Gas smell & missing

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Gas smell & missing

Postby Socks » Mon Jun 19, 2017 8:52 pm

Got a new motor put in and now I smell gas when I stop or turn quick. Cant see any gas leaking any where. Also seems to miss a little around 30mph then seems to clear up on highway speeds. Seems to be using a lot of gas. [new motor?]
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Re: Gas smell & missing

Postby robertbweltzien » Tue Jun 20, 2017 11:02 am

Socks, what year is your Mark and is it a TBI or SEFI engine? Has the fuel pressure been checked? Has the ignition timing been checked and are you getting spark advance? Has the pcv valve been changed? Also, what condition are the vapor recovery system/hoses in? New air filter? A silly question, but is the fuel tank cap on tight? Just a few places to start.

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Re: Gas smell & missing

Postby Socks » Tue Jun 20, 2017 11:18 am

Its a 88 LSC The guy put a ATK rebuilt 5.0 motor from Advance in it. It sounds good mot of the time. I don know what checks he did as he left for another job? I am going to have all the fuel and timing system checked out for the rough running at 30mph. But seems to be ok at highway speed. I thought it might be some old fuel but have treated it and have run a tank full of new in it. Still has the gas smell when ever I stop or turn quick. Motor feels real tight and really doesn't get very good millage at 17 average
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Re: Gas smell & missing

Postby robertbweltzien » Tue Jun 20, 2017 5:31 pm

Socks, I "average" 17-19 mpg with a mix of driving. I have an '89 LSC with 190K on the clock. You should get north of 22 mpg at 65 mph, and as lo as 10-14 in city stop and go. That's after a break in period of 500-1000 miles. The best I ever did was a 50 mile stretch on a flat road at 55 mph in warm, dry weather; the trip minder said 27 mpg. You have sequential electronic fuel injection. One of the main things is correct fuel pressure, around 30-35 psi (may vary slightly) with the pressure regulator hooked up to vacuum and around 40-45 with the hose disconnected. Also retarded ignition timing will kill your mileage; it should be 10 degrees before top dead center with a total of around 32-40 total advance at speed (others please chime in to correct me on any of these numbers). I have mine set at 14 degrees to max out power and economy with a total advance at speed of 38 degrees, which is pretty high. I use regular fuel with no pinging. Of course, you need a fuel pressure gauge and timing light with an advance knob to check these. Also, you clearly have a fuel leak somewhere if you smell gas. Going around corners will force fuel up the filler tube, so your gas cap should be checked. How is the car on power?

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Re: Gas smell & missing

Postby Socks » Tue Jun 20, 2017 6:18 pm

I just went out and checked to see if the guy replaced the air filter. pulled it out and it was full of dirt and leaves. Will put a new one in as soon as I can. maybe this weekend. Going to have another mechanic check the rest out. Haven't seen any gas any where. Could the bad air filter be causing some of this? It had good power but you really have to lay into it to make it go. It feels like the motor is tight. Just takes a little to get up to power Not getting enough air?
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Re: Gas smell & missing

Postby robertbweltzien » Wed Jun 21, 2017 1:07 pm

Definitely! Just make sure he checks everything else out!

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Re: Gas smell & missing

Postby robertbweltzien » Thu Jun 22, 2017 2:33 pm

Dirty air filter and retarded ignition timing will kill your fuel economy!

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Re: Gas smell & missing

Postby Socks » Wed Jul 12, 2017 1:50 pm

Got a new filter in and that helped the gas mileage. Still has a missing around 30-35 and again 55 Seems to run fine at hiway speeds 70 Still have a gas smell when ever I stop quick or turn quick. No signs of any gas leakage or leaking. Gas gauge goes down and then comes back up when ever I turn fast.
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Re: Gas smell & missing

Postby oldschool1 » Tue Jul 25, 2017 11:49 pm

Our injectors ~can~ leak.
Is there anyone else at the shop that did the job?
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Re: Gas smell & missing

Postby Socks » Wed Jul 26, 2017 9:35 am

I am having another guy check everything out. He is going to put it on his machine and check it all out. He thinks the gas smell is coming from the charcoal canister.
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