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AQ131C Bogs above 1300 RPM even in neutral

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mrmark19682006

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"I have a 1989 Imperial 1900 w

"I have a 1989 Imperial 1900 with a Volvo AQ131C 4 cyl, inline sterndrive setup. It has a closed cooling system with a heat exchanger.
VERY low hours, super clean garaged boat.

I was out on the lake today, Lk St Clair in Michigan. It was running awesome. New fuel (3rd tank this year), not a hiccup at all.

Ran across a low sandbar at about 28 knots or so.... Just enough to let you know it was there, no jolting hard hit or anything. Reduced power immediately, and put into port to pick up a friend.
Picked him up, headed back out to sea. Got past the Bouy, went to give it some juice, and it would just bog and die. I was running fine at idle. I tried increasing the throttle the same way in neutral. Same thing, it bogs and dies.
Tapped on the carb thinking maybe stuck float? Nope.
It WILL momentarily run up to 4 grand or so if you go up and back down real fast, but will not stay at those R's in gear or not. Temp was fine, not overheating at all.

Trailered it home, pulled the plugs, dry and light brown. Pulled the water separator, that was fine as well, but replaced it anyhow.

Pulled the flame arrestor, hit the throttle and you can see the gas squirt, so the accel pump in the carb is OK.

Disconnected the fuel line at the carb and turned it over, and it shot quite a bit of fuel into a jar.

Hooked up the muffs and it started right up, but still will not run above about 1300 RPM without bogging down and quitting.

I have searched a few other threads in search of a similar problem, and only other thing I picked up on is maybe a stuck anti-syphon?

Any ideas men?
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"The fist thing I would do is

"The fist thing I would do is open the raw water strainer by the coolant expansion tank and check for sand.

The second thing I would do is disconnect the fuel hose at the suction side of the fuel pump and attach a jerrycan with fresh fuel, then run the engine and see if the symptoms have disappeared.

If the symptoms don't clear, I would remove the carburetor's fine filter and clean it; and I would further drain the fuel in the bowl.

If the symptoms don't clear, post again and we'll look at a few more possible causes."
 
"I did check the strainer, and

"I did check the strainer, and there was no sand.
I removed the cover from the pump and there was no sand there either. It idled at least 1/3 mile back to the ramp w/o a problem too.

I will do the jerrycan bypass, that would rule out the syphon line.

Do I need to remove the carb to get to the fine filter, and how is it removed?

Thanks very much for your help El.
Mark"
 
I just recently check my fine

I just recently check my fine fuel filters and you can take them out without taking the carbys off.you have to remove the linkage that is in the way.time consuming but can be done.
 
"Ok, I was able to get to the

"Ok, I was able to get to the fine filter by removing the Accell pump diaphram and letting it hang out of the way.
Remove the fuel line from the carb as well.
I unscrewed the filter, and it WAS gunky. I put it in a container of gas, and shook it around, , and slid the screen off the bolt carefully.
Put it all back together, and will be giving it a go in a half hour.
Also have a 2 gallon can of gas and if the filter doesn't work, I will try that by bypassing the fuel tank.
At least this way I can isolate one thing at a time.

I will keep you posted.

Mark"
 
"No dice.
Tried running with

"No dice.
Tried running with the cleaned filter first.
Same deal, starts, but will not run above 1300.
Pulled the fuel line off the water sep filter, and put it down into a 2gallon can full of fuel.
Starts, but still, not above 1300. Bogs and dies."
 
"Have you checked the ignition

"Have you checked the ignition timing with a timing light? You may also want to remove the spark plugs to check their condition and, once they are out, run a compression test."
 
"I did check all the plugs, th

"I did check all the plugs, that was the first thing I did. They were all dry and light brown. No wetness, no oil, no fuel.
I have not checked the timing.
I thought maybe it was the advance not coming in as well.

I sent you a video of it running el.
This thing has super low hours, and is super super clean. The oil isn't even discolored. It's been very well maintained....that is what has me stumped, it was running PERFECT, then this...so odd.

Only thing fuel wise I haven't checked is the metering jets."
 
"Funny, I was just thinking ab

"Funny, I was just thinking about the main metering jet myself. Well, it shouldn't take too long to take the carb apart and verifiy that it is clear.

Also, yes, I got the video, but could not make much out of it because of the noise an low quality. I only could see that the engine idles fine (600 RPM is a bit low I would say) and it hunts between 2100 and 2400 RPM."
 
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