LX178 Won't stay running after starting

[t2rx7]

Hi,

It's been a lot of years since my last post, still have the same 1996 LX178. This year I did full maintenance, changed trans oil, coolant, new plugs, belts for the deck, shined it up like new. Then, of course, it returned the favor by starting to run poorly. Engaging the PTO would immediately kill the motor. I checked the PTO, electrically it was in spec. Found a thread about how sensative the carburators on these engines, so got a new can of carb cleaner, sprayed it in the jets and on choke plate, etc. They are a little shinier now, but they were not horrid. Ran much better, huge improvement, and I can engage the PTO and while it sounds harsh, it gets the deck going. I did lubricate the deck, sharpen/balance the blades, the whole assembly (44" pirhana mulching deck) turns quite freely. I still suspect the PTO or the charging system may have an issue.....

Anyway, my dad (has a Kubota diesel) suggested engaging the PTO at lower throttle, so I tried that, killed the motor. Fired up again, got the deck going, starting on the lawn and a few minutes in I'm smelling fuel.... Odd I thought... pulled up on the concrete, and it's leaking fuel. Shut down immediately. No further damage other than the original fuel pump failed. The replacement part has the extension hose to not dump fuel right on the muffler. Whew, coulda been a lot worse.

Put the new pump on today, and it starts right up when cool/using the choke, then after 5-10 seconds it just dies. Almost like it's not getting fuel, but I can see flow through my newly replaced fuel filter. I did both of the gaskets on the fuel pump mount, and it is a JD part from a Deere dealer.

I wonder if I could be flooding the carb now with the new pump? I wouldn't think so, but I'm somewhat stumped at the moment. If I let it sit for a bit, engage the choke, it will start right up again and run for 5-10 seconds before stopping.

Any suggestions would be helpful.

Thanks,

Greg O.

 

[tomplum]

You could test how the output is which would tell you a lot. I ran into something similar a few years back but it just isn't exactly coming to me. The added port is a vent hose so you want to know that isn't kinked or obstructed.

 

[t2rx7]

tomplum,

Thanks for the suggestions. I did just double check the vent hose, thinking maybe I zip tied it too snugly, but it was fine just loosely holding the tube where I want it. I did remove it and confirm the tube is indeed clear and not obstructed.

Not sure how else to test the fuel pump output other than to disconnect it from the carb, and run a line into a jar, which I did. Then cranked the motor for 5-10 seconds, and it pushed quite a bit of fuel, so I'm going to see if there is a flow rate spec and do a more precise measure/time.

But I'm pretty sure, the motor dying doesn't appear to be from lack of fuel, but based on me getting what appears to be a cup and a half of fuel in the jar, I'd empty my 2.5 gal tank in 10 minutes.... I'll also double check the part number, there are no numbers on the new or old pump, but they look pretty much identical except for the new one having the vent & hose. I'd have to track down a fuel pressure gauge to see if that's in spec, but if the part is correct for my engine, that seems like unnecessary at this point. Could be a bad pump, I suppose... The new fuel pump is p/n AM132715, so I guess I'll run that down first.

Thanks,

Greg O.

 

[t2rx7]

Looks like the fuel pressure should be 2.45kPa (.36 psi) so if I had a fuel pressure gauge, I could confirm that. I also found that the flow rate should be 800 mL/60 seconds at slow idle (Page 3-79 of the service manual). Not sure how I can have the engine running and capture the flow rate without something that sounds expensive. I measured what I captured, 225 mL in 10 seconds, but this is battery cranking engine flow. By my math, I'm flowing 1350 mL in 60 seconds, which I have to think is the problem.

Thoughts?

Thanks for viewing my post. Even more thanks if you can help me figure this out :thumbsup:

Greg O.

 

[tomplum]

Leave the elbow off that heads to the filter. You'll need to make up the space w/ some bushings or what have you. That way you can see if it is flooding over. I can't remember whom it was with the similar issue, or I would look them up. I remember replacing the carb and pump on separate occasions - but which one first? Someone had buggered up the main. The carbs are simple enough to clean if done with care and you will want to know that the solenoid at the base keeps retracted and you're not losing power. Float valves are replaceable if need be.

 

[Rocky J]

I just went through a like problem.Mine is a Woods 6180 with a 18 hp Briggs vanguard horizontal shaft . Starts good and idled fine, Five minutes into mowing it would start pulsing the rpms up and down . Changed filter with no luck, changed the fuel pump with no luck, left the fuel tank cap loose no luck.To get the carb off was a nightmare on this Woods mower. Looked like pull the engine out to remove the blower shroud to get the intake bolts out to get to the carb bolts from the under side of the intake. Anyway I removed the fuel hose from the gas tank and set it in a jar with 50/50 mix of sea foam and gas and let it idle until it was chugging and stinking with black smoke, shut it off came back in a hour and put the hose on the tank, started it and waited for it to clean out from the mix and has been fine the last two times I mowed. My deck engage is a trick also ,At half throttle I pull up on the pto button and when it pulls the engine down I quickly push it down and pull it back up again ,the governor seems to like the bounce and has been my best method .

 

[t2rx7]

Thanks. Given that my unit is 22 years old and I've been having the idle problem (helped immensly by carb/choke cleaner) I decided to order a new carb assembly. No local dealers have them in stock, but they can still get them. Hopefully this will resolve the issue, there isn't much else to these fuel systems. Carb is very easy to get to and remove.

I'll let y'all know how it turns out in a few days. I'll figure out what to do about the PTO engagement once it's running again

Greg O.

 

[t2rx7]

Well, new carb arrived yesterday, installed it today. Actually pretty easy job, but could use one more elbow in my arm to get at those connecting rods and springs......Running like new and holds idle at all throttle settings. Best it's run in years.

Thanks to everyone that has looked at my post, and to the suggestions. Throwing parts at a problem willy-nilly isn't always a good answer, but changing the fuel pump wasn't an option, it just wore out. While carb cleaner helped some, I wasn't confident removing the carb and trying to clean it was the best use of my time, and a new carb really wasn't outrageous in cost. So it was the right approach for me.

Call this one case closed.

Thanks,

Greg O.