1996 Chevy S-10 2.2L, 81K miles
This problem only started happening within the last couple of weeks. The truck has never had any trouble at all starting up; it could be freezing cold all night, and the next morning it’ll fire right up with barely any cranking.
However, now it’s taking at least a full 1.5 seconds of cranking to get it to fire at all, and usually it will sputter and spit for a moment after that before settling into a normal idle. If I turn the ignition on and let it sit for a moment, it tends to start quicker, but not always.
My own thoughts are a dirty fuel filter, or a weakening fuel pump. I’m concerned that it’s the pump because whereas it used to be pretty easy to hear when you turn the ingition on, now it’s much quieter. Sometimes I can’t hear the pump come on at all. The fuel filter was replaced about 25K miles ago so I know it’s due, but I’m thinking that’s not what’s causing this. The quietness of the pump operation happened around the same time the starting troubles did.
I would love to check the fuel pressure, though I don’t have a pressure gauge. Does what I’m describing sound like a failing fuel pump to anyone? Should I start with the filter and see what happens?
1996 Chevy S-10 2.2L, 81K miles
When was the last tune up? Spark plugs, pcv valve, air filter, cap and rotor if used?
This truck does not have a cap/rotor; ignition coils direct to the plugs.
Air filter was changed less than 10K miles ago and is clean. Plugs and PCV valve were changed less than 20K ago.
I should also add that once the engine is running, everything is fine. No loss of power, no sputtering, no misfires, no nothing. At the moment, this problem occurs only when starting up.
Can we determine fuel pressure from a symptom? Nope! We can determine fuel pressure from the fuel pressure test gauge attached to the fuel system. That sounds incredible, doesn’t it; but, a lot of people will swear by it.
Hey, thanks for your smart-assed sarcastic reply. I appreciate being told what I already know as though I didn’t know it at all. Big help there, pal.
I didn’t ask you to tell me what the fuel pressure was; I asked for an opinion if this sounded like a failing fuel pump. If you’d like to be helpful, then please do. Otherwise, insult someone else.
I’m having a similar problem with my 2000 Chevy Silverado 1500 with about 130K on it. First attempt to start, usually nothing, but every 10th time or so it will turn over, sputter for about 2-3 seconds, and then idle and run just fine. Every time I try a second time, it starts up just fine. First idea was the fuel filter, so I replaced it…no dice. I’m replacing the plugs and wires tomorrow, and I’ll let you know if that’s the issue. I’m guessing not, but it’s due for new plugs and wires anyway, so better to start with replacing old items. You might want to check out this thread too:
If you find out anything in the mean time, please post!
Acturally I would say you did ask what the fuel pressure was. [i] I would love to check the fuel pressure, though I don't have a pressure gauge. [/i] Even you know you need to check the fuel pressure. You want us to out guess you to determine if it is low or not without measuring the pressure. Hello is a regular here and has a long history of helping out many people. We see people every day asking us to tell them that what they already know is not so. You are doing the same thing. You know you need to chack the pressure and yet you ask. It is not like suggesting tearing down the engine to check something, pressure test are not difficult or expensive and we both know that is the only way of finding the answer.
If you don’t know that failing fuel pressure is a significant sign of a failing fuel pump, why do you discount finding out what that fuel pressure is as a means to ascertain that? Since you know all the answers, why do you come here asking? It wouldn’t be doubt in your own fabulous abilities, would it?
When you ask for advice, no one said that you would LIKE the advice that you get. You choose to be discourteous, and insulting, in the extreme. Who wants to help a person with your attitude and manners? Certainly, not I.
Wow guys, all I was looking for was second/third/whatever opinions. I reiterate that I at no time asked anyone to tell me what the fuel pressure is, whether it was low or not, nor to tell me “Say it ain’t so!” The fuel pump is only one guess I have among others, and all I was asking for was if that seems reasonable, or if there’s something else I might not have thought of.
The other topic that phocylides posted provided me with one (bad stop valve isn’t allowing pressure to be maintained when the engine is off), which is something I’d never have thought about.
Any attitude I’m showing is because of the attitude of others here. I thought I’d get some helpful suggestions or other ideas, and instead I’m getting talked to like I don’t know a wheel from a floor mat. Sorry that I don’t own a fuel pressure gauge (which I’ve never needed) and didn’t check it before posting here (which I’ve never needed to do). I won’t ask for opinions ever again, scout’s honor.
You won’t be missed. Quite the contrary.
Just replaced the plugs and wires yesterday…no dice. So now it’s on to the mechanics shop to get that fuel pressure tested. I’m thinking it’s a fuel pump going bad, but I’m trying to avoid that conclusion, mainly because of the cost. One thing I can’t understand is why the truck consistently starts on the second attempt. If the fuel pump was bad, wouldn’t it be unable to build up pressure on any attempt to start?
I am all for not letting problems exist longer than necessary but do you think your sympton really indicates a problem? 1.5 seconds of cranking does not indicate a problem.
This is a central port system? If it was a 4.3 I would almost be postive it was but perhaps with the 4cyl they continued with TBI. Have you looked at the troubleshooting chart for your sympton? what direction do you see it taking you?
Any possibility the problem lies in a F.I. circuit? Perhaps one of those poppet valve injectors giving trouble caused by fuel quality? (GM liked to say fuels with ethanol in them was the cause of injector failure).
I’ll admit I’m a bit of a hyopchondriac when it comes to my vehicles, but I’m also aware enough to know if something’s amiss (even slightly). It’s not just that it takes more cranking time, it’s also that it spits and sputters for a moment before settling into idle which has never happened at all before. I changed out the fuel filter since it was due and a possible cause, however that didn’t correct the problem. Inspected the spark plugs and they’re in excellent shape.
This engine uses an MFI (multiport fuel injection) system, and my Haynes guide’s troubleshooting chart isn’t very helpful. The only things it tells me are “Fault in the fuel or electrical systems”, or “Fuel not reaching the injectors”.
I’ve only guesses at this point, and I really should purchase a fuel pressure gauge so I can get some idea of the fuel pump’s operation. A vacuum pump might be worthwhile too so I can test the pressure regulator’s operation. Not sure how to check whether there’s a problem with a F.I. circuit, any advice there?
Several TSB’s exist that deal with your symptons and the TSB recommends to use a GM product for something that has not proven its self, a fuel injector cleaning. The symptons match you exactly,longer crank time and rough running after start-up.
No Central Port Injection (I could not picture a spyder set-up for a four cylinder). I was not aware GM used a Multi Port system as early as 1996 on the 4 cyl. The 6 cyl info I revieved did deal with Central Port injection.
They went to multipoint for the 2.2 in 1994, FYI. The central port injection on the 4.3 is junk in my opinion, and expensive junk at that. The repair bill to replace one of those units will usually about make someone fall over.
ah, heck, my friend’s truck is the same exact one, and he had the same problem.
Get a good cleaning done with some Sea-Foam, It’s about 5 bucks a can. Follow the directions for running the stuff through the vaccuum lines. Then put it on a diet of Marvel Mystery oil. Again, follow the directions for putting it in the tank. After about 2-3 tanks of this treatment, it should run very well.
I wouldn’t worry about the fuel pump just yet. I usually get paranoid too when I think something is going wrong.
Ok, so after some more testing, it seems like it’s the fuel regulator or a leaky fuel pump check valve.
After reading this thread, and reading up on fuel systems, I decided to take the advice of y’all and just test the fuel pressure. I bought a $35 fuel pressure gauge, connected it up to the fuel line just before it enters the rail, and tested the pressure at three positions: key off engine off, key on engine off, and key on engine on. Here are the test results in chronological order:
Key off, Engine off: No pressure at all
Key on, Engine off: Pressure builds to 60psi, holds for 1 second, then drops at about 5psi per second until it’s back to 0
Key on, Engine on: Cranks, but no start
Key off, Engine off: No change, remains at 0
Key on, Engine off: Pressure builds back up to 60psi, holds for 3-5 seconds, then drops at about 5 psi per 3 seconds (slightly slower bleed than before) until 0
Key on, Engine on: Cranks, starts right up
So, the symptoms are that when I go to start the truck, it turns over, but it doesn’t start. If I turn the key on, wait 5 seconds, turn the key off and repeat, THEN try to start the truck it fires right up.
So, I’m guessing that the fuel pressure is such that on the first attempt, the pump is priming the line to the proper pressure, but when the engine cranks there isn’t enough fuel getting through the injectors to start it up. On successive attempts, the residual pressure from the previous attempt adds up and there is enough to eventually start the engine. So, since the gauge was hooked up before the fuel got to the engine, and that’s where we experienced the pressure drop, I’m ruling out injectors. I’m also ruling out a fuel line leak since I don’t smell or see any gas on the ground. That leaves either the fuel pump check valve, or a leaky fuel pressure regulator, both of which would allow fuel to leak back into the system, creating a bleed on the pressure that I’m seeing. So I bought a fuel pressure regulator to try first, since it’s the easier of the two pieces to replace! I think…
Here is a great page I found for troubleshooting fuel injection and fuel pump issues:
If anyone finds holes in my logic here, PLEASE post…I’d be happy to have a second opinion! This is just a hobby of mine, and I am by no means an expert. Hope this helps those that are troubleshooting similar problems.
It sounds to me like you are on the right track.
The fuel pressure should stay high for 1/2 hour, or longer, after the ignition key is turned off. If it doesn’t, as you say, the fuel pump is allowing pressure bleed-down, or something else (fuel pressure regulator, leaking (into engine intake manifold) fuel injectors, etc.
To see if the fuel pressure regulator is bleeding off the pressure, pinch off the fuel hose going back to the fuel tank (from the fuel pressure regulator). If the fuel pressure stays up, the regulator is not holding the pressure.
To see if the fuel injectors are bleeding the pressure down, the fuel pressure hose (or line) between the fuel pressure test gauge and the fuel injectors would have to be blocked (pinched off, or otherwise), and the pressure observed.
The saga continues! I’d like to give all you guys a thumbs up for helping me out so far, I really appreciate it. So I replaced the fuel pressure regulator, and I was wrong. I’m still getting the bleed, so I’m down to the fuel pump check valve, and a leaky injector. I added the injectors back into the equation because after reading hellokit’s reply, I went back and looked at the fuel lines again, realizing that where I placed the fuel gauge is actually in parallel with the injectors and not in series like I had originally thought. I also noticed something I hadn’t before…a hissing noise coming from below the fuel rail. The noise occurs after the fuel pump comes on and finishes pressurizing the line. Immediately afterwords, the line pressure starts dropping. It’s not the vacuum tube because the engine isn’t turned on yet.
This is just a guess…but could that hissing be gas leaking through a fuel injector into the manifold like hellokit suggests? If it is, and the problem turns out to be a bad injector, what is the best way to find out which one of 8 it is? Maybe unbolt the fuel rail, pop the injectors one side at a time and then turn on the key (but not the engine) to see which one leaks? Is it ok to replace just one injector? $70 vs $540 is a big difference there…heh. Thanks guys!