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AQ140A hesitation

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pugetsounder

Advanced Contributor
"Took the boat out for its sec

"Took the boat out for its second sea trial after almost sinking it on the first one. This time we had better luck! Found a few leaks that were easy fixes. The seawater strainer cap was spewing but took it off the cleaned the gasket. Also noticed water weeping in around the rubber connector from the exhaust mani to the exhaust pipe, so I tightened the clamp a couple of turns. I will definitely get a bigger sump pump. I'm running a 400 GPM now would like 650-700.

Anyway to my problem. A boat acts way different in the driveway on a hose than it does under load in the water. At idle in neutral it is a fairly smooth acceleration. Under load it really hesitates between 1000 and 2000 rpms. After that the motor runs fairly smooth. At first there were hesitations at all rpms but as the motor warmed and the more we ran it the better it ran. We tried to run it hard on purpose. Lot's of start and stops and some WOT for a bit. But there is always a hesitation coming off idle and the idle isn't always smooth. And when it's warm it idles higher than when it's cold (1100-1200rpms) which is causing me hard shifts. I'll do another complete tune-up and I am waiting for my Uni-sync tool to come in the mail to set the carbs. I didn't check for moisture in the dist cap or check the point gap yet. Anybody else have any other suggestions? I am hoping not to rebuild the carbs if i don't have to."
 
"Until you get your uni-sync t

"Until you get your uni-sync tool, you can attempt to synchronize the carbs following the instructions (as a reference) for the downdrafts in the AQ130 or AQ151 manuals, as the procedure is very similar for the sidedrafts. Once you have set both carbs to open simultaneously, then you can follow the instructions for the sidedrafts provided in the operator's manual for the AQ140.

http://www.volvo.com/volvopenta/na/en-us/marineengines/pub_search/

I also experienced (occasionally) the change in idle RPM when the engine was warm on my AQ140A. I could never figure that one out 100%, but I noticed an improvement when I switched from points to Pertronix. This, however, did not cure the problem 100%. One thing I used to do when the idle RPM were high was to switch off the ignition, then turn it on again before the engine stalled, and that usually brought back the right idle RPM. I could never determine for sure whether the symptoms were caused by the distributor advance weights sticking open, or it was the control cable acting up, or...? Sorry, but I do not have a definite answer for this one."
 
"Thanks El,

Just got my uni

"Thanks El,

Just got my uni-sync delivered about 15 minutes ago! Can't wait to try it out. I am a little confused, the tag on my engine says AQ140A but I am not sure what carbs I have. It has the square carb box and the spark arrestors are rectangular but look downdraft. I know the engine didn't come stock with the boat. The Clymer manual doesn't state what carbs came on what engine. You just have to know what carbs you have.

As far as the control cable goes, I noticed it runs close enough to the exhaust to cause discoloration on the housing. Maybe the heat affects the cable? I'll try and reroute that tonight.

I would like to hear from someone that swapped out their OEM distibutor for an after market one to see if the idle fluxuation disappeared. The Pertronix is on my list, I wanted to make sure the engine was a keeper before I put that kind of money into it. We'll see how it goes next time out.

This is a llittle off topic and I know it's been brought up before but what about FI? When I was scouting out motors in a wrecking yard I noticed a lot of the Volvo 240s came with Fuel Injection. There are two things I believe in when it comes to gas engines: Electronic ignition and fuel injection. They work so much better than their replacement parts, ie. points/condensor and carbs. Anybody done this swap?"
 
"If you have the AQ140 and rec

"If you have the AQ140 and rectangular flame arrestors, then you have the sidedrafts. To use the uni-sync tool with the sidedrafts, you have to remove the flame arrestors first (part 15) by removing the 4 bolts (part 18). Then the tool (with its gasket) fits on the carb flange.

http://www.volvopentastore.com/FUEL_SYSTEM_AQ140A/dm/store_id.366--session_id.86 6663201--cart_id.010876839--category_id.333010--list_time.1179943637--view_id.32 5940

Fuel injection was used in automotive Volvo 4-cyl engines but to the best of my knowledge not in marine applications."
 
"Thanks El! It's nice to k

"Thanks El! It's nice to know I won't have to jerry rig a fit to the carbs.

Hey I was searching around the internet and found this product:

Hot Spark electronic ignition conversion kit.

http://www.hot-spark.com/

At half the price of Pertonix I am willing to try it. They have a specific kit for Volvo-Penta AQ140. Anybody tried this company or heard of them?"
 
"I have heard from them before

"I have heard from them before but never tried their products. I looks to me like a Pertronix clone, but if the quality is the same (or better) and the price is lower (significantly lower I might add), then why not switching to them? A good thing about competition is that usually prices go down.
biggrin.gif
Let us know how it goes if you decide to install one of those kits."
 
Volvo OHC engines should idle

Volvo OHC engines should idle a bit faster when hot. This is due to the simple design of the Solex carburetor. When it heats up the atomization level is altered and the mixture changes slightly. IMO
 
"You may be right, but that do

"You may be right, but that does not explain why (as I explained 4 messages above) when I turned the ignition switch off, then on, the idle RPM returned to normal."
 
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