phDiesel

I posted in the FaceBook C4 Forum and didn't get as definitive of an answer as I would've looked for.

Over the past 3 months or so the strength that my car starts has been getting weaker by the day. It started getting worse this past week and I feel like somethings about to give here.

Car cranks hard for 5-6 seconds and finally limps into life once I feed in some gas. If I just try and let it idle right off the rip it will die and the process starts over again. If I feather in a little throttle and let it get some heat into it, the car will idle but rough.

After it really warms up it seems to be normal unless I sit at a stop light for an extended period of time. Feed in some gas and it doesn't seem to even do anything. Then it'll pick up RPMs and I can let the clutch out.

If I lean into it at 2000-ish RPMs it also doesn't seem to want to go anywhere. Gotta downshift and then use the top of the rev range.


Also getting a rich gas smell at idle, but I had the Cats removed recently, and might tack it up to that. Should be mentioned this issue was around before I got the cats pulled but I'm sure that's contributing to the rich condition.

billschroeder5842

Sounds like a fuel pressure issue to me. Pumps, filters, FPR are all in play. We need more information.

You need to take some pressure readings at the fuel rail. that will tell lots.

phDiesel

Unfortunately I'm going out of town tomorrow morning and I won't be able to get readings.

This seems like the "Throw money at it solution" but to be honest doing a pump and filter I know isn't that expensive. Cars got 130,000 on it.

Where is the FPR even at on these cars? (LT-4)
I'm down to order a pump and filter and throw it in and see if it does the job. I don't have gauges either to get a fuel pressure reading nor am I really experienced in how I would even affix them.

aklim

Yes, that is a "Throw money at it" attempt at a solution

FAUEE

I think at 130k a lot of "throw money at it" solutions are also good preventative maintenance. Doing a new pump, filter, and regulator would be upkeep IMO.

You need a fuel pressure gauge and to start checking the ignition system with a meter. You could have plugs and wires that need replacement, or weak spark from corrosion. I. The cap and rotor section of the opti, or a failing coil or icm.

I'm a big shbox's lt1 no start troubleshooting guide. Google it. It's for f bodies but the same things apply to us.

ghoastrider1

auto zone will loan you the fuel gauge set. I agree with the fuel pump answer but don't forget the 02 sensor.

aklim

Sure, you can go the replace everything route. Just do come complaining that you spent $5000 and countless hours and the POS is just as bad if not worse.

haxxx

Testing for fuel pressure takes like 5 minutes start to finish. It also could just be ignition related and the fuel pressure test would basically confirm it. You can replace the entire engine and call it preventative maintenance

Paul Workman

RollaMo-LT4

Under the fuel rail cover, drivers side, rear of manifold.

Mr. Peabody

1) This is not a car that you EVER want to throw parts at as the parts are rather expensive.

2) You do have to replace parts as the car gets older and .... you do not have to wait for something to fail prior to replacing it ... that IS preventative maintenance.

3) In this case you have a specific problem that you are trying to diagnose. Wouldn't it be nice to know what it was that is causing the problem?

To me your symptoms sound like a failing fuel pump or a clogged fuel filter (attached to frame rail under passenger side door.) or.... and this one is easy to check .... a very clogged air filter.

Best of luck and please let us know what you found the solution to be.

phDiesel

THANK YOU. Others gave me some good responses, some decided being rude was a solution, but this was what I needed to hear.

Constructive criticism and some advice.

I will definitely check into all of those things when I get back into town on Friday.

Cliff Harris

Check the FPR (Fuel Pressure Regulator) for a ruptured diaphragm. Disconnect the vacuum line and turn on the ignition. The fuel pump should run for 2 seconds and if any fuel comes out of the FPR vacuum port then that's your problem

phDiesel

Update:

Got around to doing some diagnostic work.

I did a fuel pump for preventative reasons. Car seems to be running smoother but I'm still dealing with the hard start issue.

Fuel pressure at the rail is 41lbs at key on, slight spike during the crank, and it levels back out after the car is running. I see that's pretty normal.

Since the fuel system seems to be doing well, I guess that would point towards the ignition?

billschroeder5842

Can you be more specific on your description here?

Ones mans "hard to start" is another man's "spun an extra few seconds."

phDiesel

Of course.
Previously starter would hit for 1 second and car would fire to life no hesitation.

Now:
Starter hits for 4-6 seconds and requires me to feather in gas. Once car fires up I usually have to feather more pedal in until the idle mellows out or it'll die on me.

aklim

Would Sir recommend that one do this in the smoking or non smoking section?

aklim

Throwing new parts at it often makes the user feel the car runs better.

That alone wouldn't sell it to me. I would want to see if it holds pressure after shutdown and for how long. Also what does it do at WOT? You see, there could be a leak somewhere BUT the pump is able to keep up for the most part so do those tests BEFORE you declare the fuel system to be good.

ASSUMING that you are right, sure. Check for a good blue flame and no leaks from the wire. However, I'd beat the fuel system to death BEFORE moving on. Just my $0.02

FAUEE

Plugs and wires ever been done? Sounds like spark, maybe replacing the coil as well.

Unfortunately, weak spark is harder to troubleshoot than no spark.

aklim

What if he does it in a dark garage? Run engine and spray a fine mist around the wires. If it lights up, dump wires. If not run till stable operating temp and respray. Plugs, remove one and let the car run. Stick a plug tester and see if there is a blue flame or not. Just a thought.