4.3gl pefs backfiring and popping under load

[bnicov]

So my trusty 2001 4.3gl pefs has decided to run lousy. It backfires and pops under load and has no power. I have checked the accelerator pump and it squirts a healthy amount of fuel down the throat of the 2bbl Holley. My thoughts are bad gas or the carb has issues. I pulled off the fuel filter and there was some sediment in the bottom of it. It is a stock VP 6 micron water separating filter. Any thoughts on what I should look for. It is being pulled out tomorrow for the winter and any repairs will have to wait till spring since tomorrow is thanksgiving here and nobody will be open to get parts. Thanks!!

 

[jerryjerry05]

A little bit of sediment means the filters doing its job.
Any water?
The accl.pump is one of the lowest/deepest spots in the carb and gets fuel first.
The pump might be bad and not be supply'n the right amount of fuel?
The pickup tube in the tank might have a filter on the end and if the filter has crud it could be blocked?
The hoses could be effected by Ethanol, they get soft, mushy and the inside of the hose can break down and block the flow?

 

[Saline Marina]

Keep in mind the accel pump is separate from the main fuel pump. Just a rapid fuel feed from a reservoir to respond to the throttle being quickly opened. Under generalized engine load I'd be more worried about the main jet circuit. If its something that started suddenly I'd suspect the fuel pump. A fuel pressure test would tell you more, to avoid throwing money at spare parts. However...a new fuel pump is also an investment into the future...you have gotten ~13 good years at this point. A carb kit could also be in order and would be another good investment into the future.

 

[bnicov]

Before firing it up this morning to load onto the trailer, I pulled the distributor cap off to check it and the rotor, what a mess, moisture in there and badly corroded contacts. I cleaned them up a bit and fire up the boat, started easy and ran much smoother, still backfiring but only under 3/4 and up throttle. So, looks like a new cap and rotor in the spring. Hopefully thats it.

 

[bnicov]

The carb was rebuilt 3 years ago and works fine, the choke works as it should as does the accelerator pump, it shoots a healthy squirt. I was thinking bad fuel or a stuck float but after tapping the carb and checking the filter, those were ruled out. After searching the web I decided to check the ignition system and found that the cap and rotor were a mess. There was carbon on the top that wiped off but lots of corrosion on the contacts. So I am hoping that a new cap and rotor will fix it. I hope it is not a bad module or coil but whatever it is, it will get done.