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Virtual Wrench
Virtual Wrench, Classic car expert
Category: Classic Car
Satisfied Customers: 14620
Experience:  35 years experience Foreign and Domestic
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I have a 1790 mg midget , it was running great , stop & got

Customer Question

I have a 1790 mg midget , it was running great , stop & got gas . Next day to it out went about 3k's(2miles)it started to miss fire & run rough buy the time I got it home it was running really, really, rough . I changed the gas filter , put new plugs in , cleaned the air filter(weber carb)it also has a electronic distributor no points etc. The fuel pump seem to be ok?? . Car still running real rough.
Submitted: 2 years ago.
Category: Classic Car
Customer: replied 2 years ago.
I also add LUCAS upper cylinder lubricant to gas at fill up would adding to much lubricant cause the problem gas tank holds about 5 gal. of gas
Expert:  Virtual Wrench replied 2 years ago.
Hi,sorry for the delay.
Did you add the Lucas before or after filling it with gas?
What size bottle of Lucus was it?
Customer: replied 2 years ago.
bottle is 32 oz. I put about 3-4 oz. in
Expert:  Virtual Wrench replied 2 years ago.
Oh good! I was hoping you didnt add 32 oz's to only 5 gallons of gas....
If you only added 3-4 oz's to a FULL tank, it should be ok, but we cant rule it out because it seems to have started running bad at the same time right?
Customer: replied 2 years ago.
This all I got to tell you , don't know much on mechanic
Expert:  Virtual Wrench replied 2 years ago.
How did the plug tips look when you took them out? Were they wet, or black. Or were they a sandy color?
Is the new fuel filter a clear plastic where you can see gas in it?
2 questions there..
Customer: replied 2 years ago.
2 wet ,1 sandy ,1 a little black new filter see thru , cut open old filter not dirty
Customer: replied 2 years ago.
Just check old plugs they are black ,they all might have been wet , wipe all off after taking out ,I do know to were wet
Customer: replied 2 years ago.
that's I know 2 were wet
Expert:  Virtual Wrench replied 2 years ago.
Thanks, ***** ***** helps.
If you can see fuel in the filter we can assume that it's getting fuel, and being that it does run, even though its rough, it means the electronic ignition is working. So we have eliminated it being a fuel supply or ignition problem.
With the color of the old plugs i would bet that the spark plug wires are breaking down and need replaced along with a new dist cap and rotor. These are regular maintenance items that need replacing about every 50K miles anyway so it is a good idea to replace them and i think it should make it run like it was before. At the very least they need replaced for maintenance reasons anyway so its not like you are replacing un-needed parts.
Customer: replied 2 years ago.
the dist is a new electronic dist
Customer: replied 2 years ago.
will get new wires & see if it works ,any other suggestion ??
Expert:  Virtual Wrench replied 2 years ago.
Only the coil if it hasnt been replaced, or low compression. I would bet it's the wires though and doubtful on the compression but is possible.
Best wishes my friend!
p.s. these sure are fun cars to drive!