Continental C125/C145/O-300 Fuel Pump

Subj: Possible O 300D Problem
From: Ed Lloyd <>
Hi Jim.
Had a fuel leak in my aux tanks. (Alturair Belly Type) De fueled to " O ". Took the tanks out and had a split weld seam repaired on the left tank and spotty pinhole leaks in the welds repaired on the right tank. Tedious job but I got it all back together today, recorded the fuel / gauge readings in 5 gal. increments while refilling and all checked ok. When I started the engine for the first time, manual fuel pump only, the engine quit about 15-20 seconds after start. Not surprising I thought, due to no fuel in the lines to the engine. I re primed the engine, started a second time and the same thing occurred. I noticed on the second start, that the fuel press was variable from 2 to 3 psi. I turned the electric boost pump on and the engine started and ran normally with fuel press at 4 to 5 psi. I let it run this way for 3 or 4 minutes and then turned the boost pump off. The fuel pressure dropped to 1 to 2 psi and began pulsating or varying from 1 to 3 psi. Engine was operating ok but the fuel pressure continued to "hunt" at a steady rpm. 1500 rpm and manual fuel press was 2 to 3 psi but moving 1 to 3 psi. Turn on the electric boost and pressure would smooth out at about 4 psi.

Guess my question is, do I have a pending failure of the manual pump or should I run it longer on the ground to see if in fact I have air in the lines from being "o" fuel and the fuel system opened up? Is the manual pump a dual diaphragm type pump? If one diaphragm has ruptured, is there a weep hole or drain line I can check to verify a ruptured diaphragm? Lastly, can I check the pump pressure with a vacuum gauge like an auto fuel pump is tested? Jim, my thanks in advance. -- Ed

You should get an electric pump. If you have a reliable 1 pound of pressure the engine pump will work. Check all the lines under suction for air leaks and make sure the screws in the pump are tight. Yes, the aux pump can be tested, but I would just install an electric pump. Sorry to be so short, but my computer got fried by lightning and I'm on a friends computer. -- Jim

(So... Since Jim's computer time is limited for awhile, we had Don Bartholomew take a shot at this one too...)

From: Don Bartholomew <>
Subject: Re: Monty and fuel pump question

> Guess my question is, do I have a pending failure of the manual pump or
> should I run it longer on the ground to see if in fact I have air in the
> lines from being "o" fuel and the fuel system opened up?

The problem is not from being opened up and zero fuel. That problem will take care of itself as soon as fuel starts flowing. The problem described is most probably an air leak on the suction side and most probably in the gascolator. To get the tanks out, you either remove or at least bump the gascolator and that can start leaks. If it was put together with new gaskets, make sure the round screen was put in first, the flat screen second, and the top gasket third. Then the body and the bottom. Another place that can suck air is the cover on top of the fuel pump (if it is a 125, 145, or O-300). There is a 1/4" bolt that is safety wired on top of the pump. Remove the safety wire and tighten the bolt and re safety.  The third place you can be sucking air is in the fuel lines or valve that connect the sump, gascolator, valve, engine pump.

> Is the manual
> pump a dual diaphragm type pump? If one diaphragm has ruptured, is there
> a weep hole or drain line I can check to verify a ruptured diaphragm?

The pumps I have seen are a single diaphragm type and there is a drain fitting (since the 70's AD) to detect leakage.

> Lastly, can I check the pump pressure with a vacuum gauge like an auto
> fuel pump is tested?

You can check the pump the same way, but do it at the pump itself, not some line down stream. This is probably not a pump if it was working ok prior to pulling the tanks.  Don and the technical one, Helo (Sorry to hear about Jim's problems.)

From: Ed Lloyd <>
Subject: Fw: O 300D Problem
Howdy Don, and thanks for your help. Strange thing, the next day, I went back and looked over everything and then ran the engine again. Walla, no problem. Only thing I did any different was I used the electric boost pump on start and I hadn't done that the day before. After start, I turned the electric pump off and the engine driven pump held steady at 3psi. I went ahead and did a short test hop, got a safe altitude and turned the electric pump off. Kept on purring. Based on your input though, I'm going back and check all the fittings at the sump, gascolator, and shutoff valve. Strange thing, everything was fine until the leak in the aux tank. For that reason, I feel if I have a problem, I induced it during the maintenance. Cheers.........Ed Lloyd

O-300 FUEL PUMP... (040200)
Subject: Re: O300D Fuel Pump
From: Ed Lloyd <>
Hi Jim, Made up my mind to get a fuel pump before the inevitable happens. Question is should I go for a reconditioned pump or a new one? Secondly, what do I ask for? Are they ordered by any part # or engine type or what? Aircraft Spruce is showing both in their catalog on Pg154. Thanks, Ed

I must confess I don't have the current Aircraft Spruce catalog. Mine is a couple of years old. The part number for an O-300 is 9051. I am curious as to the price difference, a few years ago they were selling "reconditioned" 9051 fuel pumps that were actually new, because they didn't have the necessary FAA PMA. I remember when the price on the 9051 pumps was $19.95. Good old days. Whatever you get, after an hour or two of operation, check the screws that hold the pump together for tightness. If they are loose, remove the safety wire, tighten, and resafety. I would go for the new, unless the price difference is outrageous, and like I said, the "reconditioned" used to be new. -- Jim

Subject: Re: O300D Fuel Pump
From: Ed Lloyd <>
Mornin Jim, like you said, the price is outrageous! They show a pump for Continental C-145 (-2,2A) part no 9051/9867 overhauled and a price of $273.00 +$100.00 core charge. Maybe we need to go in business and overhaul fuel pumps at half the price. Think we could still make money. I think I've seen Cont pumps advertised in Trad-a-Plane much cheaper. I've also heard that these pumps are hard to find. Won't a pump off a 125 do the same job? Or, why not a pump off a "later" model Cessna? I'll have to do some shopping around. Thanks, Ed

You need a 9051 pump. That is the same pump as a C-85 and C-125, the only Cessna 170 that used a fuel pump on a C-145 was the very first year, 1948. Those pumps were not produced for several years and the supply in the pipeline had just about dried up. I have plenty of cores if you need one, I might just ask for a couple of bucks for my trouble and postage. I have rebuilt them using kits that are available from antique car parts sellers. I'm a little nervous about using those, and never have, I thought at one time the supply of 9051 pumps would completely disappear and rebuilding them would be the only way to get one. Now, even though the price may be high, at least they are available. Look in Trade-A-Plane, I believe I saw an ad there where they were not priced too highly. I bet Joe at Swift Parts can get them. I'll bet that rebuilt for $273 is actually new. Remember my previous mail. -- Jim

FUEL PUMP VENT??? (040300)
Subject:O300D Fuel Pump
From: Ed Lloyd <>
Jim, I received a engine driven fuel pump from Joe at Swiftparts. I believe I recall someone saying awhile back that the area below the diaphragm should be vented to an overboard line in the event a diaphragm leak. This pump I have has only a suction inlet and a pressure outlet, no overflow vent provision. Should it be modified before installation? Thanks.......Ed

I think somebody got nervous some years back and published that service bulletin about the overboard vent line. I have installed it a couple of times, but I don't have one on my present fuel pump. It's not too hard to tap the hole in the fuel pump and install a fitting but it seems to me if it were real important the manufacturer would have done that. I have never heard of a problem. (I can just see the letters coming in now....) -- Jim

From: Terry McCartney <>
Subject: fuel pump source
A couple years ago I repaced the fuel pump on my O-300A with a new pump from Aero Accessories, Gibsonville, NC. phone 336-449-5054. The pump is new FAA-PMA approved and at that time cost $149.00 and a core. -- Terry McCartney NC3787K

Subject: Fuel Pump
From: "Ed A. Lloyd" <>
Hi Terry, thanks for the input. Got a pump from Swiftparts for $265 and it was supplied by the same people you got yours from. In this inflationary world we live in I guess that's to be expected. Talked with Jim Montague and he says he recalls when those pumps were $19.95. Told him we're in the wrong business. We could rebuild those pumps for half the paying price and still make money. Cheers....Ed

From: (Donald Thomson)
Monty:  I ordered the 9051-FP fuel pump from Swift parts and received it in yesterday's shipping from UPS. A card attached to the gasket had the following warning on it:

"Fuel pump models 9051, 9867, 9076, and 40695 ARE NOT to be installed on engines which have been assembled with camshaft p/n 626608 or supersedure to which p/n 630403 or supersedure. Damage or destruction of engine and pump wil occur."

It then mentions that the cam lobe diameter for engines using pump 9051 is 1.937". The cam lobe diameter for engines using pump 6861, and 631391 is 2.062". I guess I wonder what that means. When I overhauled the engine, the camshaft with bad, so the A&I replaced it with a yellow tagged one. I don't have the part number readily available. The pump Swift sent me looks like the one on the engine, but how do I know for sure it's the right one??? -- Dt

It's the right one. Your camshaft p/n is 530803. The problem is some C-90 engines have the larger diameter camshaft eccentric. The fuel pump for a C-90 has a different arm. Compare your old fuel pump with the one you just got. I'm sure it will be the same. -- Jim

From: Bud England <>
Subject: Fuel Pumps
Monty:  I'm a little concerned about using the old fuel pump in my C145 after a 50 year hiatus. However, I also know that Mark would get in it go cross country! Can I replace the diaphragm etc. or do I need to send it out---or do I need to worry about it at all? Seems like I had written down the address of an overhauler, but if I did, I lost it in the move. Thnx--Bud

While it is possible to overhaul your fuel pump, it's not a very good idea. A few years ago new fuel pumps were almost impossible to find and I located a source of the overhaul kits. I overhauled a couple of pumps and put them on the shelf. Then they made a production run of the 9051 pumps and they were again available -- albeit at a price -- approaching $300. Our Swift parts company has been selling them for somewhat less than that. They are also available in ads in Trade-A-Plane and from Aircraft Spruce, but I don't think you can beat our (Swift Parts Co.) price. When I overhauled my engine two years ago, I didn't use a pump I overhauled, I bought a new one and am more comfortable with it. Think about it -- an engine failure on takeoff could ruin your whole day. The price of a fuel pump is small compared to the potential loss a fuel pump failure could cause. BTW - Aircraft Spruce has both new and overhauled pumps, the catalogue is confusing to me (maybe I need to read it again) It looks more expensive than a new one from Swift, plus a $100 core charge. I would get a new one from Swift. -- Jim

The O-300A-B-C-D take the same fuel pump as a C-85 and C-125. It is p/n 40585 in the TCM catalogue, or 9051 in the AC list. These pumps were out of production for a few years, but are now readily available from many suppliers, such as Wag-Aero, Aircraft Spruce or our Swift Parts Company. -- Jim

Ran across this on the TCM Link site. Has anyone ever found any contaminants in that screen in a Swift? I sure haven't, and I even check the one in my O-300, even though it's not covered under the original SB or the AD. Continental SBs and ADs regarding Continentals are available for free on their site ( All you need is a Cont serial number to sign up. And they haven't spammed me. Geoff

I consider AD 81-07-06 a dumb AD. If an engine is run regularly, the kind of corrosion they are talking about will never happen. Common sense would tell me if I were putting an engine that had not been used for years back in service to check the fuel screens. The Ercoupe than precipitated the AD had not been flown in years. The FAA and TCM are not even consistent! The O-300 (same fuel pump as the C-85 and C-125) is not required to be inspected per AD 81-07-06. Yes, I found some corrosion in a C-125 fuel pump once. It was a case where the engine had not run for years. EXACTLY WHAT I SAID WOULD HAPPEN! -- Jim

Subj: Fluctuating Fuel Pressure
From: Chuck Gallaway <>
I have been flying Swifts for over 12 years and have benefited on numerous occasions from your sound advice. I could not find my problem addressed in your GTS archive. The fuel pressure on my C-145 began fluctuating on my last flight. The pressure will be steady for about five seconds and then drop about 2.5 psi. It takes a second or two for it to correct back to where it was, then it drops in about five seconds and again repeats the cycle. When I turn on the boost pump, the fuel pressure does not fluctuate. I would appreciate your thoughts on any inexpensive reasons this might be occurring. Thanks in advance, Chuck

Those are the classic symptoms of incipient fuel pump failure. A check valve is probably leaking internally in the fuel pump. At 200 and some bucks a fuel pump is not exactly cheap but is a good investment! -- Jim

Subject: Re: Fluctuating Fuel Pressure
To: Chuck Gallaway <>
Jim Shosted sent me the following note. I will give his proposal a try and if it does not work I will invest in a new pump. I really appreciate the advise. You provide an invaluable service to the Swift community. Thanks, Chuck

***Hi Chuck, I have had the same symptoms of fluctuating pressure and I did find it to be a low cost fix. The dome on the top of the pump is held down by a bolt in the center. There is a cork gasket at the base of the dome that is the problem. I found that the cork gasket had shrunk and was loosing its seal. I tightened the bolt head and pressure was fine. The area inside the dome is a vacuum when the pump is running so you don't see a fuel leak. Try tightening the top bolt and replace the safety wire. This should be checked every time the plane is given an annual inspection but is not done. Hope this can help you. Jim Shosted Swift N3854K***

Chuck: Sounds good to me - Jim

Subj: Re: Fluctuating Fuel Pressure
From: Chuck Gallaway <>
Jim, We tightened up the bolt on the top of the fuel pump and did a test flight yesterday evening. The fuel pressure was perfectly steady. We have added an additional item to our Swift specific annual checklist. Thanks, Chuck

From: David R Rogers <>
My fuel boost pump on my 0300D doesn't seem to be "clicking" or putting out as much volume as it used to. Is there an easy way to check it and can you tell me where to get a replacement if needed ? Thanks. David R. (Speedy) Rogers

To check it out, remove the upholstery from over the pump, then turn the pump on. You should hear it and feel it operating. If you have voltage to it and it does not run, you might want to get a new one. Our Swift Parts Company had them, I don't know if they still have them or not. A friend recently got a pair of them from Chief Aircraft for his Apache. I have dismantled and repaired them. Steve Wilson just tracked down a source - maybe you could talk to him. <> -- Jim

From: Steve Wilson <>
Subject: Re: fuel pump
Monty has given you good advice. Here is my take on the electric boost pump issue: If you have the Swift Museum boost pump STC, it calls for a Piper pump number 481666. They are available. I checked with Tex-Airparts here in Ft Worth, to the tune of $324. The Facet pump which is a direct replacement is number 478360. I talked to the engineers at Facet last week and he told me that they only manufacture ONE pump as far as the guts go! The Facet number is available from Chief Aircraft and Aircraft Spruce; however, they will tell you it is only for use in experimental aircraft, at the tune of about $80-90. Now, I will tell you this, Facet makes another pump with 1/4" NPT fittings which are the correct size for the 3/8" fuel lines which attach to the pump. The part number for this pump is 40007; however, you will not find this pump in your usual aircraft parts locations, nor will you find it in the usual auto parts stores. It can be had from J&N Auto Electric in Cincinnati for about $90. Their website is: I have one on order and it is back ordered... That is the bad news right now! Personally, I prefer the 1/4" NPT fittings. Are they legal? Well, are the Facet pumps legal? I don't know, they make them for Piper, Beryl D'Shannon, and others; however, if I am going to use an illegal pump it might as well be the "correct and safest" illegal pump! SW

Subj: Fuel Pressure
From: Marco Figueroa <>
I wann'a know what is the fuel pressure of the GC-1B with O-300 engine, in flight, and climb fuel press. Thanks.

The limits are from .4 psi to 6 psi. That's from 4/10 of a pound to six pounds. That's the limits. Most Continental powered Swifts, including the C-125, C-145 and the O-300 powered airplanes run about 3 psi normally. (3 pounds) It makes no difference whether they are in level cruise or climb, the fuel pressure stays the same. -- Jim

Subj: At second glance
From: Jack Gladish <>
Jim, when I flew the Swift last, I had mist on my windscreen, and a little stream of fluid running down my cowl from the front, and alittle to the right of the spinner.In the past this meant a oil seal on the crank, that's when I e-mailed you for the part # of the oil seal, and thought, well that's it.. After removing the cowl, spinner, and prop, I looked the seal over real well, and couldn't find a different leak. I got to thinking I had a smell of fuel on the last flight, and wrote it off to topping off the tanks.Looking at the fuel pump, it was alittle discolored, so I turned on the master,and hit the ele. fuel pump switch. Holly cow, did I have a leak!! Come to find out EVERY thing had loosened up, and thank goodness for safety wire. I'm not sure if the oil seal is leaking, the fuel pump certainly is! Remember, the A/C sat for 4 years,I'm sure the gaskets dried, then expanded again, but left the hardware loose. I felt this was worth writing you about, so others might give it some thought. I'll let you know later about the seal!! Jack N3321K

Thanks. I have heard of that before, even with a brand new fuel pump on the first flight after installation. Now I always check those screws for tightness and re-safety if necessary. -- Jim

Subj: Fuel Pump/Pressure
From: Bob Price <>
I was doing practice TO and Landings yesterday in 3361K. On the 8 th TO I decided to shut off the electric fuel pump. ( I had not done so earlier since due to the short time between TO and Landing). When I shut the electric fuel pump off I noticed a drastic reduction in fuel pressure... next to "0".. The engine did not falter but the sudden drop gave me concern. I have notice this before on cross country when at a higher altitude but at that time the pressure only dropped to about 2 lbs but would go back to over 5 PSI on the engine driven pump.. Yesterday it dropped to 1 lb but returned to over 5 PSI when I cut the electric pump back on. Is this normal or is there something I should look into? Jim: could you also prvovide me with your mailing address.... Thank you for all the help you have been to me and 61K... Hope all is well with you.... Bob Price

If you read the "Answer Man" archive on the Swift site, you will note the fuel pump pressure limits are .4 lb to 6.0 lb. (that's four tenths of a pound to six pounds) It appears your system is well within limits. My address is there and also in the Swift membership directory. I have had the same address here on Klondike Ave in Lake Elmo, MN for 29 years. -- Jim

Subj: Fuel Pump/Pressure
From: Bob Price <>
Thank you for your reponse. I read all 4 pages from the archives but did not pick up on the decimal point! I read it as 4 to 6 lbs. Is there a reason for the pressure to drop so much when shutting off the electric fuel pump? Thanks Jim...

That is very normal. If the mechanical pump is only putting out, say, 1 psi and the electric pump is putting out 5 psi and you shut off the electric pump, you are going to see a 4 psi or more drop. --