cold:
Jackrabbit starts, stalls. Slow takeoffs, fine.
Hard left turns stalls, hard right turns no problems.
When it does stall it doesn't start right up. Throwing it in neutral it won't just start up. Sometimes takes waiting 10 seconds.
And when driving a long distance (over 25 miles) it starts to hesitate while driving.

Anyone? Ideas? I HAVE replaced the injector, fpr, plugs, wires, coil, map sensor, iac valve, temp sensor under the egr, heater core hoses (no more leaks), pump last year, fuel filter.

My suspects. bad tranny causing stalling during jackrabbit starts and hard lefts, but why won't it start right back up? possible bad icm on the distributor. could be killing the spark but why when I turn? Something still bad in the tank, the sloshing fuel could be from jackrabbit starts and hard lefts AND keeping it from restarting. But I am still showing good fuel pressure though I do have the drop off after shut off.

I'm planning on going to the junk yard to pull off another icm and this weekend dropping the tank again. Any suggestions?
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1995 GMC Jimmy SLT 4x4
4.3 V6 Vortec
over 200k miles and still purrin
  #7  
Old 10-06-2010, 02:20 PM
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OK Progress. I'm getting close. I found I was doing something wrong. I had my fuel pressure guage screwed on too tight. It wasn't getting a correct reading. So I loosened it enough to get an accurate reading. I took it out and took some hard left turns. And sure enough, the fuel drops off before it stalls. And it not starting is because the fuel is not rengaging when I try to restart. I have the glove box open and the relay isn't kicking on. When it does it starts right back up. So it IS a fuel issue. something is killing the fuel pump. Looks like I'm dropping the fuel tank this weekend.
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1995 GMC Jimmy SLT 4x4
4.3 V6 Vortec
over 200k miles and still purrin
  #8  
Old 10-09-2010, 07:39 PM
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OK now that was a stupid bitch. I THINK I found the main original problem.

Today I went to the pick a part after doing some tests. I went up and it drove fine but on the way home I had a BAD fuel pressure issue. I got it home. I kept doing tests. I even opened up the plenum again to check the fuel pressure regulator. So I figured it HAD to be in the tank. I dropped it (This is something I don't want to EVER have to do again, Yeah right) So after draining 11 of the 13 gallons I put in it this morning I had the wife turn over the key while I listened under the truck with the tank on the ground. I could hear the pump engage. But I heard something else unusual. I could hear spraying inside the tank. Now before I started dropping the tank it was to the point that It took three tries to get it to start. Well I got the tank out and pulled the sending unit. The top plastic clip on that little fuel line that goes from the pump to the sending unit didn't have the grip god gave a banana peal!

So I took it off. Put a metal screwdown clamp on and put it back in the tank and reconnected the lines (with it sitting on the ground) Got the plenum back on gave the key a turn. Fired right over. First shot. Not even an idle fire. Turned over on the first fire. But ran out of light so locked everything up and will get the tank in place in the morn. Now this DOES give me a chance to plug in that vent at the front of the tank I couldn't plug in the first time I dropped the tank.

Now I have a couple follow up questions. First is there any actual REASON you can't use the metal screwdown clamps IN the tank? Those plastic clips are useless.

Second. When doing some tests I unplugged one of the lines from the canister at the back of the truck. Fuel came out of there. Should this happen? Isn't that the evap canister? Should there be fuel in there?
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1995 GMC Jimmy SLT 4x4
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over 200k miles and still purrin
  #9  
Old 10-09-2010, 07:59 PM
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That metal clamp should do nicely! Glad your problem!

The EVAP canister should not be full of fuel, but it can happen if the tank gets overfilled repeatedly.
  #10  
Old 10-10-2010, 08:13 AM
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It wasn't full of fuel. The evap. I undid one of the bottom two tubes and fuel came out. There are 3. And when I undid the top line no fuel came out. So I'd say about a 1/4 of it had fuel in. Should I drain that out?

I've gotta say, especially since also replacing the coil and wires, the truck hasn't run this good in the year and a half I've had it.
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1995 GMC Jimmy SLT 4x4
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over 200k miles and still purrin

Last edited by cage47; 10-10-2010 at 12:07 PM.
Old 10-10-2010, 08:13 AM
 
 
 
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1995, 43, blazer, canister, chevy, cuts, cutting, evap, fuel, gmc, kickback, making, stalling, start, turns, warmer


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