1989 s10 4.3l v6 t.b.i., injectors throw out easy too much fuel - Hot Rod Forum : Hotrodders Bulletin Board
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Old 12-06-2011, 07:48 PM
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1989 s10 4.3l v6 t.b.i., injectors throw out easy too much fuel

My 88 s10 had a 2.8 v6 t.b.I. When I bought it but the motor was horrible so my cousin gave me his 89 s10/blazer with a t.b.I. 4.3 v6 with a blow head gasket. I put new gaskets in the 4.3 while it was still in the blazer and it ran perfect after I fixed the head gasket issue. Then I pulled the engine out of the blazer and put it in my s10 and swapped over all of the wiring harness's and computer and got it to start and it started first crank but dies due to the injectors putting out way too much fuel it can't run. I'm prett sure it is an electrical issue most likely an open ground or not hooked up, Im thinking that I may have missed a ground or some wire under the dash in the cab somewhere or it mite be in the engine compartment. So I am wondering if any one has any other ideas for a solution to my problem or able to tell me where grounds are usually located mainly hidden ones or anything!! I did this swap 6 months ago and have not Ben able to drive my s10 since, it does not rub any longer then 10 seconds

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Old 12-06-2011, 08:10 PM
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I would check/change the temp sensor for the ecm, they cost about ten bucks. Probably located on the intake manifold somewhere. Did you change over the ecm as well? If you have a Haynes Manual for that engine look through and read what the sensors do and start from there.

Another thing you could do to make sure it is the fuel issue is unhook one of the injectors and see if it will stay running.
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Old 12-06-2011, 09:48 PM
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Check the fuel pressure and check the fuel pressure regulator built in the TBI unit. The pressure is supposed to be 9 - 13 psi. Sometimes when the regulator goes bad it can jack up the fuel pressure.
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Old 12-06-2011, 10:17 PM
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Yes I have changed the temp sensor along with pretty much every other one and I put the fuel regulator off th 2.8 motor and it did the same thing and yes I swapped ECM's
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Old 12-06-2011, 10:20 PM
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And yes the fuel pressure is good last time I checked about 12 p.s.I but I haven't tried unplugging one injector to run I will try that tomorrow
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Old 12-06-2011, 10:29 PM
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I have talked to many professional mechanics and they r stumped to, I have it narrowed down to maby a vacuum leak but not likely or bad grounds such as the injectors are not grounded well or the ECM isn't getting grounded or the engine itself is not grounded well enough or something along those lines.. So can anyone help me by telling me how to ground it better or where there may be grounds that I mite of missed when swappnig harness's becuz I had to take the whole dash off and there mite of Ben a ground behind it that I missed when I put the dash back on... Any ideas, clues, or suggestions or anything will be helpful
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Old 12-07-2011, 10:14 AM
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Quote:
Originally Posted by The donkey
My 88 s10 had a 2.8 v6 t.b.I. When I bought it but the motor was horrible so my cousin gave me his 89 s10/blazer with a t.b.I. 4.3 v6 with a blow head gasket. I put new gaskets in the 4.3 while it was still in the blazer and it ran perfect after I fixed the head gasket issue. Then I pulled the engine out of the blazer and put it in my s10 and swapped over all of the wiring harness's and computer and got it to start and it started first crank but dies due to the injectors putting out way too much fuel it can't run. I'm prett sure it is an electrical issue most likely an open ground or not hooked up, Im thinking that I may have missed a ground or some wire under the dash in the cab somewhere or it mite be in the engine compartment. So I am wondering if any one has any other ideas for a solution to my problem or able to tell me where grounds are usually located mainly hidden ones or anything!! I did this swap 6 months ago and have not Ben able to drive my s10 since, it does not rub any longer then 10 seconds
This would be something that's either keeping the injectors "on" too much of the time, or there is dirt or a failure in one or both injectors causing a leak, or the system pressure is too high. The Injection temp sensor could be off but that would keep the thing in cold enrichment which is a lot of fuel but not so much the engine gets flooded. I don't see grounds as a problem.

Hook a timing light up and shine it on the injectors, you should see them pulse, this will at least sperate the continuous flow (leak) from other potential problems. I'd put an adjustable regulator in the system and dial the pressure down to see it that helps, another trick on this same line is that if you have a rubber fuel line under the hood clamp it with a Vise-Grip to reduce its size till you get a lower pressure at the unit. This isn't a fix just a means of forcing the thing to run long enough to do some diagnostics.

The thermostat needs to be no lower than 180 degrees or the computer will not get out of cold start mode. Throttle position sensor can be another issue that needs to be checked. If it has failed or is misadjusted it could be telling the computer to fuel for WOT when all is needed is idle.

The chip could be toast, the computer is very sensitive to currents and static charges that it could have been subjected to in the interchange process from vehicle to vehicle.

The wiring could be off somewhere, you'll need to go back and look at everything, especially inside connectors to be sure there are no bent or missing pins or broken wires and that the correct wires go to the correct pins in the harness and connectors. You'll need a manual from both the 2.8 and 4.3 installations correct to the year of each engine and the body to be sure about body wiring. On the surface there usually isn't a lot of difference but the OEM does change things between models and years, sometimes very subtly so you need to look carefully.

Transmission types and sensors between models, some of the engine management data comes from the transmission speed sensor, there are changes in the clock speed on the output shaft between models and years, I don't know without going digging if this is in here, but again it's something that you need to check out. Vehicle security also falls here, you need to check and see if there's security circuit in either of you computers that needs to be satisfied.

When I get back in the shop tomorrow I'll see if I dig some of the specific data on this stuff out for you.

Bogie
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Old 12-07-2011, 05:52 PM
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K so I don't know what I did but now it don't even turn over I can hear power going to the starter it may be shot from turning it over so much, but any ideas on what could cause my injectors to do that would be much appreciated until I put my other starter in
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Old 12-07-2011, 05:58 PM
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I was thinking it may be a pinout problem but you said you used the 89 harness engine and computer in the 88.should be fine actually.
At this point I would at least see if there are any trouble codes stored. If you have access to a scanner look at the live data and look for anything that may be wacked. Like the coolant temp registering at -40 degrees when it is 65 degrees outside, that would be a pretty good indication.
MAP sensor vaccum is very important so be sure your vacuum hoses are hooked up correctly.
The ECM may have been damaged somehow in your build process.
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Old 12-07-2011, 07:57 PM
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I've triple checked the vacuum lines many times they should be all good, my injectors have an ohms reading of about 1.5 each which is rite I believe but my injector plugs both read close to 500 ohms on both, that can't be rite is it? And ya I have a buddy with a scantool I am just waiten on him to borrow it.. I've put different sensors that I know worked in there for the temp, tps, all those sensors, I don't THINK those are my problems but maby..
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Old 12-07-2011, 08:00 PM
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And i thought that it mite be my computer to so I went and got one out of pretty much the same vehicle and it did the same exact thing so the computer is towards the bottom of my list of solutions, any other ideas?
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Old 12-07-2011, 08:02 PM
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But how much is a new computer for that old of engine?
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Old 12-08-2011, 07:56 AM
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So wat all should I look for that would cause my injectors to have 500 ohms
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Old 12-08-2011, 08:36 AM
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If the injectors are putting out too much fuel to idle, unless they're completely stuck open, there should be some amount of throttle you can give it that would allow it to continue to run, at least briefly until the engine RPM got too high. You could try cranking it up and let it run until you feel it start to die from too much fuel, then open the throttle completely. That should allow it to keep running/rev up w/o stalling.

That said, are you positive the injectors are really putting out so much gas that it's actually stalling the engine? How are you able to tell this- are you using a timing light to watch the spray pattern, or ? Because it takes a LOT of gas to kill an engine outright, and it could be easy for anyone to mistake too much gas for something else that could be happening.

The reason I ask is there are other good reasons for the engine to fire and die after running for a short time. Like if the ECM doesn't detect oil pressure, the fuel pump won't run- but it WILL come on when you turn the key on to pressurize the system, it just wouldn't run after the engine cranked up if there were no oil pressure detected. That doesn't mean the engine doesn't have oil pressure, just that the computer doesn't see it has pressure.

If opening the throttle to keep it running like I described above didn't work, you could try to keep it running by starting it up, then as it starts to die you hold the throttle about 1/2 open, then give it short hits (just enough to keep it running, not a continuous blast) from a can of starting fluid. If that keeps it running, you'd know there was a problem other than too much gas.

If there's a factory anti theft system on the truck, I have heard (but have no experience with) some anti theft systems will allow a short start up, then will kill the engine if something isn't right. Your truck might be older than this set up, though. Maybe someone w/more info on this could help here.

Last edited by cobalt327; 12-08-2011 at 09:06 AM.
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Old 12-08-2011, 10:56 AM
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Quote:
Originally Posted by cobalt327
If the injectors are putting out too much fuel to idle, unless they're completely stuck open, there should be some amount of throttle you can give it that would allow it to continue to run, at least briefly until the engine RPM got too high. You could try cranking it up and let it run until you feel it start to die from too much fuel, then open the throttle completely. That should allow it to keep running/rev up w/o stalling.

That said, are you positive the injectors are really putting out so much gas that it's actually stalling the engine? How are you able to tell this- are you using a timing light to watch the spray pattern, or ? Because it takes a LOT of gas to kill an engine outright, and it could be easy for anyone to mistake too much gas for something else that could be happening.

The reason I ask is there are other good reasons for the engine to fire and die after running for a short time. Like if the ECM doesn't detect oil pressure, the fuel pump won't run- but it WILL come on when you turn the key on to pressurize the system, it just wouldn't run after the engine cranked up if there were no oil pressure detected. That doesn't mean the engine doesn't have oil pressure, just that the computer doesn't see it has pressure.

If opening the throttle to keep it running like I described above didn't work, you could try to keep it running by starting it up, then as it starts to die you hold the throttle about 1/2 open, then give it short hits (just enough to keep it running, not a continuous blast) from a can of starting fluid. If that keeps it running, you'd know there was a problem other than too much gas.

If there's a factory anti theft system on the truck, I have heard (but have no experience with) some anti theft systems will allow a short start up, then will kill the engine if something isn't right. Your truck might be older than this set up, though. Maybe someone w/more info on this could help here.
I have to agree with a lot of Cobalt's analysis.

I checked my ancient history files last night and the 88 and 89 S10 Blazer to S10 pick up wiring schematic is the same between these engines. It looks like you could have used the 2.6's wire harness for the 4.3 with just the computer change. That of course is the schematic, the actual wire harnesses may physically vary for component locations on the engines. The actual change that I was concerned about doesn't happen till the 91 to 92 change over.

I missed the 10 second shut down in your first blog, as Cobalt said, and that's a darn good indicator, that it may be the computer isn't getting the oil pressure signal from that sensor. If it doesn't see pressure the computer shuts the engine down (actually the fuel pump and ignition to off) in about 10 seconds after firing. This could also be a fuel pump relay problem to where it doesn't engage the run side when commanded by the computer, could also be a harness issue resulting in this same similar event.

Bogie
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