I recently replaced my fuel pump and ever since, the car doesn't seem to run quite right. I just checked the fuel filter and blew out all the lines and it seems to run a little bit better. However I'm getting a fair amount of backfire flame out the carb when I rev it up. Should I just replace the air filter and test drive the car, since that should not allow the flame to catch, or should I try to figure out what is causing the backfire first? I haven't changed anything else on the car like timing or plug wires and it ran great before the fuel pump went out. Also, the car hasn't been run in several months.
Timing doesn't move all on it's own so I would go with some simpler things. How about some bad gas from sitting? Carbs will gather the water condensation from the old gas in the bottom of the float bowl until you rev and then you will get a little down the throat and get a backfire. You could empty the tank the best you can and add some high octane. It might take a while to get it all out of the system.
if you have a Holley , you might need a new 'whatchsmacallit*' that blows (usually) at a back fire.... *totally drawing a blank! someone, step in here and help out!
If it's a Holley, power valve. But perhaps a piece of sediment from the fuel line settled into the needle and seat. Or if you blew compressed air into the fuel inlet, perhaps you unseated it.
Last edited by Yellowbird; 04/10/0708:52 PM.
Vikki
1969 Goldenrod Yellow / black 400 convertible numbers matching
I'd check the timing, rotor, cap, points. My timing would creap over time. If it is a Holley you should jack it up and replace it with a Rochester.
Timing really doesn't change all of a sudden. But points could. I would get rid of the points and go electronic. I have one Rochester and one Holley and they both work great.
I guess I missed the part about not run in several months...I should actually read the entire post. If it ran fine prior to the several month period and now runs different I'd suspect the points are corroded, the mechanical weights are stuck in the advance position, or the lifters have bleed down. I don't see anyway for a simple fuel pump change to cause this. BTW my timing did change all of the sudden once...turns out I had an a$$ of a roommate. At least he didn't loosen all my lug nuts like he wanted to.
BTW my timing did change all of the sudden once...turns out I had an a$$ of a roommate. At least he didn't loosen all my lug nuts like he wanted to.
or "friends" like me and others , who used to go out and open the hood , switch some plug wires around at parties.... its especially hard to figure out after a drink or more...
It had always run great, actually, up until the fuel pump went out. After I replaced it is when it started running bad. But there was like a 3-4 month time period where it sat.
I did change the timing and that didn't help at all.
Needless to say, I'm going to replace the power valve this weekend and see what that does. A friend of mine also recommended that, since I surely blew it out (and I also shot compressed air into it). Thanks!
While you are replacing the power valve, spend the extra $10 and put the power valve check ball in. You will have to remove the carb, but it is a simple modification.
I know that washing and waxing my car with the present condtion of my paint is like polishing a turd.....but it's my turd and I want it polished!