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More AQ171c woes…Idling

M

moresparks

Regular Contributor
I have lost a lot of confidence in my twin engine installation .. I know they are 20 years old but I was hoping to extend the life a little longer but they are so fragile!
Having spent months rebuilding the top end of one due to timing belt problems caused by an unseen water leak all seemed fine. Also having replaced all the seals and hoses and it starts great. Several tests after the boat was launched and all looked well. Last job was to balance the throttles between the 2 engines before giving it an extended run.
Then for some reason the newly rebuilt engine wouldn’t idle. Starts fine but if you lower the revs to below 2000 it just dies – really strange as all was perfect the week before and I cannot use a uni-sync tool to reset the carbs.
Now I have since changed the filter, stripped, cleaned and rebuilt carbs again, and changed spark plugs all to no avail. The next test is another compression test and to swap the distributor.
The last time I had this problem it turned out to be the fuel pump – can it be that again? The pump was new last year and has had very little running. I guess its back to basics again but this is really frustrating so any pointers would be appreciated.
:mad:
 
Definitely sounds like fuel or carbs, blockage in the high speed circuit. Those carbs can be a real pain.

Have a great day,

Rob.
 
Just an update:-
Compression test was round 170 170 160 170 so should be o/k. Disappointing that one cylinder was a little low but within the 10% range, I shouldn’t have thought that would cause my problem – any thoughts?
I also undertook basic checks on the ignition and distributor according to the manual and this looks o/k.
It’s looking like fuel and the symptoms are identical to the last time when the fuel pump was replaced so I may just need to eliminate that.
I would appreciate if anybody else has ideas, and if it is the pump why it should it fail so quickly. Could contaminated fuel cause this?
 
Your compression numbers are great, nothing to worry about there. Regarding fuel pump I have heard of new pumps having a short life due to a restriction in the intake. Because of a partial blockage line from the tank to the pump they failed after a short time since they had to work much harder to pump the fuel. I think this is unlikely though.

Your idle problem sounds to be fuel related, either vacuum leaks at the manifold or carbs, or carb base, or a blockage of the idle circuit in the carb.

Good luck and have a great day,

Rob.
 
Many thanks for the responses.
Just an update:-
I have rigged a safe temporary fuel tank with fresh petrol and still no change which would eliminate “stale fuel”. I did notice that the acceleration pump on the first carburettor (nearest the front) seems to jam in comparison to the other carbs, so I have removed the carb for further investigation.
All the gaskets are new and “torqued” according to the manual.
Forums like this are really useful to give me the confidence to tackle these jobs so a big thank you.
 
Just a question…
I have a couple of Solex 44PA1 repair kits where I have replaced all the gaskets .. but the idle screw looks totally different in the kit. Has anybody swapped out the idle screw successfully from the one in the kit?
 
Sorry for the late reply,
You have a problem with the idle circuit on one of the two carbs on the engine that won't idle. Probably a piece of the fuel line as it could be breaking down. Just remember it is just a carb and it can be fixed. Swap the carbs one at a time from one engine to the other and when you find which it is, just take your time to find the dirt. Also make sure the power valve is working. I gave my engines throttle and put a rag over the carb (not enough to stall it) to clean it when I had a similar problem and it worked for me. Try taking the idle screw out and use compressed air to clean the passage, beware of fuel spray...
 
moresparks said:
Just a question…
I have a couple of Solex 44PA1 repair kits where I have replaced all the gaskets .. but the idle screw looks totally different in the kit. Has anybody swapped out the idle screw successfully from the one in the kit?
Click to expand...

Nobody seems to be able to get hold of those darn idle screws, and that's why (amongst other reasons) some members have got rid of the twin Solex installation and have installed single Weber. Interestingly enough, all of them seem quite happy with the upgrade, so I guess they must be doing something right. :D

One of these days we may find out that the infamous idle screws you are looking for (the correct size does not come with the overhaul kit) are probably also used in some sort of automotive Solex (like Volkswagen). But until then, everybody will keep asking the same question for which (so far) we have no answer.
 
I did find a couple of the phantom screws! Chuckling with glee, I screwed one into the (*&^%$ Solex and the point promptly broke off. As did the second $%#$%& point. Now the whole sheebang sits in about 100 feet of salt water :) Go WEBER!!! (but with the 171 I don't believe that is an option :(
 
thostorey said:
:) Go WEBER!!! (but with the 171 I don't believe that is an option :(
Click to expand...

I guess there is only one way to find out, contact Redline. My Weber works awesome on the AQ131. This year with the Weber it was much easier being pulled up on the wakeboard than before. Very pleased with it.

Have a great day,

Rob.
 
Hi …Just to let you know that it’s all working now.
Sometimes it’s easy to get caught in a loop and although you can check everything if one thing is done out of order you can still have problems.
It looks like dirt in the fuel and despite cleaning the carbs, re-cleaning again did the trick, especially the idle jets.
Thank you for your help.
 
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