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1994 Chev 1500 Pick-up Won't Start - Engine
Question: Problem intermittent, vehicle ran OK for father but has been parked for two years. First replaced dead battery and added five gallons of fresh gas and a good dose of methyl hydrate, after several attempts to start the engine started though a bit rough. I drove it around for a half hour or so then parked it, three hours or so later, engine turns over but doesn't fire up. I removed the air filter and adapter ring, and inserted a dry piece of paper under both injectors and the paper remained dry. I removed the fuel line at the throttle body and turned the engine over and observed clean fuel from the line. I then drained the tank, flushed the fuel-line and replaced the filter. The engine turned over though still refused to start I then tried starting fluid the engine fired over yet failed to start, further attempts showed that the engine would run as long as a constant flow of starting fluid was supplied and died when the flow was discontinued. I gave up and skipped a day and tried the day after with a quick squirt of starting fluid not really expecting results but the engine fired over right away and stayed running after a few revs, the engine ran smoothly for 20 minutes or so and I restarted several times successfully and again ten minutes later then twenty minutes after that. I broke off thinking all was well, but a few hours later, it was refusing to run again and now here I sit, perplexed and looking for help.
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Owner: Engine is a V6 4.3L throttle-body injection with 43, 000Km
Technican: These engines have a lot of problem with hard starting due to weak fuel pressure. Replace your fuel pump and filter and it should good to go.
Owner: Thanks for the fast reply, buddy, but I stated that it was NOT starting now, *Period* certainly 'hard starting' in the extreme. Also, I Did replace the filter, first thing, as stated in my description. But if this still sounds 'classic' to you, and the stock fuel pump is so fraught with issues, is there an in-line replacement or add-on booster available? What would your charge be with shipping to PO Box 1871, Sechelt BC VON 3A0 on the Sunshine Coast, Mainland BC. or Via Bus to the Sechelt depot
Technican: If the truck starts only with starting fluid, you have an obvious fuel problem. If you have power and ground to the pump while cranking, you will need to replace the pump.
I do not have available any in line add-on pumps, check with your local parts supplier.
Owner: I DO appreciate that fact. I Thank You for your patience.
I can hear the stock pump running (sound issues from fuel tank) for 2-3 sec followed by a click-stop sound which I assume this is the pressure regulator at work turning off the pump, since it always occurs after ignition is turned on and/or returned from the start to the run position. If this is correct, shouldn't the engine attempt to fire after the pump supplies the correct pressure even if it is incapable of maintaining the correct pressure and/or flow? If so, this is not happening. Is there a component other than the ECM (or whatever) that could (if faulty) cause the throttle body injectors not to fire, yet leave the timing and ignition able to function using starting fluid ?
I ask this as I am unsure yet, which traditional trouble-shooting methods don't apply to fuel injected systems.
Technican: Do you have proper fuel pressure? This engine needs 60psi or it WILL not start. Have you done a fuel pressure test?
The 3 second run time is preprogrammed by the computer whether there is fuel pressure or not. Obviously your wiring is good. Sounds like low fuel pressure to me.
Owner: Not yet, I was hoping to find a difinitive answer without testing the pressure as I don't have the tool for that pressure. :-L But Common sense told me it would be the only way to confirm whether the pump was the problem or not. I'll check the pressure then.
Technican: You can either change the pump, or get a fuel pressure gage to tell the pump is bad. There is no way to tell with out a gage whether you have 50psi or 65psi. It make all the difference.
You could remove the fuel return line and if no fuel comes out from the engine while cranking, you likely have a bad pump.
Owner: Weeeeellll... I drained & cleaned the tank, replaced the pump & filters, re-attached the battery, purged the line to the throttle body... still no go, -Doug-
Technican: Doug,
What is the fuel pressure? Does the truck start with a strong shot of starting fluid?
Can you still hear the pump running?
Owner: I don't have a data interface nor a fuel pressure tester, so at your advice, I replaced the pump. I can hear it pump and there is a strong flow at the throttle connection but the injectors aren't injecting. I did notice that after I reconnected the battery and turned the ignition on, there was evidence that the injectors had sprayed a few times then stoipped. Yes the engine fires on ether but doesn't run. I was going to disconnect the fuel return at the throttle body to see if the regulator may be plugged somehow. I was wondering if the ECM could have been damaged when the battery was going dead and we had to boost it, and ultimately replace the battery.
Owner: This site says the issue was settled, but it isn't as I have yet to recieve a resolution to this issue. The Battery was replaced before this problem occured as the truck was in storage.
Owner: I'm having difficulty updating because your site says "accepted". I have to 'refresh from 'history' to ask or update. Does this mean you give up? Hardly fair if so...
Technican: Hi Doug,
My name is . (ASE mastertech)
I have been advising you on your truck.
I work for as a tech in addition to my regular job. The problem you are having is through the site. They believe you have accepted the advice and that all is well. I will address this with the site administrator to see if he can reopen your request. In the mean-time, you can open the return line from the injectors and see if there is fuel flow when the pump runs. The pump is supposed to pump extra and the pressure regulator is supposed to bleed off the extra so as to keep the pressure at the injectors at a steady 60psi. If there is return, then either there is a different problem, or the regulator is bleeding off too much fuel.
Owner: Thanks, that's what I was wondering. There are no leaks in the system, and I don't know what the 'something else wrong' could be, If the regulator is allowing too much fuel to bleed, is there an adjustment? Or is it a replacement? If the regulator is not allowing fuel to bleed, can an over-pressure situation cause the injector to fail to open? And lastly, is there a cold start bleed into the throttle body such that the injectors fail to initialize when engine fails to fire over? 8-D oug
Technican: Doug,
The regulators are not adjustable. Overpressure will cause the engine to flood. The injectors fire with a pulse from the computer. There should be power to the injectors whenever the key is on and the computer supplies the ground to provide spurts of fuel.
Lets backup a bit. Do we have strong spark from the end of the plug wires when cranking?
Remove the air cleaner so you can see the fuel injectors. Can you see them spray any fuel when cranking?
If you have spark, but no fuel, then use a test light to check if there is power coming to the fuel injector when the key is on. Check both sides. Ohm the 2 injectors to see if the resistance is nearly the same. Ideally, get a noid light to see if the injectors are being turned on. They should flash brightly when cranking.
Feel free to respond with your answers. We want to see this truck run! Here's How To Get Guaranteed Solutions In Minutes
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