Orline Mustang trouble

[RadRacer203 1]

I picked up a pretty nice original Orline Mustang saw yesterday but I'm having a bit of a problem getting it running. It's got good compression, really good spark, and it's getting gas but it won't stay running. When I prime it with the button, it'll run for a couple seconds and die. I replaced the spark plug with a new CJ14 (gapped to .030) and the carb diaphragm. It's also leaking some gas out the bottom through what looks like a vent next to the fuel pickup. Should there be a hose coming off of that? Hopefully this picture works...

 

[Webhead 95]

Crank seals??? Please show a clear close up of the "vent".

[RadRacer203 1]

 

Here's a picture of what I think is a vent of some kind. I decided to rob the diaphragm off my running Tiny Tiger generator so that's basically new. I'm pretty certain it's not the crank seals since I didn't feel any play when I had the flywheel off, and even though it was dirty and oily, there was hardly any oil behind the flywheel.

Sorry about the bad quality of the picture, but what I was talking about is the little fitting that looks just like the fuel pickup but to the right and down from the fuel pickup

[revmix 2]

I have the same Mustang & color, that copper tubing is the vent & goes up to the top of the fuel tank, can be seen next to the fuel cap opening, maybe the needle valve needs to be adjusted or the hole cleaned [built up dust due to long storage], also the idle RPM maybe too low, when starting give it a bit throttle

Edited February 10, 2018 by revmix

[RadRacer203 1]

Yeah, I sort of suspected it might be something to do with the carb. It's really a pain to get it off and back on

[revmix 2]

the tube looks clean if gas comes through & no need to remove the tubing [mine was plugged with oily sawdust & cleaned it with wire pushed through], try to run the engine spraying fuel-mix into the carb, I always do that before getting into the carb 

Edited February 10, 2018 by revmix

[factory 487]

Did you strip & clean the carb? Sometimes the check ball valve can stick, also there is a fine mesh filter in some carbs that can get blocked (which they recommended removing if it caused trouble).

 

Is the fuel leak definitely coming from the vent pipe? If not it could be either the seal between the two tank halves, a cracked fuel line (they can go hard & brittle with age), or even the carb gaskets where it attaches to the induction housing. Also I've seen really bad corrosion on the bottom of some tanks, I have one myself where the sawdust was never cleaned off & left to cause it to rot through.

 

I can't help thinking it's better to clean the fuel line off the engine rather than pushing the crud back, be careful not the make a hole it the tank filter if unblocking it this way.

 

This probably isn't going to help if it's a fuel problem, but there is a service bulletin where they recommended changing the CJ14 spark-plug to a CJ8 as it was found to be a cause of difficult starting, see bulletin below;

 

 

Some other problems they had were; the brass grommet the starter cord goes through wearing out quickly (changed to steel for later engines), some chainsaw sprockets where found to be soft (the teeth wear into the sprocket & can cause chain to seize) and some tank caps became soft when exposed to fuel & early ones swelled making them difficult to remove.

 

David

[RadRacer203 1]

I'll try all of those things out. I just completely stripped and cleaned the carb. There was a little dust but not too much. The first thing I did when I was swapping the diaphragm was to check the ball valve, and everything seemed ok there. I've got the cj14 plug in it now so I'll switch that out. And i'm definitely going to need a new gas and oil cap. Does anyone reproduce these? Mine are both full of hairline cracks. 

[revmix 2]

you could also remove the bar & chain so no load on the gearbox, much easier testing the engine  

[RadRacer203 1]

I made sure the tank seal was intact as soon as I got it, and it seems fine. The gas cap is definitely leaky, and that's the main culprit, but there's definitely some fuel seeping out of the vent.

[revmix 2]

Quote

some fuel seeping out of the vent.

it's normal, there is no check valve on the copper tubing, a rubber duckbill can be installed on the bottom

[factory 487]

6 hours ago, RadRacer203 said:

Hopefully this picture works...

 

Is there a reason why you didn't post the pictures using the forum? I only mention this as they can disappear at any time with external sites like "photobucket" leaving the posts a bit confusing for anyone looking for help in the future.

 

Here is a note about the tank seal used in these saws from the service manual;

 

 

The manual doesn't have a picture showing the tank half with the vent pipe, is it leaking out of the vent pipe or from around the join where it fits into the tank?

 

Try asking Webhead if he has any tank caps available.

 

17 minutes ago, RadRacer203 said:

The gas cap is definitely leaky

 

There should be seals on both tank caps, check they are not split or missing.

 

David

[RadRacer203 1]

It's leaking out of the tube itself, not from the seam of the vent pipe. I assumed a little bit would be normal but it seems like more than should be normal is coming out. David, would you happen to have a full scan of the service manual? I think that would come in very handy. And I posted with photobucket because the max size on this website is less than 1mb. My pictures tend to be around 4 or 5 mb.

[revmix 2]

Quote

It's leaking out of the tube itself,

if the saw is turned sideways or nose down the fuel splashes into the tube & leaks on the bottom, no big deal, keep the machine near level

[RadRacer203 1]

Ok, I'll keep that in mind. It just seemed like there was more than there should have been coming out.

[RadRacer203 1]

After rebuilding the carb and cleaning everything out, it runs, but not well. What's a good starting point to set the jet at? I had it about 1.5 turns out and it seemed to run the same no matter where I put it. 

I think I'll take the carb off one more time and pull that little filter. I had cleaned it out but I suspect it's just not letting any fuel through.

[Wallfish 698]

If it's shutting down quickly after priming then it's not getting fuel or enough fuel. Leaking crank case seals can cause this because there isn't enough vacuum and positive pressure to make the diaphragm push enough fuel. The stiffer the diaphragm is the more pressure it takes to pulse it. This condition can also cause a poor lean running condition. There is a procedure for doing a leak down test near the end of the engine rebuild thread posted by webhead.

Leaking carb gaskets could also be an issue. Spray a little carb cleaner on them while it is running, if they are sealed you should hear no change in the rpm. If rpm does change, they're leaking.

If you are twisting that carb adjusting needle open quite a few turns and it isn't changing or flooding the engine, it's not getting enough fuel so it could be clogged somewhere or the previous stated conditions.

[Webhead 95]

2 hours ago, Wallfish said:

If it's shutting down quickly after priming then it's not getting fuel or enough fuel. Leaking crank case seals can cause this because there isn't enough vacuum and positive pressure to make the diaphragm push enough fuel. The stiffer the diaphragm is the more pressure it takes to pulse it. This condition can also cause a poor lean running condition. There is a procedure for doing a leak down test near the end of the engine rebuild thread posted by webhead.

Leaking carb gaskets could also be an issue. Spray a little carb cleaner on them while it is running, if they are sealed you should hear no change in the rpm. If rpm does change, they're leaking.

If you are twisting that carb adjusting needle open quite a few turns and it isn't changing or flooding the engine, it's not getting enough fuel so it could be clogged somewhere or the previous stated conditions.

He's alive!!!!

[RadRacer203 1]

I checked over the carb and couldn't find anything obvious, and no air leaks. I think it's probably that little filter. It's getting fuel, just not very much.

[Wallfish 698]

6 hours ago, Webhead said:

He's alive!!!!

It's been a while but still checking in every chance I get. Just haven't had any time for hobby stuff.

David seems to have a handle on answering most of the questions so by the time I check in they're already answered.

 

On 2/10/2018 at 5:59 PM, RadRacer203 said:

And i'm definitely going to need a new gas and oil cap.

Your in my area of the world. Whereabouts in MA are you? I might have some caps for you but will need to look around for them.

[RadRacer203 1]

I'm in Shrewsbury, right next to Worcester. Upon closer inspection, the oil cap is good after a coat of super glue and a new o ring, but the gas cap is beyond saving

[Wallfish 698]

There should be one around here and your close by.

On 2/10/2018 at 6:10 PM, RadRacer203 said:

there's definitely some fuel seeping out of the vent.

That happens more often when the tank is full because fuel can more easily enter the top of the tube inside the tank.

 

Another thing to check on for the lack of fuel is a clogged fuel pick up. Connect a piece of clean fuel line to the tank and try blowing through it. Air should flow fairly easy. If clogged you can try spraying carb cleaner through the tube and let it soak, spray a little more, let it soak and so on.

[RadRacer203 1]

I didn't even think to check the fuel pickup. I guess when I pull the carb off to take out that filter I'll see if it's clogged

[factory 487]

On 2/10/2018 at 11:29 PM, RadRacer203 said:

It's leaking out of the tube itself, not from the seam of the vent pipe. I assumed a little bit would be normal but it seems like more than should be normal is coming out. David, would you happen to have a full scan of the service manual? I think that would come in very handy. And I posted with photobucket because the max size on this website is less than 1mb. My pictures tend to be around 4 or 5 mb.

 

This is the problem with photobucket (google somehow manages to find the actual pictures when using image search, but that doesn't help with the original thread though), image below taken from a Drillgine thread on here;

 

 

Also the previous O&R forum got ruined as the third party image hosting it used broke removing all the pictures.

The pictures on here are hosted by the forum and presumably to keep server costs down (funded by supporters) the image sizes are keep to a more sensible size. I don't know how many mega-pixels 4-5Mb relates too but high resolution pictures aren't really needed for most things on here.

I keep the originals (i.e. high resolution pictures or PNG format scans for documents) on my PC and create a cropped/low file size version using free image editing software (1024 x 768 pixels is fine), I use IrfanView for this but others are available, some of which are probably easier to use.

 

I do have scans created from my manual, I just haven't had the time to fully edit them & create a PDF for the forum. I could probably upload the exploded parts diagram (two pages) if that would help.

 

17 hours ago, RadRacer203 said:

I'm in Shrewsbury, right next to Worcester. Upon closer inspection, the oil cap is good after a coat of super glue and a new o ring, but the gas cap is beyond saving

 

I had a quick check of the three saws that are accessible yesterday, it seems the red gas caps suffer the worst as they were exposed to fuel/gas (although one doesn't bother me as the tank is rotted through from the tree sap in the sawdust that a previous owner couldn't be bothered to clean off). I wonder if they were made from the same plastic as the deteriorating bearing cages used on the early engines.

 

David

[factory 487]

On 2/11/2018 at 5:14 PM, Wallfish said:

Leaking carb gaskets could also be an issue. Spray a little carb cleaner on them while it is running, if they are sealed you should hear no change in the rpm. If rpm does change, they're leaking.

 

Good advise, will add that check to my repair notes, I've definitely had fuel leaking from one before, just be careful not to over-tighten the carb screws as it could potentially break the casting, new gaskets are the probably best solution if they are damaged.

 

David