High-octane versus Regular

canadian_fisher

Petty Officer 2nd Class
Joined
May 17, 2005
Messages
130
Folks.<br /><br />I have one more question.<br />Would 94-octane cause significant starting problems on an older 1988 150XP Evinrude?<br />I am trying to eliminate obvious problems on why my outboard is way out of synch.<br />(ie. backfiring and not starting)<br /><br />CF
 

walleyehed

Admiral
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Jun 29, 2003
Messages
6,767
Re: High-octane versus Regular

I don't believe 94 would cause starting problems of the severe level...Now, I believe your octane rating system is different than what we use in the U.S. is it not??? I run Basically the same engine you do with 200 ports and XP heads, and I find that 87-89 works best. I've found no advantage to higher octane, and in fact have lower fuel economy with 91-up octane.
 

canadian_fisher

Petty Officer 2nd Class
Joined
May 17, 2005
Messages
130
Re: High-octane versus Regular

Hi Walleyehed.<br /><br />Dealer told me to by gas from Sunoco 94-Octane.<br />Not exactly sure why to be honest, but it was an offical Evinrude dealer here in Ottawa.<br />Either way, I have a miserable timing issue that two mechanics have been trying to solve.<br />Grasping at straws......<br /><br />Cheers Corey
 

moderator1

Lieutenant Commander
Joined
Dec 5, 2002
Messages
1,668
Re: High-octane versus Regular

If that's a stock XP 150, and your octane rating is the same as ours, 94 is not a good deal..<br />What Octanes are available there? What's considered "std" unleaded?<br />I think walleyehed is right...that's sounds mighty high for that engine.
 

BF

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Joined
Apr 8, 2003
Messages
1,489
Re: High-octane versus Regular

I don't know sunoco... is it an ethanol blend? I don't run ethanonl blends (like Mohawk gas) in 2 strokes. Ethanol gives their "regular" a 92 octane rating, but the alcohol can cause problems if a 2 stroke is jetted close to the edge.<br /><br />I think our octane ratings are the same up here... 87 is normal, 89 mid, and 92 or so high grade. I burn regular in my stuff, but I don't have the same motor as you, and none of it is tricked out or running overly advanced.<br /><br />I'd run whatever octane the owner's manual calls for and ignore the dealer's advise. <br /><br />I don't know how the coils etc. are laid out in that engine, but you might wanna check that someone didn't switch around some spark plug leads by mistake.<br /><br />Last spring my Dad was having rough idle, backfire etc problems with his I/O... turns out he had switched 2 wires on the distributor when he put a new cap and rotor on.... but probably an easier mistake to make on an I/O than an OB.<br /><br />that's my $.02
 

Chinewalker

Fleet Admiral
Joined
Aug 19, 2001
Messages
8,902
Re: High-octane versus Regular

Had a problem with a V4 I recently rebuilt - found I had inadvertantly swapped two coils when reassembling and wrong coil was firing the wrong cylinder on the port side bank. Aside from lack of power and no heat from that side, the other symptom was an occasional backfire. Might want to check that the proper coil is bolted up to and wired to the proper cylinder...<br /><br />- Scott
 

canadian_fisher

Petty Officer 2nd Class
Joined
May 17, 2005
Messages
130
Re: High-octane versus Regular

G'day.<br /><br />Well the Timing issue turned out to be a broken key under the flywheel. I was about 60 degrees out of phase and running the engine in REVERSE. This only took me about 2-weeks of iBOAT.com to figure out :) <br /><br />Eitherway, the Octane discussion is very interesting. My NEW mechanic (not the dealer) just timed the engine and recommended "Mid-Grade" which is more like 89 Octane. He says I was just wasting my $$$$, which I agree.<br /><br />Cheers. Corey
 
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