Snap crackel Pop

I have had an aircooled guy tuning up my car. We're to the point where the car is running strong, but it snaps and carckel's out the exhaust. He's an experienced aircooled guy. He has adjusted the values, fuel pressure, carbs etc.

Any suggestions?

Tony

exhaust gasket leak?

is it all the time, at idle only, during acceleration only, at specific rpm ranges only?

Hey Spyder Mike

The car will be driving fine when your on it hard then it will start starving for fuel. I also get popping out of the exhaust when I let up after being on it hard or once it's warmed up & you're coming to a stop. I went to Tom's post from 3/02/05 about 44 IDF synching and learned a lot. Everything you guys were talking about me and my guy went through with the exception & my aircooled guy mentioned I try next is cleaning out the gas tank. I took it off yesterday and boy was there a lot of crap floating in the tank. The car has sat all winter and spring. I cleaned it out yesterday. I'm going to reinstall it today with new filters, and I'm also going to blow out the fuel line. My guy installed an electric fuel pump up front by the gas tank to aid the mechanical one. He also mentioned the fuel line is about a 5mm. That seemed small to him for a 175hp motor. Do you run a 1/4" or 5/16" fuel line? Should I put one on while it's apart? He suggested I do.

Have a great 4th Spyder Mike.

Tony

Make sure the idle jets are all clean. I had similar symptoms on my 44's.

Tony,

I am not sure about needing an electric and mechanical pump. What fuel pressure/flow is the electric pump putting out? Any idea?

You might want to check the carb inlet sceens for crud also and clean them out when you hook everything up.

I use 1/4 inch line.

Keep us posted...
regards,
Mike

3.2 mm equals 1/8 inch, so 5mm seems small. I ran a 5/16 or maybe 3/8 steel line from front to back, then put a tee in the back to each carb, I think 5/16 or the metric equivalent.

Where are the carb inlet screens located? I cleaned the tank; it was dirty with a lot of crap floating around. I installed a 5/16 fuel line. I just test drove. It's like jekell& hyde. It runs greatvand hard then starts hesitating and popping. I went to the 44 IDF synch post. I'd like to adjust the carbs. I believe it is running to lean. My aircooled guy adjusted it that way.

Tony

The carb inlet screens are where the fuel lines meet the carbs. You take off the fuel line at each carb and there should be a screen in there to clean out.

Thanks guys for the help. I located the carb inlet screens and cleaned them. They weren't really dirty; they had a couple floaties. The way it is acting, it's running really good than starts running lean like it's starving & popping out the exhaust has to be some kind of something in the carbs. I mean if the timing was off or the valves were off or the spark was bad it would run crappy all the time. Yes no? Help.

Tony

I have always been told to suspect carbs last. Check everything else first. Alot of other problems will seem liek the carbs, but aren't. My opinion as passed down to me...

I do the valves first then points when the engine is cold, then I check timinng when warming it up, and lastly mess with the carbs.

Mike

Mike is right, it could be as simple as a plug wire broken or not on all the way.

Problem solved!! It was the mechanical fuel pump. It went bad. The car was starving for fuel. Nothing was out of adjustment.

Tony

Tony,
Thanks for publishing the resolution. It may help someone else in the future.

Which raises the question: When a mechanical fuel pump goes bad, does it do it gradually, or all at once? Anthony's problem seems to point to a pump's gradual failure, since his car continued to run even though the pump was apparently faulty. And...would it not be prudent to carry an extra pump along on a long trip?

My fuel pump (two of them actually) went bad all of a sudden. With the original Brosol, the horizontal pin that allows the rocker thing to move up and down just fell out leaving me stranded right away. With the replacement Carter unit, the diaphragm ruptured, again leaving me stranded immediately. So far, the replacement Brosol works fine, but I keep a spare in the car, and will go to an electrical unit as soon as I can pay for the other repairs that have been plaguing me (and my checkbook) lately. v v

And as I mentioned in another thread, make sure your carb return springs have enough tension to return the butterflies to complete closure. Kragen carries pairs for around $5.