way to test the carbs? vaccum?

[hookdonspeed]

helped a friend rebuild his carbs the other day, the one carb's fuel inlet was 100% blocked (non fuelpump carb), he took it to a local PWC shop and they "fixed" it for him, got it all back together, starts and ran find on land, started and ran fine in the water for about 10minutes, then cut off again and wont start back up...

is there a way to test to see if the fuel lines are blocked without having to pull the carbs off and disassemble again?



its a 2001 sportster with a 951, non DI obviously.

 

[Waterluvr]

Yea, that's easy to do just remove the fuel supply line from the carb and attach a brake bleeder hand vacuum pump with an inline recovery cannister and introduce vacuum to the supply line. You should have gas flowing into your recovery cannister right away and be sure to test the fuel selector valve next to the helm seat for proper function in the primary/off/reserve positions.

You should get fuel flowing from the primary and reserve and nothing when it's switched to off, also if there's trash in the line you'll see it accumulating in the recovery cannister, 10 minutes of high speed operation with fuel lines full of garbage is just about right to choke out the small internal carb filters and shut it down again.

 

[hookdonspeed]

sweet, ill have a vac pump somewhere around here, easy enough check!

as for the lines, we just replaced the lines, and added a second in-line filter just before the carbs, so *shouldn't* have been anyway for anything to get into them.

edit: wait.... we want to test the carb inlet itself, not the line from the fuel tank.

the "plate" that bolts to the carb with the barbed fitting is what was clogged.

 

[Waterluvr]

Good idea on the second filter, those selector valves are known to fail internally and cause issues. Just replace it if it's messed up, they are actually pretty cheap cost wise.

 

[hookdonspeed]

edit made to my previous post... it was the "plate" we need to test, the one that covers the internal filter, thats what was clogged up before.

 

[grinditout]

Mix gas in spray bottle, pull flame arrestor, spray in carbs, should start.

 

[hookdonspeed]

yea, i know that, but is there a way to test that port without pulling the carb??

 

[Waterluvr]

yea, i know that, but is there a way to test that port without pulling the carb??

That carb needs two things to work, fuel supply and pump impulse line in good working order. Start there first.

Do yourself a favor and try the supply line test I suggested. It only takes a couple minutes and you need to isolate that part of the fuel system as working or not to diagnose your problem doing anything else is putting the cart out in front of the horse.

If all is well, check the impulse line to the fuel pump for any air leaks pull it off and see if it holds vacuum and if that isn't the problem then pull that carb back off.

 

[hookdonspeed]

holds vac on the pump side i assume?

 

[Waterluvr]

holds vac on the pump side i assume?

What I want you to do is remove the impulse line from the motor case and carb and pull a vacuum on it using a T and two nipples in each end of the line to verify hose integrity. The slightest leak from an over tightened clamp having split the line and your fuel pump won't work.

You've already been into the carbs with no results, it's time to find out why.

 

[hookdonspeed]

oh, the carbs were bad, hadnt been done in years, filters were clogged, and like i said the feed tube on the 1 pump was 100% clogged.
be a few days but ill get to his boat and check the lines for vac leaks. pulse line is brandnew, but coulda split when installing it i suppose.

 

[Sportster-2001-951C-Stock]

Trash in your fuel system is a common issue.

http://www.passagemaker.com/channels/a-rube-goldberg-solution-for-dirty-fuel-tanks/

 

[Waterluvr]

Trash in your fuel system is a common issue.

http://www.passagemaker.com/channels/a-rube-goldberg-solution-for-dirty-fuel-tanks/

It really is, and after the ten minutes they ran the motor on the rebuilt carbs I suspect it's full of garbage again. Just about every time I hook my Mity Vac and a recovery cannister up to a fuel line that's suspect I get all manner of trash back into the cannister.

I suspect their impulse line is just fine but the 30 seconds of time it takes to check it isn't worth leaving it out of the diagnosis.

My 2 cents are they find the guts of the fuel selector seals coming apart and into the fuel line back to the carb.

 

[Sportster-2001-951C-Stock]

Correct! That article is such a classic though, right down to mentioning galvanic corrosion caused by the incompatibilities between metals.

 

[Waterluvr]

Correct! That article is such a classic though, right down to mentioning galvanic corrosion caused by the incompatibilities between metals.

I made two fuel polishers some years ago, one for diesel and one for gasoline both of them consisted of a series of enormous Racor sight filters that would handle anything from sediment to pure water and 12 VDC fuel pumps mounted to Radio Flyer wagons so they could be used dockside. I did in fact have to replace the wheels on those wagons more than once from being used nearly non stop.

That Passagemaker article is classic and I have a couple sets of SBN Mikunis on my bench from people that destroyed the screws attempting to take them apart. Galvanic issues from stainless fasteners and aluminum threads are a joy to fix after someone strips the heads clean off.

Classic example of Japanese Industrial Standard fasteners meet manky old boat bilge, I retired a few years ago and have no idea why I keep messing with this stuff