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-   -   First start- no start. (https://vansairforce.net/community/showthread.php?t=147517)

SportAvServ 03-10-2017 07:36 PM

no fire
 
From past experience, disconnect the "P" leads at the mags, then try the start.
A friend had the same problem first start, he swore he had pinned the ignition switch out correctly. He pinned the switch out again with help from others and it seemed fine, I asked him to just disconnect the leads but after pinning them out again decided to have them rebuilt, the engine was mid time off of another RV, but the mags had not been touched. When he got the mags back he put them on and it wouldn't start again, I again asked him to humor me and remove the "P" leads from the mags. He did and it lit in 2 blades. He did have the switch wired correctly, but when he put the leads on the mags the shielding would ground out, so when he pinned them out off of the mags they would pin out correctly then ground out when they were put back on the mag. I'm sure it's something simple. Make sure that the mixture goes to full ICO, before you do this.

Rt

RV7A Flyer 03-10-2017 09:27 PM

Quote:

Originally Posted by SportAvServ (Post 1156827)
From past experience, disconnect the "P" leads at the mags, then try the start.

Just be careful here...this is a dangerous condition (although you might already have one if your wiring is messed up so that "on" = grounded, but "off" = ungrounded). With no way to ground the mags, the only way to stop the engine is via idle cut-off and if, like a friend of mine, the control was not *quite* able to reach idle cut-off on first engine start (it was easily fixed), the only way he could stop the engine was via grounding the mags ("off"). If you have disconnected the p-leads, AND the mixture won't reach full ICO, you won't be able to stop the engine. (I suppose you *could*, by pulling mixture all the way back and then pushing the throttle forward until the mixture reached on incombustible ratio, but...)

skylor 03-11-2017 12:48 AM

Fuel Valve
 
Quote:

Originally Posted by RV7A Flyer (Post 1156843)
Just be careful here...this is a dangerous condition (although you might already have one if your wiring is messed up so that "on" = grounded, but "off" = ungrounded). With no way to ground the mags, the only way to stop the engine is via idle cut-off and if, like a friend of mine, the control was not *quite* able to reach idle cut-off on first engine start (it was easily fixed), the only way he could stop the engine was via grounding the mags ("off"). If you have disconnected the p-leads, AND the mixture won't reach full ICO, you won't be able to stop the engine. (I suppose you *could*, by pulling mixture all the way back and then pushing the throttle forward until the mixture reached on incombustible ratio, but...)

All RV's should be equipped with a fuel selector that has an off position. This can be used to shut down an engine if the mixture won't reach idle cut-off.

Skylor

snopercod 03-11-2017 06:10 AM

P-Lead Adaptors?
 
In 2013 I decided to replace my homemade P-leads with Bogerts. One of the pair wasn't long enough and caused the mag to short out. Just a possibility...


Ron RV8 03-11-2017 08:03 AM

On my first start attempt, the engine would occasionally fire but not start. I checked and cranked at intervals until the battery was getting weak. No start.

When I was climbing out of the aircraft, I noticed the mixture lever in the idle cutoff position. Idiot!

I put the battery on charge and went to lunch. Next try it fired up on the second blade...

Of course all my helpers who had come to hold fire extinguishers and see the engine run had great fun at my expense...

olyolson 03-11-2017 08:14 AM

First engine start
 
Dave,

Probably a silly question but did you perhaps look up the lower intake and see if there is a plug just above the throttle body/carb?

Engine manufacturers and rebuilders sometimes put a rubber cap in the lower opening at the throttle body to keep debris & foreign matter out during shipping.

Might be worth a look, sounds like the appropriate symptoms if everything else checks OK. That would definitely prevent a start since there is no air going into the engine, (fuel, air & spark req'd).

I had my 1991 engine recently rebuilt by Poplar Grove Engine rebuilder up in Chicago. While installing it we did a thorough inspection and found a red rubber plug right at the bottom of the engine intake at the throttle body attachment so it was fairly easy to pull it out. And no, they said nothing about it so I assumed it might be standard procedure. It would have definitely prevented a start. Except for that remission of information they did a superb job and the engine has been running flawlessly.

Hope this is your start problem because it would be a super easy fix.

Good luck!

bret 03-11-2017 08:43 AM

Confirm, plug wire firing order?

snopercod 03-11-2017 09:02 AM

Quote:

Originally Posted by bret (Post 1156886)
Confirm, plug wire firing order?

There was an RV-10 at my airport that wouldn't catch on the first start; It just popped and coughed. The problem turned out to be what you said: plug wires were crossed. When he fixed that, she fired right up and the engine purred like a kitten.

bret 03-11-2017 09:14 AM

Quote:

Originally Posted by snopercod (Post 1156891)
There was an RV-10 at my airport that wouldn't catch on the first start; It just popped and coughed. The problem turned out to be what you said: plug wires were crossed. When he fixed that, she fired right up and the engine purred like a kitten.

Ya...don't ask how I know this......:rolleyes:

Xkuzme1 03-11-2017 09:27 AM

Quote:

Originally Posted by RV7A Flyer (Post 1156843)
Just be careful here...this is a dangerous condition (although you might already have one if your wiring is messed up so that "on" = grounded, but "off" = ungrounded). With no way to ground the mags, the only way to stop the engine is via idle cut-off and if, like a friend of mine, the control was not *quite* able to reach idle cut-off on first engine start (it was easily fixed), the only way he could stop the engine was via grounding the mags ("off"). If you have disconnected the p-leads, AND the mixture won't reach full ICO, you won't be able to stop the engine. (I suppose you *could*, by pulling mixture all the way back and then pushing the throttle forward until the mixture reached on incombustible ratio, but...)

Or turn the fuel selector off...


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