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deek |
15 minute fuel pump install
Hey Gang,
Here's how I installed the fuel pump in 15 minutes (engine on the plane). First of all, my engine came with a plate over the hole, so the bolts were the wrong length. I decided to use studs instead of bolts to help guide the pump on. So, I put permatex on the studs and installed them, then slid the gasket into place. Now comes the 'trick' I read on this thread bout using waxed string but I don't have any so I used a piece of 20g wire tied into a loop. I hooked the end of the plunger rod then hooked the other end to a ball bungee and clamped it to the top of the engine under tension. Now I reached in the hole and pushed the rod up and it stayed put. With the studs, there was just enough tilt down to get the pump in (with the arm clear) and start the nuts. I tightened them some, leaving just enough room to cut the wire and pull it out. Then I tightened it the rest of the way. It took me longer to type this that to do the install! I read all the depressing stories and studied the advice, and used some of it to make the job easier, so thanks to those of you who posted previously. I hope this helps. Lance |
fuel pump install
I have to thank all those whom did this job and posting their problems and results on this list. It helped me to easily do this repair.
I have an IO-360 on and RV-7A. I was seeing intermittent low pressure warnings, with the fuel pressures dipping randomly below 20 PSI (normal is 25-30 psi). Ground test resulting in fuel flows of 30 GPH using the AUX pump, so it wasn't a restriction. Running the engine at lower RPM's and leaned appeared to lessen the issue, but didn't completely eliminate it. Also, when fuel pressures dropped, with the engine leaned way back (two PMAGs allows this) RPMs would fall off with low fuel pressure, indicating it wasn't a sensor error, but a real low fuel pressure (and injector flow) issue. So I ordered a new pump and a shroud and installed them today. Removing the old pump required me to remove the left P-MAG and some other hoses that were restricting access to the pump. The shroud from Spruce did not have to be modified as long as all the fittings were put onto the pump while it was on the bench. I tried using the grease trick to hold the actuator in the UP position, but, in the Florida heat, it didn't work out. Instead I looped .020 safety wire around the actuator and had a helper put tension on it after pushing the actuator into the UP position. After installing a new gasket with a sealant onto the accessory case, I was able to insert the pump into position and, by hand, get both cap screws started, and turned then further in with a 5/16" ball Allen wrench. Before snugging up the cap screws the .020" safety wire was pulled out. The cap screw safety wiring job was tricky, but given the access with the left P-MAG removed, went smoothly. Then all the fuel lines were again connected. To test the pump functionality, I removed the lower four spark plugs and turned the engine over with the starter, resulting in 29-32 PSI fuel pressure indications. I then reinstalled and timed the left P-MAG, and connected the other hoses I had disconnected. There were no oil leaks after running the engine... I did not use a sealant on the cap screws, so will be looking for any oil leaks in that area. I hope this write up helps others too..... |
Fred,
I have had intermittent low fuel pressure warnings haunting me for months. In the process of chasing it down I have replaced all of my fuel system components, eliminating many restrictive fittings etc. I thought I had the problem solved when I replaced the Kavilco sending unit and then could not re produce the problem. Months later it is back again. Mechanical pump experts tell me the pump cannot fail on an intermittent basis but your experience seems to indicate otherwise. Did the new mechanical pump solve the issue for you? Anybody else have experience with intermittent low fuel pressure due to faulty mechanical fuel pump? Charting fuel pressure after the events shows the pressure would drop down to around 13 PSI from the normal 25 PSI. My engine has never run rough during these events but that may be because I was quick to turn on the electric backup when I get the warnings, (Dynon System). I may install a backup mechanical gauge to have a way to verify the pressure is actually falling. Precision Aeromotive tells me that the engine may actually keep running OK in cruise conditions with the low fuel pressure I have experienced due to the way the servo adjusts to different pressures. This makes it difficult to verify the pressure reduction is real... Randall in Sedona RV7A, IO-375, WW RV200 |
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Thank you all for the tips
Just replaced the mechanical fuel pump using the safety wire trick. It was quite easy to get the pump on and bolts installed. As suggested before I used a loop of safety wire connected to a bungee cord. After looping the safety wire around the plunger I hooked the bungee cord and created a tension. Pushing the plunger up and it stayed. The first time I installed the pump and had the bolts almost in before taking it out. Using the mirror and later my finger I confirmed that the plunger did not drop. It was just to verify for myself that it is working. Second time I pulled the safety wire out before it got pinched by the pump. I did not have to take mag or anything else out to safety the bolts. I did have to move around the engine to tighten the bolts.
It is raining and I have not run my engine yet so I can not report the outcome. My 1,800 hr fuel pump (O-320, carb) intermittently drop pressure to 0.1 psi. It also start leaking oil. Even after I tightened all screws it still leak a few drops (shown on my nose wheel pant) each time I fly. Without reading the experiences from others on the forum I would not have known what to do. Now, I have a new fuel pump on the engine and my arms are not even scratched. It all because I read the forum! |
fuel pressure vs flow
can I ask a newbie question? there are a few references in this thread that are about mechanical, low pressure, hi-pressure pumps....so bear with me.
My mechanical pump is about 120 hrs old, but 10 years of age. the fuel flow was good when tested in the climb attitude, but the pressure on the van's gauge is often in the 1psi range, if the scale is to be believed. Never had an operational problem, so is it safe to assume all is well? volume being more important than pressure, in a carb? also, I thought something was strange, as there was always a drop of oil on the pump lower case bolt heads. Apparently, not that unusual for a little to seep thru the studs? the gasket seems dry, as far as I can see. |
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Laugher.....
I replaced my pump over the weekend - wow what a diff a few years and a few tricks make. When Alex and I did this back in the day, there was swearing and blood. On Friday using bundling lace to hold the plunger up, and an unregistered, sawed-off, 5/16 ball-tipped hex driver, I had the pump on and safety wired in 35 min, and I stink at safety wiring anything.
Don't fear da pump! |
I assume there's no Lycoming SI for how to replace the pump (which I am thinking I may have to do...been seeing increasing deviations in fuel pressure, with the occasional drop over a few seconds to ~14-15 PSI and then back up, over about 8-10 seconds).
I'll probably add the cooling shroud, although I have a blast tube aimed at it now. But, my real question here...what sort of sealant is recommended, if any, for the gasket and/or the bolts? |
Another thank you for all the tips!
I had suspicions about the low pressure mechanical fuel pump on my carbed O-320 that is 40 years and 1300 hours old. No indication in the logs it had ever been replaced. So I got a new replacement and blocked off a full day. I used a full length ball end hex tool, Hylomar M to seal the gasket, teflon thread sealant on the bolts, fuel lube on the fittings. Made sure the cam was in the proper position, installed the inboard bolt one turn, and was able to tilt the lever arm on the pump under the cam driven piston, no securing tricks required. Then I installed the outboard bolt one turn, and confirmed proper installation by mating the pump to the case easily by hand. Torqued and safety wired the bolts. Full power ground run, no leaking oil or fuel. Two leisurely hours.
What to do with the rest of the day? :) |
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Hi all
I have an O320 in a RV4 and had a fuel pressure drop in a full power climb, which caused the engine to lose power until I turned the electric pump on and went back to the airport. The engine would run ok at lower power settings but not at full power. Pulled the pump off and found two hard ?granules? of some crumbly substance which were obstructing the diaphragms, holding them open. One granule in each diaphragm. Weird! After thoroughly cleaning the pump and gascolator I reinstalled it. I had not found this thread so I had to figure this out myself and surprisingly, it worked quite well. I put the bolts through the housing and held the pump in place, ensuring the arm was in the correct position. I found if I tilted the pump clockwise, I could get the left bolt in easily and tightened it up, only enough to keep the flange faces aligned but the pump could still be rotated. I then pushed up on the right side, rotating the pump against the spring pressure on the arm to get the right side bolt hole to line up. It took a couple of tries to get the threads to take but once they did it was easy. Did a run up and had a firm 5 psi, leak checked everything and then did a test flight over the airport. Great fuel pressure at low power but at full power it would drop to about 1 psi, no faltering of the engine though. However, after reading the threads here, I am concerned about what I did. If overhaul kits are no longer sold because a jig is needed to set the diaphragm pressure, there is no guarantee that my reassembly was correct. I plan to replace the fuel pump anyway since it?s old but it would be nice to fly until I get the new one. I would welcome your opinions. Merry Christmas, Gary |
Ground your plane until the pump is replaced. Aircraft Spruce can put a pump in your hands a couple of days after Christmas.
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Chris |
After a flight last week, I noticed a drip from the fuel pump overflow. It appeared to have leaked enough to leave a small streak on the lower fuselage, although I never had any indication of a fuel pressure fluctuation. After reading this thread, I could hardly wait to replace the pump (NOT). I picked up a new pump at Air Power in Arlington. I removed the cowling and set about removing the old pump. Access is rather limited, so I removed the scat tubing for the cabin heat and removed the lower line from the oil cooler. I removed the pump overflow tube and the fuel lines from the pump. I zip tied all of these lines to various places on the engine mount--this helped free up some space. I cut the safety wire and removed the bolts. I found that a ball end hex tool was the only way I could get on the bolts. So, old pump off, then cleaned off the old gasket material from the engine with a scraper and some disc brake cleaner. At this point, I called it a day. The next day, I ran some string around the rod that operates the arm on the pump and clamped the free ends to the plate where my GPS antenna is mounted. I held my finger on the rod and slowly rotated the prop until the rod was fully retracted. Looks like the string will hold it in place. I used the old pump as a test to determine how best to position it for the installation. After I was satisfied I had found an acceptable method, I proceeded with the new pump. I coated a new gasket with permatex #2 and stuck it on the pump. I also coated the bolt threads with permatex thread sealer. I inserted the pump and rotated it about 30 degrees counter clockwise. This allowed the arm to fit under the plunger and the inboard bolt to engage. I gave it about 3 turns. For the outboard bolt, the pump has to be rotated clockwise to line up the bolt hole. This was the difficult part because the plunger rod must slightly depress the arm on the pump--and that arm has one stout spring! After several tries, I got the bolt started. I pushed the pump flush against the engine to ensure the arm was under the push rod, then tightened up the bolts until there was less than a 1/4" gap between the pump and engine. I pulled the string out and finished tightening the bolts. The safety wire wasn't much fun either, but I got it done. Re-attached all lines. Ready to test run and check for leaks, but now it's raining--will do it tomorrow. I spent about 4 hours on this project--I stand in awe of the gents that did this fun task in 15 minutes and 35 minutes. Thanks to all for the tips found on this thread!
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Good job. I think a few hours invested well. Future ones will go a bit quicker but hopefully you won't have to find out!
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Good ideas in this thread!
This was my second time installing the fuel pump. First time I needed to remove a pump cooling shroud that had a broken installation tab. This time I called Tempest to confirm there aren't any new ones without the dreaded housing interference issue. Of course, no company has gone thru the pain of a new design and faa pma process. This time I used his suggestion to be confident the pump arm is installed correctly...that is, remove the left mag, then one can see the pin. Rotate prop to up position, temporarily secure the pin in up position from inside the mag opening, and proceed to wrestle the pump and those **** hex bolts. Worked much better this time after shortening a 5/16" hex wrench, but most importantly, I'm confident of the positioning. |
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This is a great thread - we need to keep it alive for those that come after us.
I still have not won this battle yet. I went out and tried the grease trick with the stickiest grease I could find. No joy. Doesn't help that it is 95F here. Maybe if it were colder. Anyway, the waxed string/safety wire trick is brilliant. I will do that tomorrow. It would make life much easier to shorten the screws, BUT the amount of thread engagement into the case would be potentially inadequate. It might be fine to take 3/16" off the screws, but it might not. I won't do it. Knowing that you can see in through the left mag hole is encouraging. It means I have to re-time my Light Speed hall sensor afterward, but that is a small price to pay to be SURE the lever is properly engaged on the plunger. |
Having that left mag removed also allows you to route the string through the mag access, rather than slipping it between the pump and flange.
The way I did it was to basically tie the string off at one of the engine mount tubes, nice and tight, through the mag hole. Left it that way until the pump was in and the bolts were tight. And you are correct, having the mag out is a small price to pay for knowing that the pump arm/pin are seated correctly. And as an added bonus, makes the safety wire a little easier to install. |
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I talked to Tempest about installing the pump and they claim that you can actually reach in the L mag hole and hold the plunger up with your hand (where it contacts the camshaft). Not verified, but a good source...
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That is true,,
But I found I needed both hands to manipulate the pump, to orient the holes,, and to start the bolts that do not align when the pump is square on the mounting flange. |
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Engine Fuel Pump Replacement Hints
Hi All
This was sent to members of our chapter of the Sports Aircraft Association of Australia (SAAA). I didnt go through all seven pages of replies, so maybe this has already been posted. Link is to another forum that has hints on replacing the engine driven fuel pump. Here it is: https://www.matronics.com/forums/vie...php?t=16775207 Hope that helps someone. Cheers Wayne |
Used the safety wire trick for keeping the plunger up. Got it on the second try. Really had to tension the wire to keep the plunger up.
Great use of this forum. Thanks to all. |
Better off to use regular string instead of wire. String has way more drag and will hold the plunger in place with far less pressure.
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Fuel pump bolt oil leak
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With the left P-Mag out, it was easy to get the fuel pump plunger lifted up (with the prop set approapiately) by using a string in the left Mag hole. I removed the pump, cleaned it and the accessory case (so I could easily see any new oil leaks). I reinstalled the gasket, then re-mounted the fuel pump, but this time with Teflon paste on the bolt treads. I'm still n the process of getting everything else back together again, and resetting the P-Mag timing. I'm hoping to test run the engine tomorrow.... |
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