Hard Start B&S 15hp industrial

711 Views 11 Replies 8 Participants Last post by Tom-machinery-idiot, Aug 30, 2015

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Discussion Starter · Aug 29, 2015

Hi,

I own an old Scotts S1742 which I repowered with a B&S 15hp. It is not an Intek, it's an old Commercial & Industrial which came out of a Troybilt. The engine started and ran fine before I removed it from the Troybilt. Now that it is in my Scotts, it is hard to start. The engine needs to crank for about 30 seconds before the first ignition, and then another 30-45 seconds of cranking with intermittent sputtering before it will stay running. I need to start it at low idle, let it warm up for about 30 seconds, and then slowly bring the throttle up to operational speed.

- I tried adjusting/tightening the valves, it has made no difference.
- I tried tweaking the carburetor a few times. It is currently tuned well, but I have it running a smidgen on the rich side just to keep the engine from burning up.
- The choke is useless. If I try to use the choke, the engine simply will not start. I just leave the choke off.
- I believe the carb is the one which came with the engine, although I can't recall since I did the swap over a year ago.
- The troybilt had a choke which was separate from the throttle. The scotts had one of those setups where you could choke it by pushing the throttle all the way up. I couldn't really get it to work the same after swapping, so I installed a separate choke cable and lever, which I bolted onto the side of the steering column.

Once the engine is running, it runs very well. If the engine stalls while hot (e.g., running out of gas), then I have to set the idle low again to make it start, but it does not need to crank a lot like when it is cold.

Any ideas?

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Discussion Starter · #5 · Aug 29, 2015

The engine used to have a fuel pump which ran off of the crankcase breather. I removed it because the Scotts is gravity fed. That is something which actually made me wonder, but I didn't think it would matter to the engine, because the fuel tank setup seemed to be the main reason for the pump. The Scotts has an elevated tank which is directly behind the engine, the Troybilt had a tank under the seat which was level to the engine, hence the need for a little pump.

I have drained the fuel tank a few times now for different reasons, and it has a good flow. I will try taking the fuel filter off, though, to see if that will make a difference.

The carb was cleaned before the engine swap, and the starting issues began immediately. I don't think it is a dirty carb.

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Discussion Starter · #7 · Aug 29, 2015

I am fairly certain that the pump is long gone. I have a bunch of parts sitting around, but I'm not about to start digging through them just to fix a hard start. After all is said and done, the mower runs well and does what it is supposed to do; this issue is low on my list, it's just a nuisance and not a serious problem.

All of your suggestions regarding the fuel line are intriguing though. The fuel filter is new, I put it in about a year ago. Now that you mention it though, I've seen crap at the bottom of the fuel tank from time to time, like little dead spiders and various bits of small debris.... the opening for the fuel out is very small, about 1/8", I wonder if something could have made its way into there and started messing things up.

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Discussion Starter · #9 · Aug 29, 2015

I am thinking that it is indeed a fuel delivery issue, because when it first starts, the engine putters very weakly for about 15-30 seconds, and then it suddenly starts to rev up. You guys are probably right, the engine is fuel starved and has trouble drawing fuel until the carburetor has generated enough vacuum.

Perhaps if I could implement a primer bulb....

Part of me wants to say that I swapped the Scotts carburetor onto it, though. So it should have a setup for gravity feed already.

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Discussion Starter · #11 · Aug 30, 2015

OK,

I will take the air housing off and verify if the choke is closing fully.

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