i have a 94 e 420 the other day my car crunk up but when i put it in reverse it went dead then it would not crank. i had codes 4,6,17,19,20 could someone help me with codes. while i was trying to crank it it would act as if it was going to back fire.

Won't crank or won't start?

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1989 300E 144K

it will not start 94 e 420 .guess what it crank up an ran for awhile then cut off then it just turns over an over an acts if its wants to backfire while u try to crank it

Too much Fuel? Not enough Air? Delayed spark? After you crank for a while, and it sounds as if it's going to backfire, stop turning the engine and take a wiff of your tailpipe. Does it smell like fuel? Also, check for a clogged air filter/fuel filter.

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1989 300E 144K

yes it does smell like gas. even while running u can smell it

ive cleared the codes but code 19 comes back in the little box that in front of the 38 pin box do i need to get the homemade tester out to test the 19 pin in that box