Hi,
I have a Chevrolet 2500 with a V8, 5.7L and it won’t start. I had not used it for 3 weeks. When I tried to start it, it started well but stalled 2 minutes later. It kept on stalling all the way to the grocery store (5 minute ride). After doing groceries, the truck wouldn’t start anymore. I had it towed the following day to my studio.
It seems like it wants to start, though. I am guessing that gas is not getting to the engine. I looked at the injectors while my boyfriend was turning the key on. There was nothing coming out of the injectors. I am not sure if that’s the proper way to check them, since the air filter housing was open. I verified and there is voltage getting to the injectors (11.5V) but the resistance is slightly higher (1.5 ohms) than what is specified in the Haynes Manual (1.16-1.36 ohms). Is this big enough of a difference to prevent the truck from starting or should I look at something else? Would cleaning the injectors fix the problem or should I simply replace them? Does anyone have any other suggestion?
I checked:
Battery voltage is fine, with and without a load
There are 50 litres of gas in the tank (half of its capacity)
I added one can of fuel cleaner to the tank, in case the gas went bad (I have not used the truck for 3 weeks)
Fuel filter has been replaced 2 months ago and seems to work fine
I can hear a nice wwrrr under the truck when the key is turned on - so I think the fuel pump is working
I just refurbished the fuel pressure regulator
I replaced the ignition coil
I replaced the spark plugs, wires, distribution cap and rotor about 2 or 3 months ago. I looked at one plug. It is mainly brownish and it has a little bit of black deposit on it (not much). Is this enough to needing replacement again?
I changed the oil and oil filter about 3 months ago as well
Other symptom: the engine light has been coming on and off since I bought the truck (a year and a half ago). Could the problem be coming from the computer system? How can I check this?
I did not check the fuel pressure because I do not have a gauge. Would it be worth getting a gauge and checking the pressure?
Could it be related to the engine compression? engine timing?
What year is this truck? Since you can SEE the injectors firing, let me guess that it is a throttle body injected 5.7 liter engine maybe still using the old OBD 1 diagnostic port. In other words a pre 1996 truck? Am I right? If you can get the engine running the injector flow pattern should be a nice fine cone from both injectors. If you can’t get it running then, pull the stored diagnostic codes from the truck to see what it says. Lean fuel codes are most likely.
If I missed my guess and it is a later truck, '96 and up, it is an OBD II truck. Take it to a local parts store and have them read the codes or borrow or rent a code reader. Faulty injectors with these symptoms usually set lean fuel codes as does a failing fuel pump … and these trucks are notorious for failing fuel pumps… slowly and intermittently. Check the fuel pump fuse and relay first to make sure they are not the problems. Getting a pressure gauge and actually testing the fuel pressure is your best bet to diagnose a failing fuel pump.
Hate to say, but since you have 50 liters in the tank, it will be the pump. Murphy’s Law says the pump fails when the tank is mostly full!
What with all the ignition and fuel system work done recently, it seems like this truck has been causing you some grief. Is that true? Or is all that work just routine maintenance, and no drivability symptoms were noticed before this latest stalling incident started to happen?
Assuming the latter … well, it could be an assortment of things. For the engine to run correctly it has to have proper spark, ignition timing, valve timing, compression, correct amount of air & fuel moving freely in, and exhaust moving freely out.
So where to start? My guess is that the fuel system work recently done has clogged up something in the fuel injection system. I had an early model VW Rabbit years ago, and whenever I changed the fuel filter or opened up the fuel system to test something, soon thereafter the fuel system would stop working due to debris that somehow got lodged inside. I never did figure out how it happened. A thorough cleaning of the works would bring the Rabbit back to peak performance in short order.
The problem with this theory of mine is that for your truck – unlike the Rabbit – you may run out of money replacing and cleaning stuff before you find the problem. The first thing I’d do in your case is have all the diagnostic codes read out of the engine computer memory. It could be the case that the computer already knows what is wrong, and is just awaiting your query. If you post the codes here, the group of experts here might can help figure out what the issue is.
I concur with Ok’s advice, the injector resistance you measure isn’t likely what is causing this problem.
Edit: If you think the engine isn’t starting b/c no gas is being injected, sometimes folks here say to spray some carb cleaner into the intake air port and see if it will briefly start and run that way. If so, that confirms the problem is lack of fuel.
Yes, the truck is a throttle body 5.7L with two injectors. It is a 1992. I think the fuel pump is fine. I can hear a nice wrrr sound when I the key is turned on and the fuel is flowing all the way to the fuel pressure regulator.
This is the first time it stalls and refuses to start since I have this truck (a year and a half). I think it has been using more gas than it should (I am getting about 11.6 miles per gallon - highway and city driving) and has been running rich (the spark plugs were a bit black when I replaced them).
It does not start at all, so I cannot drive it to any garage, unless I have it towed… or pull it behind my bicycle.
I checked the code with the jumper trick and it reads 12: “start of diagnosis - no engine speed (rpm) signal received”. What does it mean? Should I turn the key all the way to the “start” position or is it ok just to have it on “accessories”?
No engine speed code? hmmm, that’s probably derived from a crank shaft or cam shaft sensor signal. If that signal isn’t present, there would usually be no spark present either. Which would explain why it won’t start. When it won’t start, has your shop checked for spark?
Crankshaft position sensors – due to where they are located – tend to be a common failure item, so maybe that’s the problem.
I think the truck should normally throw a code 12 when the diagnostics checked with the engine not running. Code 12 just tells you the computer is OK and the diagnostics recognize the engine is not running. So no codes set. Strange, since the plugs indicate a rich fuel condition.
Try a little starter fluid in the intake, crank and see if it fires, even for just a few seconds. If the injectors are OK, you will see a spray pattern and you can concentrate on ignition, as @ok4450 recommends. Since the coil, cap, rotor, plugs and wires were replaced, ignition module sounds pretty likely.
Since you have no flow from either injector, that kinda rules them out. Check for spark. If you have none and no injector pulse then your ignition module would most likely be suspect. If adding fuel makes it run then it’s obviously a fuel delivery problem. If that’s the case, I would perform a fuel pressure test. Even though you can hear the pump run, if the hose is split between the fuel pump and the pipe then the fuel will be getting pumped back into the tank. This is a fairly common problem on the TBI trucks.
Many cars won’t turn on the fuel pump or pulse the injectors if the computer detects the engine isn’t turning. It’s a safety thing, in case the car is in a wreck you don’t want to add fuel spray to the problem. If it is correct what Mustangman says above, that the “no rpm” code is normal when there are no other codes present, then the ignition system is still probably the place to focus.
My OBD I Corolla has the same weird code thing. When everything’s ok, it shows a code 51, which is a code for the throttle sensor. But a code 51 means the throttle sensor is working correctly, not that it is broken. Sometimes it is difficult to understand why the car engineers – when all the other codes mean something isn’t working – why they would illogically come up with a code to identify that something else is working … lol …
Thank you to all of you for your input. I have had someone spraying some starter fluid in the TBI yesterday while I was cranking the engine. It did not start WHILE I was cranking the engine BUT it kind of started for a tiny fraction of second just right AFTER turning the key to the off position. I don’t know if this is enough to rule out ignition, though, and focus solely on fuel delivery. What do you think?
I have not done a proper fuel pressure test (I do not have a fuel pressure gauge and the cheapest one I found at the local auto part store was $70 - maybe I should invest in one at this point). But I know that fuel is reaching the fuel pressure regulator. Since it’s supposed to get only 9-12 psi, I am not that worried about checking the exact pressure. Should I be? (Yes, I know).
I took the injectors off the truck and tried to clean them by making some kind of apparatus with a piece of clear hose, the little red tube from the carburetor cleaning fluid can and a bicycle tire valve. Of course, I plugged (pulsation) the injectors (one at a time) to a battery and sprayed carburetor cleaning fluid at the same time. I could hear the clicking in the injectors but the rest of the cleaning process was a mess, as I was unable to get a very tight seal between the injector and the hose. Result: I squirted carburetor cleaning fluid in my face a couple of time (good thing I was wearing goggles and had some old dish water in a bucket to rinse my face!) and I didn’t see any good spray coming out of the injector. I think I should try again with a better seal before tossing them.
I checked the MAP sensor, it’s good. I will work on checking the ignition module (thank you for the suggestion). I might have to wait until Monday, though, to go back to my truck.
I am finally making a little progress. The truck starts now but the idle is not even. I don’t want to risk it on the road yet. It would just stall, I think. I can hear the injectors pulsing and squirting a bit loudly (loud hissing) when the hood is open and was wondering if this was normal. Does anyone have a video of what normal injectors should look and sound like on a 1992 Chevrolet 2500 V8 5.7L?
A loud hissing would point to a vacuum leak. but if you have the intake open…flex hose removed… you may be hearing the rush of air into the throttle body.
I doubt that you would hear the injectors atomizing the fuel.
Injectors don’t make much of a sound, but they do make a low volume sound, and it tends to be a sort of whine sound. The frequency (or pitch) of the whine might go up with higher rpms, but not necessarily.
A definite “hissing” sound is usually some kind of undesirable vacuum leak. Are you sure the injectors are seated and sealed properly? If not, it might be air rushing past the injector seals, which would indeed cause a rough idle.
That hissing sound will most likely go away with the air cleaner installed. My bet is you are hearing air being pulled through the IAC passage. If you were to “hear” the injectors, you would hear them clicking. Something that got me to thinking was when you stated that it acted like it wanted to run AFTER you turned off the key. Reminds me of a symptom of a lot of bad ignition modules I’ve replaced through the years.
I can still hear the hissing sound coming from the injectors, even when the air filter is well installed. It pulsates at the same (somewhat irregular) rate as the injectors’. Maybe it’s a sealing problem around the injectors, as GeorgeSanJose suggests. It definitely comes from that direction.
After testing the resistance of the injectors once again (1.55 ohms, instead of 1.16-1.36 ohms that should be) and doing a little more research about injectors, I decided to order new injectors (I found some at $41 at the local auto part store). If it’s not the main problem, they need to be replaced anyway, so it won’t hurt. I should get them tomorrow and I will see from there.
The engine has a very poor idle (it sounds like an oval rater than a circle, if you understand what I mean), but sounds better when I depress the gas pedal. I am taking from there that not enough gas is getting to the engine at idle. My plan is to replace the injectors tomorrow. If this does not solve the whole problem, I will indulge in a fuel pressure gauge…
Pete Peters, do you still think this could be linked to the ignition module? How can I check it?