Jim Shepard Posted March 11, 2020 Report Share Posted March 11, 2020 Took the truck out yesterday morning and it drove great. Went out in the afternoon and it started acting up - sputtering and hesitating through acceleration and losing power at cruising speed. Pulled and cleaned plugs and they looked fine. Gas is not that old and it starts right up. At a fast idle (2,000rpm) in the shop it was hard to keep it steady as it kept falling off. At regular idle (450rpm) it’s fine. This is a 230 bored .060 over with mild cam, Fenton headers and factory two barrel Stromberg. Any ideas? Quote Link to comment Share on other sites More sharing options...
Los_Control Posted March 11, 2020 Report Share Posted March 11, 2020 No mechanic, just curious what type of ignition system, points or hei and have you checked the point gap if points? Quote Link to comment Share on other sites More sharing options...
RobertKB Posted March 11, 2020 Report Share Posted March 11, 2020 Dirt in your fuel system? Just a tiny bit in your needle and seat can cause those kind of described problems. Quote Link to comment Share on other sites More sharing options...
Tooljunkie Posted March 11, 2020 Report Share Posted March 11, 2020 (edited) Points,weak coil or tracked cap. Also vacuum advance as well as mechanical. Condenser too. Edited March 11, 2020 by Tooljunkie Quote Link to comment Share on other sites More sharing options...
kencombs Posted March 11, 2020 Report Share Posted March 11, 2020 Hard to hear it from here, but if it sounds like it's missing/erratic combustion, I'd look first at points and condenser. OTOH, if it just smoothly looses power and slows, it could be a fuel delivery issue. Pump not producing enough volume, filter, air leak before the pump etc. Quote Link to comment Share on other sites More sharing options...
Jim Shepard Posted March 11, 2020 Author Report Share Posted March 11, 2020 Forgot to mention: my ignition is Pertronix with Flamethrower coil. So, no points, no condenser. 1 Quote Link to comment Share on other sites More sharing options...
Jim Shepard Posted March 11, 2020 Author Report Share Posted March 11, 2020 Also, the only thing I’ve done recently is add a few gauges - oil temp, volt, vacuum, tach. Quote Link to comment Share on other sites More sharing options...
JBNeal Posted March 11, 2020 Report Share Posted March 11, 2020 Disconnect the tach and take it for another test drive... 2 Quote Link to comment Share on other sites More sharing options...
48Dodger Posted March 11, 2020 Report Share Posted March 11, 2020 Possible vacuum leak? Have you tried the hand over the carb to see if it tries to surge back to life? If everything is snug, it should start to stall and die. If it has a leak, it'll "fight" to stay running. 48D 1 Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted March 11, 2020 Report Share Posted March 11, 2020 Jim; Not absolutely positive.....but the tach might not be compatible with your Pertronix module. I could never get mine to work correctly so I ended up leaving it disconnected. Others have had similar issues. I found I can live without the Tach.....and do not want to take a chance damaging the module. Jeff Quote Link to comment Share on other sites More sharing options...
Jim Shepard Posted March 14, 2020 Author Report Share Posted March 14, 2020 On 3/11/2020 at 11:53 AM, Jeff Balazs said: Jim; Not absolutely positive.....but the tach might not be compatible with your Pertronix module. I could never get mine to work correctly so I ended up leaving it disconnected. Others have had similar issues. I found I can live without the Tach.....and do not want to take a chance damaging the module. Jeff Seems to me if that were the case it would have started as soon as the tach was installed. The tach has been installed since the first of the year. That being said, it's easy enough to pull the coil wire and see what happens. I'm leaning (no pun intended...) toward fuel delivery problem. What would cause it to suddenly act up? If the issue is the pump, could the diaphragm be the problem? 1 Quote Link to comment Share on other sites More sharing options...
Jim Shepard Posted March 14, 2020 Author Report Share Posted March 14, 2020 I did pull the air cleaner and look into the carb while it was running. It does appear as though the gas doesn't shoot out as much under acceleration. As I said, it'll idle fine but when I accelerate it stalls. I guess the pump could have just failed... 2 Quote Link to comment Share on other sites More sharing options...
CO54 Posted March 14, 2020 Report Share Posted March 14, 2020 Good find on the fuel pump! Quote Link to comment Share on other sites More sharing options...
Jeff Balazs Posted March 16, 2020 Report Share Posted March 16, 2020 On 3/14/2020 at 11:50 AM, Jim Shepard said: Seems to me if that were the case it would have started as soon as the tach was installed. The tach has been installed since the first of the year. That being said, it's easy enough to pull the coil wire and see what happens. I'm leaning (no pun intended...) toward fuel delivery problem. What would cause it to suddenly act up? If the issue is the pump, could the diaphragm be the problem? Jim; You are probably right. I just thought I would throw this idea out there. Electronics devices like these modules can be sensitive to all sorts of things......like increased resistance etc. I have found it doesn't pay to take chances. Sounds like you are on track with the fuel delivery system. Jeff Quote Link to comment Share on other sites More sharing options...
Ulu Posted March 16, 2020 Report Share Posted March 16, 2020 Is gasohol damage to the accelerator pump diaphragm possible? Quote Link to comment Share on other sites More sharing options...
Brent B3B Posted March 16, 2020 Report Share Posted March 16, 2020 good find indeed Jim, I thought it was acting up because you mentioned switching to an automatic transmission 1 Quote Link to comment Share on other sites More sharing options...
John-T-53 Posted March 17, 2020 Report Share Posted March 17, 2020 (edited) This sounded like a fuel problem to me.... Also check the check ball at the bottom of the accelerator pump well. It usually gets gummed up and/or rusty/caked with mineral fallout. Carbs need goin' through every few years no matter what. Edited March 17, 2020 by John-T-53 1 Quote Link to comment Share on other sites More sharing options...
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