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'91 Chevy Lumina Euro 3.1 erratic idle and fuel smell


brohaa

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Hi guys. You were all so incredibly helpful and generous with your time in helping me with my cooling questions. I have yet another problem I would be most grateful for help with.

 

I have been catching a fuel smell occasionally, especially at start up, from my car. In particular when I run the air on "vent." I know there is an exhaust leak post catalytic. I suspect there is one at the headers now. I hear a hiss inside my car seemingly coming from the lower dashboard area near the pedals. There is also a tick which I suspect is the injectors seeing as it is coming from around the fuel rail. It sounds similar to a bad lifter.. Which is exactly what I originally thought it was.

 

Today, I went to start my car after it had been sitting for about an hour. It started, but the idle was erratic; jumping between 500 and 1500 rpm or so. It did this for about 15 seconds. I tried giving it a bit of gas to stabilize it, around 2000 rpm. I let off and it continued to idle erratically for a few seconds at which point it died.

 

It started fine the rest of the day until tonight. I had parked it for about an hour again and went to start it. The car did the same thing, idling erratically for 10 seconds or so. Though it didn't die this time. It finally settled down and slowly dropped to its 700 rpm usual idle. The oil pressure has been alright. Though at times it is a bit higher than usual at idle. It usually sits around 35 or so psi and jumps to just over 60 when I lay on the gas.

 

There is also a steady pulsing of the engine I feel when idling. Not that the tach jumps, but I feel through the brake pedal and the car as a whole a pulsing from the engine. Thank you all for taking the time to read this and I am grateful for any advice you may give me. :smile:

 

 

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You may have a leaking injector(s). Grab a fuel pressure gauge and note what your fuel pressure is. Then watch and see if the pressure goes down as the car sits, and note how much pressure is lost. If there is a big drop, that is a good indicator for one or more of your injectors leaking. What kind of mileage are you getting?

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Thanks for the info. Well, my fuel gauge likes to dance so I'm not really sure. Plus, the trip odometer is broken not that that matters. Just icing on the cake. And I've yet to be able to fill my car up completely so I'll let you know when I do.

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is your SES (service engine soon) light on? Have you checked it for codes?

 

Most times, when the car idles rough, it will set a code that you can pull, look it up, and it will tell you what is wrong, and most cases how to fix it.

 

All of your symptoms could be the results of different problems (leaking injectors, vacuum leak, misfire, bad sensor).

 

I say check for codes first, and get back too us.

 

If you don't know how to do it, just get a paper clip, bend it into a u-shape, find the ALDL connector under the drivers side of the dash, and of the 2 rows of pins, short the 2 wires together that are SIDE BY SIDE (in the picture, connect the 2 wires in the RED location on your aldl connector).

 

aldl.jpg

 

Once the paperclip is connected all you do is turn your ignition key to the ON position (do not start the car). Your cooling fans will turn on, and the SES light will start flashing the codes. It will start with code 12 (one flash, pause, two flashes, longer pause). It will flash each code 3 times before going to the next one. Just count the flashes, and let us know what you find, if any.

 

 

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Hi guys. My SES light is not on. I just checked it for codes using the method described in the last post (Thanks Taylor). Code 12 was repeated over 4 times in blocks of 3. There are no other codes being displayed. The car has not died as it did since. Though it cranks longer before it starts than it did. The only problem with the car that is apparent is a power steering leak which I am in the process of obtaining the parts. I am going to check the plugs and probably replace them. As I understand it there are a multitude of things which could cause the problems I've described. And the gas mileage seems to be pretty descent.

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Everything fuel related jumps out at me for this problem. You best bet would be to check the fuel pressure with a fuel pressure gauge (about $30 at the auto parts store). That is a super easy job and a great place to start. You should have somewhere near 40 PSI.

 

If that's ok, it is probably your fuel injectors or fuel pressure regulator. Checking the FPR is also really easy. Follow the vacuum line that runs under you "3.1MPFI" plenum. Give it a quick tug from that rubber elbow. If any fuel comes out of the vacuum line, then it little diaphram ruptured inside the FPR and fuel is getting sucked into the intake (hence the gas smell).

 

If that's ok, you can take off the plenum and "OHM test" the injectors. They should read between 12-14 ohms.

 

That's all I can think of. On 9/10 of my car's problems, I do not get a check engine light.

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