RV-List Digest Archive

Sat 06/29/13


Total Messages Posted: 3



Today's Message Index:
----------------------
 
     1. 01:06 PM - Re: Low fuel pressure injected engine (Michele Delsol)
     2. 02:51 PM - Re: Low fuel pressure indication (Charlie England)
     3. 06:19 PM - Re: Low fuel pressure injected engine (Robin Marks)
 
 
 


Message 1


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    Time: 01:06:25 PM PST US
    From: "Michele Delsol" <mdelsol@md-dsl.fr>
    Subject: Low fuel pressure injected engine
    Not exactly ' should be around 155 at 2500=92 ' should have 160+ 22/2400 at 6500=92 ' 8 US gal/hr. I have forward induction with the snorkel. A James cowl with direct forward air feed should get me some more MP and less air intake hence more power at altitude and less drag, but that is just conjecturing. And another thread. On the fuel pressure issue ' two flights today ' problem did not manifest itself ' a mystery. Outside air temp around 60=B0F. Flew between 400=92 and 7500=92. Mich=E8le De : owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] De la part de Robin Marks Envoy=E9 : samedi 29 juin 2013 07:26 =C0 : rv-list@matronics.com Objet : RE: RV-List: Low fuel pressure injected engine Mich=E8le Do you know your TAS at those settings? Robin From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matronics.com] On Behalf Of Michele Delsol Sent: Friday, June 28, 2013 11:57 AM Subject: RV-List: Low fuel pressure injected engine Hello to all, While the subject is on fuel pressure (carbureted engine) I thought I=92d relate a little problem I am encountering on occasion in my fuel injected engine. I=92d be putting along at cruise speed when all of a sudden, some slight misfire, loss of poser. I look at the fuel pressure and it is down from 26 psi to the low teens. A slight touch of the boost pump and the problem disappears. Turn the boost pump off and the pressure continues up there at 27 psi and I can continue and hour or more ' no incident. Set up : TMX-360 (AKA IO-360), Precision Airmotive Silver Hawk Fuel injection, standard injectors. Pmag and Slick. I run at 24/2400 8 USG/hr and get 150 knts ias. Temporary vapor lock ? Mechanical fuel pump is beginning to have problems ? It=92s a glitch ' it does not happen on all flights and does not seem related to outside air temp. Any ideas ??? This does not keep me from flying but since the boost pump has become a life line, I am installing Andair=92s new fuel pump in line with the boost pump as a back up boost pump in case things get a little nasty. Regards, Mich=E8le RV8 ' TMX-360 =================== bsp; - The RV-List Email Forum - o browse scription, , Chat, FAQ, /span> tronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List =================== bsp; - MATRONICS WEB FORUMS - eb Forums! .matronics.com">http://forums.matronics.com =================== bsp; - List Contribution Web Site - o:p> bsp; -Matt Dralle, List Admin. tronics.com/contribution">http://www.matronics.com/contribution =================== _____ No virus found in this message. Checked by AVG - www.avg.com :p>


    Message 2


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    Time: 02:51:29 PM PST US
    From: Charlie England <ceengland7@gmail.com>
    Subject: Re: Low fuel pressure indication
    There have been numerous threads on various lists & forums about low fuel pressure indications with carb'd engines. Most indicate a sensor design flaw, rather than an actual pressure issue. Here's a pretty good example from VAF: <http://www.vansairforce.com/community/showthread.php?t=97911&highlight=low+fuel+pressure>http://www.vansairforce.com/community/showthread.php?t=90682&highlight=low+fuel+pressure Mike, I'm not following how manifold pressure would affect a fuel pressure reading, since with a carb'd engine the fuel pressure sensor is measuring pressure between the engine pump & the inlet to the carb bowl & isn't typically in the intake path. What am I missing? Charlie On 06/28/2013 12:10 PM, HCRV6@comcast.net wrote: > Thanks Mike, excellent point that was escaping me. > > Harry > > ------------------------------------------------------------------------ > *From: *"Mike Robertson" <mrobert569@hotmail.com> > *To: *"rv list" <rv-list@matronics.com> > *Sent: *Thursday, June 27, 2013 11:25:15 AM > *Subject: *RE: RV-List: Low fuel pressure indication > > Harry, > > Keep in mind that when we measure pressure we are really talking > pressure differential. If the throttle is full open then the fuel > pressure differential may actually be zero. For carb equipped > airplanes I would not get too carried away with a zero reading at full > throttle as long as the engine is running good and you still see some > pressure when you turn on the boost pump. > > Mike Robertson > > ------------------------------------------------------------------------ > Date: Thu, 27 Jun 2013 18:07:25 +0000 > From: HCRV6@comcast.net > To: RV-list@matronics.com > Subject: RV-List: Low fuel pressure indication > > I have a puzzling problem and wondering if anyone can shed some light > on it. Under continuous high power settings, like in climb to > altitude after takeoff, my Grand Rapids EFIS fuel pressure indication > drops to zero and even shows a low negative value after a couple of > minutes, but the engine continues to run at full power. This with a > carbureted O-360 and running on the engine driven pump only. If I > switch the aux pump back on the pressure indication comes back to the > normal 2 to 4 psi range. I had this problem a few years ago and > installing a new VDO pressure sender from Grand Rapids cured it, but > this time a new sender did not help. The pressure take off is at the > carburetor and the sender is mounted on the firewall, connected with a > -2 hose. > > The thing that has me scratching my head is that the engine keeps > running fine at high fuel flow even though the fuel pressure indicates > zero or less, so I would suspect a bum sender again, but the fact that > the pressure indication comes back to normal when I turn the aux pump > back on has me baffled. > > HarryCrosby > RV-6 N16CX, 1080 hours >


    Message 3


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    Time: 06:19:31 PM PST US
    From: Robin Marks <robin@PaintTheWeb.com>
    Subject: Low fuel pressure injected engine
    I have the exact same thing happen to me (IO-360 200 Hp, James Cowl, Bendex , Mag/Pmag) I fly 21.5/2250 LOP at 6.2-6.8 GPH ~158 TAS. My cylinder & oil temps are qu ite low because there is so little pressure & minimal internal stress vs. 2 4 or 25 Squared ROP. It sort of feels like my system is gently falling asle ep and then the fuel pump takes a nap. Sometimes I hit the boost pump and s ometimes I let it drop and then catch back up with rarely a stumble. I do o ccasionally have a stumble but I thing that is more related to my most lean cylinder (LOP) getting too lean vs. system fuel starvation. Good luck, Robin From: owner-rv-list-server@matronics.com [mailto:owner-rv-list-server@matro nics.com] On Behalf Of Michele Delsol Sent: Saturday, June 29, 2013 1:07 PM Subject: RE: RV-List: Low fuel pressure injected engine Not exactly - should be around 155 at 2500' - should have 160+ 22/2400 at 6 500' - 8 US gal/hr. I have forward induction with the snorkel. A James cowl with direct forward air feed should get me some more MP and less air intak e hence more power at altitude and less drag, but that is just conjecturing . And another thread. On the fuel pressure issue - two flights today - problem did not manifest i tself - a mystery. Outside air temp around 60=B0F. Flew between 400' and 75 00'. Mich=E8le De : owner-rv-list-server@matronics.com<mailto:owner-rv-list-server@matroni cs.com> [mailto:owner-rv-list-server@matronics.com] De la part de Robin Mar ks Envoy=E9 : samedi 29 juin 2013 07:26 =C0 : rv-list@matronics.com<mailto:rv-list@matronics.com> Objet : RE: RV-List: Low fuel pressure injected engine Mich=E8le Do you know your TAS at those settings? Robin From: owner-rv-list-server@matronics.com<mailto:owner-rv-list-server@matron ics.com> [mailto:owner-rv-list-server@matronics.com] On Behalf Of Michele D elsol Sent: Friday, June 28, 2013 11:57 AM Subject: RV-List: Low fuel pressure injected engine Hello to all, While the subject is on fuel pressure (carbureted engine) I thought I'd rel ate a little problem I am encountering on occasion in my fuel injected engi ne. I'd be putting along at cruise speed when all of a sudden, some slight misf ire, loss of poser. I look at the fuel pressure and it is down from 26 psi to the low teens. A slight touch of the boost pump and the problem disappea rs. Turn the boost pump off and the pressure continues up there at 27 psi a nd I can continue and hour or more - no incident. Set up : TMX-360 (AKA IO-360), Precision Airmotive Silver Hawk Fuel inject ion, standard injectors. Pmag and Slick. I run at 24/2400 8 USG/hr and get 150 knts ias. Temporary vapor lock ? Mechanical fuel pump is beginning to have problems ? It's a glitch - it does not happen on all flights and does not seem relate d to outside air temp. Any ideas ??? This does not keep me from flying but since the boost pump has become a lif e line, I am installing Andair's new fuel pump in line with the boost pump as a back up boost pump in case things get a little nasty. Regards, Mich=E8le RV8 - TMX-360 =================== bsp; - The RV-List Email Forum - o browse scription, , Chat, FAQ, /span> tronics.com/Navigator?RV-List">http://www.matronics.com/Navigator?RV-List =================== bsp; - MATRONICS WEB FORUMS - eb Forums! .matronics.com">http://forums.matronics.com =================== bsp; - List Contribution Web Site - o:p> bsp; -Matt Dralle, List Admin. tronics.com/contribution">http://www.matronics.com/contribution =================== ________________________________ No virus found in this message. Checked by AVG - www.avg.com<http://www.avg.com> :p> http://www.matronics.com/Navigator?RV-List http://forums.matronics.com http://www.matronics.com/contribution ________________________________ No virus found in this message. Checked by AVG - www.avg.com<http://www.avg.com>




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