Chevrolet Malibu Forums banner
Status
Not open for further replies.

2000 Malibu 3.1 LS hard to start

12K views 3 replies 2 participants last post by  Rodents 
#1 ·
Hello everyone! My first post on here. My daughter has a 2000 Malibu that has had recent problems like intake manifold gasket and main head gasket replacement. Then radiator reservior replacement. Then 1 idler pulley, 1 tensioner pulley and 1 harmonic balancer LOL! This all within last 8 months.

Now i replaced her OEM radio with aftermarket and the car, that once started right up within 3 seconds, will crank and crank then finally start. Problem is, I smell gas bad, I have to move throttle to the floor to get it to hit, then back off for it to stay running at idle. After all this, about 5-10 seconds later it will rev up then idle smooth. During the rough start I can hear and feel popping noise under hood and out the exhaust like it is backfiring. But as soon as it gets over the rough start, it will run like a dream. Daughter will drive it to work and it will start right up after 6 hrs off, but any longer than that, it will start rough again.

I have not tried anything yet to see what could be wrong due to work. But I am off today and was wondering where to begin. The car has 160000 miles on it but like I said, It runs wonderful once it starts. All lights come on normal then go out on instrument panel and I definitely hear the fuel pump run before I start.

I will try the vacuum line to fuel regulator first to see if gas is in it. All that comes out exhaust is white smoke. After it smooths out that smoke dissipates alot. Could that be water?? Normally a bad fuel regulator would put out black smoke?

Any who, would love to hear some suggestions. Thanks
 
See less See more
#2 ·
Now i replaced her OEM radio with aftermarket and the car, that once started right up within 3 seconds, will crank and crank then finally start. Problem is, I smell gas bad, I have to move throttle to the floor to get it to hit, then back off for it to stay running at idle. After all this, about 5-10 seconds later it will rev up then idle smooth. During the rough start I can hear and feel popping noise under hood and out the exhaust like it is backfiring. But as soon as it gets over the rough start, it will run like a dream. Daughter will drive it to work and it will start right up after 6 hrs off, but any longer than that, it will start rough again.
Fuel pressure regulators leak intermittently sometimes and you don't always see it in the vacuum line when you check it. If the regulator is wet externally, it can cause your fuel odor as well. Injectors can drip too, which would cause long crank times and rough running on start up. Only way you'll see it is with a fuel pressure gauge hooked up, if the pressure drops off rapidly or at least doesn't hold for 10 to 20 minutes above 30 psi or so, it can be a leaking injector and to check that you pop the rail out and pressurize the system and look for drips. Just because fuel pressure drops abnormally, don't suspect the injectors without lifting the rail out, as pumps have check valves that can leak down and regulators can bleed off. The opening of the throttle is leaning out the mixture by allowing more air past the throttle plate. You can clean the throttle body as if it is carboned up, it can cause similar issues. Due to the fuel odor, I would tend to believe this is either a leaking pressure regulator or dripping injectors. If you think it's dripping injectors, you can try cleaning them up by running a couple bottles of Chevron Techron injector detergent in a full tank of fuel and let that tank run down pretty well before you refill. Some people like Seafoam, some like Berryman's B12. GM's recommendation is the Chevron Techron. The bottle you see may say good for up to 15 gallons however for good cleaning performance you want to use about 1 ounce per gallon of fuel minimum.
 
#3 ·
Thanks Rodents, I will try some techron first. Just the coincidence of taking neg batt cable off for radio replacement had me wondering about something electrical. Also, I hadnt started the car in 5 days. My daughter drove our car. I just went out to start and it hit pretty quick, but i turned the key back too quick. So i tried a second time and it hit and started after about 5 secs, ran rough, then with some pumps on the pedal she rev and smoothed out. I ran it around the block and it ran great but noticed white smoke trailing out exhaust. More than i had seen before but it is cooler today and rainy. DOnt know if that helps any. I wonder if she got bad gas somewhere?
Thanks for the help.

BTW, the car was parked on an incline with nose down for the 5 days. Just another hmmmmmm. LOL
 
#4 ·
I ran it around the block and it ran great but noticed white smoke trailing out exhaust. More than i had seen before but it is cooler today and rainy. DOnt know if that helps any. I wonder if she got bad gas somewhere?
Thanks for the help.
The white smoke leaves a question mark for me but you said the head gaskets were done. I'll assume for now the heads were checked for cracks and the surfaces of the head and block were in specification. No adapts are referenced on cold start. You are in what is called open loop fuel control. Coolant and intake air temp, throttle postion, MAP/MAF inputs are the main fuel control sensor inputs. It is possible that there is a skewed coolant temp sensor for example, and it may indicate say 10 degrees when it's really 45 degrees and injector pulse width would be a bit too wide because of that. That usually wouldn't do what you have described. This sounds like a cylinder or even 2 or 3 are getting unmetered fuel bleeding in when the car is shut off. Personally, I like the Techron detergent, there may be others just as good or better but GM has many times recommended only this detergent as in their testing they feel it is effective. Not all detergents are equal. If the Techron detergent will do you any good, you should notice it in the first 1/4 to 1/3 of the tank. Cleaning the throttle body is also a good idea before you get into this too deep. Both the detergent and the throttle body cleaning are cheap and quick, I would spray carb cleaner on a rag and wipe the throttle body out compared to spraying it in the throttle body. Get the area around the plate as clean as you can.
 
Status
Not open for further replies.
You have insufficient privileges to reply here.
Top