Firewall Forward

February 23, 2013

Engine Driven Fuel Pump - removal - 2.0 Hours

Well, now it's near the end of February already, and I haven't accomplished a lot this month. One big reason is because Jamie and I went on a little vacation trip... the first one we've taken in about 2 years, other than an overnighter or two a few times, somewhere nearby. And ever since we got back, I've been busy trying to catch up with my work and my business. We love the idea of taking off right in the dead of winter, when it's so miserable around here, and going someplace warm, sunny, and tropical. Those of you who live in an area where palm trees grow, that kind of place! It really breaks up the winter. We love it. So we had an opportunity to spend a week down in Mexico on a real budget. Cabo San Lucas, to be exact. It's our second time there together (my 3rd time, actually), and we loved it! We spent 8 days and 7 nights, and all it cost us was our airfare and some groceries. I won't spend time here explaining how we did all that, but we had a blast. If you are on facebook, "friend" me and you can see our pictures. I'm mentioning it here because of how it relates to this RV. When we get this RV finished, flying down to Cabo is on our bucket list! As much fun as we had, having our own airplane down there would be even better. So I'm more motivated than ever to get this thing going. Here's to flying off to warm, sunny places in the middle of winter!

Okay, so what's next? I found out, in all my learning, that if I'm going to have a fuel-injected engine, I need a different engine-driven fuel pump. The standard fuel pump installed on a Lycoming that has a carburator, is low pressure, about 4 to 6 psi. That's the pump that is on my engine, and it won't work for F.I. It needs to be changed out for the higher-pressure model for fuel injected engines. Those pumps run 26 to 28 psi. Funny thing is, they look almost exactly the same. So it would be easy to overlook. (I almost did!) Anyway, I did all of this research, learning, and reading, and exploring online. My time spent doing that has been well spent. I can't imagine how I could build this airplane without the resources available to us online. How did those guys do it, back in the day? I just can't imagine. I've also been watching the classifieds on VAF (the Van's Airforce forum, for those readers unfamiliar with the VAF acronym). I'm just in the habit of watching the classifieds. I've found some great deals on there. So a guy was selling his high-pressure fuel pump, and I bought it for $150. It's like new; very low time. Very similar, in fact, to the one I have now. It will be arriving here in a few days, so I'm going to take mine off the engine, clean it up, and see if I can sell it.

So I got busy today. I clipped off the safety wire, undid the bolts (there are two of them that hold the pump on to the accessory case) and pulled the pump off the engine. There was the same sticky gasket/sealant combo that I found a while back on the rocker covers. But I managed to get it off, scrape the residue off, and clean it up. Here's what the hole in the case looks like with the pump taken off, and the surface all cleaned up:

And here's the pump, after I cleaned it up. I'll put this up for sale and see if I can find a buyer for it. It's a pretty common item, so I would think someone will snap it up. New ones sell for a LOT more than I'll be asking!

UPDATE: Guess what? I sold this pump for $150, plus shipping! So all it cost me to switch it out for the high-pressure model was the shipping on the new one. Nice!

Back to the engine... the operation of this pump is pretty simple (I love simplicity!). There's a pushrod coming down to the end of the lever seen above on the pump. A cam lobe on the crankshaft pushes the rod down and let's it back up with every rotation of the crankshaft. Picture an old-fashioned well where you work that pump handle up and down. It pumps fuel. Very simple! The only thing I'm worried about now, is that if the engine, as it sits, is clocked so that the rod is in the down position, it's going to be a bear to get the new pump installed. I did a lot of reading online, and people have had nightmares trying to install these pumps. You can't just put it in place and tighten down the bolts. You must make sure the end of the lever is UNDER the pushrod. If you force it into place, you can damage the lever, or the pushrod, or break something. Not good! So next, I need to try and determine where the pushrod is, in it's cycle. When I got the light just right, a picture shows the rod sticking down inside the opening:

I could reach in with my finger and easily touch it (my finger is about as long as that lever). When I did, it easily pushed up all the way. Yes!! No need to worry about turning the crankshaft to put it in a more favorable position! That's a huge relief! I found I could push it all the way up, and when I pulled my finger out, it stayed up there for a moment or two, then slid back down. I learned that the ideal time to install a pump is when the engine is on an engine stand, nose down, with the accessory case sticking up on top. Then you don't have to worry about gravity working against you and the rod slipping back down. But I can't do that, with my engine already on the plane. So I'm going to have to figure out how to do this. I have some time, my new pump isn't here yet.

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