I just got my Impulse 2.3 running in a carbed Trooper. It was idling very rough and I noticed while I was tuning idle mixture on the carb that the canister purge line being hooked up seems to be the cause. If I take it off and plug the port on the carb it runs 100% better.

From what I read, there is a diaphragm that opens up the purge line only when vacuum is high enough on the line to the distributor advance. From what I gather, it seems like I either have too much vac on that line, or the diaphragm is stuck open.

It started to pour rain/snow so I have not had a chance to do much more troubleshooting after just pulling/plugging the purge line. What I'd like to find out is if there is a fairly simple test I can do to check the canister. I have a parts 86 Troop I could pull the canister off of, but it would be nice to know it is good before I go to the trouble. Is there anything else to look at on these things?

The only thing on the fuel system of this truck that is different from stock is the mechanical pump has been taken off and replaced with an electric. The pump is just after the stock filter by the rear wheel, and I used a filter with a return up by the carb where the stock pump was.

ON THE TOP OF THE CANNISTER IS THE PURGE VLV THE VERY TOP VACC LINE HAS TO BE HOOKED TO A PORTED VACC SOURCE SUCH AS THE DIST VACC LINE THE BOTTOM FITTING ON THE SAME VLV HAS TO GO TO THE MANIFOLD VACC PORT , THE OTHER LINE ON THE CANNISTER GOES TO THE VENT ,INE BACK TO THE TANK, IF THE VLV IS STUCK OPEN IT WOULD MAKE THE ENG IDEL TOO HI AND MAYBE STUMBLE OFF IDEL, AS THE THROTTLE IS OPENED THE PORTED VACC OPENS THE VLV AND LETS MANIF, VAC PURGE THE CANNSITER , THOSE THINGS RARELY GO BAD , UNLESS IT HAS PLUGGED VENT LINE IN THE BOTTOM OF THE CANNISTER , JUST MAKE CERTAIN THAT THE TOP VACC LINE DOES NOT HAVE MANIF, VACC ON IT , ALLSO IF YOU WANT TO MAKE IT IDEL REAL SMOOTH, ON THE NO 1 INTAKE RUNNER THERE IS A SMALL ABOUT 1/8 INCH DIA, HOSE PLUGGED ON TO THE NIPPLE, REMOVE IT AND PLUG THE NIPPLE AND THEN RUN THE LINE THAT WAS HOOKED THERE OVER TO THE LINE THAT IS PLUGGED INTO THE BOTTOM OF THE VLV ON THE CHARCOLE CANNISTER , YOU WILL NEED A SMALL TEE FITTING AND A LITTLE LONGER HOSE , WILL NOT AFFECT THE OPERATION OF THE CANN, AT ALL BUT WILL LET ALL CYL, HAVE AN EQUAL AMOUNT OF MANIFOLD VACC INSTEAD OF ROBBING ONE CYL AT IDEL , IT WILL RUN MUCH SMOOTHER JERRY

Just got to thinking maybe I was an idiot and swapped the hoses around, but I don't believe so. I will definitely check for that, but I followed the diagram on the hood just like the last time I had it apart and it ran fine then. It idles smooth as glass with the purge line disconnected and the carb port plugged, but if I hook it up it gets rough at idle and has a stumble. With that carb port open it dies almost immediately. The other line off the purge valve is hooked to the hard line the is sort of Y shaped just rearward of the carb. That hard line hooks to the distributor advance at the other end. Could be I have the source vac hooked up wrong on that hard line. Disti isn't advancing at idle though, I did check that when I got it timed. I had the purge line hooked to a small vac port toward the top rear on the side of the carb, the only thing that matched the diagram really. But even if I got that one wrong, the other should keep the valve closed at idle so it would not affect anything.

That line on #1 intake runner goes to the vac switching valve on the smog pump I believe. In my case, I don't have a smog pump any more because the impulse head had no ports for the AIR manifold. In short, it is already plugged.

The motor runs fairly strong, but it does seem rather weak in the low end. I have a slight stumble coming off idle, but not bad at all. A big plus is that the constant pop out the exhaust between shifts is completely gone.

The motor that came out of this truck lost compression in #1 cylinder after a mildly high speed run over 8-10 miles. The spark plug looked like the metal of the ground electrode had been melted. Not sure if that has any bearing on the problems I'm facing now, but I though I'd mention it. I was thinking detonation, and your comment about that #1 runner vac port got me thinking perhaps I had a leak there leaning out just that cylinder, which could have caused my problem.


Well thanks for your input Jerry. I need to get some time and really go over the vac routing again to make sure I'm not off somewhere, and maybe just try the spare canister I've got to see if that helps. Hopefully I'll have a nice day soon to get back to it, rained hard yesterday and snowed hard today. Sucks when you don't have a building to work on your rig in.