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90TLR problems: missing at idle, down on power at WOT

M

Matt Gent

New member
I have an 06 model 90TLR, bought new in 08, with about 80 hrs on it.

So far it has been great, but currently having a minor problem.

It misses at idle, a few times every 10 seconds or so, and will occasionally stall out if idling in neutral. This problem started about the same time I noticed that it is down on power at higher rpm. The boat used to run ~41mph at 5600, now it will only get 33mph at 4700rpm in similar conditions.

Especially when warming up, it seems to be dropping a cylinder then recovering.

Otherwise it is smooth when idling in gear, accelerating, and cruising around.

Things I've checked:
-new water separating filter
-cleaned out basket filter, just a few small specks in it
-replaced spark plugs, old ones looked fine (medium brown, none wet) but were pulled after idle not under load
-checked compression, all at just under 120psi on my guage
-pulled and inspected carbs. top and bottom ones were perfectly clean, didn't bother with taking apart the middle one as it had the choke assembly on it.
-pointed infared temp gun at each cylinder. all were equal, but could only do this at idle and at ~4000rpm on the hose with no load

Any ideas on what to look for? I'm not sure how the electrical is set up, could it have one bad power pack? Or a plug lead?

Next plan is to run the boat full speed, cut the ignition, and see if once cylinder's plug doesn't look different than the others.

Any help appreciated

Matt
 
Matt Gent said:
I have an 06 model 90TLR, bought new in 08, with about 80 hrs on it.

So far it has been great, but currently having a minor problem.

It misses at idle, a few times every 10 seconds or so, and will occasionally stall out if idling in neutral. This problem started about the same time I noticed that it is down on power at higher rpm. The boat used to run ~41mph at 5600, now it will only get 33mph at 4700rpm in similar conditions.

Especially when warming up, it seems to be dropping a cylinder then recovering.

Otherwise it is smooth when idling in gear, accelerating, and cruising around.

Things I've checked:
-new water separating filter
-cleaned out basket filter, just a few small specks in it
-replaced spark plugs, old ones looked fine (medium brown, none wet) but were pulled after idle not under load
-checked compression, all at just under 120psi on my guage
-pulled and inspected carbs. top and bottom ones were perfectly clean, didn't bother with taking apart the middle one as it had the choke assembly on it.
-pointed infared temp gun at each cylinder. all were equal, but could only do this at idle and at ~4000rpm on the hose with no load

Any ideas on what to look for? I'm not sure how the electrical is set up, could it have one bad power pack? Or a plug lead?

Next plan is to run the boat full speed, cut the ignition, and see if once cylinder's plug doesn't look different than the others.

Any help appreciated

Matt
Click to expand...

You need to check all of them!
Never rev your engine unloaded on a garden hose.
 
Its a little more work to pull the third one, I can do it, but the other two looked brand new.

What exactly is wrong with revving the engine on the hose?
 
Run the motor with a timing light ( laying on a seat ) and observe the flash of the light.-------Put the boat through it's paces and observe ignition behavior on all 3 cylinders.-------------Might help you pinpoint the problem and determine whether it is spark or fuel related.--------If you only use the motor once in a while , then always run the motor dry of fuel.That helps keep carburetors clean. ----------Never run a motor at 4000 RPM with no load !!
 
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