LT1046 won’t start

[LKB]

Greetings:

I have a fairly old LT1046 that’s been dependable over the years; it could sit for months (with a float charger on the battery), and it usually would start right up. Last year, it started running rough and having some starting issues, which I solved by replacing the carb, filters, spark plugs, etc.

Recently, however, it will not start at all. (Using starting fluid will get it to run for a couple of seconds, so it’s getting spark.) Have replaced the fuel filter and fuel pump, and can see that when cranked, fuel is getting sucked into the filter. Have replaced the carb. Have removed the spring from the anti-backfire solenoid (just to see if that might be the issue). No dice — it seems like no gas is reaching the carb. Checked fuel line from fuel pump to carb — it’s clear but did not smell of gas. (I use ethanol free gas in it.)

ideas?

 

[LKB]

Further details: disconnected the fuel out line from fuel pump and cranked the engine. Fuel flowed to the fuel filter but not out of the fuel pump. Ergo, that’s the source of the problem.

Checked vacuum line from engine; it’s clear and sound.

ideas? I’ve seen some suggestions online to just replace the impulse pump with an electric one.

 

[Forest#2]

You say:
I’ve seen some suggestions online to just replace the impulse pump with an electric one.

You say it's been dependable for years.
Why not just replace the impulse pump and be done with it.
Impulse pumps are cheap and dependable.

A good electric pump is going to be costly and it HAS TO BE A VERY LOW PRESSURE type and the good ones are about $75. (low pressure - not over 2 lbs and 1/2 pound even better. Electric Ok on automotive but not small engines lawn tractor types)

Sure you can maybe find a $20 China type fuel pump but you are just asking for trouble.

 

[LKB]

Thanks. I’d replaced the old fuel pump (which clearly wasn’t working at all) with one that came with the carb/plugs/filter kit I bought from Amazon. Replacement pump was able to suck fuel into the filter, but apparently did not have enough oomph to suck it up another vertical foot to the pump body.

In doing some further research, apparently these “4 bolt” Chinesium fuel pumps are crap. I’ll try one from a reputable source before trying electric.

 

[StarTech]

It would not hurt to check the fuel line coming from the fuel tank. In recent years I have seen several fuel line with inner liners coming apart and be blocking the fuel flow when a vacuum is applied to the line.

Also make sure no trash is blocking the fuel outlet of the tank.

 

[Forest#2]

Take the fuel cap off and blow back through the fuel line into the tank of use not over 5 psi air pressure. (be sure and remove the fuel cap because some cap do not vent pressure backwards, they only allow vent inward)
As star Tech says sometimes a restriction or blockage in the fuel supply will prevent the suction type pulse pump from pumping.
If it starts pumping gas after you do the back flush you need to remove the tank, (because you sent the trash back into the tank) clean the inside and replace the fuel lines. (not a fun job if the tank is the rear mount, but just have to get er dun.
Make sure the pulse hose is not cracked and if the type that fits into a OHV valve cover the hose can be pushed in to far and not get a pulse.
The fuel pump pulse hose has to also leave the pulse source going Up, if the pulse hose goes down too soon it will get full of oil and not get the crankcase pulse due to the oil block.

 

[TiIngot]

Can you hook up a temporary fuel tank with a new hose to the carburetor and gravity feed the gas to see if it starts? This will bypass the fuel tank, hoses, filter and pump to determine if you are looking in the right area.

 

[LKB]

Good ideas folks, thanks. Will try the compressed air trick and see how that works.

 

[LKB]

Unfortunately, blowing out the fuel line with compressed air didn’t solve the problem. Cranking the engine sucks fuel into the filter, but still not enough to reach the pump. But I have a sneaking suspicion that there’s some crap in the gas tank — I replaced the gas cap a few months ago because it had degraded, and some of it might well have dropped into the tank.

If I have to pull the gas tank, anyone know of a good YT video that walks you through the steps? Or is there a way to clean / flush the tank en situ?

 

[Forest#2]

You might post up the complete LT1046 model number.
Some LT tanks are behind the engine and in front of the dash and have to loosen/remove the upper dash. Little easier than the rear mounted tank under the fenders.

I've found videos for such, but sometimes had to watch several because none was exact.
You say it will suck fuel to the filter but not past the filter into the pump.
I would think about checking for a vacuum leak past the fuel filter.
I have a vacuum pump and could crimp off the line on the tank side of the filter then either pressure test or vac test.
Or maybe run another fuel line from the pulse pump to a cannister setting on the floor below the pump and see if the pump will pump fuel from the low test tank supply. (you are using another fuel supply source and another fuel line.
Do not use your fuel filter. I've seen cracks in top of fuel filters, cracks in fuel lines and fuel lines that collasp inside and get all sorts of weird results and no external signs of gas leakage.