MPTech

I have a '95 3.4L that has 120k+. I've had it for about 12 years and it used to start GREAT! Quick turn of the key and it fired right up every time! In the last year or so, it has become more difficult to start when it's cold. Once it's run a few minutes it starts up like a champ again. Last summer I had a mechanic take a look at it on-the-side (didn't have all of his garage diagnostics tools). He replaced the plugs, wires, and cap and it was a little better, but it's getting harder to start again sometimes (wierd thing is that sometimes it does start right up, but I can't correlate it to anything specific). I called him and he said it may be the fuel pump, but didn't have any equipment to test it (actually, I don't think he wants to be bothered with it). He referred me to a friend of his and said it would be $1,000 to replace the fuel pump. Is that right???? He told me to try turning the key on and listen for the fuel pump, then let it set about 10 seconds (to prime it) and try it. If that worked, it was probably a fuel pump issue. I tried it and it didn't help at all.
Could the O2 sensor be a problem?
I'm really stumped and it's getting worse (sometimes). Suggestions?
I wanted to try a couple things before I spent $1,000 for a fuel pump. (he told me they'd have to remove the rear seat and cut a hole in floor to get to it. Is this correct? I never heard of such a thing before.)

Phate

All of what you've been told is correct. Doing a fuel pump in our cars is a horror story. But please do not go the route of cutting a hole in the floor. Not only is it very dangerous (a sawzall + gasoline is not a good combo), but it is not the easiest thing to do.

Give me more of a description of what the car is doing when you try to start it and we may be able to more pinpoint the problem. Fuel pumps are typically not an intermittent problem also.

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MPTech

click, chug chug chug chug..
click, chug chug chug chug.. sputter
click, chug chug chug chug.. backfire
click, vroooom


sorry, couldn't resist (but it is pretty accurate)

when the car is warm, turn the key and it starts right up. no problem.
when it's sat and is cold (usually in the morning or after sitting all day, after work)
1 out of 10 times, it will start right up, and may do that 2 or 3 times in a row (or for a day or 2)
when it doesn't start............
it just continues to turn over and over and doesn't try
I can do that a couple times, then it will choke / sputter / backfire
then it usually starts up on the next key turn

I don't think it's the fuel pump, because it hasn't gotten any worse and it's been doing this for almost 2 years. it's annoying, but not worth $1,000. and usually after 3 or 4 tries, it starts (however, this morning it took 8 or 9, I thought the battery would die!)
last summer, I replaced the plugs, wires, and cap. I also replaced the battery 2 years ago.
Every once in a while, as I'm driving, it feels like it misses, but that is very seldom.
It feels like it needs a tune-up (why I thought O2) but I'm at a loss. Could it be as simple as a fuel-filter or PVC valve?? (I thought I had those changed last year too, but I'd have to check my records, I really don't remember)
The mechanic did hook up some hand-held diagnostic tool and read "the code" and said it checked out OK.

I wasn't planning on cutting a hole, that's what this guy told me. I guess I was surprised they don't just drop the tank to get to it(?) Sure seems easier (and safer) than going through the floor!
OK, so assuming it is the worst and it needs a new fuel pump, Is a $1,000 reasonable??

FirebirdPhil

Sounds similar to what mine was doing when the alternator was going out, but I never had it backfire and once mine started up it ran fine.

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"What if I told you insane was working fifty hours a week in some office for fifty years at the end of which they tell you to piss off; ending up in some retirement village hoping to die before suffering the indignity of trying to make it to the toilet on time? Wouldn't you consider that to be insane?"
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MPTech

I replaced the alternator I think 2 years ago.
I don't think it's related, but that would be a much cheaper thing to test / try first. It seems to be charging just fine and like I said it's being doing it for almost 2 years and I don't think a bad alternator would last that long.

but......... I've been wrong before! (just ask my wife)

Phate

Okay, here a few things for you to test.

First, check your battery voltage. When the battery is cold, its not going to produce the same power (Im sure you know this), but the catch is, if the power supplied is not enough, it can trigger the security system and make it refuse to start.

Another thing, check out your MAF. I used a vantage scan tool (with a wideband voltmeter) and checked the incoming and outgoing signals from the MAF to see if it spiked and caused the motor to run badly. That could be the cause of your misfires and backfires.

And another question, have you tried hitting the accelerator when trying to start it? I know that sounds dumb on a FI vehicle, but its an easy way to test to see if the idle air control valve is functioning correctly and letting it start and idle correctly and supply air to the motor.

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MPTech

Thanks Phate!
I'll give these a try.
the battery seems strong, it turns and turns and turns, I think it was doing this before I replaced the battery, but i can't say for sure. I have a volt meter, what am I looking for and how should I test it?

As to the MAF and a "vantage scan tool", I'm relatively confident that I don't have one of those tools. Would AutoZone or one of those places be able to quickly test it without me having to drop the car off for an analysis at the dealer / garage?

o yeah, I tried hitting the accelerater and evything I could possibly think of to help it start the first time. I tried not pressing it, I tried pressing it then not touching it, I tried holding it in, and I've tried pumping it. No difference.

Let me try the first 2 items and post back. meanwhile, if anyone else knows, I would sure appreciate it.

so do you agree that it doesn't sound like a fuel pump (I don't think so, but I don't know how to test it to rule it out).

Phate

Advance and Autozone and places like that do not have qualified techs. Most of the people working there might know a little about parts, but chances are they know nothing of diagnostics. They wouldnt have a vantage, its a snap-on scan tool. The only thing they are really good for (unless you find a rare case of an ASE certified tech at one of the stores) is putting on wiper blades and using a scan tool and telling you the code, I would really doubt they know what a multitude of codes would mean together.

If you hit your accelerator and nothing happened, then I wouldnt worry about your IACV. But, to check the MAF, you have three wires going into it. Your going to have to put one lead on the far left wire, and the other on the far right. Have the car idling (if you can) and hit the accelerator (just do it manually on the throttle body) while holding the leads on the MAF. If you get a varrying signal while at constant rpm (spikes) then the MAF is malfunctioning.

I dont really understand why the guy that checked your system didnt just put a pressure indicator on the line to see if your getting pressure from the fuel pump, if you have one, it takes all of 2 minutes.

Another thing to check, is find something about 5 inches long and metal, has to be about as thick as a pen tip (I use a steel pocket screwdriver) and take off one of the wires at the spark plug and put the screwdriver or whatever your using in it to touch the metal in the wire, and then put the other end of the screwdriver near a piece of metal on the motor and see if she arcs. You'll be able to tell if you've go spark that way.

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MPTech

I don't hold the Chain Parts store with high regard for specific automotive knowledge. They can read a meter / guage and a computer screen parts list (although I've had problems with the last items on numerous occasions). But then again, I'm not paying them $100 / hour for their services either! I guess I'll have to schedule an appointment and drop the car off (agony).

The car eventually starts, sometimes (but rarely) on the first try, usually 3 or 4 tries and recently 9 or 10.

IACV? (Idle Air Control Valve?? but I wouldn't know what that is either) So that's good that it's not the IACV? It generally idles fine, but it has idled high a couple times on startup, but i was just glad that it kicked over!

I can check the MAF (per you instructions). If it spikes at constant rpm, that's bad, ok. So what does the MAF do? (Mass Air Flow sensor, correct??) and are they expensive? Seems like I removed and re-installed this many many years ago when I installed my K&N. I don't think I need a mechanic to replace this, correct?

Should I also check / replace the EGR?

As you've probably surmized, I'm not a mechanic, but not totally an automotive newb.

As far the fuel pump pressure check, I think he thought it was fixed with the plugs / wires / cap and just did a telephone call diagnostice when I told him I was still having problems. That's why he referred me to his buddy.

Phate

The Mass Air Flow Sensor tells the computer how much air is passing through the throttle body into the motor, and the computer leans or richens the fuel mixture to make the car run correctly. And no, you dont need a mechanic to replace a MAF. Its a small black box (kinda) that goes into a hole on your throttle body, held in by 4 screws.

The EGR rarely causes any major problems, it typically just throws an annoying code making the car harder to inspect, and sometimes causes the car to run roughly (very doubtful in your case). Whenever I get an EGR code, the first thing I do, is take off the EGR and attempt to blow the carbon deposits out of it, 8/10 times that fixes it. Otherwise, you may have an EGR leak. EGR stands for Exhaust Gas Recirculation Valve, which just means it takes unburnt contaminants and fuel and puts it through again to be burned off for emissions.

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