<VV> 828 miles this weekend - car running lean - adviceappreciated

deltainc deltainc at grm.net
Wed Oct 7 15:53:11 EDT 2009

----- Original Message ----- 
From: <BobHelt at aol.com>
Subject: Re: <VV> 828 miles this weekend - car running lean - 

> In a message dated 10/5/2009 6:04:33 A.M. US Mountain Standard Time,
> guusdehaan at me.com writes:
> On our  trip to Germany it was almost on lambda 14,7 all
> the time (mine has  a Safe Guard system with sensor in the exhaust).
> But on the way back  home it started running leaner and leaner (near
> 11). Does anyone  have an explanation what could cause this?
> Guus,
> 11 would indicate a rich mixture rather than a lean one. Are you sure that
> it's 11:1?

> In my experience and research, I have found the rubber accel pump 
> diaphragm
> a problem area. The rubber hardens from natural aging and it causes the
> mixture to go rich. I don't know why this would happen during operation, 
> but
> it  happens otherwise. The diaphragm is fairly easy to replace. I would
> start with  that.
> Regards,
> Bob Helt
Also, the older fuel/air oxy sensors are notorious for only being "accurate" 
when the mix is near 14.7 .....  if he is reading 11/1, with the older 
sensors.... it really only means he is rich... not too dependable on " HOW " 
rich.  Maybe it is really 13.7, which is not too bad.

First thing I would check if its the older type Oxy sensor ... I would call 
Safe Guard and ask for a short discussion, giving them the serial # on his 

Hmmm.  wonder if he went thru any great altitude change, or even 
cloudy/clear conditions.

Just a thought... ken campbell, deltawerkes

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