Fuel in the air intake... and flames!

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samana76
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Fuel in the air intake... and flames!

Post by samana76 » Sat Nov 09, 2013 8:14 am

Hello everyone,

I hope I am putting this in the right section of the forum. If not I apologize and ask the moderator to move it to the correct section. Thank you.

I am a new member to this forum. I just bought a magnificent white 1981 GTV6 from the original owner's family. It has 155k miles on it and has been sitting a in garage for the past 13 years. It is all stock and has always been well cared for. Of course it has wear and paint fade/crackle, typical of its age, however, and this is the best thing about it, it has absolutely no rust at all – not even surface rust. I am very excited about this as I have had other Alfas in the past and rust was the major issue on all of them.

OK, enough about describing how excited I am on finding my GTV6 (I could go on and on). Let me describe the problem I encountered last night. As I mentioned above the car has not been running for the last 13 years (it seems the clutch needed replacement, which was never done). There was old fuel (and a lot of gunk) in the fuel tank so I removed it to have it cleaned and sealed. I also replaced the fuel pump, which was not functioning anymore (probably due to having gunk in it), the fuel filter and spark plugs. Yesterday I installed all the new components, put in a fresh battery and fuel, and started cranking the engine. I had previously checked the timing belt which seems new (however I did not check that the timing is correct - I’m not sure if this may be the issue with my problem).

One problem I noticed immediately is that the fuel pump will not work unless I keep the air sensor flap open – it does not even pump for a couple of seconds as it should when I turn the key. In any case I placed an object to keep the flap open so that the fuel pump would constantly pump fuel in the line and cranked the engine.

The engine started for about 1-2 seconds and died. It did this repeatedly – it would never start for more than a couple of seconds. I then looked around in the engine bay and noticed that fuel was dripping out of the air intake hose (the splined J shaped hose from the plenum to the air filter box). This is very odd. I cleaned the fuel, checked to see if the spark plugs were wet (some were, especially cylinder 2, and some were not), I dried them and tried again.

After cranking the engine a few times (with the engine trying to start, but never did) I heard a loud pop and saw a small flame come out of the plenum. I stopped everything immediately and threw water and the small flame that had developed (I had the water hose ready in case anything like this would happen). What had happened is that the rubber/silicon hose that goes from the intake runners to the plenum had popped off from cylinder 2 and the fuel that evidently was in the hose had caught on fire. I must mention that I did a compression test the other day and cylinder 2 was particularly high at 165 psi compared to the others which were around 140.

I checked to see if the flame had damaged anything. Luckily it did not even scorch any hose or electrical wire or anything. I was very very lucky.

Now my question to all the experts out there is: what happened!? :) Or more specifically, do any of you know why fuel is getting into the plenum/air hose? If not what steps do you suggest I take to diagnose the problem? Do you think it may have to do with the timing (which I have not yet checked…I should have, I know).

I will be working on it all day on Monday as I am off work, so I would truly appreciate all you suggestions, comments and help this weekend so that I can have a better understanding on how to proceed.

Thank you all in advance.
Igor
Greg Gordon
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Re: Fuel in the air intake... and flames!

Post by Greg Gordon » Sat Nov 09, 2013 10:06 am

The cold start injector is flooding the engine. It could be either because it's stuck open and spraying whenever the fuel pump is running. Or it could be an accumulation of fuel due to too many starting attempts.

In either case, you need to check the cold start injector for correct operation. There is an L-Jetronic tech article explaining how to do this on my main site, www.hiperformancestore.com

Greg,
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Giuliettaevo2
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Re: Fuel in the air intake... and flames!

Post by Giuliettaevo2 » Sat Nov 09, 2013 11:22 am

Also the injectors could be clogged up with the same gunk you found in the tank and pump. Getting them out and getting them cleaned ultrasonically will help. Or you can get injectors from Greg offcourse. :wink:

if the engine stood for a few years it's also a very good idea to change the cambelt before running the engine! Interval for change is x-thousand miles or 3 years usually, the belt also deteriorates with age, not only with use. :wink:
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Re: Fuel in the air intake... and flames!

Post by MR2 Zig » Sat Nov 09, 2013 5:34 pm

Another thing is that this injection system only turns on the fuel pump when air is flowing thru the airflow meter that you have blocked open. Opening the AFM is the way to check and see if the pump is working, only. The idle air mixture will get messed up with the AFM blocked open, even just a little bit.

Have fun with it!
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samana76
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Re: Fuel in the air intake... and flames!

Post by samana76 » Mon Nov 11, 2013 5:15 pm

Thank you everyone for your quick and informative answers.

Today I proceeded in following Greg Gordon's L-jetronic V-6 diagnosis article (thank you Greg, this is a fabulous article which I am following step-by-step to get my "new" GTV6 back into tip-top condition).

Today I checked all the air hoses (they're all in perfect condition), removed the plenum, inspected the short plenum hoses (which I need to replace), removed the fuel rail, injectors and CSI (which I will be sending to OKInjectors for refurbishing tomorrow - I already filled out the request form on the site).

I also made a list of items I will order this evening. Since I have the injectors out, I was planning to replace the little rubber seals in the inlet manifold. I've read elsewhere here in these forums that I can use BMW E28 injector seals which I can buy directly at Kragen/Autozone, is this correct?

These next evenings, after work, I will continue cleaning/inspecting/replacing hoses and ground wires as detailed in Greg's article.

Thank you all again.
Will post my progress soon.

Igor
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Re: Fuel in the air intake... and flames!

Post by MR2 Zig » Mon Nov 11, 2013 9:23 pm

I don't know if Greg carries the injector seals or not, but I was able to get them at the local parts store. http://www.sebringwest.com/parts.htm I think they are a Preadator injection part.

The kits (one per injector) have both the upper and lower seals. Trust me you want to replace both. While you are in there its easy.

I hope that helps,

Scott
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