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By Rudder2fly - 11 Years Ago
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I hate to bring this problem up but have just about gone bonkers over this problem with my 1989 Chevy K1500 truck. It has a 350 TBI engine. The first thing that happened was it would not start unless it was primed by starting fluid at the TBI. Then I had it out one day a barely got back home. It acted like the engine was running out of gas. I have had this truck 20 years bought it from the original owner. This is the first serious problem I have had. I have no service engine alarms. The bulb is good in that light as it comes on when the key is turned on. I have done the following; changed TPS, OXYS, Plugs, Distributor cap and rotor,Fuel filter twice and for that hard job a new AC-Delco fuel pump. I had 10# at the TBI with the old pump but a GM guy said that was not enough. I don't know what the new pump is putting out as I had a leak at a gas fitting by my guage and I had to pull the muffler-tailpipe to get the tank out and was worried about a fire running with that leak. I can tell you this I get the 2 second pump run with the key on but it will not prime the engine to start it. Then I can hit it with starting fluid and it will start in open loop cold. It is rich with plenty of fuel and will idle and rev up. Once it heats up it goes into closed loop it will not idle or keep running without higher RPMS if you open the throttle fast at all it acts like it is running out of fuel and quits. This is the same as with the old fuel pump. I have checked battery cables, compression is better than 170# on all cycl, timing shows ignition steady not jumping around. I now have a hatch in the bed for the fuel pump so I will not have to drop that 36 Gal tank again I hope. A side note is the tank was very good on the inside very clean. Please bear with me all help will be appreciated. My 1956 Ford has been a joy to restore. Thanks Gene Stoehr Kuttawa Ky.
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By charliemccraney - 11 Years Ago
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Rudder,
10psi is fine for tbi. Normal is 9 - 13. The GM guy is probably thinking of port injection pressure.
There are awesome tools available for these that you need to significantly simplify the trouble shooting process.
Data logging (and tuning, if so inclined) software:
http://tunerpro.net/
http://winaldl.joby.se/
A cable to connect a laptop to the computer
http://www.aldlcable.com/sc/details.asp?item=aldlobd1u
And of course, a laptop or netbook, maybe even a tablet will work.
The software is free. You can probably find a netbook under $200 to do the job, and the cable is $60.00. If you plan to keep this truck, it is absolutely worth the investment. There will be a learning curve, but I tell, you, everything else being equal, I'd take a fuel injected car any day over carbs and clunky points. Everything else is not equal, so the older stuff prevails in my mind.
With this stuff, you will be able to see what the majority of the sensors are doing in real time and in many cases be done with trouble shooting in a matter of minutes.
And don't worry, you need other stuff to actually tune the engine so you cannot accidentally change the programming and mess things up that way with the stuff I've mentioned above. TunerPro has the ability to tune but you need other hardware to do it.
I have all of that above for my '88 Firebird with a tbi 305.
Another good tool is a Helm Manual. Forget the manuals you get at the local parts store.
http://www.helminc.com/helm/homepage.asp?
It's expensive, but you get what you pay for. For instance, my parts store manual is about 200 pages and covers 1982-1992 Camaro and Firebird. My Helm manual is about 800pages if I recall correctly and only covers a 1988 Firebird. '88 Camaro is a different manual. '87 or '89 Firebird is a different manual, etc. It has much more useful info, pictures and is much easier to follow which is great when you're doing something you've never done before.
It may be easier to start with the cold start issue first. You need to 1) make sure it is getting gas 2) make sure it is getting air. It must be getting spark since it always starts with starting fluid.
1) Checking for gas is easy. Have a friend crank the engine and watch the injectors. Do you see fuel spraying. Further, is it spraying in a nice cone shape?
2) The TBI gets air for startup and idling from the Idle Air Control Valve. If you have the software and other stuff I mentioned above, this is pretty easy to check. If not, it can be a little more difficult and maybe to simply replace the IAC and see what happens is easier. The blades in the throttle body should not be open at idle. On a carburetor, they would be but not on your TBI.
One thing to keep in mind is if the ignition control unit is faulty, the fuel injection will not work. For instance, if you don't get spark AND you don't get fuel, it's probably the ignition controller. I'm not sure if you can get spark and not get fuel, though. I'm not familiar enough to know how the controller interacts with the computer.
The hot running issue also potentially indicates an issue with the ignition controller because when they go bad, they tend to start the car fine but when it gets hot, it dies and the car will not start until it cools down. If you can start it immediately after it dies when hot, it's probably not the issue. The coolant temperature sensor also comes into play in closed loop.
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By Rudder2fly - 11 Years Ago
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Thanks for the info Charlie. I would say it is running out of fuel. Pressure regulator in the TBI? This is what happened this AM on cold start. I decided to try and start it without starting fluid. To my surprise it did start after a few revolutions. Running rich and would revup on throttle opening. Checked the timing again and holding ,slight movement around 10 degrees BTDC. I felt the upper radiator hose and as it start to warm up I had the SFluid ready. The motor wanted to quit but I kept it running with a shot of SFluid every 2-3 seconds. then it level out and would run at idle hot. However as I tried to open the throttle fast it would go down but I closed the throttle and kept it running. I could bring up the RPMS slowly and it would rev up.You could hear the idle air control valve opening with each shot of SFluid. After I shut it off I tried to start it again and it hit a couple of times but did not start. I have a 220 TBI and the regulators are not rebuildable so the manual says. I do not have a laptop so am hesitant about going that deep into the bank account! I will keep the truck as it is very nice for a 1989 and I use it to haul wood for my wood stove. Any more info would be appreciated. G.S.
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By sundance241 - 11 Years Ago
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Gene, I had the same problem with 1997 , 350. thottle body......seemed like it was running out of gas..............Checked everything with no luck ,,,,,,,,,,,Finally had it hauled to a small garage where a friend works there......Come to find out it was a sensor ,,,,,,,,,now get this , the sensor is located underside of the intake manifold.......cant see it from the top side ,,,,,, so had to remove the intake , replace sensor , and has runs like new ...............Chevy has a better idea, right............Hope this helps..........Sam.................56 victoria .....Fla
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By charliemccraney - 11 Years Ago
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Rudder,
Since you have good pressure and it's running rich, I would not suspect the regulator. Have you been able to observe the injector spray pattern when it starts to act up?
On my Firebird, when you check timing, there is a plug on a brown wire that you disconnect that takes the computer control out of the equation. With that wire disconnected, static timing is 0. When it's plugged back in, the computer sets the timing. I imagine your truck is similar and if 10 is static, it may be contributing to the problem at least. Check your shop manual.
Since you plan to keep the truck, investing in the proper tools will be worthwhile. You should be able to find everything you need for under $300.00. Just like you need screw drivers and wrenches for an older vehicle, a computer and logging software are necessary for an electronically controlled vehicle. Just think about how much time and money you have already spent with guesses that haven't fixed the problem. I can't guarantee that the laptop and software will help you in this instance but it has come through for me so many times. Like I said, everything else being equal, I take modern (or newer, anyway) electronics over clunky old carbs and points. I've found it much easier to diagnose, but you have to have the right tools.
I don't know about sensors under the manifold. I can tell you positively, my '88 305 has no sensor under the manifold.
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By Rudder2fly - 11 Years Ago
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Charlie & Sundance 241, I had a good temperature sensor so I put that in today. The engine started up after the 3rd try cold. I can't see what it is doing during cranking as I live alone. I'll try to get a buddy over to take a look at that. I also loosen and retighten the ground wire at the thermostat housing. I have a good cone spray of fuel both injectors on cold start open loop. Nothing changed on close loop. Would not rev up hot so today I had the SFluid ready and as it started to die I gave it a shot and the motor picked up with the throttle blades opened up. I still see a gas spray on each injector during this time but it is apparently not enough for the engine to rev up? Today it did not want to idle hot without feathering the throttle to keep it running. I can't see that I have a sensor under the intake. Nothing in the drawings show a sensor. Also I have yet to find the brown wire to take the computer out of the basic timing setting. I am looking at the 10 degrees BTDC with the computer in play. Charlie I may buy that laptop yet!!! I have attached a picture of the truck taken in 2003. It still looks nearly that good with 180,000 miles on the spedo. G.S.
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By pintoplumber - 11 Years Ago
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My '94 burb has a brown wire under the dash in the neighborhood of the glove compartment that you disconnect to set the timing.
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By Rudder2fly - 11 Years Ago
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I found the single brown wire on the firewall hid behind a bundle of wires in the engine bay. It was a single diconnect wire and I diconnected it. It made no difference in engine timing disconnected or hooked up. Timing set at 6 degrees BTDC. It revved up hot the same way. Would go down on WOT and had to shut back to keep running. There was about 6 more degrees advance revved up, for a total of 12 degrees brown wire hooked up or not. Computer is not advancing the timing! The idle was a little better probably because I put in a new IAC valve. While it was idling I unhooked the electronic spark control. It ran just the same and the timing stay as I mentioned earlier. Should the engine keep running with the ESC disconnected? Thanks G.S.
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By charliemccraney - 11 Years Ago
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6 degrees now, but 10 degrees before, and no change when you disconnect the wire. It does sound like something funky is going on with the timing.
The engine will keep running with that wire disconnected. It will run pretty badly, but it will run.
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By Rudder2fly - 11 Years Ago
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Charlie, That initial timing change was me I had move it from 10 degrees. Today I installed a new electronic spark control module. Engine started cold as it had before. Running rich and a little rough. I had the timing light on it and the timing mark was well advanced I am guessing a good 30 degrees. I unhooked the computer wire on timing and I got 6 degrees. So i'm seeing advance in open loop running. When the engine got hot and into closed loop I saw no change. Still would not idle without feathering accelerator pedal and would go down on WOT. No change with ESCM part. This truck was a smooth runner before this happened. Good start up cold, great idle, when the air was put on the RPMS would pick up to compensate for the extra load on engine. My box of good parts is filling up. You may wonder why I have not taken you advice. I live in a inground home. Cell phones do not work here nor do laptops. It would work on the truck but not inside the house. So I will keep buying parts sooner, probably later I will hit the right one. Any suggestions on what to buy next? Thanks G.S.
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By charliemccraney - 11 Years Ago
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Make sure the initial timing is set correctly, just to be sure it is not causing some issue. Like I said, on my Firebird, it should be 0 with the brown wire disconnected. Consult your manual and set it accordingly. It may be fine at 6 but for now, everything needs to be at the specification to help eliminate variables while troubleshooting.
I did not notice that you replaced your plug wires. Mine developed a miss a couple years ago and it was bad plug wires.
Aside from that, I don't really know. I think the only sensors you haven't replaced are the knock sensor, map sensor, and distributor pickup. The map sensor will probably be the easiest to replace. A test you might try there is to simply disconnect and plug the hose to see if there is any change. If it is working properly it should run even worse. If there is no change, then it might be the problem. Make sure the hose is good, too.
Many times a vacuum leak can be a little more difficult to detect because the fuel injection will compensate for it. If that leak is in the map sensor hose or possibly even one teed into it, it will caues problems.
I don't understand why a laptop won't work. Are you saying that if you press the on button, it will not turn on if it's in your house??
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By Rudder2fly - 11 Years Ago
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Charlie, Knock sensor has been replaced, Plug wires 8MM are good, total rebuilt distributor. Haven't done the MAP sensor yet. Will try that next. What I meant on the laptaop was it will not get any reception from an outside source in the house. I would be able to use the program from the truck in the house but any other signal you would have to outside to use the laptop. G.S.
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By charliemccraney - 11 Years Ago
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Oh, well you can plug a laptop in. You don't have to use the built in wireless. Also, the majority of laptops do not use an outside source, like a cell phone or satellite internet. They use a wireless source from within your home or a local source like a restaurant.
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By Rudder2fly - 11 Years Ago
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I finally hit on the problem; MAP sensor is the culprit. The only sensor I had not changed. Thanks for the suggestions to solve my problem. G.S.
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