No spark on one cylinder

[jvaccarino]

I am sans a spark on Cylinder #3. Brand new coils on all 3. Moved middle coil to bottom just to verify. Still no spark.

Am I looking at a Power Pack issue? How can I troubleshoot w/out a DVA meter?

 

[ottertail]

Re: No spark on one cylinder

Need a little more info here. Brand, hp and year would be nice. Yes you can trouble shoot with out the meter.

 

[jvaccarino]

Re: No spark on one cylinder

'93 70hp rude - model: ve70tlets

 

[jvaccarino]

Re: No spark on one cylinder

BTW - I pulled the plug wires while engine was running :

#1 - No change (have on going fuel issue w/ this one)
#2 - Engine stalls
#3 - RPM's Drop

How can I not have spark but the RPM's drop while running?

 

[ottertail]

Re: No spark on one cylinder

Sounds to me like you need to be working on #1 and leave 3 alone. Are you looking for spark with a spark plug or a spark board? It is possible for a 3 cylinder to run on 1 cylinder but it would sound so bad that iti s very unlikley. and it would instantly die when #2 was pulled. If what you state is true, then you are running on #2 and #3 but not running on #1

 

[jvaccarino]

Re: No spark on one cylinder

using spark plug tester (bought from store) has gap measurement

why does the engine stall when #2 is removed?

Why don't I see a spark on #3? THe engine doesn't sound that bad.. Have to idle at 1200 rpm or else it won't run. But it runs full throttle and plane's.. On WOT it does run a little slower/not as powerful.. probably because I am missing a cylinder.. but just curious on what is going on w/ the spark.

As for #1 - Gas is entering the carb.. and the float is not stuck..(can tell by the amount of gas in the chamber) jets are clean... maybe something with the reed?

How else can I tell if gas is getting in? The spark plug looked to be a little wet.

 

[iwombat]

Re: No spark on one cylinder

If you really have a fuel issue with #1, continuing to run it will ruin your powerhead. Remember, in a two-stroke fuel=lubrication.

 

[ottertail]

Re: No spark on one cylinder

First of all do a compression test of the engine. It is always the first place to strart. I prefer a leak down test but not everyone has a tester. It is so much more accurate than compression. I have seen scored engines pass a compression test and then ber found on the leak down. the second thing you can do is when the engine is running add fuel from a squirt bottle-contact solution bottle works great here, and see if the cylinder (#1) picks up rpm. The engine dies on #2 Because it is pulling the greatest load. you indicate #1 is dead and sounds like #3 is weak. Lets get #1 on line and see where we end up. oher wise what is the power pack out put voltage to number 3 coil?

 

[jvaccarino]

Re: No spark on one cylinder

I don't have a DVA meter.. I have a regular voltage meter.. but only up to 100 volts I think..

So spray a fuel additive directly into #1 Carb and see if the RPM's change?

I can do that tomorrow.

 

[jvaccarino]

Re: No spark on one cylinder

Compression was done about 3 months ago.. (when I first replaced a coil problem - was only running 2500 rpm on full throttle)) - and Compression across the board was 115-120.

 

[jvaccarino]

Re: No spark on one cylinder

Is it possible for spark plug to fire while running, but not while testing off of the coil?

My #3 cylinder - No spark with spark tester, while boat is running and plug wire is removed, I get a drop in RPMs.

 

[Kettler]

Re: No spark on one cylinder

I had a similar problem and saved alot of time and just bought a new powerpack then all was fine. e-bay $75