1980 spitfire won't stay running

KawiSpitfiretony · Post by **KawiSpitfiretony** » Mon Jan 18, 2016 3:07 pm

Hello everyone I'm new to this site I was recommended by a guy riding on the trails said if I had any issues come to this forum
I bought a 1980 spitfire 340

I've always owned skidoos and decided to have spare sled for the gf or friends

So far I've done
-plugs
-new wires spliced from the coil
-cleaned carb
-new crank seals
-rebuilt fuel pump with new lines

Took it out for the first time since I did all the work to it and it was running okay had a low end bog I thought it was normal cuz it's old and kinda slow compared to my 800 rev

Than after it got hot from riding it would just die almost like it was ignition stopping it didn't feel like a fuel issue

I unplugged the kill switch and it did the same thing

It would only start when I let the engine cool down and it would still be hard to start! It's getting spark and it had good compression

I can't find any cdi"s for this machine only for the older spitfire with the other engine

Thanks guys

Sent from my iPhone using Tapatalk

KawiSpitfiretony · Post by **KawiSpitfiretony** » Mon Jan 18, 2016 3:36 pm

https://vimeo.com/152196367
Not sure if this is normal just noticed this now coming from the pulse line

Sent from my iPhone using Tapatalk

AirborneX4Special · Post by **AirborneX4Special** » Mon Jan 18, 2016 4:50 pm

There shouldn't be any fuel in the pulse line. Carb float setting could be incorrect or the inlet needle is not sealing properly, overloading the mixing bowl and then into the crankcase. Shut off the ignition switch, take the impulse line off the crankcase, and pull the recoil to see if fuel is in the case. Can also be a bad pump letting fuel bleed into crankcase, just pull the impulse line and see if it leaks fuel before you do anything else.

KawiSpitfiretony · Post by **KawiSpitfiretony** » Mon Jan 18, 2016 4:57 pm

Someone told me that I shouldn't of used clear line on the pulse line cuz it can collapse at high rpm kinda makes sense cuz the old line I removed was pretty thick black automotive line

Sent from my iPhone using Tapatalk

KawiSpitfiretony · Post by **KawiSpitfiretony** » Mon Jan 18, 2016 5:15 pm

AirborneX4Special wrote:There shouldn't be any fuel in the pulse line. Carb float setting could be incorrect or the inlet needle is not sealing properly, overloading the mixing bowl and then into the crankcase. Shut off the ignition switch, take the impulse line off the crankcase, and pull the recoil to see if fuel is in the case. Can also be a bad pump letting fuel bleed into crankcase, just pull the impulse line and see if it leaks fuel before you do anything else.

I pulled off the line and crank it over a acouple sprays off gas came out not like a full blown spray but I saw some fly out and the impulse line was rock hard already it's only like a week old

Sent from my iPhone using Tapatalk

AirborneX4Special · Post by **AirborneX4Special** » Mon Jan 18, 2016 6:50 pm

Typically the impulse line is similar to heater hose. There shouldn't be any fuel in the case, so it's flooding somehow.

harleysportster · Post by **harleysportster** » Mon Jan 18, 2016 9:14 pm

More than likely the fuel pump diaphram is leaking, needing replaced.

Sent from my XT1080 using Tapatalk

KawiSpitfiretony · Post by **KawiSpitfiretony** » Mon Jan 18, 2016 9:33 pm

harleysportster wrote:More than likely the fuel pump diaphram is leaking, needing replaced.

Sent from my XT1080 using Tapatalk

I rebuilt the fuel pump already and tested it and found no leaks

Sent from my iPhone using Tapatalk

KawiSpitfiretony · Post by **KawiSpitfiretony** » Mon Jan 18, 2016 10:45 pm

Im going to try and pull the carb off and inspect the inside and also drain the crankcase and change the pulse line

Sent from my iPhone using Tapatalk

JDT · Post by **JDT** » Tue Jan 19, 2016 12:06 pm

I always use clear line of the impulse.
How else can you look at it and see if you have a problem.

I am with Pat that you have a fuel pump issue.

KawiSpitfiretony · Post by **KawiSpitfiretony** » Tue Jan 19, 2016 12:25 pm

JDT wrote:I always use clear line of the impulse.
How else can you look at it and see if you have a problem.

I am with Pat that you have a fuel pump issue.

The original clear hose that was on it was a lot thicker than the small fuel clear hose I put on it

And I tested the fuel pump the fuel came from the engine side into the hose not the pump

Sent from my iPhone using Tapatalk

AirborneX4Special · Post by **AirborneX4Special** » Tue Jan 19, 2016 1:10 pm

The fuel, if there is any, will move out of the crankcase and into the pump the way it did because that's the source of impulse that runs the pump. What you need to decide is how the fuel is getting into the crankcase. It's either through the pump via a back feed when it's not running, especially when the tank is full, or through the carb. You've rebuilt the pump but sometimes the rebuild kits can be an issue.

sledhead16 · Post by **sledhead16** » Wed Jan 20, 2016 11:25 am

I only use thick wall 1/4" black fuel hose on the impulse to prevent collapse and fuel starvation and lean running. I'd recommend trying that first, then move to the carb. New carb parts are essential i.e. needle and seat, clean jets, float bowl gasket and all set properly. Genuine mikuni is preferred

KawiSpitfiretony · Post by **KawiSpitfiretony** » Wed Jan 20, 2016 11:45 am

sledhead16 wrote:I only use thick wall 1/4" black fuel hose on the impulse to prevent collapse and fuel starvation and lean running. I'd recommend trying that first, then move to the carb. New carb parts are essential i.e. needle and seat, clean jets, float bowl gasket and all set properly. Genuine mikuni is preferred

Ya one of my friends said they had the same thing with the clear fuel hose collapsing on him so I'll try a new fuel line

And I can't find anything for a the butterfly mikuni carb

Sent from my iPhone using Tapatalk

sledhead16 · Post by **sledhead16** » Wed Jan 20, 2016 12:00 pm

Switch it to a mikuni slide carb, easier to deal with imo