Fuel pump?

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Matthew denton
Posts: 18
Joined: Thu Sep 12, 2019 6:43 pm
Vintage Karting items owned: Maybe a 1970 margay pro x
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Fuel pump?

Post by Matthew denton » Wed Sep 18, 2019 1:25 pm

Does my margay pro x with a mc101 need a fuel pump? I can’t get the fuel to “syphon” to the carb. The engine does fire up with sprayed into carb. What am I missing?

Rob Voska
Posts: 1460
Joined: Fri Jun 15, 2007 9:04 am

Re: Fuel pump?

Post by Rob Voska » Wed Sep 18, 2019 4:53 pm

Stuck needle in the carb?
Carb kit old and hard?
Do you know the condition it was in when put away so long ago? A stuck engine will not pulse a carb.
Are the reeds stuck open?

What kind of carb is it?

Also if it has been sitting DO NOT START IT UP.
First take the stuffer off and wash engine out with a solvent. Be sure to soak the rod needles, main bearings and piston bearings very well. All you know at this point is it has spark.
Turn it over a few times by hand and do it again and then again.
Then pressure check it if you have to tools.
The carb should really be rebuilt before attempting to start it.
Remember it's been sitting for a long time and you can ruin things quickly not knowing what you are doing.
Are you prepared to shut it down if it has an air leak? Do you know what an air leak is?

There are a of things to check before trying to start it so you do not do any damage.

Matthew denton
Posts: 18
Joined: Thu Sep 12, 2019 6:43 pm
Vintage Karting items owned: Maybe a 1970 margay pro x
User Agreement: Yes

Re: Fuel pump?

Post by Matthew denton » Wed Sep 18, 2019 5:58 pm

Thanks ROb for the reply,

I got the engine with the kart not knowing anything about the kart, the owner did say the engine was completely rebuilt, and never ran, I took out the plug and removed the exhaust and it literally has a fresh hone on the walls and piston looks brand new. I do not know what a air leak is? What is it? Should I take this engine apart anyways? Also did these engines need a pulse fuel pump externally or no? Thanks for input!!

ted johnson
Posts: 1470
Joined: Fri Jun 15, 2007 7:59 am

Re: Fuel pump?

Post by ted johnson » Wed Sep 18, 2019 7:01 pm

An air leak is exactly what it sounds like. A bad crank seal, or any gasket that allows the smallest amount of air to leak past the seal. Air leaks in two cycle engines are certain death, as they cause the engine to run "lean" (too much air, not enough fuel/lubrication). A severe air leak can cause the engine to "run away" until it seizes from lack of lube. An air leak in the fuel tract, or a bad diaphragm in the carb can cause the carb to fail to pump fuel. Of course, this means the engine will not start. EC Carburetors in Dickson, Tennessee has kits for all Tillotson carbs, and as for the big Mac Walbro carbs, the guys on this forum can help with parts. If the carb is a diaphragm type unit (no float), it should need no external pump. Photos would help! Ted

Matthew denton
Posts: 18
Joined: Thu Sep 12, 2019 6:43 pm
Vintage Karting items owned: Maybe a 1970 margay pro x
User Agreement: Yes

Re: Fuel pump?

Post by Matthew denton » Fri Sep 20, 2019 11:42 am

Took apart carb and this is what I found.
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Rob Voska
Posts: 1460
Joined: Fri Jun 15, 2007 9:04 am

Re: Fuel pump?

Post by Rob Voska » Fri Sep 20, 2019 4:56 pm

Is the diaphragm soft & pliable? Duckbill? Did you take the head off and check the cylinder to see if it's stuck? Did you move the top of the piston around and see if the rings are stuck in the piston?

Put a good coat of oil on every gasket before putting it back together.

See how dry that carb is? The inside of that engine is just as dry! Do things right before you damage anything. A 2 cycle engine gets it's fuel through lubrication and it dried out long ago. When it dries it leaves behind oil residue that turns to glue over time. Bearings won't turn they will skid and damage them. That is why my other post tells you to soak things before trying to start.

Matthew denton
Posts: 18
Joined: Thu Sep 12, 2019 6:43 pm
Vintage Karting items owned: Maybe a 1970 margay pro x
User Agreement: Yes

Re: Fuel pump?

Post by Matthew denton » Fri Sep 20, 2019 6:36 pm

Hi.

The diaphragm seems like it’s really soft and supple, almost looks new but old. If that makes sense. I’m in the process of taking it apart further and checking the bearing, I don’t want to ruin this engine! I’ll keep u updated. As far as a rebuild kit, I’d like to purchase new seals if possible, would u be able to point me in the right direction?

Thanks again

Rob Voska
Posts: 1460
Joined: Fri Jun 15, 2007 9:04 am

Re: Fuel pump?

Post by Rob Voska » Sat Sep 21, 2019 7:15 am

Tip of the Month

This month’s tip is for you guys doing your own rebuilds. I get asked all the time where can I get seals for my engine. If you don’t want to use seals that have been sitting around in the bottom of a box for 30-40 years here’s where I have been getting mine. If what you need is not listed here if you take a crank and block with you they can measure what you need and set you up. I have used these seals for both Gas and Alky without any problems.

I get my seals at NAPA! Now how easy is that? They carry Chicago Rawhide seals and can get them in a day. This is the number on the box and if what you need here is not listed this will get up into the right family of seals. It’s a lot easier than telling some parts guy that you need a seal for 12,000 RPM with Alky fuel. It saves both you and him a lot of head scratching.

#9243 ¾” PTO seals for both 100 and 125cc Mac’s.

#6816 is the PTO seal for 92,93 & 101 engines.

#7421 is the 101 dust shield.

#7414 is the seal for the inner 101 and both sides of a 91 series engine.

Matthew denton
Posts: 18
Joined: Thu Sep 12, 2019 6:43 pm
Vintage Karting items owned: Maybe a 1970 margay pro x
User Agreement: Yes

Re: Fuel pump?

Post by Matthew denton » Sat Sep 21, 2019 12:50 pm

Hey rob. Thanks for the info! Helps a lot, Just got done tearing this engine apart. The inside looks new. Like “rebuilt” new. The bearing were still lubricated and the needle bearing on the rod was even lubed still. I did take your advise and soak everything anyways. Here’s a quick pic of the piston and sleeve. I’m amazed by how clean this thing is. I nor the gentlemen I purchased this kart/engine from had no info other then he got it from a storage auction.
Attachments
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Matthew denton
Posts: 18
Joined: Thu Sep 12, 2019 6:43 pm
Vintage Karting items owned: Maybe a 1970 margay pro x
User Agreement: Yes

Re: Fuel pump?

Post by Matthew denton » Sat Sep 21, 2019 12:51 pm

Cylinder
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